I think this is my first post...Hello
I recently bought a 7D as an upgrade to a 40D. I have 3 lenses:
- Canon EF50mm f/1.4 USM
- Tokina 11-16mm f/2.8
- Canon 24-105mm f/4 USM IS
I've taken sharp/in focus pictures with each of these lenses with my 40D (along with some OOF shots too!) In fact, I know the nifty fifty has a slight front focus issue at wide open f-stops.
Before purchasing my 7D I thoroughly researched this camera and was aware of the "focus issues" reported on just about every forum that caters to Canon DSLR owners. I am aware that some of these issues are user error, but that there appear to be legitimate problems among a select few that have been repaired via adjustments at Canon service centers.
Right after receiving my new baby I set out to determine if I had issues (user error or otherwise). I've read the manual and believe I have a firm grasp on the different AF modes. One thing that is clear to me: when the AF gets it right, this is an incredible camera.
I've conducted several tests and believe:
- Im doing something wrong; or...
- I have a "real" AF issue; or...
- I have a expectations that are not aligned with reality; or...
- I don't have a firm grasp of the different AF modes and how they work
I feel that I am a reasonably skilled photographer, and will post some samples of past work if asked. Using the post "-=What to do if you suspect a focus problem with your DSLR=-" as a guide, I'm submitting myself to critique, suggestions, and hopefully corrective actions/advice about how to "fix" these issues.
- My 7D can auto focus, but in this limited experiment and some handheld walkaround shots, the AF was somewhat unpredictable. I varied lighting to see if that had some effect, and also varied subject matter for contrast, etc.
- I also tried some handheld shots in bright conditions with different subjects with the same unpredictable results
- I tried different lenses, with similar results
- Wow, that nifty fifty has some CA at wide open...
- In most instances, my 40D would have nailed these shots easily
- Some images, taken right after each other, grab/miss focus
- I probably need to send this body in for some adjustments...but what do I tell them so they fix it?
Here is goes:
1. Please post some sample shots that show the problem, with Exif information intact or included. Linking to full sized images is useful
Here are some images. Each image pair is a screencapture of the focus points as displayed in Aperture and a 100% crop of the relevant area. Each frame was captured using a tripod, flash, mirror lockup, and a wired trigger. All shots were taken at ISO 100 or ISO 200. Looking back on these tests, I know that the ambient lighting was a bit low, which required the flash to fire a focus beam every now and then. Nonetheless, I received a focus lock beep before each shot was taken, and verified that the focus light through the viewfinder. Each shot was taken using manual (center) AF selection point.
2. Verify the camera/lens can in fact focus under good conditions first.
Done. I know these lenses and have shot them with my 40D. As stated above, the 50 has slight front focus, but nowhere near as bad as some of the images show.
b. Verify adequate shutter speed – suggest a minimum of 1/(2 times focal length) for troubleshooting, to keep it simple use 1/1000 or faster, or use a tripod/stationary camera with remote release or self timer
All shots, and some other tests not posted, were taken with fast shutter or a tripod. All shots posted above were with camera on tripod with mirror lockup and remote trigger.
c. Use a reasonable depth of field
All of these shots were taken wide open with the 50. Typical exposures were ISO 100, f1.4, at 1/25.
d. Verify the lens switch is set to AF not MF, IS is off if shooting on tripode.
AF was on, tripod used.
f. If AF seems to be causing problems try manual focus, Live View is easiest for this if your camera has it. Verify you can focus sharply in manual.
Manual focus works like a charm...I've confirmed it is slower than AF
g. If it's the camera that is in question verify the problem with a second lens if possible, if the lens is the question try a different camera if you can.
Done; AF issues when shooting with prime, wide, and zoom lenses.
h. If with the above there seems to be consistent problems there may be front or back focusing, testing for this is well described here, member Teamspeed has a free lens adjustment tool to aid focus adjustment, described and available here
Before getting the 7D I tested these lenses and they appear pretty good. One indication that something strange is happening is that these issues are seemingly "random" where I'll achieve focus in one shot then miss it in another.
Lastly, I'd like help/peer review "concluding" that this new body needs work...soon, because I already miss this thing
Any comments, questions, or critiques very welcome!