Anyone tried Canon 8-15mm fisheye with 2x teleconverter?

Architeuthis wrote:

I am very fond about the Canon 8-15mm 4.0 fisheye zoom lens that I use with Metabones 1x adapter on an Oly EM1II (MFT sensor with 2x crop factor) for underwater wide angle photography. The sugar side of using this lens with 2x crop factor is that one achieves tack sharp photos with utra wide diagonal angle of view (approx. 180 degree), but can zoom out when photographing cautious animals ( to approx. 85 degree).

I am speculating to switch to a Canon R or R5 camera body to get the benefits of a bigger sensor.

Misplaced confidence in sensor magic and a lack of experience with teleconverters more generally I suspect.

You put a fisheye on a 2x converter and even if it worked with a quality worth mentioning, which is unlikely , you have to put the iso up 2 stops to get the same shutter speeds as before. It's like comparing FF iso 1600 with m4/3 iso 400. Why go to all the fuss and expense for that.

Ironically the 8-15mm lens provides much less flexibilty with the 1x sensor (for that it has been designed for), since it allows just to switch between a circular fisheye view and the 180 degree diagonal fisheye view. The versatility of the lens on the 2x MFT sensor could be restored by using a high quality 2x teleconverter e.g.: https://kenkoglobal.com/product/teleplus_hd_pro_2x_dgx/

Therefore my question: Did anyone try the 8-15mm fisheye with 2x teleconverter on a FF body? How is IQ and AF performance?

Thanks, Wolfgang

Just because there's a "2x" label on m4/3 equivalence, and a "2x" label on a teleconverter, don't assume the quality will be the same... at least, make sure you can return these purchases because you will probably be disappointed.