M42 first guiding attempts

[warm crag]

Additionally as a PNG, for ease of viewing :)

My bad. I tried to post the PNG in the preview, somehow deleted my original message.

350 x 3 s subs
Nikon D700
TAL2-M (6 inch Newtonian, f/8, 1200 mm focal length)
Original mount but modified

I fitted my TAL2-M mount with a 3D-printed gearbox and a stepper motor. It’s a bit wobbly, about 60 % of the 5 s exposures were sharp.
I‘m still having trouble with these horizontal lines propagating from brighter stars. I assume, this might be read noise of some sort. The dashes in these lines come from my flat frames, as they appeared after calibration and a grid can be seen in the flat frames. Any help appreciated, I might try different ISOs but potentially this is something I can’t get rid of. With starnet+ I be able to reduce these lines through photoshop somehow, but haven’t found a clever way of achieving this.

Any help appreciated :)

[olive girder]

you got a nice shot in this, it just seems that the issues from the flat frames are making the image entirely unusable. Honestly, I would recommend trying to stack it without the flat frames for now, and seeing if that improves the final product at all.

this is just an autostretch in siril

im curious if the lines are actualy coming from flats, as they seem to triangulate in the brightest sports of the image. I wonder if this is just an issue with the sensor on the camera you used.

[olive girder]

Im not really an expert, I'm just making a bunch of assumptions. I 'd really recommend sending this image to the ask_a_nerd channel and seeing if anyone has faced a similar issue.

but for now take out the flats and could you show me what the final product is like there?

[warm crag]

I‘ll redo the calibration and stacking. Although the major lines are present in each single image if stretched far enough. My point about the flats was all the tiny perpendicular cuts to these lines. Thanks for all your input.

Additionally it must be said that the images were taken in more than suboptimal conditions. Street lamp right next to the telescope, shot from my balcony. So I expect some of the unevenness in the background to come from these circumstances

The other interesting thing to note: you can see a slightly tilted line crossing the horizontal lines where the bright star is. I remounted the camera at some point, as I recollimated my telescope during the night. I also have a roughly equal amount of data from earlier that night of M1, which might have less of these defects with generally lower brightness stars in the FOV

Found this: „D700 is an old camera with old tech sensor. It suffers banding and noise (both read and thermal) when you push images in PP. Newer Exmor sensor bodies are much better in that sense.“

https://www.dpreview.com/forums/thread/4022496

Maybe it’s just my camera :(

[olive girder]

Ahhh thats unfortunate, sorry to hear it may be the camera. Lovely setup btw, I am relatively new when it comes to live-view setups on the laptop, I only ever take a bunch of shots and then stack them later after they've moved off the SD card. Excuse the ignorance, but what program is open on your computer? Give me more details 🤣

I'm currently running an 8 inch dob untracked, 0.5s shots and stacking like 700 of them 😭

[warm crag]

@olive girder
I‘ll gladly give more details :D it’s not really a „live-view“ setup. Well to some extent, but not yet live stacking.
So what I’m doing is running a program called „kstars“ on my laptop, windows could use „Nina“, but yeah. My mount is not controllable, it is only a motor running the main axis of the equatorial mount at roughly the correct speed. My camera is connected via USB to my laptop running kstars. Within kstars there’s an option to set up a camera and this can then be controlled from the laptop. I tell the camera to take 100 consecutive images at let’s say ISO 1600 and 3 s exposure and kstars downloads each image. Best thing about this for me is the plate solving, which makes it very easy to line up shots and find dark targets like M1. With Siril I could also do live stacking alongside it, which I will definitely try next time, but haven’t dipped my toes into yet.
Regarding your method, I did very similar beforehand, my 6 inch f/8 let me do 0,4 s untracked exposures, what f stop does you dob have? I took 1800 images of M27 before and stacked them. Good image but very low data. That’s why I motorised my mount.
Oh and I just realised my mistake of saying „guiding attempts“, where I meant „tracking attempts“. The other axis isn’t motorised (yet, although low on my priority list, as that’ll get complicated).
For the kstars setup I followed some YouTube tutorials, which I could find again for you, if you’re interested

For the M1 image, see here
https://discord.com/channels/794642864218439681/1183372250104201358