... well it could actually be your lens. For a couple of years now, during some of my studio lighting classes, I’ve had some students complain about their inability to get a sharp focus. Since all manufacturing processes have some degree of variability, the chances of getting a lens/body combination that don’t quite match is a real possibility.
In many cases the lens will either Front Focus or Back Focus and unless you have a camera that provides micro adjust capabilities the only solution is to send both the camera and lens to an authorized repair facility to correct the issue. However, if you have a higher end camera body that allows you to make Micro Focusing Adjustments then you can do this adjustment yourself. Not all DSLR manufacturers provide this adjustment capability and for those that do, they don’t provide it on all their cameras. Check your users manual to see if your camera has this adjustment capability.
- Canon calls it: “AF micro adjustment”
- Nikon calls it” “AF fine tuning”
- Pentax calls it: “Front/Back focus corr”
- Sony calls it: “AF Micro Adjustment”
There is a product by Datacolor called the Spyder LENSCAL that you can purchase to see if your lens is front or back focusing. For those of you interested in buying an off-the-shelf product here’s the link: http://spyder.datacolor.com/portfolio-view/spyderlenscal/
However, rather than purchasing a product of this kind I demonstrate to my studio class a method of achieving the same results using a tripod and a ruler. The technique is effective and works quite well although I have to admit that sometimes getting the autofocus to lock in can be a chore and unless you are using the center single-point-of-focus, it’s quite unlikely you get get my method to work.
Recently I found an article on a PPA group site that shows you how to make a DIY Focus Calibration Target; it even provides a PDF template you can print out. After reading the post, the DIY template looks strangely similar in form and function to the Spyder LENSCAL device whose link I provided earlier in this post. So if you’re interested and want to save about $70 , I encourage you to check out the link below. Enjoy.