Alley in Pisa, Italy

by Lars Kotthoff

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I did a shoot with the Tokina 11-16mm f/2.8 on my Nikon D5000. Most of the pictures came out good but a lot of them weren't as sharp as I would like. I used that lens because it was a shoot in a poorly lit nightclub and small spaces so I needed something fast and wide.

I am thinking they didn't come out sharp due the the shallow DOF from shooting at f/2.8, am I correct?

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It would be helpful if you could post a sample image and EXIF data. –  mattdm Jan 29 '13 at 21:56

4 Answers 4

Yes, shooting at f/2.8 will generally produce not-as-sharp images, both because of shallow depth of field and because it's hard to produce sharp images with a wide aperture — most lenses reach peak sharpness stopped down a bit.

High ISO in the darkness will tend towards increased noise (and perhaps you have noise reduction enabled, which will reduce sharpness). And of course, long shutter speeds mean motion blur, both from camera shake and from the motion of your subjects. Nightclubs are dark even at f/2.8.

And, finally, that particular lens is not renowned for sharpness — not that it's bad, but that's what you get from a $600 fast ultrawide zoom.

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I have both the 35mm and 50mm f/1.8. I shoot them wide open and get great results. But those are both fantastic lenses. I bought the Tokina because there wasn't a lot of fast, ultrawide DX options. In retrospect I should have gotten something else I think. I got it mainly for the f/2.8, but I think investing the money in a good flash would have been better. –  Taylor Huston Jan 29 '13 at 22:05
    
As far as I can tell, the only reason for a fast maximum aperture on an ultrawide is so that you can frame in the dark. The circles of confusion grow so slowly in out-of-focus areas that any attempt at bokeh just looks like a DoF/focus error. –  user2719 Jan 29 '13 at 22:06
    
@Taylor — if you look closely, you'll see that those lenses definitely get sharper stopped down. But something else may be going on; a sample image will help us figure it out. –  mattdm Jan 29 '13 at 22:14
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@TaylorHuston - That shot looks very acceptably sharp in the center where it looks like you focused either on the DJ's face or the wall behind him. –  dpollitt Feb 7 '13 at 3:14

Even though the 2.8 is as wide as it gets for UWA lenses, the depth of field at 11mm is still huge at most distances. If you're a meter away from your subject, your DOF is one meter deep, at two meters it's 16m and at 2.27m you've hit infinity. I'm pretty sure shallow depth of field is not your problem.

Get a DoF calculator app, they're very handy

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Without any additional info:

  • I would make sure you were focused where you thought you focused
  • Check that you used a reasonable shutter speed
  • Check your ISO
  • Make sure what you wanted in focus was at least the min focus distance away (1ft).
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They posted an example photo in the comments of another answer. –  dpollitt Feb 7 '13 at 3:15

It's possible that your backfocus is off. This means that your lens focuses in front of or behind the sensor. Backfocus depth of field gets smaller the wider the lens so it's most critical with an ultrawide.

This can be checked and the lens matched to your camera by a camera service shop.

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Wouldn't backfocusing be less noticeable on an ultrawide given the greater depth of field/hyperfocal distance? –  MikeW Feb 7 '13 at 22:44
    
No, it's the other way round for backfocus. It's most critical with wide angle lenses. That's why when you adjust a video zoom lens, you zoom in for focussing and then zoom out to adjust the backfocus. –  sbaechler Feb 9 '13 at 10:23

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