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p.1 #16 · Leica R for Canon telephoto alternatives | |
ADAM HIRSCH wrote:
The 280 2.8 APO is a lot less expensive than the 280 4. Is there a difference in IQ?
Yes. The f/2.8 has some astigmatism that limits resolution outside the central area, you have to stop down to about f/8 to minimize it. The f/4 is glorious at any aperture and "pops" into focus on the viewscreen much more than the f/2.8 does.
Regarding the other combinations you mentioned I can do some testing this weekend. I can test 100 APO with 2x APO extender, 80-200 f/4, 80-200 with 2x APO, 180 f/3.4 APO, 180 f/3.4 APO with 2x APO, 180mm f/2.8 APO, 180mm f/2.8 APO with both APO extenders. I can pretty much guarantee none of these will match the 280mm f/4 APO. I no longer have access to a 280mm f/2.8 APO for testing.
Unfortunately my tests will not be full-frame, only the area covered by the DMR.
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