Extenders A & B

[kerkko_kehravuo]

<p>Recently there has been discussion of Canon FD extenders 2x A and B at the forum. Manufacturer gives it´s guidelines of use. What is your experience, witch one works better and with witch lens? I have both extenders, but have mostly used only B, with TS 35 mm f:2,8 and FDN 300 mm f:4 L. TS stopped mostly down to f:22 and 300 mm tele wide open. In both case results have been exellent.</p>

<p>K.</p>

[Bill C1664885404]

<p>I happen to have both as well, only recently getting the 2x-B. Per Canon's instruction that the 2x-A was designed for use with 300mm lenses and larger, I've only tried it that way and can say it did a surprisingly excellent job mated with my FDn300/4.0-L on a tripod.<br /> <br />The past couple weeks I've been testing the 2x-B with a variety of lenses shorter than 300mm for which the 2x-B was designed, and so far have gotten some favorable results. Not sure the results are precisely as good as using the prime lenses by themselves so given a choice between using a 100mm + a 2x-B extender vs. a 200mm prime, I'd prefer a 200 prime every time, and to also avoid the 2 stop loss of light.</p>

<p>But I see the biggest benefits of a 2x-B in the utility of being used on multiple lenses while having a significant reduction in space & weight if on a day walk in the woods or an extended hiking trip where those might be issues vs. carrying a seldom used large / heavier prime lens.</p>

[John Crowe]

<p>I would test the 2x-B and 2x-A on your 300/4 L to find out. I suspect the A will be better.</p>

<p>2X-A won't focus properly on the 85/1.8, but the 2x-B will. As per Canon.</p>

<p>The only lens that I had that didn't care which 2x was used was the Canon FD 300/2.8 SSC Fluorite. </p>

 

[rick_janes]

Kerkko, since teleconverters are magnifiers it follows that they will more reveal the partnered len's aberrations, and a 2X

moreso than a 1.4X (assuming that the two TCs are of the same brand and optical quality level). This would be true even if the TC had zero optical faults of its own- an impossibility. That's not news by any means, yet how often is it spoken that folks like the 1.4X but the 2X not so much because the latter looks worse? As if surprised? Hello, science!

 

If the attached lens starts out with a native resolution at or even beyond the film or sensor you're using then life is good, some (or

even much) of the image quality degradation of an added teleconverter may not be apparent. Truly stellar lens & TC

pairings can produce beautiful large prints and files which stand up to critical viewing, and I think these results are most

often associated with lenses which exceed the medium's native resolution. In comparison, normal sized postings on the

web are not critical tests...what looks okay here might not look so great at 13x19" or larger. That's good news too, you

won't need the very best gear to get decent results.

 

You'll forgive my crossing the lens mount border briefly, I'm very curious to see how Canon's new EF 400/4 DO II works

with the TC IIIs. It might be a stellar pairing...

[awahlster]

<p>My experience has been that Canon Knew exactly what they were talking about when they said to use the A with lenses of 300mm and longer and the B with lenses shorter then 300mm. Not hard to imagine the company that designed both the lenses and the extenders would know what worked best.<br>

I own all 3 of the Canon extenders and have owned multiples of the A and B at one time or the other. </p>

<p> </p>

[rick_janes]

Canon produced five specific designations of teleconverter in the breechlock era:

 

FL 2x, dedicated for use with the FL 300/2.8 SSC Fluorite

FD 2x, as sold with the FD 300/2.8 SSC Fluorite (black lens with green stripe, as is the FL)

FD 2x-A

FD 2x-B

FD 1.4x-A

 

The first two are extremely rare!