Blurry Image Problem

[CuriousOne]

Hi Everyone,

I shoot for a clothing company and the president insists using his old Novatron 2100 kit with his digital back Canon 50D. I did some test shots with a model today and the images come out blurry with crazy fringing on the edges. I don't know if it's the dust, the lens (Canon 17-85mm 4-5.6), or the strobe itself that is causing this problem. I shot at 1/250s, f-20, iso 100, 22mm.

My set up includes the 2 Novatron strobes on the either side of me and the model is about 2-3 foot away. Behind the white paper backdrop are two Impact 300w/s strobes on either side of the paper.

Thanks in advance!

The Close-Up Image:
http://img.photobucket.com/albums/v2...psef19fdf9.png

[pnodrog]

Personally I would try to reduce the lighting and keep the aperture at f11 or below. You should have plenty of DOF at 22mm and the lens will be sharper if you use it around f8. Not sure that 22mm will give a very flattering perspective - why not move the front lighting and the camera further away?

[CuriousOne]

I will definitely try again tomorrow with that suggestion. Do you think that would solve the fringing problem as well?

[pnodrog]

If the fringing is due to diffraction caused by stopping down to f20 it should disappear.

[William W]

That enlargement of her head is quite (unusually) soft.
What does an enlargement of her feet look like? - goes to ruling out (or in) the lens being out of alignment.
Any filter on the lens? if so, ditch it.
F/22 is not a place to be - I concur that about F/11 should be nicer.

I think you might still see a little bit of purple fringing (at enlargement) with that lens at the wide angle, even at F/11 - any other lenses?

Using that lens a bit longer is a good idea too - (could reduce fringing) as well as less foreshortening of the Model (already mentioned)

WW

[dan marchant]

Agree with the above. No reason to be shooting at such a small aperture, especially when there is the diffraction issue to be considered.

[jounpla]

I'm not a professional photographer, so I usually turn to fix photos to enhance. I used to clear blurry photos with image processing software.

[Brauerworks]

I agree with the above as well with this additional info:

The lens you have performs at peak at f/8.0 and 50mm
Much higher resolution, less fringing and distortion.
50mm would give you a field of view equivalent with 1.60 * 50 = 80mm on a fullframe camera, making the perspective much more flattering. (smaller nose, smaller ears and better facial features.)

Hopefully you can back off enough to get the shot.

[William W]

I will definitely try again tomorrow with that suggestion. Do you think that would solve the fringing problem as well?

So . . . what happened?

WW