Ritchey–Chrétien enjoyers thread

[bleak solar]

I screw them in after setting everything up and rotating the camera 👍

But tape is a better idea 😅

[harsh matrix]

good

[stiff mason]

Or what is stopping us amateurs from using mask interferometry to achieve diffraction limited results even in the most turbulent of atmospheres

[harsh matrix]

Cost probably

[crisp flower]

@slate falcon im able to make adjustments tonight
U dont know by which amount i roughly have to adjust the secondarys Position do u?

[slate falcon]

try a quarter of a mm first

[crisp flower]

Alr tyyyyyy

[tight lodge]

Very uncommon. They are extremely hard to control

[slate falcon]

ah

[tight lodge]

With phased array antennas you don't measure how much signal each element receives... but rather, when you receive it

[slate falcon]

ah

[frosty shard]

I find myself starting on all sorts of targets too late tbh

I kinda want to just get started on the Eagle Nebula now

[harsh matrix]

I would

Thats why I played with M17

Im going to shoot it once the weather clears out

[frosty shard]

You also have 10 degrees of extra altitude to work with for the Milky Way core targets compared to me.

[tight lodge]

Juicy🤤

[slate falcon]

🤤 🤤 🤤 🤤 🤤 🤤 🤤

[haughty steppe]

Looks like a LOT of flex to me

[frosty shard]

Is this the framing I go for...probably

[haughty steppe]

personally id do 3x2

[frosty shard]

I'd like to but I don't think I have the time for that

[harsh matrix]

Even more of a reason to start on M16 now

[harsh matrix]

I doubt you have time to do this much

[frosty shard]

the 3x1?

[harsh matrix]

Yeah

At least if your goal is to do more than 1 hour per panel.

If you want an incredible image, it needs to be deep, not just wide.

Part of the reason mine is so insane is that I put almost 30 hours of exposure into the same exact spot.

I didnt split it up

[frosty shard]

I'm aiming for 18 hours total: 6 hours per panel, 2 hours per channel (though the ratio may change)

But also I'll probably do it one panel at a time so I can just dump more integration into a single panel if it seems to be the better option

[harsh matrix]

Id probably focus on a single panel at a time if youre content on a mosaic.

Dont forget that the wildfires will start up as soon as the season changes and you will be under wildfire smoke lockdown until the Fall.

That's ignoring the short nights.

[frosty shard]

Oh yeah, I'm very aware of this... it's gonna be joever any day now

But the good thing is I'll have a ton of free time on my hands when I graduate

so I can actually take advantage of pretty much any clear night until mid-August

[frosty shard]

What optics/camera?

[harsh matrix]

As long as you are aware

You get it far worse than I do down here

[frosty shard]

@harsh matrix PrimaLuceLab is cancelled.

This genuinely looks rigged lol

and/or someone used a laser to collimate

https://www.primalucelab.com/blog/celestron-edgehd-un-telescopio-versatile-molte-applicazioni-versatile-telescope-many-applications/

[harsh matrix]

Ew

That doesn't look accurate at all

If thats supposed to be a central obstruction comparison, that's not even what id consider to be valid.

Looks like drastically different conditions or really bad collimation for the RC

[harsh matrix]

imma play with real decon once again using my M33 lum

@frosty shard what function would you say is best at approximating the PSF of an RC again?

nvm it auto selected Moffat

lol

this is the average PSF for my M33 lum

also the decon isnt messing with the noise all that much

im surprised

actually not enhancing noise at all with a mask

it's certainly an improvement

is it as good as blurx

i dunno

[waxen mountain]

What do you use for stacking?

[frosty shard]

What's the kernel size you're using?

[harsh matrix]

wavelets 👀

[harsh matrix]

i dont know

didnt look

uh

I think Pixinsight automatically determined one

what i will say is decon did do an overall pretty good job

[frosty shard]

I can just measure it from the image you sent once I'm at my PC

This data was taken with the reducer right?

[harsh matrix]

yeah

0.72"/px roughly

honestly ngl

judging by the decon results from pixinsight's built in decon tool, I am willing to buy into the blurx using this tool to the maximum theory

you definitely can sharpen the object without sharpening the noise

takes good data to pull it off though

[frosty flicker]

Russell Croman donated over a million dollars to scientology

[harsh matrix]

wavelets actually do a pretty good job too

[harsh matrix]

we knooooowwwww

[frosty flicker]

hey guys did you know Russell Croman donated over a million dollars to scientology?

[frosty shard]

You can attempt to recover a PSF if you have the original image and its deconvolved version I think?

[harsh matrix]

https://tenor.com/view/shock-shocker-shocked-black-guy-gif-27526370

[harsh matrix]

interesting

now im tempted to try that

i closed the PSF i had though

😭

that one was the average for the whole image btw

im surprised it was basically the ideal PSF

[frosty shard]

Idk if PixInsight is using the damped Richardson–Lucy method used by the HST team. I know SIRIL isn't (there's an open issue for it)

The damped version can limit noise amplification

[harsh matrix]

the only thing this decon doesnt do is round out stars in the corners but that's likely due to it running with a generalized PSF on the entire image, not on a small segment

[harsh matrix]

it is using regularized richardson-lucy

[frosty shard]

That's not the damped version

[harsh matrix]

ik

but it answers your question

damped is not an option

[frosty shard]

In principle you could use a spatially varying PSF for Richardson–Lucy

The reason it's not done is because it takes a lot more computational power (you can't use FFTs to do it)

But I don't think it's actually an unreasonable amount

So you could use a different implementation to correct aberrations

[harsh matrix]

wavelets kind of accomplishes the same thing as bx's nonstellar sharpening

[harsh matrix]

[harsh matrix]

true

[frosty shard]

I want to write code for that, as well as a method that will use the PSF uncertainties/pixel standard errors to quantity the noise amplification

[harsh matrix]

well the program would need a way to iterate on its own right?

it would have to know what PSF corresponds to what part of the image and when to move on to the next segment, where that segment is, etc.

it cant all be user defined

since making masks like that is virtually impossible outside of photoshop or something

[frosty shard]

The idea is that you could have a model that corresponds to the PSF for your telescope using various contributions (seeing, collimation error, tilt, diffraction, aberration)

Then you can use that and your star shapes to define a PSF for each pixel in the image

Then you perform deconvolution with the modeled, spatially varying PSF

[harsh matrix]

👀

[frosty shard]

There is genuinely so much information we are leaving on the table in astrophotographic image processing, it's not even funny

Like it's hilarious to me that we use denoisers which operate on an image stack

Stacking throws out so much useful information

[frosty shard]

So I step outside to have a look outside and see if it cleared up

And guess what I found

The Ronchi eyepiece I ordered

[harsh matrix]

Interesting

[harsh matrix]

Yeah

[bleak solar]

Nah not really. Since most is screwed in it is quite rigid and does not bend that easily in total

[slate falcon]

idk its just stuff

[stiff mason]

You can literally 3d print it altho i think the software might need money idk

[stiff mason]

No

Also what are the limitations of deconvolution like can it only sharpen details that were already there or can it like bring a fully defocused star back into focus after the image was taken assuming you know the psf

[frosty shard]

Do you know what the modulation transfer function is?

