focus-recompose theory

[CaptainTom]

Ran across this in another forum, and thought it might be interesting here.

Focus-recompose problems.

[brad]

Interesting.. and makes sense... might even explain a couple of wide aperture shots I've made recently.... will have to keep this in mind.

[CaptainTom]

Originally Posted by brad

Interesting.. and makes sense... might even explain a couple of wide aperture shots I've made recently.... will have to keep this in mind.

It does make sense, but perhaps someone can refute it as well.

Combine the "focal plane" error with a lens that tends to back focus and you could have a serious problem.
My first thought is that if you need to tilt the camera to put the focusing spot on the intended target, you should instead raise the camera on a parallel plane, focus and then recompose on the same plane. Or, compose the picture and use an outer focusing point that coincides with your focusing target without having to tilt the camera.

Come to think of it, these are basic large format camera "skills" that would work well in close up DSLR use. "The more things change, the more they stay the same!"

[Silvernic]

Crap, now I have to go home and do a little scientific experimentation before I can convince myself of the truth of this.

[jeffkohn]

When shooting wide apertures at even moderately close distances this can definitely be a problem, and I think it definitely trips up people when they start using a fast lens for shallow DOF. This is the reason that I change to the appropriate off-center AF sensor rather than recomposing.

[Gordon]

This is in part what I was complaining about in the gig photography thread.

In low light, the center spot has better AF capabilities with certain lenses (2.8 or faster)
but if you focus/ recompose you get a lot of soft shots.

85mm lens at 5ft at f1.8 - about 1 inch sharp DoF, focus/ recompose - you are way off

[bburton]

Originally Posted by CaptainTom

Ran across this in another forum, and thought it might be interesting here.

Focus-recompose problems.

Thanks for the info, Tom.

BTW: I like your current avatar much better than the one immediately prior.

[Roy]

Originally Posted by bburton

BTW: I like your current avatar much better than the one immediately prior.

I agree Tom. Your Avatar is much improved

[engstrom]

This article is absolutely true. And I too like your new avatar Tom.

[srwatters]

Great resource Tom. Filing it away for later reference!

[CaptainTom]

Originally Posted by srwatters

Great resource Tom. Filing it away for later reference!

The link, or my avatar ????

[srwatters]

Originally Posted by CaptainTom

The link, or my avatar ????

Both! is she local? Want to share?

[Hogleg 44]

I have seen this theory/fact before from other sources, and it makes a great deal of sense. Each time I see it I have to wonder if this is the reason so many people complain that their brand new lens is not focusing properly!

[brad]

That's Kara Oest, Scott:

http://modelmayhem.com/member.php?id=60402

[Roadrnr]

That is an interesting read. My cousin and I were just talking about this the other day. She was having that problem when doing portraits.

I wonder if another soloution would be to set your focus with AF on and then turn it off, and recompose. that way when you take the picture, the focus doesnt change.