Ritchey–Chrétien enjoyers thread

[runic violet]

I'm not european

[tulip iris]

Ah

[runic violet]

I don't see the prices

[tulip iris]

Lmao idk what to use as weather app at this point, i used to check even the astronomy tools related one

Ah

[runic violet]

Seeing can't really be predicted especially in places that have very variable topography

[tulip iris]

Wow i tought was pretty solid

[runic violet]

Its similar to the ones they put on their fracs and that gives people a bit of misery occasionally

Again it might just need loctite but if the steeltrack isn't much more costly why bother

[tulip iris]

On chart seemed pretty good, it can rotate, r&p, all sort of stuff i mean

I alr saw the steelrack price

[runic violet]

Stability is the real goal, features are secondary

[tulip iris]

Its the same basically

[tulip iris]

Yeah i pretty much noticed

[tulip iris]

Has the steelrack a threaded side tho?

Look what i reslly want in a focuser is that because im tired of using compression rings that most of the time are floppy or in the end ruin evn the only thing the focuser should do which is yeah guess what keep focus

[tulip iris]

Otherwise i was thinking abt the new gso provided one which is just like the usual linear bearing one but r&p

Costs 100 bucks less

[runic violet]

Yes steeltrack is threaded

The only non threaded focuser I would recommend is the feathertouch and even then I wouldn't really recommend it lol

[tulip iris]

Perfect

Im tired of using compression rings

[tulip iris]

I woildnt get it tho

Costs 1k

Does anybody trade all their setup for stupid ahh guinea pig?

[runic violet]

People buy used

That's the trick to buying one lol

I love me a free feathertouch

[tight lodge]

Send me a single raw sub of your choice and I can measure the FWHM for you

[tulip iris]

In italian market its pretty much absent that so buying it from usa would cost me another 300 bucks

[tulip iris]

Ah btw, the steelrack can be motorized w the eaf or no?

Yeah seems like it def can lmao

[tidal hearth]

If i could acces my files from back then sure

,,could,,

[harsh matrix]

Yes

Today's the day when I stack all of the data from this week

2 scopes to test

[high aspen]

also, imagine having data to test!!

hahahahha

-# i laugh in sorrow

[desert locust]

get m82 data

[high aspen]

no

[frosty shard]

@harsh matrix did I ever tell you - I think I figured out why using high conversion gain and high full well mode at the same time doesn't allow for good flat calibration with the Touptek 571 and 533

[harsh matrix]

You didnt but I was told by somebody else that high full well mode doesnt allow for calibration at all

Which i found out on my first night out with my 571

Haven't enabled it since

It behaves like negative gain

[frosty shard]

It's because if you set the gain too low, the sensor behaves nonlinearly. The effective gain drops off because the well can't hold electrons as effectively (it's probably the accumulation of lots of negative charge)

I use HCG+HFW on my 533, but the sensor has a different readout mechanism (14 bit only) and I'm actually not taking advantage of the full well depth with my gain setting

[harsh matrix]

Interesting...

That makes sense

[frosty shard]

In my case I am getting pretty much exactly unity gain across the sensor with my settings so I don't mind not taking advantage of the full well depth

Calibration is fine

I guess I could disable HFW, but these settings work and disabling it changes the effective gain

[harsh matrix]

True

[harsh matrix]

If it ain't broke, don't fix it.

[frosty shard]

Same with my autofocuser. It Just Works™

With the backlash settings you used

[high aspen]

did they just quantum entangle an autofocuser??????

‽‽‽‽

[harsh matrix]

interesting

[high aspen]

bob thought those leaves on the conservatory roof were on the mirror

[harsh matrix]

okay I am worried it is the shadow of the secondary mirror

I found a similar example online and that's what they suggested

I am not sure how or why it would be visible and what all I can do to make it disappear

considering I can't even fix this on my RC without making things exponentially worse for myself

[high aspen]

ohhh

that could make sense

i hope ur flats can correct it

[harsh matrix]

lights are done

[harsh matrix]

it was visible in the flats

as long as it was the exact same size and shape, we should be good

[high aspen]

[harsh matrix]

finding out now

[high aspen]

https://tenor.com/view/drum-drums-drumming-drummer-drumline-gif-9905446792274791925

[harsh matrix]

looks like my scuffed RC

a dust mote survived too

however

I somewhat expected this

still not quite as bad as I was expecting either

here's what I think happened

this is how I installed it, the only way I could reach focus

this is quite obviously far from ideal with such a massive imaging train on it

[high aspen]

nooo

[harsh matrix]

I was worred this could cause flexture in the system

guess what

after meridian flip, the tilt in the corners changed.

[high aspen]

poor guy

[harsh matrix]

So, I need to find a more secure way to attach this to the focuser

number one

lol

[high aspen]

brace

[harsh matrix]

number 2 is I should paint the inside of the focuser

[high aspen]

that is a very nice and sharp image tho

[harsh matrix]

yeah

only an hour of lum too

the same issues are present in green and blue too

meaning this isnt a luminance only/light issue

this is definitely what I suspect it is

flexture somewhere

(like I said, probably that sketch af attachment )

[high aspen]

tiny stars

and tiny details

[harsh matrix]

@tight lodge the test was a successful failure

[harsh matrix]

@high aspen

shadow of the secondary perhaps...

[high aspen]

i love the perfect mini donut

[harsh matrix]

💀

it's dust on the sensor itself

the bigger ones are all on the AR glass

[high aspen]

sneaky lil guy!

[harsh matrix]

this does not look like color out of this scope

holy

[frosty shard]

@harsh matrix do you have a Mele Quieter 3C? If you have any WiFi trouble, see this: https://www.cloudynights.com/forums/topic/876807-mele-quiter3c-wifi-inadequacy-fixed/#findComment-14023099

I'm going to check if the 4C might have a similar issue, because I feel like I'm not getting the range I should

But I also may sidestep this to get a dedicated router for my setup tbh...it actually makes sense

[harsh matrix]

I have the 3C

I don't have big issues with the Wifi

[frosty shard]

I find my OTA blocks the WiFi way too easily, and I've been told that with carbon fiber telescopes this shouldn't be the case

Meanwhile my friend's ASIAIR gets reliable signal 50+ feet away through multiple buildings

though I forgot it does have antennae

[high aspen]

wher colour?