And what it represents

[stiff mason]

No to both

[frosty shard]

This is one of the most important concepts in all of imaging honestly and it's a good thing to know about if you want to understand what makes an image good

The usual way we approach images is as a set of pixel values over space

But another, very useful way of thinking of them is as a sum of waves

Your lowest (zero) frequency wave is basically just the average of the image

Then the next lowest is a sine wave that goes through one full cycle along a particular image length

and so on and so forth, up until the highest frequency waves, which are determined by the pixel scale

When we think about the resolution of an optical system, we are basically asking the question of what the highest frequency wave is that it can still capture

The modulation transfer function (a, d) is just the Fourier transform of the point spread function (b, e)

The top one is an idealized MTF for a perfect lens, the bottom one is the MTF for an imperfect/aberrated lens

[stiff mason]

Makes sense

[frosty shard]

For real optical systems we use, the MTF decreases smoothly as the spatial frequency increases, so finer details tend to blur together a bit more

Eventually the MTF becomes zero, and that corresponds to detail that is beyond the resolution of the optical system

@stiff mason what deconvolution does is essentially reshape the effective MTF of the image so that the higher frequency components that are suppressed/blurred together are made more distinct

It rescales the MTF at every possible frequency

Though because it rescales the MTF, it it's zero at a particular frequency, deconvolution cannot restore that detail

[slate falcon]

what does an ablated lens look like

[frosty shard]

Frosted glass

[slate falcon]

what would the mtf look like

[frosty shard]

crap

[stiff mason]

Oh okay so if this image was an out of focus star the MTF would be compressed to the left effectively removing all the higher frequency data completely how would the MTF look for a blury star caused by the atmosphere

[frosty shard]

Well, to be clear, the MTF is independent of the contents of the image, it's determined by the optical system

[slate falcon]

i want evidence

i just remembered i have a frosted lens

[frosty shard]

To get the MTF you can just take the Fourier transform of a PSF

From your image

But your intuition is correct, the MTF would fall off much harder if the system is out of focus

[stiff mason]

How would the mtf of blurry point source look I'm guessing it will be similar to that of an out of focus point source

Assuming perfect symmetrical blurring

[frosty shard]

It's highly dependent on the details of how the blurring occurs actually

Some types of blurring are irreversibly destructive to image data and others are not

I think technically defocus can be undone with deconvolution, but you need a lot of data to fix it without blowing up noise in your image

Gaussian blurs are entirely reversible

[slate falcon]

it is yea

[stiff mason]

What kind of data

[slate falcon]

weiner is especially good for it

[frosty shard]

Just more exposures/image data when you're stacking, though at that point just refocus your scope and retake the data

[stiff mason]

But what if you had the exact data of how the blur occurred and by how much

Ig that wouldnt really matter since the deconvolution will still try to deconvolute the noise as well and thus increase it

[frosty shard]

Yes, exactly. In practice, we do have the blur data with stars, but the problem is that if image data of a certain frequency is suppressed enough, it can blend into the image's noise

So when you amplify that component you also amplify noise

[stiff mason]

Is there a way to avoid that other than to have higher snr

[frosty shard]

Nah not really

though this is why higher SNR can be achieved by getting your scope in collimation

[stiff mason]

So it would be far better and easier to just use an aperture mask instead

If you want to remove atmospheric blur

[stiff mason]

Because an aperture mask (multi array sparce mask) cuts your light gathering down to 20% and with a 16 inch telescope it would be like having the light gathering of a 7 inch telescope altho at f14

F16*

[stiff mason]

Okay hear me out what if you had perfect knowledge of the gaussian blur could you perhaps use that to help the software ignore the noise and only focus on sharpening the actual data because it knows exactly where all the missing data went and how much of it and will ignore everything else

[frosty shard]

Well, I have an idea regarding this that I'd like to implement in software.

The idea being that you can extract higher order statistics from a set of raw frames

i.e. not just the mean we use to make the stack, but the standard deviation and standard error in the mean

If you have all that information, you can propagate it in a deconvolution operation and get error bounds on pixel values

Then you can denoise way more effectively by smoothly interpolating between the error bounds

[stiff mason]

Uhh can you dumb it down a little cause I'm still new to the world of deconvolution

[frosty shard]

I will have to dumb it down later because I have gotten Tired™

[stiff mason]

Yeah me too i need to go to bed cause it's 1:40am

[frosty shard]

yeah it's 3:50 here

[stiff mason]

Damn

[bleak solar]

Which screws do I need to loosen in order to attach my Baffle extension?

The large ones or the hexagonal ones?

[slate falcon]

eepy

[sinful sapphire]

@frosty shard I suggested LOic to do a small RC, they replied with:
„Small RCs are just not worth doing. They are expensive to manufacture and glass elements will be used anyway 70% of the time, making it pointless. I will only ever make 12“ or bigger RCs, because then you have a properly corrected image circle that’s large enough with just reflective elements.“

[slate falcon]

meanwile the 6" can use apsc at native fl

[harsh matrix]

[harsh matrix]

It isnt corrected well

[slate falcon]

slightly elongated :(

[frosty shard]

To which I say "your mom is just not worth doing"

[sinful sapphire]

but

he did say he understands the appeal of a pure reflector

its just not worth producing

[stiff mason]

Why are you trying to put a baffle extension on the back of the telescope

[stiff mason]

Also neither idk what the hexagonal ones hold but the large ones hold your mirror cell in place but again people usually put baffle extensions at the front of the telescope

[bleak solar]

It’s supposed to be at the primary mirror, that is why I am pulling out the screws

[bleak solar]

Like this

[stiff mason]

Ohhh that type of baffle extension

[stiff mason]

How much improvement will it give

[bleak solar]

No idea 🤷🏻‍♂️
But I saw it online and thought it wouldn’t hurt because of stray light

[stiff mason]

Fair enough

[bleak solar]

Also it was the larger ones… which I learned when the entire backside jumped backwards, which caused my front dust cover to jump off and fly through the room 😂

[stiff mason]

Lol

[sinful sapphire]

Have you checked if you need one?

the best way to take apart a telescope is to get rid of the reason to take it apart

[bleak solar]

Yes I need one… the flats had quite strong vingiete (however you spell that 😅)

[sinful sapphire]

Thats doesnt necessarily mean baffling needs an extension. Look through the focuser without anything attached and move your eye around. if you can see through the baffling out of the entire tube (so to say, sky, instead of the secondary), you need an extension.

If however that is not the case, an extension is redundant.

