Highlight Priority on the 1D Mark III . . .

I have had my 1D Mark III for almost two weeks now, and have to say that I am happy with the camera for the most part (will post a small review on my first two weeks hopefully in the next few days). I have tried the highlight priority function with several hundred shots and am trying to figure out whether it is software based or whether the image is actually captured differently. The images seem to look perfectly exposed on the camera LCD, and then when I load them up into Aperture they look great for a second, then when Aperture has loaded them all in and processed the previews they go really dark -- and I have to adjust the exposure by 1 to 1 1/2 stops. Does this mean that Aperture reads them how they were shot and the applies the "highlight priority" or is aperture underexposing the original shot? Has anyone else had some experience with this?

I have found that if I overexpose the picture by a full stop when taking the picture that the pictures look bettere exposed in Aperture -- but I hate to have to do this on all the pictures that I use the HP function on.

Not really sure to visually show you what is going on -- some help would be great. I will be testing a few shots in DPP this evening and will try to give an update.

Thanks!

did you make sure that Aperture is not setup to automatic RAW settings? i know that in ACR, when you load the image, it automatically adjust the settings unless you setup it up not to do that.

It must be a Mac OS X problem because the same thing happens when I open a "highlight tone priority" enabled image with the Mac Previewer, too. The image turns out looking darker than normal. However, ACR totally ignores the fact that the image has highlight tone priority set and processes the image just like it does any other images shot under the same condition. DPP, no surprisingly, does process the image correctly. The fact that ACR doesn't seem to recognize (or is totally ignoring) the highlight tone priority attribute leads me to believe that this feature is probably indicated via metadata tags and implemented via software when shooting raw.

OS X seems to be recognizing the tag but doesn't seem to be doing a very good job of processing the image correctly.

You're using Highlight Tone Priority with Raw??

I'm sure no expert on it, but from what I can tell HTP underexposes the Raw by about 1 stop and then adjusts the in-camera JPEG conversion for the new midtone point along with some kind of "S curve" for handling the extended highlight range. If you're shooting Raw, all that you get is the underexposure.

The reason that you're seeing the "correct" exposure for a moment is that Aperture is showing you the embedded JPEG preview while it works on converting the Raw. The embedded preview has been adjusted for the reduced midtone point, so it looks fine.

Presumably, DPP recognizes the EXIF flag that tells it that Highlight Tone Priority is in effect, and adjusts for the reduced midtone point. You should be able to see this on the labeling of the Raw histogram, which should show an extra stop or so of highlight headroom above the reduced "0" point.

Doug Pardee -- that was exactly what I was looking for! I guess I hadn't thought about shooting in HP mode in RAW vs JPEG. After playing around in DPP I think that is exactly what is going on. Thanks again!