Those Having Back focus Issues

[sulhan]

Hiee Guys/Gals....

I would like to gather some inputs on those facing the problem of back-focus.

1 - How bad is your back focus?
2 - How do you discover that you have(think that you have) back focus issues?
3- What focal lengh(lens) that you experienced the back focus and what aperture did you use when taking those shots?
4- Being in digital world - do you review the image and do a remedy by say increasing depth of field by stopping down aperture - or - you just insist on "that" aperture size(e.g f2.8) to get the maximum background blurr effect?
5- Is your Back-focus experience on your "that" lens repeatable /consistent and never get the right output till today?
6- Your back-focus is on what type of shot? Portrait/ Macro/Landscape ...share...

Well, lets hear for those who have results to share (preferable one photo only with a photo-shopped arrow to point on actual focus area).

rgds,
sulhan

[Drudkh]

I used to have back-focus issue only with an older Minolta lens, the 135mm f/2.8. It gets very obvious when subject is about 2 metres away and further. I use this lens mostly for portraiture photography and I like to frame the model in half-body to full-body.

This problem has restricted my usage in f/2.8 where I have close the aperture until f/5.6 and above to get pretty sharp images but that compromises the bokeh and blurred-background I want to have. The other option I have is to frame my model close up as I have to get very near to the model in order to get sharp images. I'll have to only frame the model's head and shoulders which is pretty tight framing.

I'll be able to post up some examples tonight if anyone of you is interested.

This however does not happen with my other 2 lenses, KM 28-75 f/2.8 and Tokina 100-300 f/4. Both lenses gives very consistent sharpness but I do get backfocusing once in a while, more often with the 100-300 f/4.

Just a few months back, someone managed to find out a simple way to DIY correction on the backfocusing. I would strongly suggest anyone of you not to to do it. Why? I did it but it didn't work. Instead, it create a little more trouble for the KMSC to refine the problem even though I've reset to the default. Human estimation is not precise without proper tools to such sensitive and delicate mechanism that requires precision.

If you have back-focusing issue, sent it to KMSC straight away.

[ileaf]

Originally Posted by Drudkh I used to have back-focus issue only with an older Minolta lens, the 135mm f/2.8. It gets very obvious when subject is about 2 metres away and further. I use this lens mostly for portraiture photography and I like to frame the model in half-body to full-body. This problem has restricted my usage in f/2.8 where I have close the aperture until f/5.6 and above to get pretty sharp images but that compromises the bokeh and blurred-background I want to have. The other option I have is to frame my model close up as I have to get very near to the model in order to get sharp images. I'll have to only frame the model's head and shoulders which is pretty tight framing. I'll be able to post up some examples tonight if anyone of you is interested. This however does not happen with my other 2 lenses, KM 28-75 f/2.8 and Tokina 100-300 f/4. Both lenses gives very consistent sharpness but I do get backfocusing once in a while, more often with the 100-300 f/4. Just a few months back, someone managed to find out a simple way to DIY correction on the backfocusing. I would strongly suggest anyone of you not to to do it. Why? I did it but it didn't work. Instead, it create a little more trouble for the KMSC to refine the problem even though I've reset to the default. Human estimation is not precise without proper tools to such sensitive and delicate mechanism that requires precision. If you have back-focusing issue, sent it to KMSC straight away.

i have that issues as well.
previously i didn't really care whether it's having back focus or so, as my pictures turn out to be quite ok.
but recently after i bought the KM 50mm f/1.4, i tested out and found that it's quite obvious, with that, basically the advantage of this len (max aperture of f/1.4) is not usable at all, as the focus point is going to be out-of-focus.

hmm, thanks for the advice drukh, i'll send to KMSC probably this saturday...

[Timber Wolf]

Hello. I've got a new high-performance sigma lens which shows frontfocus with the 7D. My Minolta 35-105 also shows frontfocus but to a smaller extent. What's my best course of action?

Thanks
QX

1. Front. On the sigma 70mm is perfect, 24mm is hell.
2. By looking thru the viewfinder
3.f/2.8 24mm
4. Insist
5. Fine tune using DMF, consistent
6. Anything at wideangle

[tao]

so can i say that this issue is due to the wide aperture lens f2.8 and below? or is it because the body needs to be calibrated?