[tight lodge]

Or it can mess up your telescope. Ask Veloren

[bleak solar]

I do… I already tested that 😭

[sinful sapphire]

didnt know that

its just that a lot of rc users mod it when they dont have to, and learn from veloren. modding it can cost you years of patience 😭

[bleak solar]

Yeah I know, I didn’t say that I already tried it, sorry 😅

[sinful sapphire]

also you guys wont believe this

so at the ATT, the european NEAF, there was a company that made carbon truss RCs

thats like their whole gig

but the baffling was wrong

very wrong

lots of stray light

pointed that out, and they deadass said

"yeah thats intentional cause otherwise there will be a vignette, stray light will always find its way in anyway so"

[slate falcon]

[frosty shard]

Do they just like...do vibe optics or something?

Instead of hiring an optician?

[slate falcon]

my parents keep tryna get me into engeneering

i would be an optical engeneer tbh

idk the pay tho

[stiff mason]

Thats not always caused by stray light could be because of your imaging train

[stiff mason]

Same

[stiff mason]

Google says 90-148k heavily dependent on skill

[slate falcon]

yup

marine biology is like max 70k

[stiff mason]

Idk i don't really want to go into engineering it's really hard and the pay isn't worth the effort it takes

[slate falcon]

frr

[tight lodge]

#📡-radio-astronomy message
@slate falcon

[slate falcon]

lookin good

[tight lodge]

I hope I'll be able to test it next weekend

[slate falcon]

hope it goes well

[tight lodge]

Also, the other day you asked if I can use multiple of them patch antennas as an array. This is how they actually work. They don't work like a camera sensor

[slate falcon]

why not just use it likr a camera sensor?

[tight lodge]

You can't. Radio frequencies induce a current in the antenna. It doesn't get stored.

[slate falcon]

i mean like in the way pixels work

not actually collecting for better snr

[slate falcon]

thats what i thought you meant

like it cant be used to construct an image

with each sensor being its own pixel

[tight lodge]

it cant... welll... kinda. VLBI uses this kind of black magic to reconstruct an image

[slate falcon]

huh

why is it difficult to?

[tight lodge]

No... each sensor will sum up to the radiation lobe. so instead of obtaining multimple lobes, you obtain a single lobe with a much higher gain

[tight lodge]

because it requires atomic clocks, stupid amount of math, storage and time

[slate falcon]

so its just easier to use them as one super pixel?

[tight lodge]

exactly

[tight lodge]

You technically have multiple pixels and you let the earth rotation build the image for you

[slate falcon]

my brain is too small for this i think

adding an exta layer of confuse

[tight lodge]

Wanna know something even more confusing?
A radio interferometer, doesn't really image the target from it's perspective. but reconstructs the image from the target's perspective

[harsh matrix]

If you have a strong vignette that normally means the opposite.

Anyway

To be able to tell if you need a baffle tube extension, you need to see if you are always getting some kind of glowing ring in your images that never comes out.

[harsh matrix]

Internal reflections out the booty hole

Guess you wont be using any of their RC's outside of a remote imaging site

[harsh matrix]

Did you test with or without the focuser attached and did you do see the inside of the scope from the camera's perspective?

Ray tracing the inside of the scope with a collimation cap in the shape of the camera sensor is incredibly helpful

Even moreso for determining if you need an extension or not.

I thought I did for the longest time but I was able to determine that I didnt by using a collimation cap that was in the shape of my 571

[sinful sapphire]

I won’t be using them at all or I’m going to make the obstruction larger lol

If the obstruction were larger you’d at least not get stray light directly on the image sensor

[slate falcon]

what the hell

[tight lodge]

Now you understand why radio astronomy is so much fun? It makes absolutely no sense

[frosty shard]

Boiga.

[slate falcon]

spiral nebula?

[gloomy hawk]

do you ever get scared something will snap?

[quartz meadow]

its a threaded connection so I'm very sure none of the threads will shear off

[bleak solar]

Nah not really. It’s really sturdy

[tight lodge]

@slate falcon taking shape

[slate falcon]

yipeee

[harsh matrix]

@frosty shard any dark sky site target suggestions for my RC?

[slate falcon]

Abell 2218 :3

[harsh matrix]

I may revisit NGC 4725

[harsh matrix]

Im not shooting any clusters

I guess i should specify the rules here

[slate falcon]

WHYYYYYYYYYYYYYYYYYY

[harsh matrix]

Im looking to shoot a spiral galaxy that is either a barred spiral, an interacting pair that is close, or a shell galaxy.

The Umbrella galaxy is quite a ways up there atm.

Was going to do M101 and still havent eliminated that

[harsh matrix]

It's a waste of that time

It doesnt match anything I want to shoot.

Id like to take advantage of the resolution and the dark skies.

[slate falcon]

:c

[harsh matrix]

Clusters take more exposure time, and that will already be a set back.

[tight lodge]

Cheshire Cat

If that doesn't test everything in your rig, idk what else does

[slate falcon]

but thats just another cluster

[frosty shard]

Have you shot M83?

[harsh matrix]

It's much too low

[harsh matrix]

No

Not worth it

[tight lodge]

In the future?

[harsh matrix]

Maybe

But im not going to waste my first trip in 3 months on something i may not even see

I think M83 doesn't reach 30 degrees

Yeah M83 maxes out at 26 degrees here at home

At the site it'll only reach 25

Definitely not a candidate, sorry.

Cheshire is a snowball's chance in hell

Almost out of season too

Definitely not happening

[slate falcon]

ngc6332?

[slate falcon]

ngc2276?

[tight lodge]

APG 104

[harsh matrix]

Is this another one that's farther away than Stephan's Quintet?

[tight lodge]

🤏

[harsh matrix]

Too small

[tight lodge]

I'm trying to think of unique ones😅

[harsh matrix]

Too small

[harsh matrix]

There are some unique ones

You just keep finding the ones that are way too small to consider

All of these do not match the "close" description I said above

[slate falcon]

cLdsell six?

[harsh matrix]

"Close"

[slate falcon]

caldwell 6

[harsh matrix]

Not shooting a PN either

[slate falcon]

its agalaxy

[quartz meadow]

hey look up NGC 3718

[slate falcon]

im an idiot, caldwel 3

[quartz meadow]

its really unique

[slate falcon]

okay i got double the nubler i wanrted

[harsh matrix]

It's nearly out of season

That's why im not doing it.

[slate falcon]

c3?

[harsh matrix]

Im trying to spend the vast majority of each night on whatever I pick.

I dont want to split my time.

[harsh matrix]

Eh

Maybe

It fills my frame

[quartz meadow]

hmmm I see i see

but its circumpolar?

[harsh matrix]

Nope

It sets for me

Oh I see

[quartz meadow]

ahhhh yeah of course

[harsh matrix]

That's going to be a problem

[slate falcon]

its visuble all day all night for me

[harsh matrix]

That's why these suggestions are pretty bad

I live too far south

[quartz meadow]

it never goes below 20 for me

[harsh matrix]

So far south that nobody knows what my sky is like

[quartz meadow]

but you cant get carina yet?