[harsh matrix]

wow

big RC data

this is more than my disastrous NGC 981

[high aspen]

12hours lumi :3

[harsh matrix]

I just trimmed all of these

first night of color was pretty rough at the start

[high aspen]

oh god 😭

[harsh matrix]

offsets were bad so the stars looked more like lines than circles

[harsh matrix]

green lost an hour of data

red and blue only lost about a half hour

lum lost 3 subs

[high aspen]

lum is just too cool for that stuff

[harsh matrix]

not all that bad

[harsh matrix]

it's also just going to be the best channel considering that's what the general focus of the system is based around

[high aspen]

isnt lums purpose to add signal and sharpness

[harsh matrix]

yes

which is why ive worked so hard to get the channel to be clean

it will always be the best focused

[high aspen]

[harsh matrix]

I'm so nervous lmao

@runic violet bro, after 12 hours of luminance with a moon, it is definitely fixed

thanks so much man

this is incredible

none of that structure in the background lines up with dust

this is far cleaner than the last time i shot this much lum

it was the baffle tube length after all.

IFN EVERYWHERE

WOW

HOLY

[runic violet]

There's a dark halo around the galaxy

If you want to make sure there's nothing you should MSGR or image something emptier

[harsh matrix]

you might be able to blame that on me

I have a good MSGR reference from myself

that's why I chose this

I set the DBE tolerance pretty high and put samples everywhere

[runic violet]

smh

[harsh matrix]

if any of them hit the halo of the galaxy even a little, it would nuke the halo

sorry im just

not accustomed to good data

I can give DBE another shot

I went aggressive because I'm used to needing to do that

DBE doesn't want to play nice

[harsh matrix]

how's them apples

gaps in the IFN line up with the dark regions now

up against a reference

admittedly that is quite denoised to look for any other structure

the "raw" result is this

[runic violet]

Still see a large dark circle

But it is moon data so whatever

[high aspen]

looks yummy

[harsh matrix]

exactly

[high aspen]

are your stars ever so slightly oval?

[harsh matrix]

if this was moon data from 6 months ago, this would have been a nightmare to look at

[high aspen]

or am i tripping

[harsh matrix]

you are tripping

high compression screenshots, especially on mobile love to make my RC images have oval stars

[high aspen]

okay yea, those are really good stars

[high aspen]

was about to say its probably compression

how does it even happen

is there like a sliight ellipticity that causes it to get amplified or something

[harsh matrix]

no idea

it's happened to all of my images in some capacity

LOL

okay it is not the stars at all LMAO

[high aspen]

guh

[high aspen]

whats your fwhm in arcwhatchamakallits

[harsh matrix]

not the best ive had

ive had rough seeing as of late

and i think collimation is still slightly out but the seeing is so bad that you cant even tell

3.06"

that's smack dab between my average and my worst

so it's on the least sharp side of everything ive shot but not bad

[runic violet]

Fwhms not good enough to collimate precisely

[harsh matrix]

the color is sharper lol

[harsh matrix]

I don't collimate based off of them

don't worry

[high aspen]

@frosty shard the 850nm filter is probably the best light pollution filter i have

and its a broadband filter

i got 108 photos

and only half of then are usable

biiig w

(cloud and wind)

the clouds completely dissapeared 50 seconds after i turned off my laptop

massively infuriating

[harsh matrix]

computer is playing games with me

this does not look anything like it does in pix

imma revist it tomorrow in affinity photo where ill have much better control over the colors

honestly im going to try MSGR too

gonna do MSGR for DBE to get it right

Affinity for absolute control over the color

there's no way this goes wrong

[high aspen]

[frosty shard]

Since switching to Linux I've found I get way more consistent results with color profiles across applications

[high aspen]

yes!

[harsh matrix]

man!

which one is sharper!

I can't tell!

[high aspen]

im thinking right but i feel thats bc less int time

[harsh matrix]

the right has twice the int

https://tenor.com/view/spiderman-funny-laugh-gif-11964564

[high aspen]

damn, i was guessing bc of the gradient

[harsh matrix]

nah

star size

the left is HUGE

we love fractor bloat

[frosty shard]

What refractor?

[high aspen]

who needs gradient anyways

(i fucjked up focus sooo badly i have to do 4x bin)

[harsh matrix]

redcat

which btw

[high aspen]

the gradient here im guessing is caused by tha moon

[harsh matrix]

roughly 3 hours of luminance in bortle 3 is equivalent to about 14 hours of luminance from home with a moon

💀

not quite as bad as i expected tbh but it took a silly amount of light dampening to get the SNR on the RC to be this insane

in the past it was as bad as 8x more data from home to equal whatever i got in bortle 3

[high aspen]

i love how sparse m13 is looking

[harsh matrix]

yeah that looks dead wtf

is that with the 850 nm filter?

[high aspen]

yup

[high aspen]

it is only 50 secons of data

theres no gradient

and minimal atmos distortion

if i wasnt rushing and i focused properly it would have turned out well

its like all signal and readout noise

[harsh matrix]

yup

do like

20 minute exposures

get that noise down ez mode

[high aspen]

i will do a 4x bin on the sensor and do thaT

easy fix

[high aspen]

it should be good when i actually have the chance to take a nice photo 😭

i may have to wait until the summer

[harsh matrix]

the MSGR result is not much different from my DBE result

there's a tad bit more contrast and that's it

or I can use MSGR to get the colors right

[versed roost]

what ref did you use? i need one

[harsh matrix]

my own redcat data

[versed roost]

could you perhaps send a file

[harsh matrix]

https://drive.google.com/drive/folders/1buPxNNUiOeN74IoBv9ZDIzjjXnLNkJL6?usp=drive_link

[harsh matrix]

😩

is it perfect

hell no

could it use some work?

maybe

could it be better?

sure

but for 30 hours with a >50% moon, with a scope that used to be super rough, I kind of can't complain

that red bias is strictly from the much weaker blue and green channels

that's where that moon hit the most

[stiff mason]

Well whats the avg

Sure but it's more expensive and can carry less weight besides the tracking accuracy of a harmonic is good enough for diffraction limited 8 inch telescope and seeing like that hardly ever happens unless again you live on mauna kea which I'm 99.999% sure nobody on this server does

[harsh matrix]

looks very healthy

pretty sure new skywatcher mounts run worse than the old ones

I mean ones assembled in the last 2 years

before that they seemed to come out great as long as it wasn't an EQM-35 or EQ5

I have heard and seen multiple instances where people have new EQ6-R Pros, like less than a year old, with main board issues, or worm gear problems

i wonder if the same could be said for those HEQ5's considering it sounds like the new ones can rarely do better than 1" RMS

I caught my EQ6-R Pro doing 0.24" RMS on the second night of the M 81 project, and it averaged roughly 0.45" ish RMS last night

[stiff mason]

What do you think a harmonic track at? 3 arcsecond?

