Teleconverters Help

futureal33

futureal33

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Nick
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Hi all,

I am looking to buy a 1.4x teleconverter to use on my 5DMk2 with a variety of lenses.

I have no idea when it comes to which is best etc, just wondering if anyone could give me a steer?

Ive read something about some which don't report the increase in aperture to the camera...would that mean I could increase the length by 1.4x and not have to sacrifice the extra f stop?

Lenses Id be looking at using it with

70-200 F4L IS
135L F2
300mm F4L IS

Thanks for any help
 
The extra stop is lost whether it's reported or not...that's simple a focal length divided by the aperture calculation.

Bob
 
Hi Nick


I would just like to tell you that no matter which tele-converter you use you will lose some f-stops, the reason being you are putting extra glass between your lens and the sensor. the general advice is to but thy same make converter as your camera, but i have a KenKo x2 teleconverter and I use it on my sony A550.
So the choice is yours pay the massive price canon want or go for the cheeper option like the Kenko...
 
You will lose one stop with 1.4x, and two stops with 2x. It's not the extra glass as such, but the magnifcation factor as Canon Bob says. By the same token, the f/number is reduced whether or not that is reported to the camera, and also, while you may be able to fool the camera into auto-focusing (because it doesn't know the true f/number) that's no guarantee that it will work.

The quality you get is mainly down to the mother lens, and long lenses tend to work better. There is no point in using a telecon with anything except the 300mm - you have other focal lengths covered without a telecon and you'll get better quality.
 
Ad already said, with an f/4 lens you'll likely lose AF function. They are normally designed to AF with lenses of f/2.8 or faster.
 
odd jim said:
Ad already said, with an f/4 lens you'll likely lose AF function. They are normally designed to AF with lenses of f/2.8 or faster.
Click to expand...

He'll be okay to AF with a 1.4x, which takes an f/4 lens up to the f/5.6 ceiling on a 5D2. All telecons slow the AF a bit though.
 
niv2 said:
Canon
Click to expand...

Yes, and the (much cheaper) Kenko Pro 300 1.4x also gets good rep. It also has the benefit of fitting a few more lenses than the Canons, because the front element doesn't protrude.
 
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