Should I raise my ISO?

[smr]

Hi all. Imaged Andromeda last night and will image again with clear skies forecast later.

Just wondering though... at ISO 200 and 3 or 5 minute exposures my histogram data looks very close to the left. Is it ok or should I raise my ISO up to bring the data over to the right a bit more?

5 min at top and 3 min below

Edited August 7, 2019 by smr

[Scooot]

http://dslr-astrophotography.com/iso-dslr-astrophotography/

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

These articles should help. Assuming you’re using the Canon 80D in your signature it suggests ISO200 is the most appropriate.

 

[smr]

Yes, thanks. Just didnt know if i was clipping any data?

[Scooot]

If I understand the article correctly, and you are clipping your data, increasing your ISO beyond 200 for your camera wont help, because you’ll increase your noise by the same amount the signal is amplified. So if you are clipping it you need a longer exposure. However, I’m not sure you are as you’re clearing the left edge.

 

[smr]

18 hours ago, Scooot said:

If I understand the article correctly, and you are clipping your data, increasing your ISO beyond 200 for your camera wont help, because you’ll increase your noise by the same amount the signal is amplified. So if you are clipping it you need a longer exposure. However, I’m not sure you are as you’re clearing the left edge.

 

Thanks Scooot yeah that makes sense. Left it at ISO 200. 

[Nigella Bryant]

Hiya, my histograms are usually a little more to the right, but I shoot at Iso800 on a canon1000dm. 

[catburglar]

If iso200 is optimum for that camera and I got that histogram I’d be tempted to expose for longer to get more signal in each frame.

Obviously you need to make sure your guiding is good enough for the longer exposures and you don’t introduce too much thermal noise.

[Alien 13]

The 80D is a bit of an oddball in the Canon range as its more like a Nikon camera, the theory suggests that an ISO less camera suffers no image degradation when shooting at say ISO 200 and applying post processing gain than if it was shot at a higher ISO in the first place.

The gain applied however is slightly different, the camera ISO control is effectively analogue gain like a volume control and post processing purely digital in that it multiplies the values. I expect there is a compromise between the two methods although its probably best to stick to low ISO values but still worth experimenting.

Alan

[smr]

I did mostly 5 minute exposures last night. As a test at the end of the imaging session I did a 10 minute exposure... 

[SteveNickolls]

Hi, if you haven't already seen this it is worth watching it may help you save time regarding exposure times-

There's also a handy calculator here to input your own imaging site, camera and filter data-http://tools.sharpcap.co.uk/

Best to experiment with different values and see what actually works for you at your imaging location.

 

Happy imaging.

Cheers,
Steve