70-200mm f2.8L IS - Focus Problem? at DVinfo.net

Go Back   DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon EOS Full Frame for HD

Canon EOS Full Frame for HD
All about using the Canon 1D X, 6D, 5D Mk. IV / Mk. III / Mk. II D-SLR for 4K and HD video recording.


Reply
 
Thread Tools Search this Thread
Old October 4th, 2009, 11:19 AM   #1
Major Player
 
Join Date: Mar 2007
Location: Sussex, UK
Posts: 317
70-200mm f2.8L IS - Focus Problem?

Hi, Just bought a Canon 70-200mm f2.8L IS and noticed when I zoom full at 200mm to focus and then pull back out to frame I loose focus.

I have to turn a couple of millimeters to refocus, that kind of defeats the purpose of zooming to focus.

I assume this is a back focus type issue? Is this a fault or a characteristic of the lens.
Can anyone confirm this.

Thanks, James
James Miller is offline   Reply With Quote
Old October 4th, 2009, 12:34 PM   #2
Major Player
 
Join Date: Mar 2007
Location: Sussex, UK
Posts: 317
Quick update, I have found that at any zoom range once focused sharp, there seems to be a bit of free play on the zoom ring.

One side of the free play is sharp the other soft, free play travel is about 1.5mm. My other zooms have a bit of freeplay in the zoom ring but it does not change the focus.

Now I found this freeplay I can zoom to 200 focus then pull to 70 twist the freeplay and it is sharp. This must be a defect.

Paid a quick trip back to 'Park Cameras' and they had no more units in, they sold 4 yesterday. 7-10 days for restock.

A young chap had a quick look and agree it was a problem, he only tested it for a couple of seconds and I'm not sure if he was just agreeing with the customer.

He told me to use it until they had restock, so I brought it home.

Model number UX0918 - September / 2009
James Miller is offline   Reply With Quote
Old October 4th, 2009, 01:09 PM   #3
Major Player
 
Join Date: Mar 2006
Location: Chicago
Posts: 706
here's a list of parafocal lenses:

Parfocality - Canon sez: Canon SLR Lens Talk Forum: Digital Photography Review

note this is from 2004
Don Miller is offline   Reply With Quote
Old October 4th, 2009, 01:34 PM   #4
Major Player
 
Join Date: Mar 2007
Location: Sussex, UK
Posts: 317
Thanks Don, So it is apparently Parafocal.

It's the free play that seems to be an issue, wish I had another to test. Should have gone with the f4 or the Sigma!
James Miller is offline   Reply With Quote
Old October 4th, 2009, 02:32 PM   #5
Major Player
 
Join Date: Feb 2006
Location: Philadelphia
Posts: 795
Quote:
Originally Posted by James Miller View Post
I have to turn a couple of millimeters to refocus, that kind of defeats the purpose of zooming to focus.
This worried me at first because so many still zooms are not parfocal, but I've found I don't miss it much - instead of zooming with the lens you just use the camera's zoom function and it works just as well.
__________________
My latest short documentary: "Four Pauls: Bring the Hat Back!"
Evan Donn is offline   Reply With Quote
Old October 4th, 2009, 03:06 PM   #6
Major Player
 
Join Date: Mar 2007
Location: Sussex, UK
Posts: 317
Evan, I didn't notice at first because it focuses so well by hand live. It's only when I was trying to get a handle on it's limits on legs I noticed it.

I just find I automatically zoom in to focus. If it like this on another copy, I'll just have to treat her like a prime.
James Miller is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon EOS Full Frame for HD

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 06:11 AM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network