Canon EOS-40D Focus issues... at DVinfo.net

Roger Rosales · July 23rd, 2008, 05:44 PM

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

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

July 23rd, 2008, 05:44 PM	#1
Roger Rosales Major Player Join Date: Aug 2003 Location: Los Angeles, CA Posts: 254	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? __________________ -Roger Rosales www.rogerrosales.com

July 23rd, 2008, 07:39 PM	#2
Chris Medico Inner Circle Join Date: Aug 2006 Location: Efland NC, USA Posts: 2,322	It depends on the lens. Some are parfocal and others aren't. What lens do you have on the camera now? __________________ http://www.LandYachtMedia.com

July 24th, 2008, 02:40 PM	#3
Roger Rosales Major Player Join Date: Aug 2003 Location: Los Angeles, CA Posts: 254	It's the Canon Ultrasonic 28-135mm lens. Thanks for the help. __________________ -Roger Rosales www.rogerrosales.com

July 24th, 2008, 03:07 PM	#4
Chris Medico Inner Circle Join Date: Aug 2006 Location: Efland NC, USA Posts: 2,322	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. __________________ http://www.LandYachtMedia.com

July 24th, 2008, 03:49 PM	#5
Roger Rosales Major Player Join Date: Aug 2003 Location: Los Angeles, CA Posts: 254	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. __________________ -Roger Rosales www.rogerrosales.com

July 27th, 2008, 08:55 PM	#6
David Trayers Regular Crew Join Date: Feb 2007 Location: Hastings, MN Posts: 51	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.

July 29th, 2008, 02:07 AM	#7
Leigh Wanstead Trustee Join Date: Apr 2004 Location: NZ Posts: 1,276	For your information I think that I do not need to refocus with Nikon vr 18-200 lens on nikon d40 camera. Regards Leigh