I know down in FL you can

[harsh matrix]

Leo is probably a lot better of a constellation for most of you rn than it is for me

[harsh matrix]

Can't, no

[slate falcon]

never goes below 16 gor me

[harsh matrix]

I think at the farthest south you can go in Florida that is a maybe

[quartz meadow]

virgo?

[slate falcon]

meanw to reply this

[slate falcon]

nop

[harsh matrix]

Leo is already out of season more or less

It starts past the meridian here

At sunset

[quartz meadow]

Hey

[slate falcon]

leo is leaving

[quartz meadow]

draco triplet??

[harsh matrix]

Ive had a hard time finding it ngl

What is a number for one of them?

[slate falcon]

why is there a crater on top of the hydra

[harsh matrix]

That's really bad

[quartz meadow]

uhhh NGC 5981

[harsh matrix]

M 81 & M 82 are almost undoable already

[crisp flower]

What about NGC 4395, Not a barred Spiral but a very cool one imo

[slate falcon]

ita leaving meeee

[harsh matrix]

Okayyyyy

Now we might be talking

[quartz meadow]

It got 3 different galaxy types

[harsh matrix]

NGC 5982 appears to be a shell galaxy

[quartz meadow]

and 5985

I think that was the eliptical

[harsh matrix]

https://app.astrobin.com/i/obfhi7

[harsh matrix]

5985 is the spiral

The near face on one

[quartz meadow]

ah wrong 5050

[harsh matrix]

Im not sure i find it terribly interesting

[slate falcon]

vel, hear me out, IC342

[harsh matrix]

I did at one point in time but I dont get any appeal 😭

[harsh matrix]

Out of season

Almost underground

I would definitely do that one if it was in about 6 months

[slate falcon]

wait how

[harsh matrix]

It's lingering below 25 degrees altitude all night

That's how

Im too far south

[slate falcon]

whats ur thingy

the thingy

the doodad

the line

[harsh matrix]

33 degrees

[slate falcon]

HOLY

[harsh matrix]

You all are like twice that

[slate falcon]

im 55 or somethi

[crisp flower]

@harsh matrix NGC 2634? Im Not Sure in which Constellation it is tho

[harsh matrix]

This is why im making fun of you for being so far north

You get none of the cool summer targets

[harsh matrix]

Too small

[crisp flower]

Even with the surrounding ifn?

[harsh matrix]

At that point I'd be better off finding random IFN to shoot than shooting that target in particular

That galaxy is not even 2 x 2'

[crisp flower]

Alr fair

[quartz meadow]

may be a bit tiny but NGC 5905?

nvm its not really tiny

[harsh matrix]

Too small

I think I have a good selection going now

Draco Triplet, C3, NGC 4725, and the Umbrella Galaxy

[quartz meadow]

aight

[harsh matrix]

Ngl

Draco is looking the most appetizing

Doesn't look like the shell is too hard to capture

And the spiral looks incredible with any size scope

👀

Btw my goal for whatever I shoot is to better learn how to process tidal tails and/or stellar streams and galaxy halos.

So whatever I pick will have those sorts of features.

Shell galaxies are things ive almost always been more fascinated with so Ill naturally be drawn more towars those.

[plush raptor]

draco triplet

[slate falcon]

[plush raptor]

what

[slate falcon]

@sinful sapphire do you know how easy it is to make shmidt corrector plates

[sinful sapphire]

yes its very hard

[slate falcon]

its not

[sinful sapphire]

the mental pressure of knowing it will be put in a SCT

is unbearable

[slate falcon]

[slate falcon]

ive had a greater idea

just make the mirror with the shmidt plate inbuilt

no more need for the plate!

[slate falcon]

as in make the mirror in the way you make a shmidt plate

then just use a regular spherical secondary

[frosty shard]

So basically just make a Dall–Kirkham

[slate falcon]

yeah

when you remove the center of the mirror you get rid of the un functional part of the shmidt plate (its un functional as a mirror at least)

and you basically get a dall kirkam

but slightly different

[harsh matrix]

looks like the seeing will be good

for once

i will see when i get there and if it is good i may unironically shoot M101 like I planned to do this whole time

[harsh matrix]

well im already about 2/3rds of the way packed

i have some last minute things to throw in the car before i take off tomorrow

the forecast is still holding and it looks even better than it did last week when i requested these days off

[frosty shard]

Ronchigrams for my RC

There may be a touch of spherical aberration but it shouldn't be significant

[frosty shard]

@harsh matrix @slate falcon @sinful sapphire y'all might be interested

[harsh matrix]

almost negligable ngl

[frosty shard]

I think focal plane tilt from the adapters is the worst aberration I can see here, which is fine

[tight lodge]

Yo @harsh matrix Maybe I get the adapter this week?

[harsh matrix]

forecast at the dark sky site became cooked for tomorrow night

[harsh matrix]

wouldnt see cheshire cat at all bruh

there's no way id get enough separation

[harsh matrix]

also that's just one forecast, another still says clear

and the prediction for the clouds that will sweep through makes no sense

the clouds will be going the exact opposite direction that clouds normally travel through this region which i doubt will happen

it's this tiny little smudge

barely distinguishable from foreground stars

im leaning on Draco Triplet heavily rn

[tight lodge]

Well... it's up to me I guess

[frosty shard]

@harsh matrix @crisp flower oof
(This is a synthetic red channel I was trying to make out of an incomplete dataset, but here be the ring of death)

[crisp flower]

Dead Center over the Galaxy as Well xd

[frosty shard]

I am also not sure why I'm seeing imperfect correction of the dust mote in the lower right, but I do have a suspicion

There is a bright school in opposite direction

[crisp flower]

When i Had Ring of death, dust motes never corrected perfectly

[frosty shard]

Do you still have it?

[crisp flower]

No

[frosty shard]

That's because of the focuser upgrade right?

I guess the rack and pinion is not good enough

[crisp flower]

Not entirely
The Main think causing it for me was a loose collimation screw in the primary in Combination to the focuser

[frosty shard]

Oh really...what's funny is I had a loose collimation screw on my primary but I've fixed that now

Did you disassemble the scope to fix it?

[crisp flower]

Interesting

[crisp flower]

I didnt
The screw was in need of replacement so i used that opportunity to Switch Out all of the collimation- and Locking screws and then recollimated

After that it was fixed

The focuser was Just to make Sure it doesnt cause it as Well as me Being annoywmed by the fov drifting

[frosty shard]

Did you get the TS-Optics one though?

[crisp flower]

I have the exact Same one vel got

Or do u mean the old one?

[frosty shard]

Oh the Baader one?

