Extender Question

sweigner · Apr 10, 2008

I currently have a EF 75-300mm f/4-5.6 III Lens on my Digital Rebel. I was looking at the Canon EF 2x II Telephoto Lens Extender. Can I use this with the 75-300mm?

JimmyO · Apr 10, 2008

I think it only works with L glass, sorry. But i might be wrong.

250Gimp · Apr 10, 2008

I think JimmyO is correct. There may be a work around by taping pins, but I'm not sure.

Kenko makes extenders, and I believe that they will work with your lense, but I would confirm on their website. You will loose a couple stops on your aperature when using extenders, and it may affect auto focus on your camera, unless it is really bright out.

CHeers

JimmyO · Apr 10, 2008

Also keep in mind that the lower the less the multiplaction the better the image quality. If you can you should consider the 1.4x or 1.6x before the 2.0x. And like gimp said you will lose 2 stops of light with the 2x, which is alot. This is why there mainly used on f/2.8 lenses.

sweigner · Apr 10, 2008

Thanks Guys!!

Mystwalker · Apr 10, 2008

sweigner said:
I currently have a EF 75-300mm f/4-5.6 III Lens on my Digital Rebel. I was looking at the Canon EF 2x II Telephoto Lens Extender. Can I use this with the 75-300mm?

My understanding ...

x1.4 - you will lose 1 stop so you are basically @ 300x1.4 f/8 ... unless you have a 1D series, you lose autofocus after f/5.6 - 1D series, after f/8

x2.0 - you lose 2 stops so you are @ 300x2 f/whatever it is after 8 (11?)

... you lose autofocus period.

I think recommendation to use on f/2.8 Lens is that losing two stops will still allow you to autofocus. Do not know about that pin stuff ... but something expected of Canon. I have the Kenko x1.4 Pro - not as metallic as Canon, but works well. It is not weathersealed either.

table1349 · Apr 10, 2008

Here is the compateable lens list
http://www.bhphotovideo.com/FrameWork/charts/canon2xExtender.html

christopher walrath · Apr 10, 2008

Say you have a 50mm f/2 lens. If you use a 1.4 teleconverter your maximum aperture becomes f/2.8 because you extend your focal length to 70mm and your maximum aperture diameter is still 25mm. If you use a 2x teleconverter you reduce your maximum aperture to f/4 because you have extended your focal length to 100mm while keeping that 25mm aperture diameter. With a zoom you only lose about 1-1.5 stops of light (70-210 or so). With a teleconveter I tested with my MD lenses I had an additional light fall off when compared to similar FL zooms, about an addition half stop. And the image quality goes down. And on long telephotos I found a slight focus shift mear infinity.

This said, if you have four or five prime lenses, a teleconverter could be an economic means to get even more focal length options. But a couple of zooms would honestly be the highest quality way to go.

soylentgreen · Apr 10, 2008

The Canon teleconverters ONLY work on the L series telephoto and super-telephoto lenses minus the 100mm soft-focus.

davebmck · Apr 10, 2008

Mystwalker said:
My understanding ...

x1.4 - you will lose 1 stop so you are basically @ 300x1.4 f/8 ... unless you have a 1D series, you lose autofocus after f/5.6 - 1D series, after f/8

x2.0 - you lose 2 stops so you are @ 300x2 f/whatever it is after 8 (11?) ... you lose autofocus period.

I think recommendation to use on f/2.8 Lens is that losing two stops will still allow you to autofocus. Do not know about that pin stuff ... but something expected of Canon. I have the Kenko x1.4 Pro - not as metallic as Canon, but works well. It is not weathersealed either.

You don't lose auto focus after 5.6 on the Rebel. I have a zoom that is 6.3 fully zoomed and it works fine. It can hunt in low light, but I have no problems in good light.