Photographic Dynamic Range (PDR) is a More Useful Measure than the DxOMark Landscape Score

Started Apr 17, 2015 | Discussions thread
Detail Man
Detail Man Forum Pro • Posts: 17,073
Re: Clarification - Read Noise and Engineering Dynamic Range

bclaff wrote:

Detail Man wrote:

bclaff wrote:

Iliah Borg wrote:

Above 10 stops flare starts to play significant role in real-life shooting.

Detail Man wrote:

If such is indeed the case, how (at least in relevant, so affected cases) might such phenomena influence the ("practical", "real world") significance of both "PDR" as well as DxOMark numbers ?

Since PDR measurements are made from photographs I suspect that any other influence, such as flare, would be built in to the results.

If we are talking about flare appearing in the region around -10 EV below maximum levels in your "PDR" source image-data, those effects would seem to have significant effects upon the data (?) - whereas DxO Labs' DxOMark testing is performed on image-sensors without attached lens-systems.

Yes, but remember, I'm trying to produce a measure that has photographic significance.

When was the last time you took a photo without a lens?

The last time that I recorded dark-frame RAW images on my Panasonic DMC-GH2. As no light was allowed to illuminate the image-sensor, it seems that there might as well have been no lens attached.


Bill Claff wrote (shown in the italicized quoted statements from this thread below):

Regarding "sensor characterization" as being distinct from "lens/camera system characterization":

There is no doubt that read noise (engineering dynamic range) is a key sensor characterization.

Regarding the "PDR" testing regimen as conducted:

In this area of the PTC we are still very much in the read noise dominated region.

Regarding the potential "visibility" of (periodic and random) Read/Dark noise components:

If an image or an area of an image is entirely read noise then it has no detail and is essentially black.

I mean that a measure that is solely read noise and has no photon noise component is not photographically relevant. (It has engineering relevance.)

Is anyone really arguing that read noise in the absence of photon noise is relevant to landscape photography?


(I don't want to wander too far OT ...

Such does not (to me) seem "off topic" to a discussion of the averment you have made that: "Photographic Dynamic Range (PDR) is a More Useful Measure than the DxOMark Landscape Score".

... but you could argue that the lens used affects the results in a way that is different for different lenses and undermines the repeatability of the PDR measure. When I have had multiple sets of data from different lenses I have not found this to be so.)

Question: Is your defined (linear) SNR=20 test condition then modified by (or, does it somehow take into account) any lens-system flare effects existing within the test-shots that are then relied-upon ?


It seems that the (actual) amount of image-sensor illumination that exists in the test-shots relied upon due to lens-flare - even if those amounts by your estimation appear to be comparable in the case of the use of different lens-system on the same camera body - is not a known quantity (and thus the SNR that the image-sensors have operated at is also an unknown) ? More "real world" ?


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