[crisp flower]

Yes

[frosty shard]

Just wondering in case I do actually need to upgrade the focuser

[crisp flower]

I got Mine with a 3d printed Adapter for an eaf but i'll dump it as it Not Fitting properly

[frosty shard]

Oh right Veloren mentioned that one

Also I realized you may see fewer artifacts than I do, because your skies are better than mine

I took this L data in a high Bortle 4 site and I see no evidence of imperfect correction

actually maybe a tiny bit in the bottom right corner

[crisp flower]

You May be able to hide it in the process, so its Not too evident in the final image

[crisp flower]

Just barely

[frosty shard]

Well, I'd like to prevent this from happening at all starting with the acquisition phase

[crisp flower]

Yea
What u can do is Look INSIDE your scope and try to move the camera assembly
When i tried that, i saw the primary moving, so that was a huge giveaway

(idk why that one word got Capsed xd)

[frosty shard]

And I think I have some evidence that this is due to the focuser flexing, at least in my case. When I shot NGC 5907, there were no artifacts at all

and I think that's because the scope was pointing up for the majority of the session

I think I'll give this a try tonight. Not sure if the weather will let me image but I can test this

[frosty shard]

(and this was with a full moon all night!)

[crisp flower]

Fingers crossed

[frosty shard]

Same with my NGC 5434 IR session too - no gradient correction was done here

nor was it done in NGC 5907

[crisp flower]

Maybe u caught the issue right as it is about to start

[slate falcon]

do you still have darkness?

[frosty shard]

Yeah the minimum is 4 hours in the summer here (43° north)

[slate falcon]

weak

i have 0

[frosty shard]

I haven't really done visible light broadband at home, just IR and narrowband, so I haven't had many opportunities to see when this issue comes up

[crisp flower]

I have Had the issue across all of my Filters
When i was at "hight of the issue" i checked all of my Data i Had taked Up to that point and noticed it in almost all of them regardless of NB,bb or nir

[frosty shard]

I have never actually seen it in my narrowband data

I was gonna say I've seen it in IR, but that was actually the reflective adapter problem, which showed up even in data at dark sites

This is the first time I've really seen the ring of death proper, but it required some special processing

Here is my raw B stack (80 min) taken in Bortle 6

it is there, but very faintly

and you can see the uncorrected dust mote

[crisp flower]

Ive Had it Here before i knew what it was in ha and bb

[harsh matrix]

Yuuuuuuup

There it is

I managed to get to the dark sky site and fully set up already

I setup a remote access point for this trip so I can access my PC's from the bunk house

It actually all works

No issues, other than my quattro trying to hide itself on the network...

But it was the PC itself making that choice, otherwise, it's been connected since I turned it on.

No connection issued and it is snappy well over 100 feet away.

[frosty shard]

Do you have a router with you?

or are you just using one of the PCs as a hotspot

[frosty shard]

also from what I've read about the Ring of Death saga, I'm going to

• check if the primary mirror is loose
• check the focuser for play
• check the focuser for light leaks
  is there anything else I should check/do to try to mitigate the issue (barring an equipment upgrade)?

[harsh matrix]

Im using my RC8 PC as the hotspot

[harsh matrix]

Is your camera threaded directly to the focuser?

[frosty shard]

It is

[harsh matrix]

One less thing to check then

[harsh matrix]

Im concerned that the ring of death is caused by deviation in the primary mirror and/or imaging train which means that the induced mirror flop could very well be playing a role here. Another consequence of not having the primary decoupled from the focuser.

[harsh matrix]

@frosty shard guess what I found at the dark sky site

On axis coma

My weather was so bad for so long that I couldn't see it with the camera

Anyway I have it collimated slightly better

There's some funkiness going on with everything but I cant pin any of it down

Im just going to rely on averaging and decon to figure out the rest.

[frosty shard]

Did you evaluate this with the camera or by eye?

[harsh matrix]

Camera

I dont have equipment on hand to check by eye

Nor is it worth it

Id have to tear everything down here and it would take forever to reconfigure

[frosty shard]

I wonder what your autofocus HFRs are gonna look like

I've been getting better ones (like 3.6) but I'm not sure if it's just because I have worse seeing (which is pretty likely tbh) or I still have room for improvement

At least I know it isn't spherical aberration

[harsh matrix]

Bad

3.00 on this last one

My collimation isnt really much better or I have severe tilt

Can't tell which anymore

Im really starting to get angry rn

I think ill try to fix it tomorrow

Ugh

Not what I want to be doing here.

[frosty shard]

I'd slaughter armies to get an HFR this good

[harsh matrix]

https://cdn.discordapp.com/attachments/1128673711042592829/1503630600672907304/20260512_003042.jpg?ex=6a040c9f&is=6a02bb1f&hm=1f9b032aefa7f3a8b7c5dbcd74eab5cb7f132271719a4b6327d774bf6f9a00aa&

[harsh matrix]

@frosty shard the Milky Way is casting shadows tonight

[frosty shard]

HOT DIGGITY DAMN

[harsh matrix]

Lagoon is so bright that it looks similar to a star in my peripheral

You know the DSS sky projection in Stellarium?

[frosty shard]

Check for the North America Nebula if you can

[frosty shard]

Yes

[harsh matrix]

Looking at the Milky Way in binos is like having that projected onto the sky irl

[slate falcon]

yooooooorrraaaaaaayyyyy

[harsh matrix]

My eyes cant catch that level of detail but im still seeing way more detail than before

[harsh matrix]

I have

I can see it with and without binos

Actually I can see the shape of the whole thing

Why it's called that

The Cygnus wall sticks out like a sore thumb

[frosty shard]

Do you have a UHC filter?

[harsh matrix]

Yes

Tried to see it with the dob but it has too much focal length

[frosty shard]

You might be able to pick up the Swan or Eagle naked eye

Certainly it'll enhance the North America Nebula

M22 should also be visible naked eye

(no filter needed for that one)

[harsh matrix]

I can see M24 without blinking or trying

[harsh matrix]

I think i am seeing that

Keep thinking it's an open cluster

[frosty shard]

On good nights I can see M22 naked eye from here up north, and M24 is easy from Bortle 4 and below.

The North America Nebula is not easy though

At least not without a filter

[harsh matrix]

I can see the dark notch where the Cygnus Wall is lol

Naked eye

@frosty shard I could certainly see hints of M16 and M17 but the real kicker

I could see the Pipe Nebula and the dark streaks going to Rho Ophiuchi

Which ive only seen in binos before now

[harsh matrix]

@frosty shard got a 2.63 HFR lum sub lmao

https://cdn.discordapp.com/attachments/1128673711042592829/1503662062365311106/20260512_023514.jpg?ex=6a0429ec&is=6a02d86c&hm=77b9018af6c5c31892f42caf27b3f398bc32ad7174442176cb65060eebbc50e7&

[frosty shard]

...how

At this point I just think you have goated seeing

[harsh matrix]

I ain't even at home boss

I cant explain it

Although...

