Canon Extenders

CarlukeDave

CarlukeDave

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Evening all,

My lurvely 70-200 f2.8 arrived today, not had the chance to use it yet, but hopefully covering a footy game at the weekend to give it a workout :)

I was wondering, will using this lens on my 40D as opposed to my 5DmkII be the equivalent of using a 1.6x extender? If so, would using it with a 1.6x extender on the 40D, be the equivalent of a 3.2 extension factor?

Also, does using an extender affect the performance of the lens? I think it affects the maximum aperture, but does it also have an effect on the autofocus speed or anything else?

Thanks

Dave
 
CarlukeDave said:
I was wondering, will using this lens on my 40D as opposed to my 5DmkII be the equivalent of using a 1.6x extender? If so, would using it with a 1.6x extender on the 40D, be the equivalent of a 3.2 extension factor?

Also, does using an extender affect the performance of the lens? I think it affects the maximum aperture, but does it also have an effect on the autofocus speed or anything else?

Thanks

Dave
Click to expand...

No such thing as a 1.6 x teleconverter (TC). Canon make a 1.4x TC or a 2x TC.

The TC increases the focal length of the lens by 1.4x or 2x, creating either a 98-280mm lens or 140-400mm lens respectively. The TC also reduces the size of the aperture that the lens is capable of achieving wide open, in effect with a 1.4x TC you lose 1 f-stop of light (f4), with a 2x TC you lose 2 f-stops of light (f5.6). You also lose autofocus performance (about 50%) on the 1.4x TC and (upto 75%, depending on the lens) for the 2x TC, you also lose image quality with the 2x TC.

The crop sensor does not change the focal length of the lens, it changes how the image is framed due to the smaller sensor. To create a image using an 80mm lens on a full frame camera, you would only need to use a 50mm lens on the cropped sensor camera. Have a read of the link.

Info
http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm

Peter
 
Thanks Peter,

It's something I've never really got my head round, I was sitting near a pro at a game the other week and he was using one with a 70-200, not sure if it was 1.4x or 2.0x though.

Dave
 
The TC's are generally not reccomended for use with zoom lenses, not even ones as good as the 70-200 range. They are best suited to your nice big primes (300mm+ etc.). They do work but it's generally accepted that you will see a more dramatic drop in quality on zoom lenses compared to primes.

Tom N.
 
A 70-200 2.8 and 1.4 x TC can produce some good images providing you stop down a bit. The 2 x however is a different story.
 
Thanks Tom and Euan, I might get a loan of one to try! The 1.4x anyway!

Dave
 
Hi Dave,
I can say the 1.4 is excellent on the 70-200 f2.8 non IS, i used it for a number of years before heading to Nikon.
I found very little fall off of IQ even at f4 while shooting an air show and even managed to capture BIF with no problems.
If you need one get one as it is a lot cheaper than a new lens.
 
+1
The 70-200L IS and 1.4TC combination works well and is value for money compared to a whole new lens.
Certainly worth experimenting with, esp. if you can borrow one.
Plus it can give you options with all your other lenses.
Mike
 
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