Hard to get a good AF lock on with high ambient red light. Anyone else?

<p>I was just looking through different images stored on my HD from the last several years and noticed a consistent problem in indoors scenes with high ambient red light.. My cameras just aren't focusing correctly. I assume it's front focusing since most of the shots are from a fair distance and infinity doesn't look sharp.</p>

<p>Does anyone - really I guess I'm writing to music photographers, stage photographers, and anyone who works under the bright red par lights from theatrical lighting - have problems with that? Only when the scene is dominated by a red wash do I have AF impairment.<br>

This is with multiple body + lens combinations, to include a 20D, a Rebel XT and an Elan II; 28mm f/2.8, 50mm f/1.8, 85mm f/1.8, and (I'm sorry to even have bought this piece) a Sigma 17-35 f/2.8-4.<br>

I don't think I've really had as much of a problem with L lenses, specifically the 17-40 f/4 and the 135 f/2.<br>

<br />Input is greatly valued! Thanks!</p>

<p>I'm just curious... does this type camera use a reddish color light for its AF-assist Illuminator? I have a couple of cameras that do. In that case, perhaps the light from the AF-asist lamp is simply getting gobbled up by the similar colored light on the subject. So the firmware that governs the AF may be unable to distinguish between its own AF light and the subject. Thats just a guess....</p>

<p>Your primes may have a red mark for infinity focus with IR film. You might try manually focusing midway between it and the AF point. After all red is at the end of the visual spectrum just before IR. Probably you just have to guess or lock focus before the lighting changes.</p>

<p>Alan - all of those bodies use infrared or near-infrared assist. You're on the same train of thought I'm on, but I haven't come up with a fix yet. PF, that's a very interesting idea, definitely worth trying.</p>

<p>Robert, the only seeming oddity I've noticed is the need to cut way down on exposure when shooting red and orangish-red roses, especially in sunlight even when using a polarizer. It "seems" that they are reflecting less light so that the meter is reading an amount that calls for more exposure. I've got some vermillion colored geraniums and extremely rich carmine red roses in the yard, and under spot metering (these two colors are very close to med. gray) they end up with a washed out rendition in both color and definition. Cutting down on exposure so many stops brings out their true saturation and definition. Maybe this is only characteristic of Canon or all digitals? Never occurred shooting transparencies.</p>

<p>I have the same problem with a 7D. It doesn't focus on very strong, pure reds. Shooting a vase full of red roses, for example, it would not focus on a petal no matter how high I brought up the ambient light.</p>

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<p>Maybe this is only characteristic of Canon or all digitals? Never occurred shooting transparencies.</p>

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<p>Depends on the film. I recall it was easy to blow red and orange flowers with Sensia but not so much with Kodachrome.</p>

<p>Michael - all of your lenses, or just certain FLs?</p>

<p>Robert, that particular instance was with the 100/2.8 macro under overhead kitchen florescents.I've noticed it a few other times before and since, but never to that extent and just changed the focus point. That time, it just wouldn't focus on the petals no matter what I did.</p>

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<p>White balance was a little difficult without a good reference in any of the shots. I'm not very confident of the colors. Here's another one, lit with a snooted flash and the a bit of fill with the built in.</p><div></div>

<p>I have had problems with reds in both nightclub/live music situations and when shooting roses. I take Jody's approach above and underexpose when something is primarily lit by red or orange light sources; I figured either the sensor was overly sensitive to reds or the meter was undersensitive. Now that I think about it, I tend to desaturate the reds a touch when shooting portraits, too. <br>

I've noticed this on my 20d, 50d, and 5d. </p>