What is Backfocusing?

[doctorA]

Hello:
I'm kinda new to photography (under a year old) but have what I think is a good collection of lenses, and accessories.
I read about backfocusing but I"m not sure what that is and how would I know if my 50D or any of my lenses is back or front focusing?
Is there a specific test to check for that?

Thanks

[Dunedan]

Check this:

http://regex.info/blog/photo-tech/focus-chart

Basically backfocusing is the lens focusing behind the focus point it's using.

[DStanic]

The focus chart is great, but you can easily test your lens by setting up a bunch of batteries on a table or something, standing upright.. having some closer and farther away from you. Carefully focus on one or more of the batteries with high aperture (f/1.8 on your nifty for instance) and it should be in focus. If not, it will focus on something else.

[number six]

I agree, a battery test is good. Disagree, though, that the focus chart is great.

Attempting to focus on a tilted focus chart at close to the minimum focus distance of the lens has led many a POTNer down the path of despair. Many of these poor souls would still be sane if they'd shot batteries at 25 to 50X focal length distance, as the lens manufacturers specify for focus testing.

-js

[footballdude2k3]

i agree with the battery test, very easy :)

[crn3371]

Frankly, I wouldn't do the focus chart, batteries, rulers, whatever, until I noticed something in my real world shots that gave me cause for concern.

[number six]

BTW, Doctor, you're aware that your 50D has microfocus adjustment? If your lenses are front- or backfocusing you can adjust them.

Oh, and welcome to POTN!

-js

[yogestee]

Focus charts are criminal and should be banned!!

[doctorA]

Thanks all.
This is very informative. I played some with batteries, and stacking CD cases, just for fun...

Microfocusing....I've been kinda reluctant to touch that as I don't want to mess things up in the camera. Especially as my understanding that it works only in the custom setting, but can apply it to the rest of settings..

It's a whole new world for me and I am learning as fast as I can
Thanks

[Picture North Carolina]

The focus chart is great, but you can easily test your lens by setting up a bunch of batteries on a table or something, standing upright.. having some closer and farther away from you. Carefully focus on one or more of the batteries with high aperture (f/1.8 on your nifty for instance) and it should be in focus. If not, it will focus on something else.

But us a tripod. You may think you're a steady human statue, but you're not. If handheld, you may drift a little

I have found a yardstick works better.