[harsh matrix]

which these are the sorts of numbers you want to be getting to run an RC8 with uncompromised sharpness

Although it is worth saying that high RMS with a widefield setup, and even guide scope set up doesn't mean much

you won't know how well a mount truly performs until you get high focal length and an OAG and only an OAG

a guide scope will not be representative of a mount's true performance

[stiff mason]

What about clear sky chart also thats not true 99% of normal places ive checked are at 1"

Only mountain tops it says are at 0.7" even then its slightly on the rare side

[sinful sapphire]

my heq5 dithers for me for some reason

its the weirdest thing

i dont have guiding but it dithers very very well

0 walking noise whatsoever

and no, guiding-less dither isnt enabled

[tidal hearth]

0,24 (0,55“)

[tidal hearth]

I need to find a belt mod kit for my saxon heq5 😅 🤣

[tight lodge]

@harsh matrix i think i have an idea for you to try while you trying to fix the RCT

Try to detect some exoplanets

[runic violet]

Clear sky chart is the same deal

It's giving 0.7" right now for me and I definitely don't live on a mountaintop

It might be bad for many places right now because of the jet stream, when that subsides you get impossibly low values

1" is an impossibly low value for normal places anyways

[stiff mason]

How

How come me with my 1 arcsecond per pixel i am always undersampled

My friend with worse tracking than me and bigger telescope always manages to resolve more detail under the same exact night

[versed roost]

1" is quite llow

[stiff mason]

Not really 0.6 would be low even 0.8 is low 1 is kind of middle

[stiff mason]

Also I'm pretty sure the figures they give is for the upper atmosphere they don't take into account local seeing so if you can get above the first 200m (the boundary layer) of atmosphere I'm pretty sure you can achieve that figure

[versed roost]

dawg these are mauna kea numbers

[stiff mason]

Yeah that's why they are low

[versed roost]

mauna kea is not the astrophotography standard 😭

[stiff mason]

Yeah it is cuz its the best 😁

[runic violet]

Nyquist

[runic violet]

How are you measuring this

[versed roost]

the best? why not go with space observatories? your seeing sucks if it isnt jwst level

[runic violet]

Then that's a fairly useless/misleading figure

[versed roost]

gas particulates at L2 are a little strong today...

[stiff mason]

Yup absolutely infact you seeing has to be -0.1 arcsecond

[stiff mason]

Eye ball really this was a while ago

[versed roost]

if your seeing isnt lambda/d dont talk to me

[runic violet]

Then I'm not going put much stake into it

[high aspen]

drizzle:

[stiff mason]

Its probably this tho

[high aspen]

where the fk are you

[stiff mason]

Doesnt really increase your details it makes it easier to see how much you fed up in processing but other than that not much else

[stiff mason]

Above the jet stream it's kind of hard to breath up here

[runic violet]

So your actual seeing is more or less 2-3" fwhm probably

But also aberrations also play a major role

[stiff mason]

Yeah probably but one thing and idk what the issue was my stars wonder around is that seeing or mount wobble

[runic violet]

Probably mount

[tight lodge]

There is one correct way to measure atmospheric seeing. DIMM

[stiff mason]

What is that

[tight lodge]

Dual image motion monitor

Thats how observatories measure the seeing

[stiff mason]

How do you do it

[tight lodge]

Ypu make an aperture mask that has uuuhm 2 appertures. You put a 0.06° optical wedge on one of the aperture and then you use fancy software to measure the amount of wobble of a star

[stiff mason]

0.06° optical wedge?

[tight lodge]

Yep

[stiff mason]

What is it

[tight lodge]

Something like this. It's just a prism. This happens to be a 6° one

[stiff mason]

How does it work in the optical train

[tight lodge]

Uuuh... it offsets the lightpath so you can have 2 images of the same object on the sensor

[stiff mason]

No i mean like how is it placed in the optical path

Like where do you put it and how do you put it

[tight lodge]

Right in front of the telescope

[stiff mason]

Define front after the secondary or infront of the primary

[tight lodge]

In front of the telescope

[stiff mason]

Ohh and the wedge goes in one of those "apertures"

[tight lodge]

Yes

[stiff mason]

Ohh thats simple enough what software tho

[tight lodge]

ALCOR

Although... they say "Contact us for price" that means the software is more expensive than the hardware

[stiff mason]

Aw nahhhhhh

Whenever companies say contact us for price it is always ultra expensive

[tight lodge]

Well... that's why it's mostly used by observatories 😂

[frosty shard]

Death to SCNR

[stiff mason]

Fair point

[tight lodge]

Ok... for once, i like the one on the right

[frosty shard]

You disgust me

[high aspen]

i think the 992 may be worth it

what is this qe

[tight lodge]

Hear me out. You need to balance the channels in yours

[frosty shard]

no that actually is true, the stars are too purple because I didn't cut down the green correctly

[high aspen]

i could make the craziest of images with this

with like 8 filters

across the ir spectrum

and ha sii and oiii

i love how it shows how stupid relative qe is

[versed roost]

how important is cooling

[high aspen]

@frosty shard ive sent a request for the true qe graphs for the 676mm, bet amma get ghosted or get some backwards reply

[high aspen]

very

[versed roost]

like whats a good feasible temp? -30c? is the TEC on that cam even different from other zwo cams

[high aspen]

for that price it better be

[versed roost]

should be a delta T in the stats

[high aspen]

17k is enough to work on the cooling

i also may not be able to use my coma corrector with my 850nm filter

i feel like it may reduce possible sharpness

[stiff mason]

