Not happy with new lens

scottyb · Mar 19, 2006

I was not thrilled with the "looseness" of the kit lens with my XT. I wanted a better quality general purpose replacement so I bought a Sigma 28-105 2.8-4 DG. I have found that the DOF is very tight and I am having difficulty getting focused shots. When they look good in the viewfinder, the picture is focused slightly off my target. Some pictures have come out really sharp, but many I expect to be good are not. Is this something I just need to become more skilled at, or could the lens be faulty? The kit lens definately has wider DOF across the board.

Thanks
Scott

'Daniel' · Mar 19, 2006

Are you using manual focus?

Do you understand about DOF also?

scottyb · Mar 19, 2006

Daniel said:
Are you using manual focus?

Do you understand about DOF also?

Yes, and yes. But I am basically still a beginner. The light I had yesterday allowed stops to ~ f10 or so, but those pictures didn't seem to improve the DOF. I think that I just need more time, but it's frustrating.

'Daniel' · Mar 19, 2006

Well I can't see it being a problem with the lens because what you see in the viewfinder is what is projected onto the censor.

Do yuo wear glasses? Maybe you need to change the dioptric setting of the camera so what's in focus to you is really in focus i.e what a 20/20 person would see.

scottyb · Mar 19, 2006

Daniel said:
Well I can't see it being a problem with the lens because what you see in the viewfinder is what is projected onto the censor.

Do yuo wear glasses? Maybe you need to change the dioptric setting of the camera so what's in focus to you is really in focus i.e what a 20/20 person would see.

Funny you mention that as I was just playing with it. I have 20/15 vision. I adjusted the dioptic and I was then able to re-focus and have a clear view, and then again with different adjustments. In other words, I have been able to "correct" the dioptic setting with focus. How can I get the baseline?

selmerdave · Mar 19, 2006

If you're shooting at 28mm with an aperature of f8 with a subject more than 10ft away and you are getting anything out of focus I would say something is wrong. If you are shooting at 105mm all the time unless your subject is very far away you are likely to have much less DOF.

Dave