RAW HIGHLIGHTS PROBLEM

[lightrae]

I'm not sure exactly what to call my problem so forgive me if it's posted elsewhere and just point me to it.
I had tried Raw a few times, feeling my way, using Photoshop Elements 5.0 and felt ready to jump in deeper. I shot a local event entirely in RAW, downloaded and started to browse the day's take.
About 1/2 way through the batch, the hard light accents , such as sparkling water, began to look red. It got worse with the later frames.
I've had several ideas offered to correct the images but they don't solve the root problem. Therefore, I'm disinclined to shoot any RAW until I can diagnose the problem and learn to avoid or prevent recurrence.
I'm especially stumped by the fact that the earlier images were perfectly OK and I've never had it happen shooting jpeg, large, fine files, using exactly the same equipment right down to the same CF cards.
Any help, especially any first hand experience would be appreciated.
I have posted two sample jpeg images in my galleries. The RAW image looks just the same as the jpeg conversion.
http://www.pbase.com/lightrae/failures
Images 013 FAULTY RAW ORIGINAL and 014 FAULTY RAW DETAIL

[photomary]

I think what we're seeing is chromatic aberration-in this case red fringe.

I've had it happen when there is a big light/dark difference somewhere in the photo, say between a bright sky and the side of a building and the fringe is along the edge of the light/dark area.

If the angle between the camera, the sun, and the object is just right (or wrong as the case may be) then it can happen.

Of course, I could be totally mistaken. :-0

Mary

[dougj]

I agree with Mary, it looks like CA, which is a function of the shooting conditions and the lens characteristics. This is independent of the type of digital data produced.

http://www.vanwalree.com/optics/chromatic.html

Do you have any other photos with this type of high contrast, shot with similar lens parameters?

[sheila]

Sparkling water struck a chord. This happens to my RAW images on occasion but have found a solution. Instead of ACR, I put them through Canon's RAW software converter (which name escapes me!). It handles sparkling water 100% better.

Cheers
Sheila

[lightrae]

Chromatic Aberration works for me, Mary.

The physics are interesting. Thanks Doug, for the direction to that.

Shelia seems to have hit what I need: a way to avoid the big "X" with images that suffer this effect.

So here's my thinking at this stage. PLEASE point out any flaws, keeping in mind that I'm trying to avoid using any more processing programs than are necssary. I would prefer to learn one (or two) well enough for my needs and stick to it.

(1) Chromatic Aberration is a still-debated subject and occurance in any particular image is of limited predictability.
(2) Occurance of Chromatic aberration is, from a shooting stand point, somewhat like lens flare. I have to either avoid shots where it MIGHT occur or accept it.
(3) I have to learn to perdict possible/probable occurance through practice. I will likely have to wait on this one until summer to get lots of the desired conditions.
(4) I should seek recommendations for and try alternate software until I decide which gives the best results for me.

Doug asked about other images so I've posted several at the same location http://www.pbase.com/lightrae/failures They are numbers 15 through 20, at the last of the gallery.
They were all shot in RAW, same lens, location ect. The timing between shots varies from several hours to just a few minutes.
With your comments in mind, my reviewing of these (and other) images has convinced me that your assessment of the problem is correct.

[dougj]

That sounds like a reasonable plan. There does appear to be some CA in the other shots, but it is not severe. The first shot, and the crop, might exhibit refraction from the water itself, essentially the rainbow effect.

I don't have experience with that lens, however doing some research it does not appear to exhibit excessive CA, based on reviews and user comments.

Sheila suggests trying Canon's RAW converter, which is definitely worth a try. I don't know if you have a Canon RAW converter, the current one is called Digital Photo Professional and is very easy to use. Canon's website has a download and should provide D60 compatibility details.

Digital Photography Review has a very active forum on Canon lenses. There are several members that have good experience with Canon glass. There is also a fairly high noise level in the forum with some less than stellar advise. You might consider posting the question with examples.

http://www.dpreview.com/forums/

Good luck!

[prinothcat]

I like your approach. I also suspect CA's. I believe that they are most pronounced at wide angle and large apertures as well as direction of lighting. I also suspect two things. First I think if you had shot that at a smaller F-stop and slower shutter, the highlights would be closer to if not normal. Second I suspect that Canon knows about the CA's in these lenses and may have factored that information into their RAW converter.

[lightrae]

Your thoughts are interesting, Prinothcat, especially concerning aperture and shutter settings. It will bear watching when I have the opportunity to take multiple shots at different setting combinations.
As to the characteristics of my present 35-350 mm lens, I'm not too concerned because I will be replacing it in the spring. I am thankful to everyone, though, for helping me to understand this phenomenon and steps to deal with it.

[prinothcat]

I have played with CA's myself. My 18-135 is prone to purple fringe at wide angle and large aperture....

[lightrae]

I lean towards nature and outdoor event shooting, a lot of it around water; the kind of stuff where conditions can only be roughly anticipated. Reality for me is a fairly fast shutter and/or low light.
Reality is also the high cost of quality equipment so I'm feeling my way with digital ..... sort of seeing what I can bring forward from 30 some years of 35mm and what I need to completely rethink.
I've browsed a lot of places, picked up bits of information and gotten completely frustrated with the time wasted trying to weed facts and reliable experience out of the crap. The information here has been both interesting and helpful.