I just bought a used 50/1.8 MK I from B&S forum and it is consistently focusing 1-2 inches in front of the focus point. Is this common or does this lens need to be calibrated? I single-point focused on the "7" of the tape measure but it focused between "9" and "10" (tape set at 45° angle): http://img.photobucket.com/albums/v296/gofast33/IMG_0685.jpg
Anyone have any advise for me? I should mention that I shot 5-10 shots at each aperture between 1.8 and 4.0 (re-focused each shot) and the shot was consistently focusing near the 10" mark on the tape measure.
IMHO- thats not really the best target to use, mainly because of the shadow above the stove control. There is no huge FOCUS HERE line that the camera cannot miss- there is many things it could be trying for there. If i were using such a thing, i'd put a checkerboard pattern paper next to the tape measure, or print out a real focusing chart (there are a few PDFs floating around here) or grab one here http://www.photo.net/learn/focustest/ . Then tripod your cam, place the chart at a 45° angle and make sure that you have the auto focuspoint selection turned off. Focus and shoot, do 3-4 refocusing each time (go to MF mode, turn the focus all the way out one way, AF on again and shoot). See if focusing full in or full out makes a diff. Then post your results, you will get much more help.
I have used this lens in question with no problems on my 20D. However, I am offering to refund your money in full if you can send the lens back as quickly as you can. The only cost to you will be the return postage.
Looks acceptable to me. My MKII did the same thing with my DRebel at close range; didn't have the problem with subjects at longer distances because of the wider DOF. To compensate in close distance and wide aperture shots, I just got into the habit of focusing in the lower half of the focus box.
Thanks to all who responded! This site is the best! I've decided to keep the lens. Thanks, Dan (seller: riokid), for sticking with me.
I am fairly new to SLR's as this is only my third lens ever. I think I am just not used to such a shallow DOF at f/1.8. I took a bunch of shots of real subjects today in better lighting with good results, especially at f/2.2 and up. Thanks again, everyone!
