@limvo05 wrote:
The reason I am looking at either a 300 f2.8 or 400 f2.8 is that I could use it with my 2x converter for birds or other wildlife photography, and without the converter for other types of photography and still have the sharpness that I am looking for.
Here is a sample I took with the 70-200 f2.8 without the converter. This is zoomed in at 50% of the original.
I would not use a 2x teleconverter with any of the big primes. Even the prime that has one built into it only uses a 1.4x teleconverter. I have not used one, but I can definitely see image degradation with the 1.4x III.
What body are you using? I would recommend a lens that is actually 600mm, of 800mm, over using a teleconverter with either a 300mm or 400mm lens. But, I do not know what body that you are using.
I use the Sigma 150-600mm "C" with great results with full frame sensor bodies like the 6D, and even with the 1D Mark IV. But, the Sigma and the 7D Mark II seem to be a marriage destined for divorce. The combo just simply does not work well for me. For whatever reason, the focusing is not anywhere near as crisp.as it is with the larger sensor bodies. I had similar isssues with my T5 before I sold it. I tried it with my son's 80D, and though not as soft as the 7D2, the images were i little soft just the same.
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Well on your way!
