I recently bought 50-200 2.8 and - since it's expensive - am considering selling my 300 F4 to help pay for it.
The 300 F4 is a terrific lens, IMO limited only by its lack of zoom. So I'm fond of it, reluctant to part with it. I though using it with TCs would give me the extra reach I envy in those who can carry (and afford) the 50-400 or the 150-600, both of which are too heavy for me. I tried some shots to compare lenses - see attached.
Since birds won't sit still for comparison, I put together a few things and set them about 20 meters away. I thought the lama's hat (which I got in a small village in Nepal) might give a sense of how the lenses would deal with bird feathers.
It was a cloudy day. I set aperture to F8, a nice "ordinary" value, let camera set ISO, shutter speed. Then I cropped all photos to same viewing size of objects. Photos are OOC jpegs (I usually shoot raw, but jpegs seem better for comparison without fiddling).
All shots done with OM-1 II.
IMO the 50-200 comes out really well. I was surprised the 300 F4 with TCs didn't do as well as I expected it would. It's an older lens, perhaps not optimized as much for current TCs, or maybe it's the jpeg algorithm.
IMO the 50-200 + 2.0 TC comes surprisingly close to the 300 F4 with 1.4 TC. The 300 F4 with 2.0 TC is too soft for my taste, unlikely to be a substitute for Big White or 150-600. So I'm leaning to selling the 300 F4, probably through MPB, but if you're interested shoot me a message
BTW I also played around with, but didn't post, shooting with 40-150 2.8 and TCs. Pretty good results, but less good than 50-200. Also played with 75-300, which did better than expected - very acceptable. (My take on this lens is it's highly dependent on technique). Speaking of technique, I was impressed how easy it was to slightly mis-focus at longer zooms (sometimes camera locked on one of the branches), and even at F8 it made the target objects very soft.
Oh, for the heck of it, I tried using my Sony A7RV with 70-200 F4 zoom + 1.4 TC on the same subject. I thought maybe its high resolution would let me "crop in to zoom" and get equivalent IQ. Nope. IMO there's no substitute for "real" zoom.
Hope this might be helpful for some of you considering lens decisions. I resisted the 50-200 due to its high price, but I think it will let me replace my 300 F4 (they're about the same weight/size) and my 40-150 2.8 (which I love due to weight/size, but just can't justify the $$ to have it as well).
I absolutely disagree, the 300 f4 with the 2X is superb. I also have the 150 to 400 TC. Further, I have all the long Sony GM lenses. The Sony 600 mm F4 is also superb with a 2X. Atmospheric conditions can affect results of such long optics.
