topic Re: EF 70-200mm f/2.8 IS II USM - Focus Issue? in EF & RF Lenses

EF 70-200mm f/2.8 IS II USM - Focus Issue?

Waddizzle — Tue, 01 Mar 2016 18:00:16 GMT

I've been testing the lens out. I took some shots of stuff up close, about four feet away. The below image is a screen capture of a shot, which was cropped 50%.

The red square is showing the focus point. The bud used for focus is out of focus, while one beside and behind it by a couple of inches is in nearly perfect focus. This is not the correct behavior. Any suggestions?

Re: EF 70-200mm f/2.8 IS II USM - Focus Issue?

kvbarkley — Tue, 01 Mar 2016 18:42:56 GMT

Which camera? Can you do a micro adustment?

(I am assuming you are farther than the minimum focus point)

Re: EF 70-200mm f/2.8 IS II USM - Focus Issue?

TTMartin — Tue, 01 Mar 2016 20:39:16 GMT

@kvbarkley wrote:

I am assuming you are farther than the minimum focus point

'About 4' would be very close to the 47.2" minimum focus distance of the lens.

Re: EF 70-200mm f/2.8 IS II USM - Focus Issue?

Waddizzle — Wed, 02 Mar 2016 02:38:44 GMT

I am using a 6D.

Yes, I had thought that it was 3 feet, but it is 4, but it seemed to give me a focus lock and I took another half step back.

I've taken more test shots from 5, 10, and 15 feet, and I get the same result. The sharpest focus always seemed to be a little behind where my focus had locked. So, I put on my Bob [RobertTheFat] hat, and experimented with a lens microadjustment for the specific lens.

I've been looking for documentation to explain what the two adjustment scales mean, and how they might interact with each other. I did find an article from 2011 in the Canon Digital Learning Center Knowledge Base, but it seemed to describe adjusting only one scale, not two.

So, I adjusted the top one to the maximum -20, and the bottom one to -10. Now it looks like it could be slightly in front, by about half the distance that it had been behind. I guess I need to play with it some more, but I can almost live with that for now.

Does anyone know what the two microadjustment scales represent?

Re: EF 70-200mm f/2.8 IS II USM - Focus Issue?

TTMartin — Tue, 01 Mar 2016 21:52:06 GMT

I recommend using the DotTune method for Micro Focus Adjustment.

Just Google it and watch the YouTube video.

As far as the Wide and the Tele, you need to MFA at 70mm for the Wide setting and at 200mm for the Tele setting.

Re: EF 70-200mm f/2.8 IS II USM - Focus Issue?

kvbarkley — Tue, 01 Mar 2016 22:09:20 GMT

One of these can make it pretty easy:

http://michaeltapesdesign.com/lensalign.html

Re: EF 70-200mm f/2.8 IS II USM - Focus Issue?

jrhoffman75 — Wed, 02 Mar 2016 11:40:58 GMT

Its in the manual:

Re: EF 70-200mm f/2.8 IS II USM - Focus Issue?

Waddizzle — Wed, 02 Mar 2016 13:47:29 GMT

Thanks, guys, for your persistent interest and efforts.

I finally did find an article in Canon's Knowledge Base about making the AF adjustment. Seeing how I cannot post a link to a search.... I found the 6D articles in the support area, not the knowledge base area.

The first article is the one from 2011, which doesn't go into the same detail as the 6D and 7D articles do. The first article introduces the concept of AF Microadjustments..