Jerome, Wish I could help you. I only have the 1.4X-L and a Tamron 7 element AF 2X converter. The L converters will also fit the FA* 200/2.8 (which I have and use regularly). On the 200/2.8 or 400/5.6, there is a marked difference in contrast between the two converters. Comparing images/prints between plain lens and both converters, I can't see any obvious differences with the 1.4X-L. The Tamron, however, is plain as day. The images just don't have the clarity/contrast that you would expect.
One way to look at it is that you are already compromising the image simply by using a converter. You should try to minimize the compromise any way you can. You also spend a bundle on your lens, you should want it to perform to it's best. HTH, Bruce Friday, December 6, 2002, 3:44:13 AM, you wrote: JDCR> After surfing the archives, I found the following inquiry to the list from JDCR> about 2 years ago (taken verbatim): JDCR> ____ JDCR> I've lately acquired a 300 mm F2.8 A* big glass and naturally am looking JDCR> for ways to burn off the extra F stops. If I read the materials correctly JDCR> 300mm is sort of the breaking point between whether you should use an "S" JDCR> or "L" converter. Someone know which works best with this lens/focal JDCR> length? JDCR> ____ JDCR> Surprisingly, there were only 2 responses... JDCR> Part of one response was that... "I believe the main advantage of XL JDCR> teleconverters is a reduction in light fall-off in the corners compared to JDCR> teleconverters without the long snout. The secondary advantage of XL JDCR> teleconverters is optimized image quality for their compatible lenses." JDCR> Another response mentioned, "I'd assume that the 'L' converters would work JDCR> slightly better, but I suspect you'd only see the difference under lab JDCR> conditions." JDCR> My question is, does anyone care to elaborate / confirm / disagree with JDCR> these comments? In particular, with an FA 300mm 1:2.8, would one have the JDCR> option of using either the 2x-S or the 2x-L? and if so, is the optical JDCR> difference neglible? In short I'm trying to determine if paying twice as JDCR> much for the 2x-L is necessary if the 2x-S is acceptable. JDCR> Thanks in advance, JDCR> jerome JDCR> _______________________ JDCR> Jerome D. Coombs-Reyes JDCR> PhD Candidate, ISyE, Georgia Tech JDCR> http://www.isye.gatech.edu/~jerome