You should see the read noise and dark current numbers

It's 71e of read noise

Dark current is 9e/s/pixel

It is literally impossible to take astro images with it

[high aspen]

wrong

[stiff mason]

To overcome the absurd read noise you need long exposures you can't take long exposures due to the absurd dark current

A simple peltier cooler is absolutely not enough to cool that camera

[high aspen]

obv not

[stiff mason]

It needs a minimum temperature of -100°C

[high aspen]

not really

[stiff mason]

It's infrared so yes

[high aspen]

-50 to -60 should be fine

[stiff mason]

No at those temps you would have 1e/pix/s

[high aspen]

its not like its 3um infrared is it

[stiff mason]

A black body emits radiation across the entire spectrum regardless of temperature but the amount of it changes based on temperature

That is basically what dark current is

[tulip iris]

Cant believe to open discord and find 2 guys arguing over a 20k camera

[stiff mason]

If the camera is hot enough to emit it's own radiation (in the same wavelength that the camera is sensitive to) it's hot enough to make the electrons get excited

[high aspen]

well yea but im saying its not like its a sensor for 3um infrared

[high aspen]

those are like borderline unusable

[stiff mason]

It still gets affected by it also as a rule of thumb dark current halfs every 5°C in temperature reduction

[high aspen]

i think u misread

[high aspen]

i think that should still be usable tho

barely but it should

[stiff mason]

So going based off your temperature that you said which was -60 and the dark current of the camera at -30°C that is a 3 step reduction in dark current and what is 9 divided by 2 3 times its 1.125

[harsh matrix]

people arguing constantly in here

[tulip iris]

Crazy like nobody here together w all its money can afford it

But still they keep doing it like bruh imma get it tomorrow i cant wait it ships🤣

[high aspen]

waiiiit

are you looking at the 991

amd not the 992

[stiff mason]

No not really it would if it was the same as a visible light cmos aka low read noise but because its not it you will have significant noise regardless of your exposure because noise is calculated as follow n=sqrt(n1+n2)

[high aspen]

stacking exists for a reason

[tulip iris]

Mastering ragebait

[stiff mason]

Oops i was looking at 991 still 3.5e is 0.875e at -60

[high aspen]

hehe

[high aspen]

i noticed after a second

bit better but not a lot

would have to use it with a 2 meter f2 rig

[stiff mason]

You are trading it for a lot of extra read noise the 991 has 21e read noise and the 992 has 71

[high aspen]

not averag human scopes

[stiff mason]

That is almost 4 times worst snr 😭

[high aspen]

i dont think that read noise is worth the daek current decreeas

[tulip iris]

Aura

[high aspen]

https://cdn.discordapp.com/attachments/1260385966410174517/1407957125019467816/IMG_4295.gif

[stiff mason]

Not an argument a civilized discussion 🧐

[high aspen]

they use a tec that only goes to negative 40°????

ur right they are dumb

._.

doesnt the sensor only cost like 7k to make

[stiff mason]

Personally i prefer QHYCCD version their TEC are water cooled so its significantly better

[high aspen]

the qhy ones cost 24-30k i think

i wonder if the 990 is better than the 991 or the 992

ohhh the 992 has smaller pixels that makes sense

[stiff mason]

They say their peltier can get below -80°C with cold water cooling so like i said significantly better

ZWO just sucks

[tulip iris]

Okok hope so it seemed as yall were fighting for who was the more right haha

[stiff mason]

Like idk why people keep on buying form them

[tulip iris]

The only reason i find zwo to be better is cuz im lazy and since i bought the guide camera time ago totally clueless it was that and not another brand i just stick w it

[high aspen]

dayum, worth it

[tulip iris]

I couldve bought the player one 533 instead i got the zwo one idk why

[high aspen]

wasted money :c

[tulip iris]

I just said man that extra 20ke aint gonna be useful since at unity gain all imx 533 dont go any over 18ke

[stiff mason]

Playerone way better

[tulip iris]

Tbh i feel like no difference, in my case the usb hub was very useful and since p1 doesnt have it i had another rwason to get it

[tulip iris]

Yeah yeah i know it

Zwo its just like apple

[high aspen]

what if the starvis2 sensor i want is only sold by them

[stiff mason]

They got a special LRN mode

[frosty shard]

Touptek does as well

and I think QHY?

[stiff mason]

Yeah a lot of companies do everyone but ZWO you pay more for less features its insane

[frosty shard]

Literally it's just ZWO selling subpar cameras

[high aspen]

its a newer sensor from 2024

[high aspen]

isnt that lrn mode just standard

[stiff mason]

What is it

[high aspen]

imx676

im sure if i wait a year an astro company other than zwo will sell it

its only 2 year old

[stiff mason]

Doesn't touptek have it

[high aspen]

waiiit

i dont know

i cant understand their naming converntions

[stiff mason]

No i dont think they do

[high aspen]

they dont

[stiff mason]

What does that sensor have

[high aspen]

wdym?

[stiff mason]

Like what makes it good that you want it

[high aspen]

its almost triple the responsiveness at 1um than the 585

tradeoff is a 3% lower qe peak

or so

i am currently trying to get the proper qe graphs from zwo

[high aspen]

it may actually be highter

but idk

i feel like the actual graph is flatter

it has 0.5 readout noise

which is goid

since the pixels are 2um big

so, lower dark current peak but at lower temps its higher

0.1 at 30°c is kinda based

when in the "hgc" its about same full well depth

[high aspen]

isnt LRN the same thing as zwo's HGC

[frosty shard]

Nope, they're different things

In Touptek cameras there are three modes: low/high conversion gain, low/high full well, and "Ultra" (low noise) mode

You can use any combination of them

so 8 different possible settings

[high aspen]

oh

[high aspen]

shouldnt all 3 on be the theoretical best

but that is super shitty that zwo dont have it

[stiff mason]

No LRN is low read noise mode which reduces read noise even at low gain

[stiff mason]

Eh that's not really a good thing smaller pixels are the same as larger pixels at higher f stop

[desert locust]

we talm bout cameras we never gonna buy

https://tenor.com/view/joe-bartolozzi-joe-bartolozzi-jumping-joe-bartolozzi-hitting-the-griddy-joe-bart-joe-bartolozzi-streamer-gif-3474253785075615366

[stiff mason]

No we talking about a camera shes thinking of buying

[desert locust]

with what money, aint she still a kid

[stiff mason]

Idk futur refrence

[desert locust]

https://tenor.com/view/eye-of-rah-eyeofrah-eye-of-rah-dread-eye-of-rah-dreads-i-bought-a-property-in-egypt-gif-5564801161099745076

[stiff mason]

Pov you smoke that one recipe in schedule 1

If you know you know

[versed roost]

until ur shooting orion

[tight lodge]

Why he got Cheetos for a haircut?

