R5 lunar photography with stacked EF extenders

BobKnDP wrote:

I'm still mystified.

I don't see how you could focus at infinity with a 12mm spacer between the two TCs.

The 600mm plus the 2x, combined with a 12mm spacer, would make the infinity focus come in to about 120m. I doubt that any focus capability of the 600 beyond infinity could help nearly enough to get infinity focus.

The second TC shouldn't alter that.

Unless the EF to RF adapter has been shortened, I don't know how you got the Moon in focus

Yes, that's exactly what I did. If it wasn't clear from the other photo here's another:

EOS R5 + 11mm RF/EF + EF 1.4x iii + 12mm EF/EF + EF 2x iii + EF 600mm f/4L IS II; 1680mm @ f/11

I kit-bashed a JJC 11mm RF extension tube with a JJC EF/RF converter (but at my own risk--don't blame me if you try this at home!). The EF and RF female bayonet flange both have the same 4-screw pattern and OD. But the release pin on the RF 11mm is shorter and is not directly compatible with the EF flange, so it doesn't lock. That's not a problem, because I support the camera with an Arca-Swiss rail to keep the extenders' optical axes aligned, and to keep the camera from rotating. If you let the camera hang off the lens, there's too much play in the five bayonet flanges, and you get a decentered lens.

I think the EF pins on the 1.4x line up with the corresponding pins on the RF connector, but the camera doesn't recognize the lens, so I have to shoot manually. I guess the EF extenders are not just a passive pass through. They must have one other trick to get the camera to recognize them. I don't see any active electronics in the EF/RF converters, so maybe just a jumper or a resistor or something?