Could you please explain how a Roddy 23mm HR in Arca mount differs from the "new" 23mm for the XT?
My understanding is that the only difference is the shutter, the optics being identical. If I am correct, I don't understand why a converted Roddy 23mm would behave differently than a native xT 23mm.
Comparing XT 23HR to a 23HR mounted in a copal.
Exactly the same glass (optics).
But X-Shutter provides:
- Automatic metadata for lens model and serial number
- Automatic metadata for aperture and shutter speed*
- Very precise shutter speeds*
- Shutter speeds in 1/3rd stops (rather than full stops)
- Flash sync up to 1/1000 (instead of 1/500)
- Integration to IQ4 UI allowing
--- electronic aperture control
--- electronic shutter speed control
--- electronic capture
- All of the above control also available in Capture One
- Automatic bracketing
Further, if that X-Shutter 23HR is mounted to an XT (rather than an Arca):
- Triggering via built-in XT body Shutter
- Metadata for X and Y movement for automatic lens correction
- No cable required (power/control passed via body connections)
*Using a Copal Shutter the shutter speed was entirely mechanically determined and so the actual shutter speed would vary by a meaningful fraction of a stop, and the metadata was often recorded incorrectly. Like any of the above features, of course, they may or may not matter to a given photographer depending on the work they do.