54% focus accuracy is this within spec? Example images

[hugodrax]

http://www.pbase.com/hugodrax/focustest


I decided to test AF with my 50mm and shot at 1.8

Each shot was one after the other is the 10D supposed to provide higher the 54% focus accuracy? is this okay.

Target was about 8-9 feet from shooting position.

[hugodrax]

I shot at 2.5meters checked exposure it is 12ev

shot at 1.8 and fired 23 shots 9 of them were tack sharp

which means 39 % accuracy

since I never used AF SLRs always worked with manual focus bodies is this typical a 39-54 percent accuracy? I would figure for 1500 you should get 80% at least. and this is a 1.8 lens I would imagine shooting with a 4 lens would probably give me 0 percent accuracy if this is the case I will send it it or return it but I am not to familiar with the expectations of AF on current bodies. anyone have examples of multiple shots or thoughts?

[Roger_Cavanagh]

Hugo,

Bob Atkins says, according to Chuck Westfall of Canon USA, cameras like the 10D are designed so that autofocus is accurate to within 100% of DOF. (See the link on this page http://www.pixelpixel.org/helpinfo/23_focuscheck.htm).

So it's no good just counting the number that "miss". What's important is how far they miss. According to the handy dandy Dudak DOF Calculator (http://www.dudak.baka.com/dofcalc.html), DOF for a 50/1.8 is 17.2 cm (using a CoC of 0.019). In other words, focus has to be of my well over 6 inches to be out of spec.

Regards,