Front/Back Focusing - is it camera or lens issue?

Hi All,

I have an A700 and a bunch of lenes ranging from ok to great.

My A700 used to have a bad BF problem with all of my lenses. I managed to get it fixed for the most part.

Weirdly enough the correction help with most of my lenses, however one lens, my konica minolta 70-200mm 2.8, still refuses to focus properly. Constantly focusing about 10-15 cm in front of the subject.

Until recently i always figured that the camera was at fault, however I recently read somewhere on this forum that it is possible that the lens could be the problem. Is there any truth to this?

If it is the lens, is it possible to have it fixed and will sony fix it if it is km lens?

Any insights to this problem would be greatly appreciated.

Cheers.

P.

Can't say if u have a bad lens but I would say that it s definitely possible. I used to have a lens that have extreme focus shift. 10cm FF wideopen and 10cm bF when closed down. The next copy that I got worked perfactky fine. I never figured out the cause but I have always suspect that it was a bad rom. It is an electronic component and is suspectible to static electricity discharged from the user.

paddycochrane said:

Until recently i always figured that the camera was at fault, however I recently read somewhere on this forum that it is possible that the lens could be the problem. Is there any truth to this?

If it is the lens, is it possible to have it fixed and will sony fix it if it is km lens?

Any insights to this problem would be greatly appreciated.

Click to expand...

Focusing issues can be caused by either the camera body or the lens. If your other lenses focus correctly, but one misfocuses in a consistent manner, then it is clear that the lens is at fault. Fixing the issue is a matter of calibrating the lens, to match the AF system calibration of your camera body, but I don't know who would calibrate your K&M lens. Of course contacting Sony and asking them would be a good place to start.

(btw, is "misfocus" a real word?)

I'm not saying that it is the reason in your case but with any lens that cannot achieve correct focus make sure that you are not using any filters on it.
--
Keith-C

Go visit a friend or a shop with a memory, a battery and your lens and pretend you want to test your lens on one of these shiny new A550 before buying it.
If you see the same FF/BF at home then it should be the lens that has problem.

daravuth lay said:

Go visit a friend or a shop with a memory, a battery and your lens and pretend you want to test your lens on one of these shiny new A550 before buying it.
If you see the same FF/BF at home then it should be the lens that has problem.

Click to expand...

good idea
will try that.
p.