Hmm. Since my HQ camera (V1.0 2018) is possibly older than that data sheet I'm wondering (w/o checking said sheet) whether the "back focus lock screw" refers to what, to me, appears to be a clamp ring locking screw, ie. the ring that clamps the threaded lens mount to the sensor which is something I've never needed to adjust. (Whether the GS camera is similar I can't check at the moment as it is "in storage", probably up in the loftI think some of the confusion here arises from the instruction in https://datasheets.raspberrypi.com/hq-c ... -guide.pdf
Back focus adjustment ring and lock screw
The back focus adjustment ring should be screwed in fully for the shortest possible back-focal length. Use the back focus lock screw to make sure it does not move out of this position when adjusting the aperture or focus.
Following this instruction results in the spacing from the outer face of the Back Focus Adjustment Ring (BFAR) being less than the CS standard 12.53 mm from the sensor surface. So any lens fitted thereafter will already be closer to the sensor than is ideal for 'infinity' focus, and the lens focus adjustment range is compromised by having to use some of it to get to the standard spacing.
Manufacturing tolerances will mean the spacing will vary from unit to unit but on an example module here the position of the BFAR that gives the 'standard' spacing is about 1 and 2/3 revolutions outwards from the 'screwed in fully' position. I'd suggest this gives a better 'starting point' prior to fitting any CS lens (or C-mount lens with the additional 5mm spacer).
)Trev.
Statistics: Posted by FTrevorGowen — Mon Dec 02, 2024 8:49 pm