canon telephoto

Old Aug 4, 15, 12:15 pm
  #1  
FlyerTalk Evangelist
Original Poster
 
Join Date: Dec 2000
Location: south of WAS DC
Posts: 10,131
canon telephoto

i have a 600mm lens(non IS) on a tripod for my wife to take photos of the osprey and the babies down their nest. the canon 6D will auto focus, she has shot a couple thousand images over the past 3 years. and we get quite decent photos. i bought a 1.4x IS extender for her. works great. i bought a 2.0x extender, and the camera will not autofocus. (all canon equipment) need help.
slawecki is offline  
Old Aug 4, 15, 5:53 pm
  #2  
 
Join Date: Jun 2004
Location: Central California
Programs: Former UA Premex, now dirt
Posts: 6,459
Chances are that ownership of such big glass is relatively rare among the travel photographers who frequent this forum. I suspect you will get more and better responses posting this question on a Canon-specific photography forum or perhaps one of the Canon groups on http://www.dpreview.com/ .

Off the top of my head, I suspect the addition of the 2x takes the maximum aperture beyond the capability of the equipment. But that is just a guess.
abmj-jr is offline  
Old Aug 4, 15, 6:10 pm
  #3  
 
Join Date: Jan 2009
Location: TPA
Programs: AA PLT, HH Gold, FM Prem, SPG gold
Posts: 560
Yup, very few lenses actually support the 2.0x extender. And even those that do lose two stops of light.

So a 70-200 f/2.8 would be a 140-400 f/5.6.

Of the short list of lenses that support the 2x extender the majority lose AF as a result. Check the extender manual for approved lenses.

The 1.4x is much more kind regarding AF exclusion and only loses one stop of light.

If money is no object and you want 1200mm I would suggest this lens.
rivlinm is offline  
Old Aug 4, 15, 8:55 pm
  #4  
FlyerTalk Evangelist
 
Join Date: Apr 2009
Location: Bye Delta
Programs: AA EXP, HH Diamond, IHG Plat, Hyatt Plat, SPG Gold, MR Gold, Nat'l Exec Elite, Avis Presidents Club
Posts: 15,087
Autofocus on the 6D does not function below f/5.6. This means AF stops working if you use a 1.4x extender with a lens with a maximum aperture darker than f/4, or if you use a 2x extender with a lens with a maximum aperture darker than f/2.8, because they cause you to lose 1 or 2 stops respectively.

Last edited by javabytes; Aug 4, 15 at 9:02 pm
javabytes is online now  
Old Aug 4, 15, 10:55 pm
  #5  
FlyerTalk Evangelist
 
Join Date: May 2002
Location: Pittsburgh
Programs: MR/SPG LT PLT, AA LT PLT, HH GLD, UA SLV, Avis PreferredPlus
Posts: 25,005
I presume it's a 600/4. A 2xTC on an f/4 lens yields an effective aperture of f/8. The only Canons that will autofocus at F/8 are the 1's, the 5DIII and the 7DII. Others are limited to f/5.6, which is what you get with f/4 plus a 1.4xTC.

It's possible to tape one of the pins between the lens and body to prevent the communication of the aperture and the AF system will try to work (Google will find it for you). But there's a reason Canon disables f/8 focus - it doesn't work very well. I've taped my 400/5.6 + 1.4TC. It works well shooting under bright sun, but starts hunting when light fades just a bit.

If sounds like the subject you're shooting is fairly static, from both the description and the fact that it's tripod mounted. If accurate, just use Live View to focus. It's not limited by the aperture, and it's also more accurate than phase-detect auto focus.
CPRich is offline  
Old Aug 7, 15, 1:09 pm
  #6  
FlyerTalk Evangelist
Original Poster
 
Join Date: Dec 2000
Location: south of WAS DC
Posts: 10,131
delete. do not know how to post image.
slawecki is offline  
Old Aug 7, 15, 3:03 pm
  #7  
 
Join Date: Jun 2004
Location: Central California
Programs: Former UA Premex, now dirt
Posts: 6,459
Originally Posted by slawecki View Post
delete. do not know how to post image.
Complete instructions in the sticky at the top of the forum.

http://www.flyertalk.com/forum/trave...phy-forum.html

In general, you can't post directly from your computer. You need to link from a photo hosting site like Flicker, Smugmug, etc. There is a list of some of the more popular hosting services, including a couple through FT, at the top of the first page.
abmj-jr is offline  
Old Aug 7, 15, 3:12 pm
  #8  
 
Join Date: Aug 2014
Posts: 91
You should stop down to F11 for best results and best sharpness.
MA330 is offline  
Old Aug 8, 15, 12:28 am
  #9  
Moderator: Trip Reports
 
Join Date: Jul 2013
Location: Dubai
Posts: 3,124
Switch to live view and it will probably still AF (@f8).
DanielW is offline  
Old Oct 15, 15, 12:15 am
  #10  
 
Join Date: Feb 2013
Location: NJ
Programs: UA-plat, HH-Diamond, Marriott-gold
Posts: 205
Originally Posted by DanielW View Post
Switch to live view and it will probably still AF (@f8).
nice portfolio btw!!
Mel Grant is offline  

Thread Tools
Search this Thread