M31 - First time imaging with a telescope

[Mark1489]

I've always used my trusty Samyang 135mm for deep sky imaging in the past, but I've always wanted a little more reach and resolution! By no means is this a close up of Andromeda but I'm halving my previous pixel scale by now using the Redcat 51.

Had an issue with overcorrecting flats...a few nasty dust motes were appearing brighter in the calibrated image but I think I've manged to contain them. Upon checking my sensor (for the first time) I saw the dust and managed to blow it off with an air blower - thankfully didn't have to go down the "wet" cleaning route....yet!!!

So here it is, first deep sky image through a telescope and not a lens!

Info:

69 x 90 seconds about 1hr 45 total integration

30 flats

D5600a, Redcat 51, ISO 400

Autoguided, GEM28

Bortle 4 - 5

[vlaiv]

This is very very good image.

Only thing that I would personally see as improvement - scaling it to 50% of original size. This is rather personal preference. Most people don't view image at 100% zoom level. If you zoom to 100% in your image, then stars look just tiny bit out of focus (might not be focus issue - it could be down to seeing or guiding performance or something else entirely), more like "balls" or "circles" rather than points:

and background is just a tad more grainy. But if you "limit" max zoom level to 50% (by down sizing image to 50% of current size) - all of that changes:

Now stars look point like and background is smoother (not entirely smooth - that is bad, but rather "right amount of grain"). Detail in dust lanes also remains sharp:

Fact that I'm nitpicking means that everything else is just spot on !

[Mark1489]

26 minutes ago, vlaiv said:

This is very very good image.

Only thing that I would personally see as improvement - scaling it to 50% of original size. This is rather personal preference. Most people don't view image at 100% zoom level. If you zoom to 100% in your image, then stars look just tiny bit out of focus (might not be focus issue - it could be down to seeing or guiding performance or something else entirely), more like "balls" or "circles" rather than points:

and background is just a tad more grainy. But if you "limit" max zoom level to 50% (by down sizing image to 50% of current size) - all of that changes:

Now stars look point like and background is smoother (not entirely smooth - that is bad, but rather "right amount of grain"). Detail in dust lanes also remains sharp:

Fact that I'm nitpicking means that everything else is just spot on !

Thanks Vlaiv! You're right they do look a little bloated...I've been experimenting using different methods of focusing. Tried the bahtinov mask that came with the scope but I found it tricky and I'd end up with elongated stars in some corners after focus, I believe on this image I used the lowest HFD value I could get on Backyard Nikon so it could very well be missed focus! I appreciate the critique and kind words! 🙂

Edit - I just remembered there was a fair amount of high cloud drifting in and out...could that contribute to bloated stars?

Mark

Edited October 12, 2021 by Mark1489

[vlaiv]

25 minutes ago, Mark1489 said:

Edit - I just remembered there was a fair amount of high cloud drifting in and out...could that contribute to bloated stars?

Usually no, but it can impact HFD readings because background brightness value can change and therefore "floor" from which star is measured can be raised.

High clouds sometimes create halos around bright stars because they scatter light somewhat, but I'm not seeing that in your image. Two brightest stars have "regular" amount of scatter for small aperture refractor.

[ollypenrice]

Very nice image, natural and clean. I have to say that I thought the stars pretty small for a telescope of such modest aperture. As vlaiv says, seen at a reduced size the image looks excellent. You also have a good, flat, neutral background sky and that's so important.

Olly

[Knight of Clear Skies]

Nice natural-looing unforced rendition, good work. The colours, with subtle blues in the arms, are probably a good representation of M31, which isn't a starburst galaxy.

Edited October 12, 2021 by Knight of Clear Skies

[tomato]

Great M31, FOV adds to the image, galaxy is not too small but just enough space around it to put it into proportion. The colours look very similar to those put out by APP, what processing software did you use?

[Mark1489]

22 hours ago, ollypenrice said:

Very nice image, natural and clean. I have to say that I thought the stars pretty small for a telescope of such modest aperture. As vlaiv says, seen at a reduced size the image looks excellent. You also have a good, flat, neutral background sky and that's so important.

Olly

Thanks Olly! There's quite a bit of local light pollution here so sometimes it's a challenge getting that flat neutral background!

 

21 hours ago, Knight of Clear Skies said:

Nice natural-looing unforced rendition, good work. The colours, with subtle blues in the arms, are probably a good representation of M31, which isn't a starburst galaxy.

Very kind words, I try not to push it too hard! 😀 Thanks

 

20 hours ago, tomato said:

Great M31, FOV adds to the image, galaxy is not too small but just enough space around it to put it into proportion. The colours look very similar to those put out by APP, what processing software did you use?

Thanks! Part of me wishes I had more reach but I like having some surrounding area on show too. Just pixinsight for DBE and Histogram transformation, the rest in PS. I actually imaged a grey card in sunlight (I know most people don't bother and balance manually) since it's a modified camera but I just find it gives me something close to a good balance to start with, then just a few tweaks to the balance if its needed 🙂