Traditional boxy cameras - RB/RZ, Hasselblad 500's - focus adjustment?

Started 2 months ago | Discussions thread
OP Raymond Cho Senior Member • Posts: 1,972
Re: Traditional boxy cameras - RB/RZ, Hasselblad 500's - focus adjustment?

Erik Kaffehr wrote:

Raymond Cho wrote:

Hi, not referring to digital back exactly but a related question. For those of you who had gotten a digital back for the boxy type medium format cameras did you have to get your focus screen calibrated?

The reason I ask is that I have a RB67 and also a Hasselblad 500CM but both of them are very sharp at f11 doing a landscape but they are not so sharp when doing a portrait on a tripod at a moderate F5.6 or something. Could it be that I am overly picky and it's film photography or maybe it needs calibration?

Cheers.

Hi,

Could be that you need adjustment.

You could do two checks.

  • Check that you get OK focus at the infinity stop of the lens.
  • Check that you get optimal focus when focusing on the ground glass.

It can be difficult to achieve exact focus based on the ground glass. I use Zeiss Monocular 3x12 Mono with the PM90 viewfinder on my Hasselblad 555/ELD.

If you have a split image groundglass, you can just find a flagpole a few 100 m away, set focus at infinity and see if the split image of the flagpole is aligned. The should work for many lenses.

The other way to check focusing accuracy is to shoot a ruler that is slanted away from the camera. You focus on a marker midway on the ruler, than check if the sharpest point is in front or behind the focused point.

LensAlign has a luxury kind of solution for that .

If you need adjustment, I think it is best to send the camera and lens to a repair shop that works with Mamiya or Hasselblad.

This is worth reading: https://www.josephholmes.com/news/2009/4/9/getting-top-quality-from-medium-format

Best regards

Erik

My Hasselblad the newer Mamiya camera doesn't have a split screen. My older RB67 does so I swapped it into my newer RB67 and I used the longer 180mm lens to look at some distant hills. The split screen doesn't show a perfect alignment when I focus to infinity stop, I need to go pass the infinity mark but the lens stops me going pass that point.

As a side note anyone know what this focus screen was originally designed for?  This came with my Japan sourced RB67

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