Dynamic Range

Started Jan 27, 2013 | Questions thread
Mark H
Senior MemberPosts: 2,823
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Re: Difference......
In reply to Trevor G, Jan 29, 2013

Trevor G wrote:

Mark H wrote:

Trevor G wrote:

The good thing about EXR sensors is that there is absolutely no trade-off when using M size images, DR400 (or DR 200 if you like) and ISO less than DR. The camera can safely be left with DR400 switched on all the time and safely shot at 0EV exposure compensation when using RAW.

Of course there is a 'trade-off' - the trade-off is only using 1/2 of the sensor's 12MP, with an associated reduced resolution, increased noise size w.r.t. image resolution (less averaging), and increased susceptibility to certain artifacts due to having 50% less 'fill factor' (aliasing from under-sampling).

Unless you have been asleep other worthy posters have pointed out, when I posted L size RAW to JPEG conversions, that there are serious (to them, minor to me) artefacts visible. L size EXR images are also more "fuzzy" and require more sharpening.

'Unless you have been asleep'... again, this thread, and the OP's original question, was not about your RAW conversions.

Furthermore - any camera's 100% size image will look softer than the same camera's 50% size image - but that's not because the 100% is worse, it's because everything is twice the size so the limits are more easily seen.

It's generally impossible to tell the difference between L and M when L is reduced to M size, except that the really keen of eye will notice a lack of jaggies in the M. M generally looks better.

The 'best' results are obtained by using the most appropriate DR settings for the scene/subject/lighting at hand.

Using ''M' size DR400% all the time is just a 'lazy fail-safe'.

I would be interested to see how you reckon someone could calculate, on the fly, just what strength DR they need for a particular shot.

1. The camera has it's own metering - within limitations it can measure for itself.

2. As with most things in photography, a certain amount of practise and experience goes a long way.

3. Failing the above - any user can very often just shoot again, or - even use 'DR Bracketing'.

Since DR in M size does not affect anything except the amount of highlight detail available in a high contrast scene, it's sensible to use DR400 all the time. I'll show you why:

There is also absolutely no difference in the RAW output IQ from one type of exposure to the next,...

Again - this thread was not about RAW.

If the OP is not even seeing much benefit from his use of +DR%, he is hardly likely to be interested in using RAW.

He might not have to. I'm going to show how to get reasonable DR results from JPEGs, too.

Why?

Why do you think anyone doesn't know already?

The crucial point to remember is:

There is no negative result from using any DR setting above 100. DR200 and DR400 will not have any negative impact on any image - hence, you may as well use DR400 all the time when shooting M size (remember, better image quality) and DR higher than ISO.

Nonsense.

You are fixated on shooting and talking about RAW - whereas most people (and this thread, OP question) are shooting JPEG.

For anyone shooting JPEG - if they use DR400% 'M' size where the scene doesn't require it - then you not only limit yourself to 6MP resolution, but also the JPEGs will never have any values higher than about 230 (of normally up to 255).

Using DR higher than ISO means that, if you only want to use DR200, you must keep the ISO at 100. If you are happy to use DR 400, then you can use ISO 100, 200, 250 or 320. These settings give the cleanest, most natural results from EXR.

Again, this is misguided nonsense - nobody 'must keep ISO' at any level - and nobody 'must' use 'EXR-DR'.

'EXR-DR' is a significantly compromised means of achieving extended DR at low ISO - and only used at low ISO for a reason, to repeat what I said above...

"...there is a 'trade-off' - the trade-off is only using 1/2 of the sensor's 12MP, with an associated reduced resolution, increased noise size w.r.t. image resolution (less averaging), and increased susceptibility to certain artifacts due to having 50% less 'fill factor' (aliasing from under-sampling)."

Example... http://forums.dpreview.com/forums/post/50417335

As long as DR<ISO, then the camera no longer needs 'EXR-DR' - and indeed, it doesn't and won't use it.

If anyone 'wants/needs' to use DR200% at ISO200 - they will get ISO based DR, along with the benefit of either full 'L' size resolution, or alternatively the slight advantage of 'EXR-SN' at 'M' size resolution - and the same applies whenever DR<ISO (e.g. DR400% at ISO>=400).

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