The EQ6R Pro has been doing this all night

[frosty shard]

Looks like there is a small amount of play in my focuser btw

[tight lodge]

HFR is an arbitrary value

[frosty shard]

All values are arbitrary, but some are more arbitrary than others

[harsh matrix]

Unsurprising

[tight lodge]

An HFR of 2.6 on him is not the same as an HFRof 2.6 on my rig. Soooo... highly arbitrary

[frosty shard]

Well, an HFR of 2.6 for him is the same as it is for me

[tight lodge]

Those who use HFR
Those who use FWHM
Those who use HPBW

[frosty shard]

HPBW?

[tight lodge]

Half Power Beam Width

[frosty shard]

Literally just FWHM

[tight lodge]

Kinda, but backwards 🤣

[bleak solar]

I found a relatively cheap flat panel on Ali express… would you guys say that is a good idea or nah?

[tight lodge]

Gemini?

[bleak solar]

Yes

[tight lodge]

Proud user of one. It works great.

[bleak solar]

Ukay

For my 6inch RC should I get one a little bigger than 150mm?

I was thinking about the 190mm version but I am not sure

[tight lodge]

Take a ruler and measure the diameter of your ota

[harsh matrix]

@frosty shard 2.46 HFR sub near the end of the night

These stars look the same as the broadband ones from my M16 project

Which were insanely sharp

[frosty shard]

I hate you.

I think at this point my seeing just isn't as good as yours

It might be better in the summer though

[harsh matrix]

They dont look good imo

Could be the dew shield tho

[frosty shard]

Oh right I forgot about that one

[harsh matrix]

Not really sure 😭

[harsh matrix]

Probably

@tight lodge 2.36" FWHM

[tight lodge]

On the stack?

[harsh matrix]

Sub

I wont stack for another 2 days

[frosty shard]

@harsh matrix do you know what gain your run your guide cam at?

I'm at 100 but I might switch to 180 or higher

[slate falcon]

@frosty shard https://youtu.be/i5kguuJmM5c

[harsh matrix]

100 as well

[harsh matrix]

@frosty shard we have triangular stars again

[frosty flicker]

certified RC moment

[harsh matrix]

At this point it is what it is.

[frosty flicker]

yea jsut send it

[harsh matrix]

Also @frosty shard do you think I should set a region of interest while I adjust the collimation again?

Maybe the corners being totally uncorrected is throwing me off???

💀

[harsh matrix]

Or it's tilt

I really dont know again

The astigmatism is even all the way around, the problems show up worst in 5th order coma where the tails don't all align to the same axis

Well the bottom half of the image does, the tails of the coma in each corner point towards the center

It's the top 2 that dont make sense

Top right the stars look like keys while the top left they look like noot coma but aimed almost straight to the bottom left corner and not the center

That's what makes me think this is tilt atp.

[frosty shard]

Probably not unless you want to run a high framerate in a bright star cluster.

How do the stars look when defocused?

[frosty shard]

Are they all pointing on the same direction?

From my experimenting, it's much more likely to be collimation than tilt. Any chance your mirrors are loose somehow?

[harsh matrix]

No

The bias and overall direction was consistent all night

[harsh matrix]

The top 2 corners are not but the bottom 2 are

The most confusing piece of crap I could look at

[frosty shard]

I assume you've run ASTAP on a frame?

[harsh matrix]

On multiple

Same story on all of them

[frosty shard]

As in they all show tilt?

It might be worth taking frames through focus to try to see what's going on

±200 steps, ±100 steps, and 0 steps outside of the focus point

Perhaps less if you can run the subs through ASTAP

that way you can get a sense of where the focal plane is

[harsh matrix]

Yes

[harsh matrix]

It's all over the place lol

It feels like there's a pretty insane amount of field curvature

I might have the primary too tight because everything is still diamond/triangular shaped after getting the corners better

The stars at the top and the bottom both have tails but the tails are slightly longer at the top than the bottom.

Although you could still move it

Which supposedly it is too tight when you cant...

@frosty shard

The stars are all some form of this 3 pointed figure which is making fine adjustments impossible.

I cant even see slight on axis coma because the light on the points dominates the rest of the star

I really could have pinched optics but I dont know what mirror is pinched.

Or why

If the seeing is too bad, meaning average for most people, and/or the sampling isn't just right, you can't see this at all.

Whatever this is, is a product of good seeing in a twisted way.

[frosty shard]

This looks like what I see when I take my very first images with my scope before it thermally equilibrates, but I assume that's already accounted for

[harsh matrix]

It has been outside all day

It's possible the dew shield is trapping some air above the primary which is causing that

But the fact that it held like this all night yesterday is worrying to me

The orientation of the triangles flipped with the meridian flip yesterday as well.

So it could be a pocket of air, I dunno

[stiff mason]

Certified

[harsh matrix]

@frosty shard ASTAP still shows almost the exact same amount of tilt to the same degree in the same places despite a significantly nicer field.

I think now tilt can explain the rest...

[bleak solar]

@tight lodge can I attach the motorised flag panel and a dew shield extension at the same time? 👀
I am being financially irresponsible again 😂

[tight lodge]

You can. However, the dewshield needs to be hard mounted to the tube😅

[bleak solar]

Ah… that could be a problem with shelf space… but that is manageable 😂

Wait

No

Does that mean the shield needs to be attached permanently to the tube? Or am I getting that wrong?

[stiff mason]

Oops i meant to say certified reflector moment

[tight lodge]

That means is permanent

See?

[bleak solar]

Aaaah. Yeah that’s no problem

(My dad is gonna kill me 😂)

[tight lodge]

You have an RC6 iirc

[bleak solar]

Yes sir!

[tight lodge]

Isn't the spider attached to the front ring that in my image I removed?😅

[bleak solar]

I believe so… but I was gonna 3D print the shield anyway and I can come up with something

[frosty shard]

What did you change? did you remove the dew shield?

[sinful sapphire]

do me a favour and at least tape over the ZWO logo on the focuser

[slate falcon]

use plasma deposition to coat in gold

[harsh matrix]

Both the position of the primary and secondary mirror

There's almost no variance in the corners now, at least as far as how well they reach focus, and what the astigmatism and coma look like.

But cycling through focus still creates problems, presumably because there is severe tilt.

[frosty shard]

Was it pinched optics?

Also I need to figure out what to shoot tonight

[harsh matrix]

Stars still look weird so it could still be.

Could also be tilt extreme enough that it is inducing symmetrical astigmatism across the entire field since there's still very little variation at the corners.

Inside of focus, all of the stars at the edges have their minor axis pointed toward the center and outside they have the major axis pointed to the center.

But just inside or outside of focus, all of the stars across the entire field are elongated either straight 90 degree vertical or 180 degree horizontal.

