First Light - Horsehead & Flame in Ha

[Knight of Clear Skies]

This is just a test stack of the Horsehead and Flame in Ha through the ED120 and 1600MM cool.

Pretty much unprocessed. Just stacked the Ha subs without calibration frames (I still need to take darks and flats), developed in Startools and some de-noise applied. 106*30 second unguided subs, so about 53 minutes of data.

Not sure if I should stick with this combination, with the reducer the scope has a focal length of 765mm and the 1600MM cool has small pixels. Have to decide whether to switch to my WO 71 ZS scope or keep the ED120 on the mount for galaxy season. Looks like quite a good result for a quick imaging run but I don't know if I'm oversampling.

 

[vlaiv]

You should really bin x2 your data in this combination.

Natively this combination gives you 0.87"/px (oversampling) and binning it x2 will give you 1.74"/px - and that is rather nice working resolution for 120mm scope on most nights.

There seems to be an issue with the scope:

Either thermal management or serious spherical aberration.

Cores of stars are visible - but so is extended skirt. This can happen if you combine subs that are in focus and provide sharp core and those that are out of focus. During the course of the evening as scope cools down - it contracts and focus changes. If you did not let the scope cool properly - it will produce such effect. It can also happen if there is rapid temperature drop and you don't refocus.

Check first and last subs to see if focus is changing between them. If not - then your scope might have optical issue.

 

 

[callisto]

36 minutes ago, vlaiv said:

You should really bin x2 your data in this combination.

Natively this combination gives you 0.87"/px (oversampling) and binning it x2 will give you 1.74"/px - and that is rather nice working resolution for 120mm scope on most nights.

There seems to be an issue with the scope:

Either thermal management or serious spherical aberration.

Cores of stars are visible - but so is extended skirt. This can happen if you combine subs that are in focus and provide sharp core and those that are out of focus. During the course of the evening as scope cools down - it contracts and focus changes. If you did not let the scope cool properly - it will produce such effect. It can also happen if there is rapid temperature drop and you don't refocus.

Check first and last subs to see if focus is changing between them. If not - then your scope might have optical issue.

 

 

Oh this is too complicated for my little brain to take in....I think I might just stick to visual observing  😁

Nice test shot by the way IMHO 

Edited March 9, 2021 by callisto
change wording

[Knight of Clear Skies]

10 hours ago, vlaiv said:

You should really bin x2 your data in this combination.

Natively this combination gives you 0.87"/px (oversampling) and binning it x2 will give you 1.74"/px - and that is rather nice working resolution for 120mm scope on most nights.

Thanks vliav.

10 hours ago, vlaiv said:

There seems to be an issue with the scope:

Thanks for the tips, very helpful. I'll look into it more closely. There was quite a variation in FWHM values but I'm not sure if they got worse over time. I was also imaging unguided which confuses matters. I'll try stacking a short run of subs and see what that looks like.

Edited March 10, 2021 by Knight of Clear Skies