Calumet 401 focal plane/GG issue

[zeitguy]

My Calumet is actually focussing about 5% toward the camera from where the ground glass tells me it is. I haven't been doing much focus-critical work with this new old camera, so I am just realizing what is going on.

Anyone have any experience adjusting the rear standard/holder to calibrate focus on this camera? Is this even something you can adjust?

[Joseph Dickerson]

Check the installation of the ground glass. It's either upside down (ground side out) or is not all the way inserted into its seat.

Or it's too far forward (unlikely I think) but you could have purchased a camera with the wrong back or one that is installed improperly.

You might also check that the film holder(s) are seating properly.

Are you focusing and then stopping your lens down? It could be a focus shift. Try focusing with the lens already stopped down and see if the focus error is still present.

This can be a perplexing, and difficult to diagnose problem. I experienced this some years ago and finally found the a Polarizing filter was inducing a focus shift, but only with one particular lens.

I'm sure someone will come up with some more things that you need to check.

Good luck with it.

JD

[Mike Anderson]

My Calumet is actually focussing about 5% toward the camera from where the ground glass tells me it is.

Is there a fresnel screen on the lens side of the ground glass?

...Mike

[rjbuzzclick]

Hi Jeff,

Reid here. If you want to compare it with the back on my CC-400, let me know and we can meet up somewhere.