I think towards the end of the night they finally started to round out which convinces me thay the dew shield could be the culprit for the weird star shapes.

[harsh matrix]

@frosty shard my AM5N is going to be RMA'd again

I tried to avoid it but this mount is destined to be a curse.

[plush raptor]

what does that mean

[versed roost]

sell it after it gets repaired 💀

[harsh matrix]

2 problems

1 I have to be honest about the history of the mount and clearly it is tainted.

2 I'm not willing to pass a time bomb on to somebody else.

I'm not going to get much of anything from selling it at this point since it is questionably functional at best.

[oblique sun]

how many times has this happened already

[oblique sun]

Astrophotographers hot potato

[harsh matrix]

This will be the 4th

[stiff mason]

Just list the problems and sell it for really cheap

[harsh matrix]

That sounds really easy to do when you aren't the one who is forced to choke on the subsequent financial loss.

[stiff mason]

Doesnt it have warranty

Maybe zwo could take it back and send you a new one

[slate falcon]

[stiff mason]

Also i mentioned that as like the nuclear option

[stiff mason]

Yeah they probably wont take it back lol

[harsh matrix]

Funny

This is AM5N number 2.

I already forced their hand

Tried to get a refund after they failed to provide me with a functioning product 3 times, 3 RMA's.

Upper management said no and forced the tech to repair the mount.

The repair barely lasted 6 months.

Actually if we go back to when I saw this start up again, it was 5 months.

The warranty is up in late September I believe.

I cant sell a mount to someone that is doomed to fail right after the warranty expires.

Maybe if theyre willing to accept the risks involved I could but I'm not down to take the loss when I need a second mount.

That uproots everything, all of my goals.

Worst case it works well as a mount for outreach or something.

Still far from ideal.

Also I start university in the fall and I need to save money.

I can't just buy another mount right now.

That isn't happening.

[frosty flicker]

shouldve gone proxisky

[harsh matrix]

Either I bide my time with the repairs done or I force ZWO to do something they are unwilling to do by no fault of my own. They dug themselves this hole.

[harsh matrix]

Oh I know but at the time I wasn't terribly sure if I could count on them.

Wasn't until I watched them evolve over time that I recognized that.

It takes time to build trust and ZWO had this AM5 that proved itself to be a great mount, the N should have been a freebie, and Proxisky was just getting going and I had no idea what would happen if things were to fail with one of their mounts, all I had were claims at the time.

The choice was obvious when I was looking.

[stiff mason]

Force them to do it it's your only hope really

Also i feel like not enough astrophotographers insure their setup

[harsh matrix]

Ofc

But pushing again right now could be too soon.

Maybe if I'm persistent enough with the thing continuing to be a problem, they could.

Through some math I was able to determine that what the tech said is true.

If this was an extension of the knocking I observed coming from the belt was in fact from the belt, I'd observe a spike once every day, not once every 18 to 20 minutes. It leaves the finger pointing squarely at the harmonics...

[stiff mason]

Especially for new gear it could end up saving you thousands

[stiff mason]

Well that should be easy for warranty claim

[harsh matrix]

It is.

In fact the tech already told me to start an RMA

I will be doing that tomorrow once im back from my trip and ive had a chance to look at my data.

All things considered, even with the AM5N actively destroying itself, things have gone really well.

I couldn't have asked for a better trip during galaxy season.

Shooting one of my favorite objects in the night sky in unprecedented depth and detail.

With a moint that is actively crumbling.

[slate falcon]

who is that

[stiff mason]

What is that

[frosty shard]

Where is that

(It's the propellant dump from the Zhuque-2E test launch)

[bleak solar]

I have been meaning to ask. With your imaging train that far back, how do you not need counterweights in the front of your scope? Is the mound strong enough?

[frosty shard]

Harmonic drive mounts are way less reliant on exact balance compared to traditional GEMs

I could probably do better with a counterweight or two though

[stiff mason]

Ooh that's cool

[bleak solar]

Aaah! Neat

[frosty shard]

Here we have what not to do (a refr*ctor)

[tight lodge]

You can tell he doesn't trust his rig to do a meridian flip by itself

[frosty shard]

ASIAIR moment

Turns out live stacking disables the meridian flip

[quartz meadow]

oof

[harsh matrix]

on Draco Triplet

holy piss balls

anyway

@frosty shard see what I mean about the cross shaped stars though?

this seems to only happen either with the dew shield or with very good seeing

i cant tell which rn

i genuinely need better weather and more time

and see how weird af my field is?

it looks like it is centered and doesnt at the same time

this + what astap is telling me is what is making me thing the problem is primarily due to tilt

ironically the top left is the most normal looking

bottom right is the worst

definitely tilt of some sort

i highly doubt this is collimation at this point since the field appears to have symmetrical coma and astigmatism

it's just some weird misalignment with the camera now

[harsh matrix]

my vote is tilt

i dont know what y'alls is but i bet it is tilt

[plush raptor]

tf you mean alll im seeing is GYATTTTTTT

[harsh matrix]

anyway

i have to RMA my AM5N which means im down a mount again and i have a project going that i am unwilling to sideline with the quattro

I think im going to retire the RC while the AM5N is gone and do some finalization to the stray light mitigation

I want to do another coat of musou black on the baffle tube inside and out

[plush raptor]

im gonna shoot it for my firstlight

[plush raptor]

threatan as lawsuit idk for a refund

[tight lodge]

Hear me out. The payload capacity on the EQ6R is just a suggestion. What if you put the RC8 and the Quattro on the EQ6R

[harsh matrix]

i dont have hardware to make that happen lol

I want an RC10

[harsh matrix]

good

[harsh matrix]

i basically already did

although I found I cant really sue them since they dont have a US HQ

[tight lodge]

But, if you could... would you do it?

[tight lodge]

But, if you could... would you do it?

[harsh matrix]

eh i dont know

probably not

not in love with the idea of both of them pointing at the same target all of the time

Draco draft

Im going to come back and give this another go at some point tomorrow, it needs a fresh set of eyes

i found out one place im processing really poorly too so i want to see what happens when i dont make that mistake

[tight lodge]

Now this is a good looking triplet

[tight lodge]

Also, BXT is really good at handling funky stars

Too good I might say

Also @harsh matrix Remember that Hubble had weird stars as well.

See?

[harsh matrix]

i can barely see anything through the compression

[slate falcon]

i want a cc500

[slate falcon]

isnt that because they messed up hubbles collimation

[tight lodge]

Which they fixed with a 3rd mirror

[slate falcon]

also yeah, those stars look like vels

[frosty flicker]

they forgor

[harsh matrix]

uhhhh

are these the half egg looking ones hubble had?

[slate falcon]

oh no, just the funky mishaped centre stars

i think they fixed that too at a later date

because all of the newer data doesnt have it

[slate falcon]

hey ur bottom left stars have spherical ab :D

wait and your bottom right too :D

[harsh matrix]

Dont say that

Probably tilt ngl

[waxen mountain]

Me too

[tight lodge]

Unfortunately he had it worse

[harsh matrix]

that's not collimation though lol

that's somebody tuned the mirror grinder wrong

[slate falcon]

yea !

