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-   -   Canon EOS-40D Focus issues... (https://www.dvinfo.net/forum/still-crazy/126547-canon-eos-40d-focus-issues.html)

Roger Rosales July 23rd, 2008 05:44 PM

Canon EOS-40D Focus issues...
 
Hey guys,

Today I called the canon tech. support because of an issue I'm having with the back focus. When I zoom in all the way and focus, when I zoom back out everything is blurry again. The tech. guy told me that cameras work differently than camcorders in the sense that if my field of view changes, regarldess if I'm in the EXACT same spot, didn't pan or anything, that I will have to re-focus regardless.

In other words, backfocus doesn't exist with digital cameras. Is this true? I don't believe so and it just sounds odd to me...I can clearly rememner doing it with this same camera no less.

My second question is, does anybody use the BReeze Syst. program? If so, can it control the focus? For some reason it wont let me, but when I go to their website it says that focus control is available. I may be readin it wrong.

One more thing, often times, the camera seems lost and when I want to autofocus, sometimes it wont find its place and it'll just keep trying to focus.

Any ideas?

Chris Medico July 23rd, 2008 07:39 PM

It depends on the lens. Some are parfocal and others aren't.

What lens do you have on the camera now?

Roger Rosales July 24th, 2008 02:40 PM

It's the Canon Ultrasonic 28-135mm lens.

Thanks for the help.

Chris Medico July 24th, 2008 03:07 PM

Sorry to report but that lens isn't parfocal so having to refocus after changing focal lengths is normal.

If you absolutely need that feature a couple of lenses that are parfocal and in that focal length range is the EF 24-70mm f/2.8L USM AND EF 70-200mm f/4L USM.

I have both of these lenses and changing focal lengths does not require refocusing.

Roger Rosales July 24th, 2008 03:49 PM

Man, I was afraid of that. I'll run it by my boss since this is a company camera and I'm taking photos for the products they sell.

Thanks a lot Chris, I really appreciate the help.

David Trayers July 27th, 2008 08:55 PM

Here is a list of all the parfocal Canon Lenses
 
See this post by Chuck Westfall of Canon (it's the second post):

http://www.prophotohome.com/forum/ca...-anywhere.html

Although not on the list, many consider the 24-105 f/4 L IS to be parfocal.

Leigh Wanstead July 29th, 2008 02:07 AM

For your information I think that I do not need to refocus with Nikon vr 18-200 lens on nikon d40 camera.

Regards
Leigh


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