Canon Extender 2x-Bgreenspun.com : LUSENET : Canon FD : One Thread
I understand that the Canon 2x-B Extender is designed for use with a prime lens up to and including 300mm. As to Zoom lenses, I found the write up confusing in that it says the 2x-B extender is also for zooms that include 200mm in their range. Is this really saying the 2x-B does not work/work well with a 35-70mm or 35-105mm? This item is a bit pricey and I don't want to make a bad choice. Any pros/cons on using extenders.
-- Rick Camilo (email@example.com), June 06, 2002
Yes, you would use the 2X-B for zooms shorter than 200mm as well. Actually the 2X-A is recommended for primes longer than and including 300mm, with the exception of the FD 300/2.8L, for which the 2X-B is recommended.
The main disadvantage of using an extender is that it magnifies the optical imperfections of the main lens. A 2X extender will also cost you 2 stops of light (often slightly more due to transmissive loss from the glass in the extender), so you may consider whether you want to use one with a slow zoom lens. On the other hand, they are convenient for situations when it may be impractical to carry a long telephoto lens, or in combination with a long tele when very high magnification is required. Given that the 2X-B is not easy to find, unless the compactness of the extender in comparison to a prime lens is a big issue for you, why not just look into an FD 200mm lens in your price range? I have the 200/2.8 internal focusing lens, which is a great lens and not too expensive. You would even be better off with an FD 200/4.0 (not the macro), which can be had for less than the cost of a 2X-B. Check keh.com for prices.
-- David Goldfarb (firstname.lastname@example.org), June 06, 2002.
None of the Canon extenders are recommended for any lens faster then F2.8 or shorter then 50mm as problems will occur with the rear element. It would be best if you very very carefully try a teleconverter on the back of your lens before buying. Also it is recommended that you always mount the teleconverter to the body then the lens to it, Rather then mounting the teleconverter to the lens and then both to the body this helps prevent misalignment of the aperture signal pin and stop down lever resulting in improper exposure. You can find a online copy of the Canon manual for extenders at this URL http://www.geocities.com/fdcanon/manuals/ this is the file page to the Yahoo Canon FD discussion group a great place if you are into FD mount Canons.
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-- Mark Wahlster (email@example.com), June 08, 2002.