Wrong exposing with XCD 21mm and 907X

[usm]

When I’m doing an exposing test for example f4 with 1/30 sec and f8 with 1/8 sec with my XCD45p lens, the image is more or less the same. Doing the same test with the XCD21 the f8 image is totally under exposed.
Left: XCD45p
Right: XCD21


Another thing: The wheel of the 907x is turning much harder with the XCD21 as with the XCD45p. The lens is touching the wheel, not much but it does.

Thanks for looking...

 

[FloatingLens]

Another thing: The wheel of the 907x is turning much harder with the XCD21 as with the XCD45p. The lens is touching the wheel, not much but it does.

Curious. In my instance, the XCD21 is not touching the dial at all. There’s an air space of at least 1mm.

 

[usm]

The xcd21 was a preproduction lens. I returned it.