The X-Factor of Fudging ISO

Started 5 months ago | Discussions thread
24hrexposure
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Re: The X-Factor of Fudging ISO
In reply to Charles C Lloyd, 5 months ago

Charles C Lloyd wrote:

I find it interesting that sites such as dpreview have not caught onto this "deception." For example, the dpreview camera reviews base their comparisons on the ISO reported by the camera rather than the aperture, shutter speeds, and focal length. It appears dpreview editors go to great lengths to have controlled experiments so head-to-head comparisons are easy to do and are meaningful. And yet, they base their comparisons on this imputed value, ISO, rather than the fundamental dimensions of the camera settings and allow themselves to further the "deception" (or whatever it is).

So, dpreview editorial staff if you are listening, please rework your reviews to accommodate this slack in manufacturers' claims. That is, ignore the ISO/ASA from the camera and compute your own value, maybe per the "International Organization for Standardization" specs.


This is exactly the issue. If a camera's "ISO 6400" requires an exposure time you'd expect of ISO 3200, then calling it 6400 is a lie. dpreview could eliminate any fudging of the numbers by comparing cameras using the same lens and shutter speed. If one camera underexposes because it has fudged its ISO numbers, then the proof will be in the pudding when you see the noisy images.

This also highlights the futility of comparing ISO numbers across formats. If you put the new Metabones speed booster on your APS-C camera (all it does is shrink the image circle to match the smaller sensor), then using the same lens and shutter speed as a full-frame camera allows a lower ISO, eliminating some of the noise advantage. It's the same lens and the same light, just concentrated over a smaller area, so each pixel gets more.

Edited 5 months ago by 24hrexposure
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