How difficult to replace focusing screen in Hasselblad 500c?

[harlequin]

Dear Team,

Have old 500c with cracked focusing screen, (looks like windshield after traffic accident)

Does this need to be done by technician from Sweden, or can I carefully remove 4 screws place unbroken screen in place and carefully re tighten screws holding frame in place?

Any comments answers or suggestions greatly appreciated!, looks not too difficult....


Regards,

Harlequin

 

[chriscrawfordphoto]

The screws that hold the screen allow adjusting the height of the screen for focus accuracy, and if you tighten them unevenly, the screen will be slightly tilted, affecting focus accuracy at the edges. You can do it, but will take a lot of work; best to let a tech do it.

The later 500 c/m was designed with interchangeable screens, so you did not have to go through that. Yoy just unlatched the screen and lifted it out and replaced it with the other one and relatched.

 

[itsdoable]

It's easy to change the screen on the 500c. Getting it calibrated to focus correctly is trickier.

The 500c screen consist of 4 parts, a spring, a Fresnel plate, a ground glass, and a frame which holds it all down with 4 screws. How much you tighten the 4 screws adjusts the height of the screen against the spring.

Ideally you calibrate the height of the screen on an optical bench. But the full moon on a clear night works too, use a fast long lens that has a known infinity stop, adjust the 4 corners so the moon is sharp there (lens at infinity), repeat till they don't change, checking the middle as you go. When you are there, pot the screws (a tiny dab of nail polish on the heads works)

If that sound like a recipe for disaster to you, then it's a good idea to take it in to a service tech.

I'll point out that now is a good time to upgrade the screen to something that is brighter than the stock 500c screen....