Checking focus on the RB67 and Hasselbald 500CM.

Seeking advice for this. I don't have a spare ground glass. I tried to put the RB67's focus glass onto the Hasselblad 500CM with the film back removed, doesn't fit. Then I put the Hasselblad's focus glass onto the RB67 but it was quite dark. I used a reversed 50mm Nikon lens as a loupe. I have the standard Hasselblad focus glass - with the 4 lines, but not split screen.

1. What sort of glass do I need and where do I get them?
2. When I focus to the infinity with both cameras the pictures are sharp - ie buildings and scenery. When I focus onto a person or a fence with the background blurred out it seems the foreground could be sharper.

Any advice cheers. May look at doing a CLA with a local guy here in New Zealand. We don't get much support in the way of film photography here.

Make yourself a poor man's ground glass. Get a new CD jewel case and cut out a 6cm square. Just score it with a box cutter and snap off. Butt strips of frosted tape to one side. Place the tape side against the film rails and secure to camera. Could use rubber bands or more tape. You will need good lighting to use this. Others will recommend strips of tape across the film rails but can be tricky to get tight and it won't cover the whole frame without multiple strips of tape.

Good luck with it.

Cheers, Martin (Kiwi ex-pat who tries to get back once or twice a year. )

PS. Bear in mind that depth of field in MF is a lot shallower than 35mm. Also depth of field extends further beyond the point of focus than in front of it. Checking focus at the film plane is more useful for calibrating a lens than evaluating depth of focus. When shooting you have to rely on the DOF scale on your lens.

instead of frosted tape, sand it with a 400 or 600 grit sand paper on one side till it looks like a ground glass?

ive used a heavy velum drafting paper which worked well too.

the screen in the rb has 4 large screws under it to adjust to match the film plane. be sure to scratch reference marks on each screw so you can move them all the same and return them to their start position in case needed.

Placing the RB screen (if you could) on the Hasselblad without the film back on will not get you the film plane. The film plane is defined by a surface that is inside the film back, which for a Hasselblad, is somewhat difficult to get to.

Similarly true with the RB, except you can open the RB back in such a way that you can put a ground glass on the film plane (and see the image). However, you cannot use a Hasselblad screen, as it is encased by a metal rim with finite thickness, so you cannot place the screen on the focus rails and have the frosted (acute matted?) surface at the film plane.

I have a Pentax 645 screen (early manual focus ones) that I use for focus calibration. The suggestions above are the way to go if you don't have a suitable "bright" screen.

rayonline_nz said:

Seeking advice for this. I don't have a spare ground glass. I tried to put the RB67's focus glass onto the Hasselblad 500CM with the film back removed, doesn't fit. Then I put the Hasselblad's focus glass onto the RB67 but it was quite dark. I used a reversed 50mm Nikon lens as a loupe. I have the standard Hasselblad focus glass - with the 4 lines, but not split screen.

1. What sort of glass do I need and where do I get them?
2. When I focus to the infinity with both cameras the pictures are sharp - ie buildings and scenery. When I focus onto a person or a fence with the background blurred out it seems the foreground could be sharper.

Any advice cheers. May look at doing a CLA with a local guy here in New Zealand. We don't get much support in the way of film photography here.

Click to expand...

According to #2 it appears that the focus is correct on both cameras. If you want to check to see if the focus on the viewfinder screen is the same as what is on the film you will need the proper ground glass adapter for each camera. These adapters can be a bit pricey. Even if you find that there is a difference in fp focus versus the viewfinder any adjustment should only be done by a highly trained repairman who has the proper equipment. Depth of field (focus) can be a bit difficult to understand especially in the close-up area as it varies with the f/stop.

Or even a woman.