[desert locust]

ayo chill out yo you playing with a

ball knowlege reqired

[tulip iris]

Well in that cass u use 0 gain and u gave 50ke fw

[frosty shard]

I just shoot shorter exposures...

[stiff mason]

What about the dark nebula around it

[high aspen]

you can still get dark nebula with short exposures

[stiff mason]

Yeah but not exactly easy especially not in 1hr int

[high aspen]

i got dark nebula with 0.3 second exposures, whats your excuse?

[high aspen]

you act like i cant get a job

https://tenor.com/view/guh-cat-pleading-buh-ruh-gif-27675874

[high aspen]

i got in 1 hr int

[stiff mason]

Yeah same but its not good is it

Too low snr

So i didn't count it

[high aspen]

then get 2hr int

[stiff mason]

Or yk get a camera with larger well depth and use two times longer dubs for better snr

[high aspen]

heres the tortured image

to bring out dark nebula

[stiff mason]

Also to double your snr you need 4 time more int

[stiff mason]

Ngl there is nothing there

[high aspen]

turn up your brightness

💀

the entire light grey background is dark nebula

[stiff mason]

Nope just looks like a gray background

[high aspen]

you can see details 😭

[stiff mason]

A little on the edge of orion

[high aspen]

the entire gray background is dark nebula

[stiff mason]

But yk isn't that visible

[high aspen]

i did kinda cheat by using infrared tho

[high aspen]

look at the background

properly

and see

the

details

[stiff mason]

No details

[high aspen]

okay, this is just ragebait

[stiff mason]

Yes but also i genuinely dont see much

[high aspen]

does this level of cookery help

ig i made the bg too flat coloured

[stiff mason]

No because the signal just simply isnt there

[high aspen]

?!

[stiff mason]

You cant capture something that never managed to even overcome the read noise let alone shot noise and dark current

[high aspen]

you can see a lot more definition in the cooked image

[stiff mason]

No matter how many pictures you stack

[high aspen]

you can very clearly see it so i feel you are just trying to make a point that isnt there

[high aspen]

i did capture it though

[stiff mason]

Yeah you did but I'm just saying that generally

[high aspen]

;-;

[stiff mason]

There is still no detail on it tho mainly because of low snr and the fact that the region is smoothish

[high aspen]

its even smoother in ir

which is where 80% of that images signal is

blue is red

and the other 2 are 685 and 850

[stiff mason]

The only dark nebula you caught is this the rest is just camera artifact and noise

[high aspen]

use an ir image at least

stop trying to compare broadband to not broadband!!

[stiff mason]

It doesnt matter dust doesnt magical change shape just cause its nir

[high aspen]

it looks different

[stiff mason]

What nir affects is most how transparent it seems

[stiff mason]

Also i would if i could

[high aspen]

nir the structure is different enough

[stiff mason]

Which now that i think about it would change the shape slightly

[high aspen]

thx for realising

in some places it can be quite different tho

depends on how thick it is and stuff

[stiff mason]

But it wouldn't change its location tho nor would it reveal dust that wasn't there in visible

Infact it would hide dust that was already there in visible which doesn't help your case

[high aspen]

which makes it a lot smoother

also, you are forgetting something

[high aspen]

it does reveal dust that isnt visible in visible light

[stiff mason]

How

Unless the dust is actually emitting in NIR

[high aspen]

some sorta radiation that causes the dust to emit ir

from stars if i remmebr correctly

[stiff mason]

Which if it is it will also be emitting a faint red color as well

[high aspen]

it may not

[stiff mason]

Then its too cold to emit in nir atleast enough to be seen by a camera in such a short int time

[high aspen]

structure looks almost completely different

[stiff mason]

Is that ground base telescope

[high aspen]

yea!

[stiff mason]

Not completely but difference nonetheless

[high aspen]

look in the middle

that almost gap looking part

gets completely filled in

[stiff mason]

There are many parts that the dust only changes slightly

[high aspen]

yea

one noticable difference is the reflection nebula sections are completely gone

[stiff mason]

But i dont think that is nir is it

[high aspen]

it is

its 0.95-1.25um

it was taken with a ccd sensor

[high aspen]

at 1.6um the structure has a massive shift again

a lot bigger than those images

idk where i could find an image to show it tho

[stiff mason]

Yeah but you used majority visible light and very NIR

So the dust will be similar to that of visible light

[high aspen]

it was taken with a ccd?!

(talking about what i showed)

[stiff mason]

Oops nvrm i misread

Mb

[high aspen]

850nm is around where reflection nebs stop showing

so im gunna be doing a lot more 850 imaging i think

[high aspen]

oof :(

eh, somewhat of a shift

(850 left red right)

[stiff mason]

But what wavelength did you use for this

[high aspen]

685,red,850

wrong order

685,850,red

[stiff mason]

Check the dark nebula between the red channel and the NIR channels

[high aspen]

gimme a sec

i was a dumbass at some point

and didnt save the process

[high aspen]

you can see "structure" in the noise

ir is left

red is right

its a lot more defined in the ir one

[stiff mason]

You overdid the background extraction on the left image

[high aspen]

beh

[stiff mason]

Also thats just wavelength mechanics because ir wavelength is larger you can resolve less detail from the same aperture

[high aspen]

ther is still the dark nebula visible tho

[stiff mason]

I meant you applied the background extraction to close to the nebula and clipped some nebulocity

[stiff mason]

Anyway case and point blue vs visible+ir

In a 6 inch telescope

[high aspen]

i fixed yea

[high aspen]

im ngl, the ir looks sharper here 😭

[frosty shard]

Taking lots of short exposures isn't bad for your SNR. It really is int time that matters more than anything

There's a lot of misconceptions around the behavior of read noise

[stiff mason]

Idk man if i take 200 0.5s subs of say orion the only thing i will have will be the core nothing else but if i do a single 100s sub i will have the full orion and some dark nebula

[high aspen]

u here to save the day

i didnt want to say anything abt it incase i slipped up

[stiff mason]

Also what you said doesn't really makes sense because if it were true why would people spend so much time taking long subs when they can take much shorter ones which reduces the amount of data you have to throw away due to various issues

[frosty shard]

In the stack of 200 0.5 second subs, what's the maximum pixel value?

