They're here! More Muvipix.com Guides by Steve Grisetti!
The Muvipix.com Guides to Premiere & Photoshop Elements 2024
As well as The Muvipix.com Guide to CyberLink PowerDirector 21
Because there are stories to tell
muvipix.com

New lens. Focusing Questions

Talk about anything here.

New lens. Focusing Questions

Postby Paz_Pazzaz » Mon Sep 26, 2016 12:00 am

Canon 70-200 f/2.8 L lens. New lens but one of the older - "new" models. It does NOT have image stabilization nor is it the IS- II version. It is the one just before those two. I bought this one because it is often on lists of so called "parfocal" Canon L lenses. Research indicates getting a "new" parfocal lens is going to be difficult since "new" lenses are adapted for fast focusing instead of parfocal characteristics and that the "lists" are not really reliable anyway:

http://www.dvxuser.com/V6/archive/index ... 10269.html

Some have expressed the opinion that what used to pass for parfocal is now showing up as not due to higher resolutions showing up errors that would not have been noticed previously:

https://www.lensrentals.com/blog/2016/0 ... oto-zooms/

The first problem I've noticed with the lens I have is that auto focus simply does NOT work correctly. As I've done more and more tests I've decided it does work well - very well - when the f/stop is high. But not when it is low. Is that normal???

thanks,

Paz
Whatever you do, don't set your coffee cup adjacent to your turps cup. :CS:
User avatar
Paz_Pazzaz
Senior Contributor
Senior Contributor
 
Posts: 304
Joined: Wed Aug 17, 2016 5:27 pm

Re: New lens. Focusing Questions

Postby Bob » Mon Sep 26, 2016 3:50 am

It's not uncommon. Both the lens and the camera can vary from unit to unit and that can affect autofocus. Focusing errors will show up more when the lens is wide open. Stopping down the lens will increase depth of field. Some DSLRs have a means to adjust the autofocus. Check your Canon camera manual and see if you have an AF Microadjustment setting. See this article for more information. In some instances, it may be necessary to have the factory recalibrate the lens. That can be expensive.
User avatar
Bob
Moderator
Moderator
 
Posts: 5925
Joined: Wed Feb 21, 2007 4:49 am
Location: Southern California, USA

Re: New lens. Focusing Questions

Postby Paz_Pazzaz » Fri Sep 30, 2016 10:15 am

Bob,

Thank you so much for that link. My Canon 7D is on the list of cameras that can accomplish the adjustments, but I want my lenses to work with my Canon cameras and the GH4. I've done more and more testing and have determined that this lens is focusing behind my chosen subject consistently with every camera I've tried it with. It's going back.

I don't think it is parfocal either. Doesn't matter - if the subject is out of focus at 200, it is still oof at 70. If I auto focus, then manually focus to actually get focus at 200, then zoom out to 70, it isn't at focus at 70.

I'm going to order the IS version. Might as well have assistance for hand holding when I choose to do so if parfocal isn't going to be there anyway. I hope this next one will be a keeper!

Thanks,

Paz
Whatever you do, don't set your coffee cup adjacent to your turps cup. :CS:
User avatar
Paz_Pazzaz
Senior Contributor
Senior Contributor
 
Posts: 304
Joined: Wed Aug 17, 2016 5:27 pm


Return to Water Cooler 


Similar topics


Who is online

Users browsing this forum: No registered users and 21 guests