I have been reading on these forums for quite a while now, but the more I read the more I worry!! I keep discovering terms and references which I have never heard of and have no idea if I am being affected by them!
For mee and any other newbe to photography please would someone explain what is meant by back/front focusing? I have checked the topoic history search but there still does not appear to be a thread that actually explains what it actually is.
I have 4 or 5 lens' I use and now I am a bit paranoid that they all need sending somewhere for an expensive calibration !!
Please someone put my mind at rest and explain what this problem is and then I will know if I have a problem .
Thank you in advance to anyone who would be so kind to help.
First, use your lenses on real life subject. If you notice problems, then look at all of your more recent, and maybe even older shots with that piece of equipment. Look for a common flaw. A front focus, or a back focus, which is different than a missed focus. Missed focus more commonly occurs in AI Servo mode, when the camera wasn't fast enough in tracking the action.
Front or back focus happen more regularly/all of the time and One Shot mode. It's when the area before, or after the intended subject is in sharp focus, and the rest is not.
More noticeable in fast lenses (f/2.8 and faster).
So after you've tried it on what you normally shoot, and found there may be problems. The next step is a tripod and a controlled setup. Use the cameras timer release and shoot a non-moving subject in a controlled environment. Take a few shots, making the camera refocus every time.
View the results. If the camera is focusing where it shot be, then you're okay! If the camera is not focusing where it should be, then a trip to Canon is due.
If it's all of your lenses on only ONE of your bodies, probably safe to say the body is out.
Basically this is the way I think you should look at it, as an admitted newbie, you shouldn't worry about it unless you notice a GLARING imperfection in the photo.
Thanks Robert, that has put my mind at rest, I have not seen problems as described, so that is good, I shall now know to keep an eye out for it though.
I was having some issues with one my lenses rear focusing so I put all my lenses thru a focus test, if nothing else but for peace of mind. I sent my "bad" lens off to Canon for re-calibration.
This is what a "good" focus should look like. The focus is squarely on the target in the center with equal oof distance in front of and behind the focus point.
!!
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