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Old Mar 18, 2006, 11:52 AM   #1
Log
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when reviewing sensitivity on cameras i found that several say things like "3200 with ISO boost"

help me out a little bit, im still learning, what does it mean by ISO boost? and if it says "3200 with ISO boost" does that mean that it can reach ISO settings of 3200?

your help would be appreciated. thanks
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Old Mar 18, 2006, 11:57 AM   #2
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I don't know about other mfrs, but with Olympus, ISO boost basically means "we don't recommend your using the camera at this speed, so don't say we didn't warn you." It simply means you're raising the sensor gain to a place beyond what the mfr belives will produce best image quality. Yes, you can use ISO 3200, but you will experience more noise. However, there are so many good NR programs out there these days that the scary talk about noise is frequently overblown. I use ISO 1600 fairly frequently with the E-300 and find that noise is handled quite well either with the native NR in Silkypix, or with standalone programs like Neatimage.
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Old Mar 18, 2006, 11:58 AM   #3
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I believe this refers to cameras that cheat to achieve high ISO by reducing resolution. Which camera?
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Old Mar 18, 2006, 12:00 PM   #4
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Yes, you'll still have the equivalent of ISO 3200 if a model shows it's available.

Extracting an image from a sensor is a complex process.

For ISO speed increases (a way to make a camera more sensitive to light), you've got more than one way of accomplishing it. One is by amplifying the output of the signal generated by each photosite, prior to the analog to digital converter.

Another is to multiply the RGB values for each pixel, after the analog to digital conversion.

It's my understanding that when the values are multiplied after the analog to digital conversion, it's referrred to as ISO boost (or sometimes "extended" ISO), and can negatively impact dynamic range.

Basically, you've got an image that's underexposed after the image is stored in digital format. Then, the manufacturers multiple the digital values stored to simulate a higher ISO speed (more sensitivity), so that it appears properly exposed.

But, only the manufacturers know for sure how it's being accomplished for a given camera model.

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Old Mar 18, 2006, 12:22 PM   #5
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JimC wrote:
Quote:
Yes, you'll still have the equivalent of ISO 3200 if a model shows it's available.

Extracting an image from a sensor is a complex process.

For ISO speed increases (a way to make a camera more sensitive to light), you've got more than one way of accomplishing it. One is by amplifying the output of the signal generated by each photosite, prior to the analog to digital converter.

Another is to multiply the RGB values for each pixel, after the analog to digital conversion.

It's my understanding that when the values are multiplied after the analog to digital conversion, it's referrred to as ISO boost (or sometimes "extended" ISO), and can negatively impact dynamic range.

Basically, you've got an image that's underexposed after the image is stored in digital format. Then, the manufacturers multiple the digital values stored to simulate a higher ISO speed (more sensitivity), so that it appears properly exposed.

But, only the manufacturers know for sure how it's being accomplished for a given camera model.
Interesting.

I also wonder why some manufacturers will list a camera's top ISO as, let us say 1600 with boost, while others simply say, 1600.

But if you shoot in RAW and can increase the exposure by one stop, you are also effectively doubling the ISO. So would this be called boost or no boost?:lol:

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Old Mar 18, 2006, 12:31 PM   #6
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DBB wrote:
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But if you shoot in RAW and can increase the exposure by one stop, you are also effectively doubling the ISO. So would this be called boost or no boost?:lol:
Yep, you're boosting or pushing it, whichever term you prefer, and all the software is doing is increasing the RGB values stored for each pixel to make it render brighter when interpreted by a viewer or editor.

But, dynamic range can suffer when you do that (as you are also boosting the shadows, losing some of the low end as you move the high end up brighter, and clipping off any high end that was already at maximum values).

The latitude you get shooting in raw is nice. But, it's no substitute for a properly exposed image.

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Old Mar 18, 2006, 12:38 PM   #7
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P.S.

You may have read this before, but it touches on loss of Dynamic Range when underexposing:

http://www.luminous-landscape.com/tu...se-right.shtml


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