70-200 f4 + Teleconvertor question
I have recently bought a 70-200 f4 for use with my D7000. I plan to upgrade to a D610 soon. I would like to pair the lens with a teleconvertor to use for wildlife shots. I'm looking for a general wildlife photography solution and not something that gets my published in National Geographic. So while I would have loved a 300+ reach at constant aperture I simply wasn't willing to invest that kind of money..
Since I have an f4 a 2x convertor is pretty much ruled out because IQ degradation.
In terms of reach, I would obviously prefer a 1.7x convertor, but my question is - in your experience of shooting wildlife and a 1.7x convertor on an f4 lens, would my IQ suffer a lot? Given the sensor size, is it better to stick to the 1.4x, leverage the better DOF and simply crop? Would love to hear your experiences.