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Author Topic: 20D ISO Extension  (Read 2858 times)
milanissimo
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« on: September 01, 2005, 06:55:00 PM »
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There is absolutely no problem with iso 3200 expansion. As far as I know, you also have to turn iso expansion on 1-D series cameras (which will expand iso to 50 and 3200), but somebody correct me if I'm wrong. Today, I shot few images at iso 3200 in low light, but overally it was sunny day (the dog I shot was in shade and I didn't want to use the flash, and I got decent shutter speed at iso 3200) and when I loaded the images to computer, I just asked myself "where did the noise go?" However, if you'll shoot in the dark, then noise will be more obvious, but still you don't have to worry about it much.

I'm afraid I cannot understand your second question.
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LesGirrior
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« Reply #1 on: September 02, 2005, 06:34:35 PM »
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The 3200 iso is a custom option so that people who don't completely understand iso and how it affects your picture and who won't enjoy the amount of noise don't accidentally set it that high.

As ronnynil mentioned, noise reduction will double your exposure time.  For 15 second night shots, it will take 30 seconds total.  15 for exposure, 15 for noise reduction.  I personally don't like to wait.

Do a google for "dark frame subtraction" if you want more info on how it works.
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maz
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« Reply #2 on: September 01, 2005, 05:07:52 PM »
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Something that's confused me since I got the 20D - this has an ISO range of 100-1600 out of the box, which you can extend to 3200 through the custom settings. Is there any good reason why I shouldn't do this? Does something get degraded if I do? If not, then why did Canon feel the need to make it a custom menu option? I feel as though I'm missing something here....

Also wondering why I might not turn on noise reduction for long exposures...?
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Ronny Nilsen
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« Reply #3 on: September 02, 2005, 03:36:56 AM »
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I belive that iso3200 is done in sw in the camera. It's a 1600 exposure underexposed 1 stop and then multiplied up. You could do the same by shooting at 1600 and underxpose 1 stop, and then correct it in PS.

Up to 1600 the amplification is done in hardware (sensor).

Noise reduction. Well, by turning it on you can't take another picture before the nr is finished (doubles the exposuretime with long exposures). But I have it on as I find it useful and can normally wait in those situastions (exposure time > 1sec.), but some migth prefer to take a darkframe manually and do prosessing in PS.
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Hutch
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« Reply #4 on: September 02, 2005, 08:15:10 PM »
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Like you I've went into custom functions and turned both "H" on along with Noise Reduction and am glad I did.

When I put the 20D in H I am able to capture a very low light image that otherwise I wouldn't have been able to capture.  For instance a long candlelit table of people.  A flash would wash out the soft candlelight glow, would be harsh on the people in the foreground and would make the people in the background dark.  

I find the images to be surprisingly fantastic.

Andy
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