DSLR what ISO and subs to use

[Dilsh]

Hey guys,

I have taken my first handful of astro photos using a Skywatcher EQ6rpro unguided, a Skywatcher ED80 and a DSLR1100D canon using NINA.

I am in Ivanhoe so my backyard has the typical light polution of the Northern suburbs of Melbourne.

What is the current wisdom on what ISO and exposure time I showed use with a DSLR under those type of skies. Should they be short(45-60s) with a high ISO (say 1600) or longer(90-120s) with a lower ISO(100-400).

Ultimately I want to shoot with a monochrome and filters but still getting the hang of this with my "cheap" setup.

Kind regards and clear skies.

Dilshan

[Drac0]

A lot of it will depend on what your target is & what conditions it's under, even which direction you're facing. You may have to consider a light pollution filter to help if imaging from home - maybe something like a Baader Neodymium or Optolong L-Pro. There is a few decent content makers on YouTube that deal with imaging in heavier light pollution - AstroBackyard, Nebula Photos & Cuiv, The Lazy Geek to name a few.

Your skies are worse than mine (you're in Bortle 6, borderline 7, compared to my 4/5) but you also have to consider other sources of light pollution like the moon phase as well as seeing conditions. My choice is to shoot at mid-range ISO (800-1600) and vary the exposure time to suit conditions. For example, Monday night the moon was pretty full so I shot ISO 800 @ 60 seconds. In darker conditions I shoot at ISO 800/1600 & increased exposure time. But it is going to take a little trial & error on your part to get it right.

And here is my poorly edited result from Monday - Canon 1100D, 102mm triplet, 105 x 60s + calibration files.

[Belsamber]

Something around ISO1600 is recommended for the 1100D:

http://dslr-astrophotography.com/iso-values-canon-cameras/

[Dilsh]

Hey Draco,

That's an amazing shot.

My stacks are very grainy and the nebulosity seems washed out.

It is probably because of my Bortle 7 skies.

Will try those light polution filters but part of me just wants to go Narrow band and monochrome but obviously a big investment...but then again what isn't in this hobby.

Thanks for that reference Belsamber. Will try ISO1600.

Cheers guys,

Dilshan

[Outcast]

Another useful tip... Turn off everything you can in the camera, shoot only in raw no jpeg... Turn off pretty much (read all) in camera processing of any kind..including noise reduction, it's uneccessry for what you are doing & adds electronic noise & contributes to sensor heat.

Also, hop on eBay & find yourself a 'dummy' battery, mains adapter.... You can use it as is connected to 240v or, check the DC requirement for eos1100d & look for a DC regulator, then you can run it off 12v battery.

For example, my 70d wants 8.1v so, I have a regulated output on my power distribution box that can be varied, it's set to 8.1v... check for the 1100d it may want less or might want more, it matters... A lot!!...:)

Why do this I hear you ask, more noise & heat reduction

These small things will add up & assist in dropping the noise levels in your subs significantly for a very modest outlay if you go the dummy battery path or, totally free if you discount that...

[Drac0]

Thanks, it's a target I can't wait to tackle with a dedicated astro cam.
The light pollution would be a big factor, it adds more noise than sensor heat. I don't know how good your editing skills are but some of it can be overcome. Are you taking calibration frames?
Imaging in mono can give fantastic results, but as you say, it's a big investment, not only financially but in time, really requiring at least 3 or 4 times as long. With the current long run we've been having with bad weather here I'm glad to have one shot colour to work with to be able to take advantage of the few clear nights we have had in the last few months.
ISO 1600 is a good setting because it's at that point the graph levels out. But with the light pollution you have the difference between 800 & 1600 will be little, but 1600 may give you a little more room to work when stretching the image. I use either depending on the conditions but definitely 1600 under darker skies.


Good luck & clear skies.

[Dilsh]

Hey Draco,

I am using flats and dark frames. I agree it must be the light pollution. I am using PixInsight for post processing (still learning) and that has helped.

Just purchased a EAF. Hopefully that will help with focus as well.

Cheers for the help and clear skies.

Dilshan