Jack Flesher
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 p.84 #12 · Fuji GFX Image Thread - all cameras and lenses | |
ruthenium wrote:
Jack, first - I don't use DR200 and DR400. These are confusing options, for sure. When I first encountered the two, I tried to obtain as much information as possible. At the end, I am not 100% sure I know what the camera is doing. What I have learned basically aligns with what you say: the camera underexposes by -1 and -2 stops respectively in DR200 and DR400. The objective is understood: to avoid clipping the highlights as much as possible. This is also understood that this exposing-to-the-left should negatively impact the shadows. This is unless there is some sort of dual-gain processing like Panasonic is doing in some of their cameras, or in the new Sony A7V. I don't know this, and this seems unlikely. Thus, if there is no clever way of processing, the HD200 and HD400 result in a loss of the dynamic range, and this isn't what I want from my camera. The metering on the GFX100S II already seems rather conservative to me, by at least -1/3 or possibly -2/3 of a stop. Thus, underexposing further is not something that I expect to be useful or generally needed. These HD200 and HD400 settings are unique to Fuji. I have not encountered such processing on Sony, Olympus, OM, or Panasonic bodies. There must be some thinking behind HD200 and HD400, but I have not seen a clear explanation for reducing the camera DR.
What is not quite clear to me is how exactly the camera does underexposing? I have just looked through the viewfinder toward my monitor. With HD100 and ISO 500, the SS was 1/5s (I closed the aperture to F8, on the lens). I switched to HD200, then to HD400 - and, nothing happened! The ISO and SS remained unchanged. This doesn't quite make sense to me. When I used exposure compensation, to underexpose by -1 stop, naturally the SS changed to 1/10.
Do you know how the exposure can be reduced by 1 or 2 stops without changing the aperture, SS, and ISO? This seems impossible. I am sure I am missing something here. This is why I said above that I am not 100% sure I know what the camera is doing....Show more →
Your experience mirrors my own when I had the GFX and to a large degree even in the XH2. When I initially went to Fuji, I dug into DR and found out pretty quickly that Fuji was pretty vague on exactly what was happening under the hood. Fuji does say however that it's a jpeg DR tool for whatever that's worth. What is obvious is that DR200 reduces a raw exposure by 1 stop and DR400 does it by 2 stops. The methodology of the underexposure is unclear, and I never bothered trying to figure it out since I am primarily a raw shooter and simply turned it off when I learned it was a tool specifically for enhancing jpeg DR.
What we do know is that a jpeg can only hold about 8 stops maximum of DR, yet with a gamma curve about 10 stops can be "compressed" visually into it -- and I suspect this is at least similar to what Fuji is doing under the hood via DR200/400. We also know the Fuji raws can hold over 12 stops, so underexposing 2 won't hurt them a lot on that 8-bit base jpeg conversion, AND at the same time it protects/retains some highlight detail. (However I do stand by my assertion that in certain circumstances, especially since it's unclear how they're doing it, the underexposure can be destructive to shadows in the higher bit raw file, i.e.; more shadow lifting and more noise.) Now they theoretically can apply whatever internal algorithm or curve internally, lift the shadows and balance the mid and highlight appearance across all 8 stops to a "reasonable" level for rendering out the 8-bit jpeg. How exactly they implement it however, I do not know...
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