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DPChallenge Forums >> Hardware and Software >> teleconverter...Which one?
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 04/05/2006 03:11:45 PM · #1
I have a Canon 70-200 L f2.8 IS lens and I would like to increase the focal length using a teleconverter.
Has anybody here used a teleconverter with this lens and if so how effective were they in terms of optical performance?

Thank you.
 04/05/2006 03:27:34 PM · #2
I would think a good quality teleconverter made specifically for that lens will not degrade quality. There will be minor issues, but nothing that can't be cropped..

Now will someone who has actually done this please answer ;-)
 04/05/2006 03:36:03 PM · #3
Thanks Ignite for the fast response.

Typical. Just after I posted the question on this forum I found this.
//www.fredmiranda.com/reviews/showproduct.php?product=119&sort=7&thecat=31

It is a very good review and provides test photos.
 04/05/2006 03:38:52 PM · #4
70-200 with Canon 2x TC at f/5.6



100% crop



70-200 with Canon 2x TC at f/10



100% crop



Hope this is of some use.
 04/05/2006 03:41:38 PM · #5
The only real problem I have heard of with this is the loss of 2 stops of light. (makes your 2.8 a 4 right?)

Other than that....

The 1.5 or 1.7 ones generally only lose 1 stop (I think), which still keeps you at an effective f/3.5.
 04/05/2006 04:00:18 PM · #6
Atually 1 stop would make it f4 and two stops would be f5.6
 04/05/2006 04:02:08 PM · #7
A 2x teleconverter loses you two stops of light, meaning that your effective maximum aperture is f/5.6 with the 70-200 2.8. The 1.4 TC loses one stop of light, meaning that you have an effective max. aperture of f/4.

edit: Oops, too late.

Message edited by author 2006-04-05 16:02:41.
 04/05/2006 04:19:22 PM · #8
Originally posted by AJAger:
70-200 with Canon 2x TC at f/5.6



100% crop



70-200 with Canon 2x TC at f/10



100% crop



Hope this is of some use.


Thanks....very usefull.

The reason I want the 2x is to get a wee bit closer to some aircraft I want to photograph at low level. sing just the 200mm was not quite good enough.
//www.pbase.com/caeclyd/mach_loop

Message edited by author 2006-04-05 16:21:08.
 04/05/2006 04:37:26 PM · #9
I've heard a lot that the 2x is not as sharp as the 1.4x. I have the 1.4x and use it on a 70-200 f2.8 lens, and find it's quite sharp.
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