D-Range

[MrB]

Contrary to what some people might think, this has nothing to do with my sanity, but it is a setting in the menus of my dslr to widen its dynamic range - Highlight Correction can be Off or On, and Shadow Correction can be Off, Low, Medium or High. Two questions that don't appear to be answered by the User Manual:
1. Does D-Range affect Raw, Jpeg or both?
2. Would it be wrong to leave these settings on? (i.e. Is a wider DR desirable for most shots?)

Philip

[Donald]

Contrary to what some people might think, this has nothing to do with my sanity,

Mmmm?

Philip - I don't know. What camera are we talking about?

If we are looking at something that impacts on the final image and is done in-camera, then I suspect that we're talking about something done to JPEG files. My understanding is that if you're shooting RAW then it doesn't matter what settings you put that to, it shouldn't impact of the file in any way at all.

Now, I hope someone who knows more than me will come in and tell us if I'm wrong.

[Dave Humphries]

Hi Philip,

Most likely; if you use the camera manufacturer's own software to start your RAW PP, it will be effective, even in RAW, but if you use say, an Adobe product, or DxO, it won't. However, I am not 100% sure, it may depend how these features are implemented - I can actually imagine a way it may affect RAW pixels.

Sorry I can't be more definitive.

As Donald says, it'll help a lot to know the exact model we're discussing.

Cheers,

[MrB]

Donald and Dave - the D-Range settings are in the photo capture (i.e. shooting) menus of the Pentax K-r and K-5 dslr cameras.

Philip

[Hero]

Hi Philip,

Most likely; if you use the camera manufacturer's own software to start your RAW PP, it will be effective, even in RAW, but if you use say, an Adobe product, or DxO, it won't. However, I am not 100% sure, it may depend how these features are implemented - I can actually imagine a way it may affect RAW pixels.

It's stored in the image's metadata. So they are not much more than a bunch of flags. For a speedy workflow, a good rawconverter should pick-up on all these flags and pre-set them in the UI. that way you'll be able to quickly save the image if no further pp is needed.

Oh and Donald, speak out loud; Dee-range(d) :P

[shreds]

Dave, i concur as far as Nikon is concerned. Assuming D-Range for Pentax is similar to Active D lighting for Nikon, then if using ADLighting, a sidecar file will produce different results in say Nikon NX2 as opposed to CS5 which wouldnt read the Nikon sidecar.

However, the RAW data is fundamentally not affected unless you start fiddling with the other controls based on what the camera is telling you. Bearing in mind the fact that rear screen always displays a jpeg, means that you wont always be getting what you see!

I assume that the same basic principles apply to Pentax and Canon etc as well.

[Tringa]

Have a look at this link to a review of the K5. It says the highlight end of the dynamic range expansion applies to JPEGs and RAW files; the shadow end applies to JPEGs only.

http://www.dpreview.com/reviews/pentaxk5/page14.asp

Dave

[Inkanyezi]

Dynamic range cannot be extended for RAW files; they have the dynamic range that the chip is designed for, which is highest at lowest ISO setting and shrinks at higher ISO.

However, the camera firmware may have different approaches with the esoteric settings, as for example Nikon's Active D-lighting holds back exposure to save highlights, a feature that might be implemented in Pentax as well.

I don't have any experience with Pentax, but I know for sure, that camera manufactures of different brands have blatantly lied about these features, so you must try them out for yourself to see what they actually do. I have a Panasonic Lumix G1 camera with an "Intelligent exposure" feature, and I also have scrutinised test shots from Canon 40D and 550D, which indicate that both these manufacturers have not implemented any such feature, even though there is a menu choice for it, and they chose, knowingly, to lie to their customers about it. However, Nikon has a such feature that works; their Active D-Lighting holds back highlights by exposing less than without that setting.

So your Pentax might have a working option for holding back highlights, akin to the one in Nikon cameras. But don't think too high about it. In a DSLR camera, no automatic highlight measuring can be done, as the camera cannot analyse the image before the shot is done. With some luck, the designer may implement a highlight measuring feature in the AF sensor system, bettering odds for highlight analysis before the shot, but there's nothing that says any highlight will fall within the sensor area.

So Nikon's approach is using its averaging metering and "underexposing" two steps, whereupon the jpeg conversion lifts shadow areas to compensate for those same two steps. If your scene has low contrast, it will be noisy and dull by this approach, but it works well for high contrast scenes. I guess that answers the question whether it would be a Good Thing to leave it on forever. If it were, it would have been the default factory setting.

It boils down to an approach to photography initiated long ago, the Zone System, best described by Ansel Adams in his book The Negative. Dynamic range in can be controlled essentially by two means, which are similar for digital photography and film: exposure and development. For digital, highest dynamic range is always at lowest ISO setting. Whenever a lower range is present, a higher ISO may be used without loss. In digital photography, the highlights set the limit, and therefore, to use the dynamic range fully, a highlight reading must be taken. No camera presently does that automagically.

So back to your camera; it has been tested, and the DPReview shows that there are differences in the image when shot with different settings. It may serve you, if you learn how it works in practice, and for subjects with higher dynamic range, the jpegs may come out better when the settings are on. Probably, but you will have to try it out, it will expose somewhat less when the highlight setting is on, which for a RAW file will be the same as compensating toward minus.

[MrB]

Thank you all for your helpful replies, ideas and links. In addition to looking up Pentax, I will also read about the Nikon's Active D-lighting, which probably works in a similar way.

Cheers.

Philip