[high aspen]

many big channels and stuff do shoot shorter subs over longer ones

[stiff mason]

Wdym

[stiff mason]

Unless you live in light pollution (which most do) shooting short subs is bad

[frosty shard]

If you're looking at previews of the stacks with identical stretch functions, the stack of 200 0.5 second subs is always going to look worse

[stiff mason]

Just auto stretch on both

[high aspen]

autostrech stretches the "best" way it can for each image

[frosty shard]

In the stack of 0.5 second subs, you're likely not even close to saturating any pixels, but an autostretch function may not handle that case well

Meanwhile in a single 100 second sub you may blow out some pixels, but the fainter features are brighter and the autostretch function has less trouble with that

The best way to compare is to normalize the brightness of each stack

and then apply identical stretch functions

[stiff mason]

Quick case and point both of these are similar lenght in int time the one on the left used 10s while the one on the right used 30s actually i think the one on the left is over an hour and the one on the right is a bit over 30 minutes same camera same bortle no moon

[stiff mason]

Wait wrong image

It was this one

Side by side

As you can see the one with 30s subs is significantly cleaner

[frosty shard]

I can't actually, needs more JPEG

Do you have the raw data to work with?

[stiff mason]

Not right now

Cause I'm not home

[frosty shard]

Np

To do a fair comparison you'll need to multiplicatively normalize the data and apply identical stretches

One thing that I should also point out is that if you take shorter subs, read noise (assumed to be additive from the pixel offset) is going to be a larger proportion of the image

However

if you take a bunch of short subs, you average out the read noise

so the per-pixel variation from read noise is reduced

[high aspen]

okay nerd

[frosty shard]

determining an exposure time, for me, is about getting the brightest parts of the image near saturation without clipping

The problem with going too short is more so about the amount of data you generate

you also have an advantage in pixel rejection/artifact removal when you take shorter subs

[crisp flower]

@frosty shard these gradient look SOOOO much more managable

[frosty shard]

Oh the fix worked, sicc

[crisp flower]

yessss, thank u again for telling me about it!

[stiff mason]

The math also says longer subs are better

It is a bit idealistic (my example in the image doesn't take into account all the efficiency losses only that of the sensor) but still works as a rough estimate

You can make it more realistic by just doing the math for more losses (i was too lazy)

Tbh i think i should make a python script for that 🤔

Question is will i have the motivation for it

[high aspen]

my laziness does not use this much effort to try prove myself right 😭

[stiff mason]

It's two steps to calculate it takes like a minute

[frosty shard]

How are you getting 22.3 mag/as² for the brightness of the Andromeda Galaxy? That is way too low

[stiff mason]

Its the avg surface brightness

The core is obviously much brighter

[high aspen]

you wrote wayy more than a min of text

[vapid patio]

Hey fella

[frosty shard]

I don't think you would be able to see it at all at my nearby dark site, which has an SQM of 21.3

[high aspen]

are we all one

[frosty shard]

But I've seen it there

[vapid patio]

Correct

[high aspen]

[stiff mason]

All you have to do is find the avg surface magnitude which you can google no need to even use my formula then find how much light it emits

[stiff mason]

Again you are seeing the entire disk you are just seeing the core of Andromeda with some really faint spiral arms

[high aspen]

takes more than 30 secons

[stiff mason]

Aren't*

[frosty shard]

oh wait it really is that dim

I mean I can see Triangulum naked eye direct vision at a marginally darker site

(Bortle 3)

Very difficult but doable

[stiff mason]

Makes sense its 23mag/arc²

[stiff mason]

There are only two variables in the final formula

The amount of photons reaching your sensor and the exposure lenght

So you can literally coppy and paste

[frosty shard]

What are the units for Sobj, Sskyfog, RN, and DC?

[stiff mason]

Unless you change setups then you need to redo the equations

[stiff mason]

Signal of object, skyfog (or shot noise), read noise, dark current

[frosty shard]

No, what are the units - is it photons/second?

[stiff mason]

Im 90% sure its electrons per second for anything noise related and signal related

[frosty shard]

Read noise is a fixed contribution and should only be measured in electrons (per exposure)

[stiff mason]

It is

[stiff mason]

Oh right i just remembered half of it is simply to calculate snr lol

[frosty shard]

But how are you adding quantities in electrons/second (Sobj, Sskyfog, DC) to a quantity in electrons/exposure (RN) without a conversion factor

[high aspen]

[stiff mason]

Thats because the dark current and shot noise are converted to quantities by using the same exposure you used in the previous calculations

Oops i just realized my example doesn't explain that

Mb

You need to add the final noise to the equation so say your dark current is 0.05e/s/pix you arent going to put 0.05 in the formula instead you multiply it by your exposure say 30s which multiplied by 0.05 is 1.5e and you put 1.5 as your noise

[frosty shard]

I'm treating this as equivalent to what you're saying (t is time and n is the number of exposures), do you object?

Like the usual SEM estimation, the noise (error) decreases proportionally to the square root of the number of exposures

the question is how significant is varying t and n given that t*n is constant

Or wait oops

Gotta multiply S_obj by t everywhere

or is it by t*n actually

yeah it has to be t*n

Actually I'll use this form instead where T = t*n is the total exposure time

D is dark current, R is read noise

For a given total integration time T we want to find out how much changing the number of exposures n will change the SNR

[high aspen]

@frosty shard yk the class cass "rasa" modification

i think i would have to remove some baffles

[frosty shard]

I'm guessing that would compromise its utility as a Cassegrain?

[high aspen]

maybe

[vapid patio]

Why are we squaring it?

[frosty shard]

Squaring what?

