Which T/C for my SAL70200G?

Serdar A wrote: FineArt wrote: I don't understand why you would want to buy 70-200G plus tele when you already have the 70-300G. What were you trying to do? He already bought the 70200G and inquiring about how it will perform with the SAL-20TC giving him a 140-400mm f/5.6 zoom. He will probably use it w/o the TC between 70-200 @ f/2.8 and with the TC between 200-400 @ f/5.6. Speed and range wise this makes the SAL-70300G he already owns redundant and probably could save a couple of hundred dollars if he sells the 70300G and buys a 2x TC. He is concerned that the resulting combo may not be as good IQ wise and asking people who have experience. Now, do you understand what he is trying to do?

I would suggest just use the 70-300G. Add a 1.4x if required for 420mm. A 2x should only be used on a prime with no filter. Teles in general are for primes. Adding them to a set of 15-20 lens elements is ugly.

Serdar A wrote: Joe and Mark: Based on what you said, is it OK to assume that SAL-20TC is OK with 200/2.8G and 300/2.8G? Maybe not wide open, but stopped down slightly.

OK yes, particularly stopped down. But, don't expect it to give the performance of a "high quality" fixed focal length of the same effective length. My 300/2.8 and 2x, while providing decent performance (publishable quality, as I have had photos with this combination published in a book), is not as sharp as my 600/4. I used to have a 200/2.8 and with the 2x it was pretty good as well. It was equal to or better than an old Sigma 400/5.6 lens that I had, probably in the late 1980's or early 1990's - before I got my 300/2.8 in 1993. But, that was then, and lenses today are much better. I can't do a comparison now, but I would bet the 300/2.8 and 1.4x is better than the 200/2.8 and 2x. Of course, more people likely have the 200/2.8 than 300. If you have both, you have even more flexibility.

Adding to what's posted above, the SAL 300/2.8 G SSM lens seems to be a bit better than the Minolta 300/2.8 which is what I have. Thus, one would expect that the Sony 300/2.8 would perform a bit better with a 2x than the Minolta 300/2.8. The only caveat here is that given the different optical formulas of the two lenses, it might affect just how well the 2x converter (which I believe uses the same optical formula/design that Minolta originally used with the first generation converters in the late 1980's) interacts with the newer 300/2.8. However, I don't think such differences would be sufficient to alter my or Jozioau's suggestions.