noise performance of x-e1 and iso accuracy.

Started Feb 22, 2013 | Discussions thread
Jeff Charles
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Re: noise performance of x-e1 and iso accuracy.
In reply to Ariston, Feb 25, 2013

Ariston wrote:

Jeff Charles wrote:

Excellent post.

wchutt wrote:


Differences in ISO between cameras is irrelevant because exposure alone determines the signal to noise ratio.

Differences are not relevant when you are using the camera, but they can be relevant in ISO tests by sites like dpreview, since ISO values can vary from camera to camera.
However, the basic problem with dpreview's tests (and other sites are similar) is that they compare cameras at the same ISOs, rather than at the same exposures. Their protocol, from many examples I've looked at, appears to be as follows:
A moment's thought, taking into consideration the facts in your post, makes it clear that this protocol is flawed. It gives an advantage to cameras with underrated ISOs, because their images receive more exposure.
  • Standardize scene illumination
  • Set each camera to the same ISO
  • Set each camera to the same aperture
  • Vary shutter speeds to produce equally bright final images
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Jeff
"Please proceed..."

it does but it would be tedious work and much confusing considering that they have to cite in each review that each camera was measured according to manufacturer's specification and actual exposure capacity which might make a comparison too difficult if not impossible to obtain in time, possibly taking a year or more just to complete a full review and comparison which would already be long overdue and new cameras are around already. sites like dpreview just put one basic common denominator for fast/quick available measurement.

DPR would need to change their methodology, but tests would not take longer. The new method would consist of taking a series of photos at specific exposures, and then standardizing the final image brightness of each photo by either adjusting ISO or applying digital gain on the computer.

Granted, they are probably not going to do this, because the idea of ISO testing is so entrenched, but it would give more comparable results.

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Jeff
"Please proceed..."

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Fujifilm FinePix X100 Sony Cyber-shot DSC-RX100 III Fujifilm X-E2 Fujifilm XF 35mm F1.4 R Fujifilm XF 18-55mm F2.8-4 R LM OIS
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