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Old May 25, 2010, 11:15 AM   #1
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Default What does ISO 3200 Enhanced H mean?

What does the ISO Enhanced H mean when I look at the specs on a 30d?
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Old May 25, 2010, 11:25 AM   #2
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Well...

Originally, that meant that the exposure was being "pushed" by underexposing, then multiplying the values in the raw file to simulate proper exposure, versus using analog amplification.

For example, it's giving you the same thing as you'd get by shooting at ISO 1600 using settings that are one stop underexposed (like using shutter speeds twice as fast for a given lighting and aperture at the ISO 3200 setting, compared to what you'd use for proper exposure at ISO 1600). Then, multiplying the values associated with each pixel by 2x to brighten the exposure so that you'd get a properly exposed image using the faster shutter speeds to simulate a higher ISO speed.

Anymore, with newer cameras, it's hard to tell what's really expanded (digital amplification by multiplying values) and what's really native (analog amplification) without carefully examining characteristics of the raw files to look for clues (such as dynamic range shifts, etc.).

Most newer cameras claim they have higher native ISO speeds than they really do, when in many cases, digital amplification (multiplication of values in the raw file to give you a brighter exposure) is being used at anything much over ISO 800 or 1600; even when much higher ISO speeds are available without using the so called "expanded" ISO ranges. Using digital amplification to give you higher available ISO speed settings will negatively impact dynamic range in the shadows, as compared to analog amplification (since you're underexposing, then "shifting" the exposure to the right by multiplying the values associated with each pixel).

That's not necessarily a bad thing though when shooting at very high ISO speeds (since you'd shift your black point level by reducing Dynamic Range in darker areas, which can help to hide shadow noise).
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Old May 25, 2010, 11:38 AM   #3
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So, do the newer cameras do the same thing, without that nomenclature, or does the newer processor or something give them better, or higher ISO ?

Would a 30D ISO 3200 H give me better low light pictures than my XT ISO 1600, with not much noise? Same lenses, canon 85mm 1.8
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Old May 25, 2010, 11:46 AM   #4
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Quote:
Would a 30D ISO 3200 H give me better low light pictures than my XT ISO 1600, with not much noise? Same lenses, canon 85mm 1.8
Chances are, noise versus detail is going to be roughly comparable if you had camera settings that simulated close to the same image processing (sharpness, contrast, etc.), which may require dialing back some of the default settings with the XT versus the 30D.

But, your XT doesn't give you an ISO 3200 setting. So, to simulate the same thing using the ISO 1600 setting with the XT, you'd need to deliberately underexpose by one stop to allow faster shutter speeds for a given aperture and lighting (by using a -EV setting of 1 stop with Exposure Compensation, or moving the needle one stop to the left of center with your manual exposure settings), then brighten the image in post processing.

The 30D would likely have the advantage shooting jpeg since it's probably doing the multiplication of values at the raw level, prior to the demosaic process to convert to jpeg. Shooting raw, I doubt you'd see much difference between them if you deliberately underexposed by one stop with the XT at ISO 1600 and brightened later during raw conversion using the Exposure slider to simulate ISO 3200; versus correctly exposing with the 30D set to ISO 3200 without the need to brighten later (since the values associated with each pixel would have already been multiplied by the camera to give you proper exposure using the ISO 3200 setting).

P.S.

For ISO 1600 and lower settings, underexposing and brightening to simulate higher ISO speeds is a bad idea with a camera (since noise will be worse with underexposed images). But, since using ISO 3200 with the 30D is an "expanded setting" (which is basically the same thing as underexposing and multiplying values associated with each pixel), then differences in quality underexposing with the XT with it's ISO 1600 setting to simulate the same thing, then brightening later in PP, should be minimal).
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Old May 25, 2010, 11:49 AM   #5
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3200 iso on the 30D is quite noise. The T1i has a better sensor that deal with 3200 iso allot better then the 30D.
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