Portrait taking problems

[gbc]

Hey guys. Over the weekend, I took a lot of shots of the extended family, and the only shots that are really lackluster are the portraits. I'm not sure if it's the lens, but when i shoot portraits at the wide end of the 17-55 2.8, I'm getting horribly unsharp pictures. I'm usually shooting at f/5.6 or smaller, shutter speed around 1/100. I'm using a speedlite 580II in ETTL mode. The room isn't all that bright, with only two or three lamps. The ISO is usually at 400. Could that be causing the lack of sharpness? I also mounted on a tripod and forgot to turn IS off.


The lens is sharp in most other cases, and I've never noticed a problem in any other shots. Even shots i've taken in really low light and slower shutter speeds are sharper. I've used zone AF and single point AF, and spot and evaluative metering, and nothing produces any area of sharpness. My main concern is that none of the shots with my other lenses (50mm 1.8 and 85mm 1.8) had any problems when shooting the same portrait.


This is a 100% crop of the zone AF area.. Shot at 18mm, f/6.3, 1/80s. ISO 400. Is the low-light while composing the problem?


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[Oren]

What camera do you use?


I doubt it should look like this at ISO 400 - even with a cheap lens as the 18-55, let alone with the great 17-55.


I don't want to tell you that it's the lens as I don't know enough yet. Maybe it is something you are doing wrong, I don't know.

[neuroanatomist]

I'm thinking it might be time for you to look into AF Microadjustment for that lens (assuming you're using a 50D/5D2/7D etc. body, which from your discussion of AF modes it seems like you are). The fact that you get sharp pics with other lenses and not this one (which is quite sharp) suggests an AF system issue to me.


Of course, I might just be suggesting AF Microadjustment because I just got a LensAlign Pro and am planning to test some lenses tonight. [:P]

[gbc]

Sorry, forgot to mention that I am using a 7D, amid all the other lens and shooting info...


I get sharp images with the lens when I'm shooting single subjects or landscapes, and haven't had any sharpness problems even when shooting with two wireless flashes at 18mm from a similar distance. The only variable is that with the group portraits, I'm using a tripod. Is it possible my cheap tripod is shaking a bit when the the shutter is released? I'm using a remote with a 2-second timer.


Of course, the other variable is my family. Maybe they're just not photogenic.

[Keith B]

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Is the IS turned on while it is on the tripod? I think that can cause problems.
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[neuroanatomist]

The IS system on the EF-S 17-55mm f/2.8 is tripod-sensing, so unlike some older lenses (e.g. 300mm f/4L IS), it turns itself off when vibration falls below a certain level (which happens on a solid tripod). So, turning off IS is probably not the answer.


Shutter release on the 7D is very well-damped, so that shouldn't cause significant vibration - not to the degree of unsharpness you're seeing in the pic you posted.

[Johnny Rasmussen]

It is difficult to say what the problem is but you can try to sort the problems one by one.


1. You mentioned that the lens is sharp in most other cases and that you never had a problem in any other shots. Does this count for all focal lenghts?


2. You used a tripod and the IS was left on. In Bryan&acute;s review of this lens he says:


This IS version is tripod sensing to prevent feedback loops between the IS sensor and stabilizer motor vibrations. The manual recommends turning IS off when tripod-mounting the lens (to save battery life) or when panning (panning mode IS is not available).


This could be the problem. I do not think movements from the tripod itself is the problem.


3. You said "when i shoot portraits at the wide end of the 17-55 2.8, I'm getting horribly unsharp pictures". Is this a problem only when shooting portraits or in general?


4. Is this a crop from the center of the image or from the side? If it is from the left or right side is the center sharp/in focus?


5. You were using a flash. Have you tried shooting the same portraits without the flash?





These are only a few thoughts. It is difficult to guess. I would have performed a few test with the camera on the tripod, no flash, IS off, plenty of light, using center focus point only and using different focal lengths. That will give you a clue if it is the lens or not.





- Johnny

[Oren]

If this was shot with a flash, I doubt the tripod or any other kind of shaking is the problem.


What program/mode is the camera set to (M, Av, Tv, Portrait etc.)??

[gbc]

The camera was in AV mode.


I'm going to try more shots using manual focus and then compare them to the AF shots. I'm beginning to worry it's the AF with either the camera or the lens.

[Oren]

Well it's not just AF IMO. The noise is too strong for ISO 400 on a 7D!