A quick test for 10D's focus problem???

[Jussi]

Unfortunately my new 10D happened to be one of those that have focusing issues - it consistantly focuses in front of its object about half inch or so when I do close up portraits with large aperture (4-5 ft, f2.5 with Canon EF 85mm f/1.8). This is not acceptable especially when you try to get model's eye(s) in focus. Luckly the on-line vender gracefully acknowledged the problem and agreed to exchange it with out any hassle.

Anway, I just noticed that it is also off focus when you try to shoot objects in infinity:

- Set the lense in MF mode and point the camera at a tree or house 300 ft or so away and set the focus ring all the way to infinity - it gives you A BLURRED IMAGE!!! To get the object in focus I have to rotate the focus ring counter clockwise about 1 degree. I don't think this is normal and my beloved old Minolta does NOT do this.

When in AF mode, it will focus clearly but the distance mark is NOT at infinity! You guessed it : 1 degree or so back, just like what happens in the MF mode.


Does your 10D do this too?

I wonder if this infinity off-focus thing is related to the front focus issue. May be it can be used as a quick indicater for 10D's potential focusing problems. This will be the first test for me to do when my next 10D arrives.


Your comments or replies will be greatly appreciated!

Yawen

[CyberDyneSystems]

300" isn't infinity... :)

But really,.. The infinity setting on most lenses is bunk... I find if you turn the focus ring all the way and point at the moon it isn't right,. you need to turn that ring back a bit to get focus.

[D60DIETER]

Hi,

there are two points why the lenses are not at infinity when you are at the end of the scale.

The one is for operation temperature -35 Celsius to 45 Celsius. Material need some small space.

And the other one which is much more important, is that the AF needs this gap to overrun the infinity point and get back to the maximum contrast.

greets Dieter

[EXA1a]

D60Dieter wrote:
Hi,

there are two points why the lenses are not at infinity when you are at the end of the scale.

The one is for operation temperature -35 Celsius to 45 Celsius. Material need some small space.

And the other one which is much more important, is that the AF needs this gap to overrun the infinity point and get back to the maximum contrast.

greets Dieter



...wishing back the old times with my FD lenses: for infinity just turning the focusing ring as far as it will go...

(okay, admittedly i missed focus so many times with manual focusing that I happily moved to autofocus :-)

--Jens--