Extnders

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I own an ef28-105 and an ef100-300 lens and am looking at extenders. I have looked a t the Canaon 2x and 1.4x but notice in B&G that they have exclusive use with specific lenses, none of which are the two I own. My question is will these extenders work with my lenses and if not why not? I have read that extenders may damage your lens? Are you familiar with this.

-- Gregory J. Bobersky (Gbober6701@aol.com), October 19, 2000

Answers

The 2 extenders will not physically fit on your 2 lens as the extenders have a potruding front element, which fits into the recessed cavities on compatible lenses. Forcefully trying to fit the extenders into lens would damage the front element (of the extenders) and rear elements (of the lens).

-- Alex Yap (hashigou@yahoo.com), October 19, 2000.

Many third party tele-converters work with your lenses. Probably all of the cheap ones will. I'm not sure about the better ones from Kenko and Sigma. I've used the cheap Kenko 1.5X with your lenses and it works ok.

Keep in mind that the 100-300 USM isn't all that sharp at 300mm unless you stop it down some and anything you put on it will just enhance the blurr & decrease the f:stop more. The older 100-300 f:5.6 (non-USM) is a bit sharper to begin with though.

-- Jim Strutz (jimstrutz@juno.com), October 20, 2000.


Tamron also offers extenders for Canon lenses : 1.4 x and 2x. Each will reduce your effective maximum aperture; the former by one stop, the latter by two.

I don't know about quality, except to say I'm very happy with my Tamron 28 - 200mm lens.

-- Roy Kekewich (roykekewich@yahoo.com), October 23, 2000.


I use a 2x teleplus converter 7 element. on my 75-300/28-105 zoom lens and have had good (good - this depends on your expectations) results 9"x6" prints. the converter is about B#90.00. but i think it trades under a different name in usa.

-- wayne walker (ws_walker@hotmail.com), October 25, 2000.

If you can afford it, I'd unload that 100-300 and get the 100-400 IS L which will use both the Canon 1.4 and 2x TC's. I have all 3 and even the 2x delivers a very sharp slide when mounted on the 100-400IS.

-- Jeff Hallett (franjeff@alltel.net), November 07, 2000.


If I'm not mistaken, I read that using EF-12 extension tube between the converter and the lens would work. Still, using a 2x converter on 100-300 would make the viewfinder very, very dark and focusing a chore. By the way, the article I read was about stacking teleconverters, not using those converters on the lenses you mentioned.

-- Tim Fisher (tfisher@beachin.net), July 14, 2001.

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