Fuji X-series: Overexpose or underexpose high-contrast scenes?

Started 8 months ago | Discussions thread
Ysarex Senior Member • Posts: 2,855
Re: Fuji X-series: Overexpose or underexpose high-contrast scenes?

Easy Lee wrote:

Ok, I am pretty confused now. I am having a hard time understanding the concept of the ISO-less sensor ...

That's understandable. The article you read and linked to utter rubbish is wrong. It's not just wrong. It's clueless ridiculous nonsense. You need to do a reset here.

"Once upon a time digital camera sensors would increase the energy pumped into them to make the photosites more sensitive to light in order to increase ISO." Complete fantasy nonsense.

"At some point Sony figured out that doing so was unnecessary, that the camera, even in very dark areas, was recording a lot of information. Thus, the “ISO-less” sensor was born." No, ridiculous rubbish.

"An ISO-less sensor, which modern Sony-made sensors are, increases ISO by simply increasing the luminosity levels with software." So wrong.

"You can try this at home by capturing an exposure at ISO 6400 and a RAW exposure at ISO 200 underexposed by five stops, then brighten the underexposed file in software to the correct exposure. You’ll notice that the the two files now look the same." No.

"In other words, the camera is actually capturing every shot at base ISO and increasing the brightness after the exposure for whatever ISO was selected. You are completely unaware, and it is automatically done, even to RAW files. That’s why they call it ISO-less."

Since I started quoting him I haven't skipped a single sentence and he hasn't gotten one correct.

"Have you ever wondered why base ISO on Fujifilm X cameras is ISO 200? It’s actually a software trick. The real base ISO on the sensor is ISO 100 (which is available as an “extended ISO”), but the camera applies a curve in software to pull more details out of the shadows, essentially underexposing the scene and then increasing the luminosity of everything (except the highlights) to maximize the dynamic range." Completely wrong.

"This is also why some people claim that Fujifilm “cheats” with their ISOs." Nope.

"The Dynamic Range settings don’t mean anything to RAW files, but they have a big effect on JPEGs." And wrong.


Sorry that happened to you. A sensor is ISO invariant when read noise in the system is negligible. Otherwise ISO is most commonly implemented by the application of analog gain to the sensor signal and/or digital scaling in the the ADC and/or both which permanently alter the raw file saved by the camera. The article's author is completely wrong in his understanding of ISO invariance. And he is completely wrong about his understanding of Fuji's DR modes.

In high contrast scenes expose to place the diffuse highlight at the sensor clipping threshold and then post process for the midtones and shadows. You can't ignore ISO since raising ISO will reduce sensor dynamic range. In high contrast scenes try and use base ISO where sensor DR is greatest.

It's going to take a lot to clear up the rubbish you picked up from that article. I'll check back later.

Post (hide subjects) Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow