City DSLR astrophotography-25hrs on NGC5139

[Phisci]

1500 x 1 min subs at ISO 100 using Samsung DSLR on 80mm refractors at F7.5 or thereabouts. Johannesburg white/red zone; Stacked and processed in Pixinsight;

Running 4 80mm is parallel so equiv aperture is 80*Sqrt(4) and equiv focal ratio is F7/Sqrt(4) (160mm at F1.9).

[Atmos]

Nice stars and nice resolution, only so much that you can get with a 80mm + DSLR.
Looks like you have some nasty gradients imaging from your heavily light polluted suburban backyard :lol:

What you can do is use the PhotometricColorCorrection utility and set it to G2V star colour and it may help with the blue bias. It is a very red star cluster but it is looking pretty good so far.

[Phisci]

Thanks Atmos, here is the result of the photometric calibration using the average galaxy option

[Imme]

Interested to see the imaging rig....can you post a picture?

[Lognic04]

I don't think 25 hours would help a cluster... But nice image anyway

[Phisci]

Thanks for the comments; Agree 25 hours on clusters is overkill but have seen in the past that imaging from the city requires about 25x more time than imaging at a dark site about 120km outside joburg, hence the decision to try and see what the outcome would be.

I've attached some pics of the setup.

[Imme]

....just wow

[Atmos]

Impressive looking setup :thumbsup:

[cometcatcher]

Strewth! :eyepop:

Nice image. 1500 frames.... I think I know someone else that does that... :question: ;)

[Phisci]

I setup the QUAD scopes because achieving a similar signal:noise ratio in the city vs a darksite required a 25 fold increase in number of images.

So saves on acquisition time by a factor of 4 but then stretches processing time by a factor of about 5.

In total I estimate it takes me 5x longer to capture and process images from the city than from the dark site (assuming a 3:1 process vs acquisition time ratio). But for the city using 4 scopes reduces total time by about 25% vs 1 scope.

The refractors are all entry level doublets (Skywatcher 80mm and William optics) and post Samsung's withdrawal from the DSLR market their nx500 model went very cheaply for a while.