[harsh matrix]

pretty sure that is 5th degree coma tho

[slate falcon]

hmmmm maybe

i womder if the big co is making the centre hollow

i do think its tilt

[harsh matrix]

good

that means i can fix it

somewhat easily

[slate falcon]

tbh, i could probably grind my own

through the summer i plan on picking up mirror grinding

i can get a 450mm plate glass mirror for £300

[tight lodge]

You know you'll have to make test rigs, right?

And you need reliable testing so you don't end up with a hubble #2

[slate falcon]

yeah

[slate falcon]

what if i want hubble 2

[waxen mountain]

Nice

[slate falcon]

a blank i forgot to mention

[tight lodge]

We don't want a hubble #2. We want hubble to stay up in the sky. Or bring the legend back on earth safely

[slate falcon]

if i just make an f20 spherical mirror it will be all good

[tight lodge]

No. Because spherical mirrors are like eggplants

https://tenor.com/view/nobody-likes-eggplant-kentycky-ballistics-gif-23404606

[slate falcon]

at f20 you are difracyion limited with a spjerical mirror

[slate falcon]

also i love aubegine

if i want to make an f3 parabolic i think it would take me ages eith a 450mm

[quartz meadow]

have fun collimating that

[slate falcon]

[gloomy hawk]

hpbw

?

tf

[gloomy hawk]

https://tenor.com/view/lebron-james-walkout-im-out-im-leaving-gif-11924645

weighted fwhm

[tight lodge]

Not really. FWHM describes the shape, HPBW describes the beam

[gloomy hawk]

bro i wanna make pretty images

not study optics and light physics

[tight lodge]

Then you're missing the purpose of this hobby😭

[frosty flicker]

it only has a backfocus of 17.5mm so can only put OSC camera on or a single filter mono cam

[bleak solar]

Do I really need a dew shield?

[frosty shard]

I've never used one with my RC

[bleak solar]

Even in the winter?

Do you have a heater for your mirrors?

[frosty shard]

Nope. It's just not the limiting factor

[bleak solar]

Ah okay

[crisp flower]

Im using one as i have experienced my secondary mirror fogging Up in high humidity

[sinful sapphire]

@short garnet

the guys here can help out with the RC question you posed in c/astrophotography

[short garnet]

Coming to AB for advice was never really on my bingo list this week, but let's see....

Question for the RC guys (which I am not)

I have a scope that depending on which side of focus it sits, the stars will slant different directions.

basically intrafocal they're \ and extrafocal they're /

Is this a collimation issue?

[gloomy hawk]

astrophotography not astrophysics

[crisp flower]

Both

[bleak solar]

@tight lodge I think you wrote me regarding the motorized flat panel. Should I use the 190mm version?

[slate falcon]

proabbyl

[bleak solar]

Is the 190 the radius or the diameter? I am never sure what they write 😅

[tight lodge]

190 would work yes

[tight lodge]

Diameter is edge to edge, radius is center to edge

[bleak solar]

yeah, I know that 😅 but on the website I did not see if the measurements were given as radius or diameter

[bleak solar]

thanks!

[tight lodge]

Diameter

[bleak solar]

thanks for the quick help

[frosty shard]

This is astigmatism. What kind of scope is this?

[short garnet]

16" GSO RC. It was suggested to me that the secondary could be too tight.

[stiff mason]

Yeah i had that same issue

For me I'm 60% sure it was caused by my incorrect back focus to my coma corrector

[harsh matrix]

Unfortunate because I have no corrector on the RC

[stiff mason]

Still could be because of incorrect backfocus

[harsh matrix]

Very interesting.

This is what a coupled RC does.

However, it could be mirror flop in the primary mirror cell considering you said it is a 16" GSO RC

I've heard of primary mirror cell issues on the truss tube RC's made by GSO but I don't know what models the problem is limited to if it is limited to any particular model.

[harsh matrix]

That would be really hard to have happen when the proper back focus is also the focal plane for the RC.

[harsh matrix]

Mainly concerning the possibility of mirror flop

Too much slop in the cell was the cause or something.

[stiff mason]

Perhaps collimation issue coupled with tilt

[frosty shard]

Actually, I think the issue might be that the secondary is decentered

Pinched optics can affect the figure, but I think you need decentering to induce on-axis astigmatism

If you're seeing astigmatism off-axis that is totally normal

[short garnet]

I don't think mirror flop is a thing here, the scope isn't moving. Just the focus.

And I swear I read somewhere that only the smaller gso RCs were coupled, but I don't know.

[harsh matrix]

Is the 16" closed tube, or truss?

[short garnet]

Truss

[slate falcon]

shoud be decoupled

[harsh matrix]

It is decoupled then hmmmm.

GSO did do a limited run of the 16" variant in a closed tube format, that's why I asked.

[frosty shard]

@harsh matrix I figured out where that missing screw goes, and now the focuser play seems to be eliminated

[harsh matrix]

You had a missing screw?

[frosty shard]

Oh did I not tell you that part? A screw fell out of my focuser drawtube

[harsh matrix]

I dont think you told me and if you did I forgot

[frosty shard]

yeah hopefully that gets rid of the flexure

On an unrelated note, do you use a temperature probe with your Gemini EAF?

A friend of mine soldered me some custom low-profile temperature probes, and when I plug either of them in, the focuser just stops working

[harsh matrix]

No

[harsh matrix]

This is what my QHY autofocuser would do.

[sinful sapphire]

no it cant

turning the focuser doesnt shift any elements in an RC

making a required backfocus nonexistent

rather what you have to adjust is mirror spacing

[slate falcon]

idkk maan chatgpt must have told him

the gpt is always right

[sinful sapphire]

The solid tube RCs are coupled, because they lack a mirror cell.

the mirror, focuser and baffles are all connected in the same system

including a sort of clamp on the primary

[slate falcon]

@tight lodge unlinked 850,685,luminance

i managed to properly extract everything

[quartz meadow]

love the boost of stars that IR has given

[waxen mountain]

Niiice

[gloomy hawk]

hmm

[slate falcon]

its an image for demo!!!

[slate falcon]

core looks pretty

[gloomy hawk]

its soooooo pretty

[short garnet]

That's neat, definitely brought out some background stars but you've barely resolved trap there.

I'm not sure what's causing your flared stars, but it's a bit distracting

[slate falcon]

oh yeah, its untracked data from ages ago

shit seeing and collimation

im waiting for next time when i can image it propper

[short garnet]

Yeah I think the collimation hurt more than anything. All good.

[slate falcon]

the diff between ir and vis is cool

look how the structure you can see is completely different

i should make myself a 450mm gregorian