Who/How to calibrate Hasselblad pme51 pme-51 prism that's off ?

Ken Wayne , Sep 07, 2007; 02:00 p.m.

I sold a friend a Hasselblad pme-51 meter prism. It's basically brand new in the box as far as outer condition. After receiving it he wrote to me and said, "It proved to be 1 stop off in bright light and varied to 2 stops off in dim light," after testing it against his hand helds that have been faithful to him for years. So he sent it back to me and I gave him back his money.

Do you guys find this to be common with yours?

I intend to send it in to Hasselblad to get it calibrated but wanted to check first to see if anyone else knows how to calibrate these or is it imperative that it gets sent off to Hasselblad U.S.A. to be recalibrated by them?

Any help or thoughts about calibration would be appreciated.

thanks and blessings, Ken

Answers

Richard Wolzt , Sep 07, 2007; 04:07 p.m.

Hello Ken,

this depends on the screen on the camera. The older cameras without the acute matte screen have a "darker" picture on the screen. As the meter measures the picture on the screen, you have to calibrate it.

If its working correct on a 500C and you put the prism onto a 501cm or 503cw or any model with an acute matte scrren, there is definetly a 1 stop difference. Hasselblad gives this information in the booklets. So check the screen with your friend, if it's the same that you have. If the screens are different the 1 stop difference is normal.

hope this helps - Richard

Ken Schuster , Sep 07, 2007; 06:39 p.m.

If the meter is giving "variable" readings, it needs more than calibration. If the meter is consistent, adjust the ISO (ASA) accordingly.

A rough way of calibrating your meter is to fill your viewfinder with a gray card that's in direct sunlight. Don't bother with focusing. Take a reading with your PME51 (with lens shade but no filter). Step back so that the area around the gray card is in the frame so that you have a reference of other objects in the scene. Focus. Do a series of exposures around your reading, changing just your aperture by a third or a half of a stop. Write the info for each exposure on something like a 3X5 card and include it in the focused part of scene.

Select the image that looks most like a gray card in a "normal-looking" scene when you view the image on a contact sheet (printed with #2 to #3 contrast if b&w), Polaroid film or on a monitor if you're using a digital back.

After you decide on the best exposure, adjust your ISO to whatever number gives you the "right" f-stop and shutter combination. That should work in sun, shade and everything in between... if the meter is working correctly, AND if you're using the meter the right way.

Reflective meters interpret whatever they're "looking" at as 18% gray (gray card). A reflected reading of white paper or snow, will give you an under exposed b&w negative resulting in gray paper and gray snow. Conversely, a reflected reading of a "dark shadow" tone will result in a medium gray tone in a print.

A meter in "averaging" mode takes everything in its sensing area and throws it in a blender. If all the tonal bits in your scene are predominantly light (light beach sand or snow field scene, for example), your scene will be under exposed on negative film, and gray in the b&w print, if you don't compensate by increasing exposure above the meter reading. Of course you do the reverse with a scene that's predominantly dark tones. On the other hand, if all the bits are comprised of about equal parts of light, medium and dark tones, just do what the meter tells you, and no compensation is necessary... unless you're exercising your "artistic license."

Q.G. de Bakker , Sep 09, 2007; 02:23 p.m.

Ken,

The last link points (when you remove the final "]") towards a user manual.
Hasselblad use a test rig, with software, to test and callibrate metering systems. Not easy for us to replicate.