another camera focus question

pmaxwell

I've been having a good string of outings lately where the picture isn't quite as sharp as I'd like.

today I followed (I think) Pathfinders test parameters and took my tripod, cable release, camera and a couple of lenses to a local church and took pictures of the brick wall as roughly a 45degree angle.

I have a bunch of them starting at the widest to the narrowest of apertures (didn't think that would make a difference, but figured what the heck). I think the camera has an issue with front focus, but I'd like a few more experienced users to take a look and give me there opinion.

All shots from 7D
with single shot AF, single point (though not the center, the point one up and one left of center by mistake).

I used DPP to get the AF Point and CS5 to draw it on pic.


Canon 70-200F2.8 IS II



Canon 400 F5.6




Canon 24-105 F4 (@105)



The whole gallery with other test focus shots (my lab Fin) are HERE


I've never played with micro focus adjust. All are under warranty so, send to Canon to calibrate, fix it myself, or you are crazy the focus is fine?

pathfinder

Pete,

I looked at your images on your website at 100%.

You first frame of your dog, with the AF point over its ( dog's ) right eye ( camera left ) I think is excellent, as I would expect at f8 with the 70-200 f2.8 IS L II. I see no focus issues.


Your second frame with the AF point over your dog's left ear, shot with your 400 f5.6 at f5.6 is a stunning demonstration of just how good that lens can be. No problem with focus, and lovely bokeh.


Your third image of your dog, shot with the 400mm f5.6 at f13, with focus on the mouth MAY be sharper on the eyes than the mouth, but you have much greater depth of field at f13, and the lens will not be as sharp at f13, as it is at f8 or so. Generally, lenses are at their sharpest 2 stops smaller than wide open, or f11 for the 400 f5.6 L.

Your fourth image of your dog, with the 400 f5.6 at f13 focused on your dog's left eye, is again superbly sharp in my opinion. I would be quite pleased with that lens.

Your fifth image of your dog with the 200 f2.8 IS L II, at f11, focused on its nose, seems very sharp to my eye at 100% on my monitor. Just a touch of Unsharp Mask and it will crackle.


Your first brick wall image, with your 70-200 f2.8 IS L II, at f2.8, may be slightly sharper in front of your AF point, but is certainly not awful as is. Micro adjusting MIGHT help this at f2.8, but if it were my lens I might just leave it alone.

Your second brick wall image, shot with your 400mm lens wide open at f5.6 seems to focus on the AF point.

Your third brick wall shot, with a 24-105 f4 I think, shot at f4.0 seems in focus, but does demonstrate some red/green fringing on the window frame to the left. Do not get too excited about this small amount of chromatic aberration, it is easily correctable in Adobe Camera Raw or the Raw engine in Lightroom 3.

I correct CA in all my images as part of my routine RAW processing in LR3. I wrote a thread about CA correction here several years ago ( 2004 actually ) but the technique is basically the same except that Lightroom3/ACR6+ actually has lens profiles for most Canon lenses now, so you do not have to do it manually your self, although it is still a good skill to have. Even the best lenses may occasionally display some CA. My Canon 300 f2.8 IS L has some sometimes. My Tamron travel zoom ( 28-300 ) does not sometime, so I don't fret about CA too much, as modern software makes it easy to corral.

One comment about your dog photos, versus your wall photos - Your dog was in bright sunlight, and I think your wall was shot in the shade or overcast, and hence the lighting was much flatter, and offered less contrast for your AF system to work with.

When testing AF shoot with the lens wide open, with it stopped to smaller apertures, the increased depth of field just makes it harder to interpret the results.

Although I have micro adjusted several of my lenses for use with my 7D, unless they are obviously out of whack, I tend to leave them alone. I have not yet found one that needed Canon factory service for focusing. I have had a few lenses serviced for a defect in the AF drive system or in the iris diaphragm, but they were obviously not working right, and were fixed fine by CFS.

pmaxwell

Pathfinder, Thank you, that was a very thorough look. sometimes I wonder if my stigmatism isn't messing with me RE this hobby.