how to test for focusing issues w/ 20d

Are you unhappy with the pictures you are getting?

Don't get sucked in, very few people have a real problem and you would notice if you did.

Just by trying to test for this in a non laboratory setting can convince you that you have a problem where none really is and that will spoil your enjoyment of using what is probably a very fine camera.

Be a photographer not an anorack.

Sure, just sit around and wait till your camera is out of warranty before realizing the film plane isn't in line with the plane of focus in the viewfinder. My 10D has a minor problem with it, I've used a friends 10D with a BIG focus problem, and it's totally f---ing annoying for those of us shooting with good glass and anything less than F8.

It's easy to test for. Lay a ruler on a table pointing away from the camera, and manually focus at a particular mark on the ruler and shoot wide open. If your 20D isn't a 'problem child', you'll get that same mark in focus in the capture image. If you have the common focus problem with many 10D/20Ds, you'll get a different point in the ruler in focus than what you saw through the viewfinder.

"Sure, just sit around and wait till your camera is out of warranty before realizing the film plane isn't in line with the plane of focus in the viewfinder."

And if you haven't noticed for a years worth of images you probably don't have a problem.

Geees!

As far as I understand it (and canon indicate in their latest litterature) the problem can be camera or lens specific so if you will need to check every lens you currently own or buy in future (even if the body waranty has expired).

Basically I stand by what I said earlier if you can't se any problem then don't worry about it.

http://www.photo.net/learn/focustest/

Test with multiple lenses at multiple zoom positions. Focus depends on BOTH the lens and the body, and the focal length setting of zooms.

Focus problems are not unique to Canon and not unique to any particular body or lens. The more paranoid you are and the closer you look, the more problems you will find. Nothing is perfect.

If you see no problems in actual use of the camera, that's a pretty good test. If you perform accurate "scientific" focus tests and you look hard enough with enough lenses and settings, I'm sure you'll eventually find a problem.

Reminder to all: The ONLY stupid questions are the ones you don't ask...

>>The ONLY stupid questions are the ones you don't ask...<<

will the SUN come up tomorrow? The only stupid answers are the ones you don't give ;)

It's just that the focus "issue" has been beaten to death, buried, excavated, sent to the morgue for further exams, buried again...and again...and again...and again.

It's understandable that people get impatient with those questions, especially since the archives must have 100s of posts with the same question and therefore, the same answers.

A focus test doesn't change with the camera model, make, year of production.

I don't think we should look for problems with each piece of equipment we purchase. Use them and *if* you see a REAL problem during the course of normal use then you will have to identify it and test it before sending it in for repairs.

To each his own, I guess. For me, I prefer using than testing...

Giampiero, HA! The SUN indeed - this is cloudy rainy England - even if it does come up (not a foregone conclusion based on this morning ;) I shall certainly not be there to watch it! Have a good weekend...

Focusing on a ruler or other oblique object is not a good test. In order for this to work the focusing sensor and the focusing mark on the screen must be 100% aligned - if not you are aiming the sensor at the wrong place. How often when shooting in real life to you shoot oblique objects ?

That's why you use MF for this test.