The Advantages of DR400 vs DR200 vs DR100 - High Contrast Scene

Started Sep 2, 2013 | Discussions thread
OP Trevor G Veteran Member • Posts: 6,577
Re: ISO 640 example at DR400

CAcreeks wrote:

Trevor G wrote:

I think Trev said that in PASM with M size and ISO 400 or higher and DR 400 (or ISO 200 or higher and DR 200), we are using software EXR. Maybe he can elaborate.

No need to elaborate - that's what I said (or wrote).

At the URL below, EXIF on my image claims Development Dynamic Range = 400, which means DR400. ISO = 640.

I guess without the Raw counterpart, I have no way of telling whether it is hardware or software EXR.

It's very simple.

DR works in hardware (sensor pixel pairing, 2 frames per image) at up to ISO400 with DR400, but at ISO400, while 2 frames are recorded, they are both at the same shutter speed.  Therefore, there is no EXR (hardware) DR at ISO400.

Below that, when ISO is less than DR, the EXR hardware system works to give two separately exposed but simultaneously recorded images which are combined in-camera to produce a single JPEG from the 2 frames.

With DR200, ISO must be at 100 for hardware EXR (2 simultaneous frames recorded per image) to work.

Please note that  the hardware  versions of EXR does not occur,  even when DR 200 or DR400 is selected, if there is not sufficient high contrast image content above 0EV to trigger it.  That is, both frames recorded will be at the same shutter speed or duration.

I'll post examples of that at some stage.

And yes, you are definitely in software EXR at ISO640.

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Trevor G
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