Why the x100s files are lacking

Started Mar 29, 2013 | Discussions thread
Jeff Charles
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Re: Why the x100s files are lacking
In reply to Asylum Photo, Mar 29, 2013

Asylum Photo wrote:

Jeff Charles wrote:

Asylum Photo wrote:

I love how this ISO problem is getting worse and worse as people discuss it. Started off at 1/3 of a stop off, now we're up to almost two stops off. Oh, Internet, you continue to amuse.

The study that the OP quoted measured ISO brightening prior to raw conversion. Other assessments of the X100s's actual ISO values have been after gain was added in-camera prior to JPEG creation, or on the computer during the rendering of the raw file.

It does appear that the final, or actual, ISO of the X100s, after all processing, applies up to a stop less brightening than some other cameras. In the field, this is not particularly relevant. However, it can matter when comparing cameras.

One thing that does matter in the field is that the X100s's max auto ISO of 6400 is actually less than 6400.

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Jeff
"Please proceed..."

So is it your assessment that Fuji is the only company to have a low "real" ISO ceiling, and use gain to "cheat"? I was under the impression that this was very common practice.

No. I'm sure that other companies do the same. And it is not "cheating." I also would not use the term "real ISO."

ISO brightening is done by applying analog or digital gain. For cameras with high read noise, i.e., noise caused by their electronics, analog gain is beneficial. However, in low-read noise cameras, which I assume the X100 and the X100s are, digital gain is fine. And digital gain applied in-camera or on the computer are equivalent.

So, Fuji's approach is perfectly OK. However, at a given ISO, it does appear that the X100s applies less total gain, i.e., less total brightening after all processing, than some other cameras. That's fine, except when we compare results at the same ISO, and different exposures (apertures / shutter speeds) have been used to equalize final image brightnesses. It's just something to be aware of.

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Jeff
"Please proceed..."

 Jeff Charles's gear list:Jeff Charles's gear list
Fujifilm FinePix X100 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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