[high aspen]

sqrt maybe

[frosty shard]

The answer to this, btw: it only matters in situations where the read noise is high the signal is low, and skyglow and dark current are negligible

[vapid patio]

The square symbol it over the function

[high aspen]

im hoping flocking could help somewhat

[vapid patio]

Maybe I’m confusing myself

[frosty shard]

you mean the radical in the denominator? That's from the assumption of shot (Poisson) noise, which is proportional to the square root of the total signal (photon count)

[vapid patio]

Ahh crap I read it wrong

Ok that makes sense

I start doing math 2 and I feel big brain ✋🙂‍↕️

[high aspen]

[frosty shard]

@stiff mason https://www.desmos.com/calculator/hmjzd3qttn

[high aspen]

line!

[frosty shard]

x-axis is exposure length, y-axis is SNR

[frosty shard]

And you're right, it's actually extremely flat for, say, imaging the Andromeda Galaxy in Bortle 3 skies

[high aspen]

luckydromeda

do i image a broadband target

or should i wait for mono to do that

yk what, i will wait for mono to do that

[candid flame]

what

explain formula plz

[high aspen]

alchaholism

[candid flame]

oh wait given constant total integration?

i understand nvm

[frosty shard]

tl;dr I'm trying to figure out how much sub length matters for SNR

[candid flame]

just swamp your read noise and ur good

but ig that's what you're trying to quantify

[frosty shard]

The answer I'm getting is "nowhere near as much as I thought, and I'm not one to take long exposures"

[high aspen]

browi are you a baked bean enjoyer (inportant)

how many millimeters is 3"

75mm?

[candid flame]

br*tish abomination

[high aspen]

you are mean :c

[candid flame]

3*25.4mm

[high aspen]

thats like 75mm

[candid flame]

76.2 🤓

[high aspen]

-# bobs singing is hella impressive, im listening to it while im doing discord stuff

[high aspen]

ur mean

[frosty shard]

For the Andromeda Galaxy with the parameters UNID gave there's not much of a difference in SNR between 3 second and 300 second subs it seems

[frosty shard]

The aperture of my very first telescope. Ah, nostalgia

[high aspen]

also, thats like 30% mirror area taken up by the corrector for a 6" mirror

huh

so an 8" would only increase price by like 200

hmmm

[high aspen]

(brobaly more than that)

[frosty shard]

There's about a 1% gain in SNR lmao

[high aspen]

PERFE-

this is why 15 second subs are the goat

[candid flame]

maximum fractional loss as a function of sub length would be interesting

because stuff would cancel out yk

[frosty shard]

fractional loss?

[candid flame]

like %SNR lost in worst case

[frosty shard]

Ah

[candid flame]

ig that just means assume optimal conditions

[frosty shard]

This is actually even more interesting when you factor in pixel rejection

[high aspen]

assume a 99% loss of snr by default

[frosty shard]

Me when I shoot with the dust cap on

[high aspen]

pinhol

amma make a pinhole with 1500mm fl

[frosty shard]

rejected pixels with short subs hurt your SNR less

though at the same time you could face issues with fixed pattern noise

[candid flame]

does it really matter in the end tho?

like more than 1%

[frosty shard]

I don't think it's a huge deal

[high aspen]

imagine doing 0.1 second subs and dithering each frame

[frosty shard]

One of the things you have to remember with the Touptek low noise (ultra) mode is that readout is slower, so I can't manage more than 4 FPS with it anyway

[high aspen]

from personal experiance you can usually dither every 60 seconds with short subs without issues with drizzling

[frosty shard]

So 0.1 second subs are pointless

[high aspen]

😭

[high aspen]

its the perfect sub length

[high aspen]

you do need to make sure you get more than 60 seconds of data tho

[frosty shard]

The thing is, FPN becomes a bigger factor when you take more frames, because you have more samples of the pixels. So when I dither it's pretty much always a frame count interval, not a temporal one

[high aspen]

a oke

[stiff mason]

What is n also RN needs to be squared

[stiff mason]

No the top Sobj doesn't need to be multiplied by t because it is already calculated before hand (the top part of my calculation)

[stiff mason]

T should be exposure time btw not integration time

[stiff mason]

Thats how noise is calculated its the sum total squared

[vapid patio]

Fancy

[stiff mason]

The reason for that is because you multiplied the top Sobj by T which is the wrong parameter

[frosty shard]

It has to be integration time because you're measuring noise in a stack

[stiff mason]

That is done after the snr is calculated

And it's quite simple 4 times the int double the snr

[frosty shard]

After which SNR is calculated? Sub SNR or stack SNR?

[stiff mason]

Sub snr

[frosty shard]

That's not a fair comparison

I want to compare stacks with identical integration times but different sub lengths

[stiff mason]

Yeah you can do that

You just have to get the snr of each sub first

Then multiply it by the int time

I believe you multiply the int time only for the snr of the object basically your noise stays the same

Actually that doesn't make sense

Oh right okay scratch what i said before @frosty shard

So basically you need to put the total time (in seconds) in this top half here

S is for time in seconds

Wait but that would be per sub

Okay I'm confused

Ohhhhhhh

Okay so noise grows as the square of time and signal grows linearly

[haughty steppe]

Quick 10x60sec Ha and Oiii in HOO pallette.

[frosty shard]

Shot noise should only increase proportionally to the square root of exposure time for a single sub

Read noise is a fixed contribution per sub

[stiff mason]

Yeah

I did the math for 1hr of total integration on Andromeda with my setup at 300s subs the snr is about 0.528 and the snr of 3s sub is 0.0527 if we use 1hr worth of images they both reach 1.72 which is interesting

Because it's a low snr considering i used the sky shot noise from b5

I think it's because when i used to measure the surface brightness (which i got the size from stellarium) the size was too large and as a result the surface brightness dropped nope it's correct mhmm 🤔

Idk i double checked the math is good probably wrong formula for calculating snr of a stack also @frosty shard watch this video https://youtu.be/EMdEhQD2WxY?si=a3bc-VP4bNlxbcNK

[stiff mason]

See look I'm stupid when i was doing the calculations for the snr i forgot to turn the photon flux of the sky fog into electrons per second 😅 correct snr is 12 took a while but i figured it out

[vapid patio]

finally a clear ish night

grabbed some m82

focuser works great but now I can see how off my collimation is

[vapid patio]

well this is what i snagged its like 24 minutes

for the time I dont have much to show but aye atleast it works again

[crisp flower]

Its there and its a beauty

[frosty shard]

I used my blue filter, are you happy now

HaIR(G+B)

[tight lodge]

Why is it green?

