After comparing 70-200mm f2.8 GM II shots taken with the two teleconverters, I decided to test both under slightly more controlled circumstances. After all, the combo using the 2X had served me well while I was shooting it on the a7cII.

It’s not that the combo with the 2X was “bad” by any means. It’s just that with the 1.4X the shots were so much better. I figured maybe either noise or autofocus could be the culprit, and in the end it looks like a combination of the two.

On static print targets the combo with 2X shows no weakness at f/5.6. Any smidgen of acuity that might be gained by stopping down to f/8 (I saw none) would be more than offset by the added noise.

Realizing that I also use a slower default shutter speed when the 1.4X is in use, I knew that the difference between the two was more than a stop of light. So when I found a cooperative critter that normally shows good feather definition, I adjusted shutter speed to get different ISOs.

The first below is at ISO 1250, the second at ISO 500. Not only does the first shot have a discernible amount of additional noise, it looks like one of two things happened: either the camera’s AI allocated focus differently, or the camera cooked some noise reduction into the raw file. I suspect the former.

Whatever the case, the conclusions are that the 2X will continue to be used in bright light and the two lens/TC combos are safe in the arsenal. Looking ahead, I may add the 70-350mm APS-C lens again for situations in which size and weight matter.

And I’m chomping at the bit to grab the R 180 and 2X next time I’m in the ant farm to see how they perform on the a7rV. Yeah, the more I see non-critter results from this sensor, the more I like it.

a7rV/70-200mm f2.8 GM II/2X . . .