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Poll: What is your general ISO setting for DSO's
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What is your general ISO setting for DSO's

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  #21  
Old 22-12-2009, 05:50 AM
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Is Humayun corrupting you too, JJJ? Taking away our quick gratification with the promise of cleaner, better quality images. It's a dirty trick, I tells ya.
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  #22  
Old 22-12-2009, 09:02 AM
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  #23  
Old 22-12-2009, 09:14 AM
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Unless its a good bright object ISO800 for me. Its the closest setting for unity gain (thought with the 20D it really splits the ISO at 1200, but being modded I'll still use ISO800). For me its a case of multiple images with higher ISO to improve the quality and S/N ratio rather than more -e/ADU to reduce the noise. (http://www.clarkvision.com/articles/...tml#unity_gain)


If you've not taken the time to read the Clarkvision site I'd recommend it for those that would like to know a bit more about the inner machinations of DSLR chips. Slip down to part 4 and check out the links
http://www.clarkvision.com/articles/index.html#part_4
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  #24  
Old 23-12-2009, 08:15 PM
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Quote:
Originally Posted by [1ponders] View Post
Unless its a good bright object ISO800 for me. Its the closest setting for unity gain (thought with the 20D it really splits the ISO at 1200, but being modded I'll still use ISO800). For me its a case of multiple images with higher ISO to improve the quality and S/N ratio rather than more -e/ADU to reduce the noise. (http://www.clarkvision.com/articles/...tml#unity_gain)


If you've not taken the time to read the Clarkvision site I'd recommend it for those that would like to know a bit more about the inner machinations of DSLR chips. Slip down to part 4 and check out the links
http://www.clarkvision.com/articles/index.html#part_4
Interesting read. Thanks Paul. I won't feel quite so guilty sticking with 800 most of the time.
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  #25  
Old 23-12-2009, 08:57 PM
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  #26  
Old 19-01-2010, 10:23 AM
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Hi All,

I just voted 400 because of what i used to use with film SLR's.

Having said that i am thinking longer exposure = more noise due to thermal and electrical interference in a DSLR, so after trial and error 800 would be where i would probably end up.

Does my thinking make sense?

Cheers, Duncan
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  #27  
Old 25-01-2010, 12:45 PM
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philiphart (Phil Hart)
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good topic for a hearty debate! I agree with the general sentiment from others that it often makes little difference.

In my view, it is not possible to make any generalisations across cameras.. you have to test your own camera to find out what works best. with my old 20D, i proved to myself that ISO1600 gave the best results for faint details.

with the 40D, there is very little difference between different ISO settings. here is my test comparing same total exposure time with different ISO settings (among other things):

http://www.philhart.com/canon_test

Here was my finding at the time: "There is little difference between ISO1600 and ISO800 with the 40D, with 1600 perhaps having a slight edge. Noise increases (only slightly!) at ISO400 and ISO200 without delivering any benefit in saturation or bright area detail."

Obviously higher ISO settings have higher noise in an individual exposure, but the signal also goes up. So what matters is the signal to noise ratio and whether that ratio gets better or worse as the ISO setting increases. The differences are often subtle since the ISO amplification will necessarily increase both signal and noise by close to the same amount (there being no such thing as a free lunch) with the end result being at least partly governed by read noise and other factors.

So every camera performs differently, but I think the 40D performance would be typical of a well engineered camera. But I encourage you not to place blind faith in generalisations nor pay attention to the grainy appearance of one high ISO sub. Take a series of subs with your camera under the same conditions at different ISO settings, stack them together and make an objective assessment of what works best.

Phil
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  #28  
Old 11-02-2010, 07:51 PM
stevous67 (Steve M)
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Noise? With or without cooling.

http://www.mpas.asn.au/Astro/Tips/cool_or_not.htm

Bye

Steve
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  #29  
Old 12-02-2010, 12:00 AM
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I've used both 800 and 1600 on a Canon 350D with roughly equal results. After post-processing I've never been able to notice a substantial advantage to either one, but my experience may be camera-specific.
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