If this is pseudo gri, it should have looked almost like an RGB image

But still... IRGB should look more like a deep red rather than green

[sinful sapphire]

why is there barely any IR in there !!!

[sinful sapphire]

speaking of IR

[sinful sapphire]

do you believe its wiser to get an autofocuser or a full set of IR filters to make an RGB image out of purely different NIR wavelengths

[frosty shard]

I never process images the way they "should" look. You should know that by now

[tight lodge]

Soooo... you just gonna image r',i',z-s'?

[sinful sapphire]

mmm no

ill divide the NIR part that the cmos sensors can pick up into 3 roughly equal parts

and image those to combine into an RGB image

[frosty shard]

The H-alpha signal is overbearing

I also compensated for the width of the IR pass filter

[tight lodge]

You just defined how the IR side of SLOAN works

[sinful sapphire]

well i havent really looked into SLOAN

mainly because i did it once and saw ridiculous prices

[tight lodge]

Isn't this what ya trying to achieve?

[sinful sapphire]

not exactly

[tight lodge]

[sinful sapphire]

though looking at this chart ill have to rethink my filters a bit

[sinful sapphire]

well essentially yes

[tight lodge]

When you said to split the nir side of CMOS in 3, ugriz was the first thing that popped into my head.
Because I don't think you are able to detect anything above 1μm

[sinful sapphire]

well yes

but not with the photometric filters nor with any overlap

and photometric filters are so expensive for no reason

getting the ones in IR would cost me 420 EUR

[tight lodge]

Nice

[sinful sapphire]

i was constraining myself to not say that 😭

[tight lodge]

Hear me out. You buy one filter at a time

[sinful sapphire]

mmmmaybe

[silver ibex]

Not a lot of people are buying them

[sinful sapphire]

gee i wonder why

[quartz meadow]

"reasons"

[silver ibex]

What I mean is that if more people were interested then the companies would have a reason to invest in faster/better machines to make more of them for cheaper

Rn they are quite niche

At least for amateurs

[tight lodge]

Low demand = less manufacturing.

[high aspen]

guuuyyysss which one

( i think i wont be able to get right target bc too late)

[crisp flower]

I thought about going for the right one myself once
Definetely one you dont See as often so id Take that one

[high aspen]

iant right a herbig haro object

im gunna struggl

[tight lodge]

This?

[high aspen]

pretyyy

[quartz meadow]

Herbig Haros are cool

[high aspen]

ya!

[stiff mason]

Which target is this

[quartz meadow]

Is it the one in corona australis?

[high aspen]

in taurus

[quartz meadow]

ah

[tight lodge]

Hind's Variabile

[high aspen]

whaaat

ive only seen the ldn numer

[tight lodge]

It has an NGC number as well.

Very simple to remember

NGC1555

[high aspen]

ohh

thats a different target

[tight lodge]

Close enough is good enough

[high aspen]

woudlnt be suprised if they were from the same clump of gas

[high aspen]

i think they are

[crisp flower]

I agree

[frosty shard]

Missing a panel, so it's time for a WFPC crop!

Please ignore the gradients in the red channel, I think I normalized the stack incorrectly

Okay corrected version

[high aspen]

sorry i was hungry

[high aspen]

such interesant targer!!

[harsh matrix]

WFC2 pic

[frosty shard]

You know I forgot I can literally just go walk and see the original WFPC

It's on display here at UW-Madison

[harsh matrix]

[frosty shard]

Wacky framing for NGC 3628...

(so I can get the tidal tail)

[high aspen]

you should just barely have it in frame to piss people off

have it in as much as you need to but no more

[high aspen]

slimy guys

buh

pretend i didnt leak half my name

[tall summit]

wow, nobody to hold the fort at all

weird way to conduct business

[high aspen]

look how long they waited too

waited a week and said nah, wait 2 more

[high aspen]

why is verybibble so bright

i can se in one second subs

[high aspen]

hubble var neb very pretty

it looks really silly too

its just a small

in a sea of nothing

oh yes

@frosty shard ir is weirdly good at shooting through clouds

im getting my avg hfr through them

(too thick clouds now its 4 :/ )

[high aspen]

noise removal works way too well due to the lack of any noise but one or two types basically

[high aspen]

brehh

im so pissed

trying to do a harsher rejection by manually doing stuff

but siril refuses to leave the data undebayered

what is this shitttt

theres no option to stop it from debayering?!?!??!?!?!?

[frosty shard]

Do you have the debayer box checked after the calibration step?

And are you drizzling?

[high aspen]

nope

[high aspen]

its auto drizzling during the registration step

even tho the option is unchecked

amma just give up

too much effort for today

amma just stick to mono stacking script and do manual culling

[frosty shard]

I'm massively integration deficient and just aiming for a quick preview, but asfter taking a very quick peek at my IR data on NGC 2403 from last night, it seems the central region is way brighter in IR

[high aspen]

yus

[harsh matrix]

Makes sense

That's where the oldest, longest burning stars would be located.

I have to figure out this crater, next.

[frosty shard]

I'm surprised how much brighter it is considering how there's no bulge to the galaxy

[frosty shard]

You took this data during a favorable moon phase right?

[harsh matrix]

I took it with no moon, correct.

I had dust motes during the first look too but they went away with new flats.

Pretty fricken weird

Also they werent embossed

They were just uncorrected altogether, like the flats didnt work.

Once I figured that out, took some new ones, I was left with this crater regardless of exposure.

M63 believes it is some kind of reflection.

If you have an ideas as to where and when it is developing, I am all ears.

The orientation of the gradient within the crater changed since the flats I took last week

Which to my knowledge, nothing has moved even a little bit since then, so I'm not sure what would make that occur.

[frosty shard]

I assume you haven't rotated your image train at all?

[harsh matrix]

No

Another thing I noticed is that, while it's always been present, it changed size after I went from the scuffed new baffle to the good new baffle

It went from about half that size to that size after I printed the new one and seated it correctly.