500cm bad focus

500r420

New Member
So I just got a 500c/m, my first medium format camera

The focus through the viewfinder is different than the actual focus.
When I set the lens to 14 feet, an object at 10 feet away looks sharp
the object at 14 feet is sharp on the negative
When it set to infinity, objects at infinity are still not quite lining up on the split-screen
the camera takes well-focused images if I focus by distance, but this is impractical
It does this with a standard (non split) screen as well as with the metal thingy instead of the prism

Can someone help?
 

qnu

Banned
David,

The focusing screen may be inserted upside down.
Remove the finder, and look at the metal frame surrounding the screen.
It should be flat and smooth. If you see a frame inside another frame, with the sides bent over the inner frame, the screen is the wrong side up.

If so, push the two retainers out of the way, turn the camera upside down, let the screen drop out, and drop it in the right way up.
The retainers will slide over the screen when you replace the finder.
 

blowupster

Member
There are 2 possibiltities:
The screen is badly set, the ligne should be on top not in the bottom.
The mirror is not well positioned. I cann't help I never had such probleme.
 

cs_foto

Member
Hi, I am new here, I kindda have the same problem. Any help?

Basically I can't focus on infinity, when I have objects far away I can never get them sharp on the focusing screen. Also the focusing distance reading on the lens is way different than the actual distance the object is from me.

I am having this problem with a 50mm lens

Please any suggestions?

I've searched the web for this problem but there seems to be no information about it and many people having the same problem.

Cheers
 

wbulte

Active Member
Carlos,

The only way to get a definitive fix on this problem is to have the whole combination of back, lens, body etc checked by a pro. There are special test riggs for this work, tolerances are in tne hunderdths of mm for tack-sharp images.

Wilko
 

ttam

New Member
> Hello Carlos,

For a single lens reflex, typically there are FIVE things that affect in camera focus: 1) lens to film plane register, 2) lens to film plane parallelism, 3) mirror angle, 4) focusing screen alignment-both distance and attitude, and 5) lens calibration.

Items 1 and 2 will normally last for the life of the camera UNLESS it is subject to misuse, e.g., dropped, mounting a very heavy lens and carrying/holding this combination only by the camera.

Item 3 should last a lifetime as well as the adjustment/alignment is NOT normally requirement.

Item 4 MAY or may not be a problem with Hasselblad interchangeable screens. My dear friend Bill Maxwell (Maxwell Precision Optics - makes custom focusing screens for cameras) once told me that their screen frames have interesting tolerance and that when he makes his custom Hassy screens, he has to precisely set the screen height within the frames. The screen situation doesn't pose a problem UNLESS the camera body has been misused. ALL Hasselblad V series use an solid cast aluminum outer chassis (much like insects with an exo-skeleton). The innards are fabricated with sheet metal. Misusing the body CAN cause the the innards to be misaligned. Some 2000 bodies have its inside loosely 'attached' to the outer casting - you can actually see movements between the mounted lens and the outer body casting.

Item 5 - lens calibration should not be a problem for the life of the lens. Only physical damage will cause focusing problems. Three questions to you:

1. Have you taken anything pictures of infinity subjects WITH THE LENS SET TO INFINITY? The normal average photographer really has no access to test equipment so commonly available subjects and test procedures are use in lieu of shop instruments - most photographers don't know what to do with these even if they have access. If this 'film' test shows that infinity subjects (targets) are in good focus, the chances are that your critical lens flange to film plan register is proper.

2. Have you a Hasselblad focusing screen design to be used with the SWC? With this, you can quick check to see if the lens flange to film plane distance is still OK. Test you camera at INFINITY and DON'T rely on the focus scale on your lens when you do a test of this kind. E.g., positioning your camera at five feet and setting the lens at five feet. The scale is not instrument accurate and in theory and practice, distances are measured from subject to film plane. A 'hairs breath' off on your lens' focus scale (at five feet) can be inches off of the actual subject distance (MUCH, of course is dependent on the focal length of the lens). This test MUST be done with an infinity subject (roughly AT LEAST 1000x the lens' focal length) and that the lens itself be set at infinity. If you see a good focus at infinity, the lens flange/body register should be OK.

2. How old is your 500c/m - has it been serviced by Hasselblad or a competent Hassy technician? Why? If has been serviced properly, your 500c/m mirror's foam cushions should have been replaced. This MAY be your problem. Have the mirror cushions checked out; it may require replacement. Bill Maxwell replaced them on some of my cameras. Unfortunately, Bill NO LONGER repair camera; a pity as he was ONE heck of a camera technician! Faulty or old cushions will affect visual focus ONLY on the focusing screen. Film focus is UNAFFECTED.

Hope I didn't bore you with my verbiage.

Tsun >
 

ttam

New Member
> Sorry, I got my own post and read it. Please excuse my poor command of the King's own! I shouldn't be proof reading my own words!

Tsun

>
 

uaiomex

New Member
David:
Both cameras I have (had) a 500CM and an ELM had at some time this problem. Maybe because I live in a tropical area, this happens more often, I don't know.

In both cases, the mirror was not parking properly, a little bit too short. this caused to a difference between focus on ground glass and focus on film plane.

It needs some kind of replacing some old linings in the chamber and of course cleaning, readjustment and lubrication.

I hope this helps.
Eduardo
 

wbulte

Active Member
Hi Eduardo,

In the ELM and 500CM the mirror glass is mounted on three small pieces of foam. That stuff deteriorates over time. When that happens the mirror is not guaranteed to come back exactly in the right location. The foam is intended as a sort of flexible mounting, if you ever closely looked at a 500ELM/500CM mirror when the camera is being cocked you will understand why. I once dismantled a 500CM for scrap, and indeed the foam behind the mirror was no longer flexible.

I don't think it is illogical to assume tropical temperatures & moisture speed up the foams demise.

This is one of the advantages of the newer gliding-mirror system.

Wilko
 

ttam

New Member
> Hello Eduardo and Wilko, These foam pieces were the ones I tried to explain in my first message to the group. Wilko is quite correct, the gliding mirror is vastly superior to the mirror design used in the early models of the 500 series.

Tsun >
 

cs_foto

Member
hi guys, thanks for the reply's.. got a better idea now on what is going on...

Tsun:

i haven't done any test yet, everytime i'd shot at (near) infinity i was doing a very small aperture "just in case" so the film looks good, but like you said, i need to shoot wide open to see, this is my biggest concern indeed: that what i am seeing is what i am registering on te film, but to tell you the truth i don't know and that is what brings me in this forum....

i also have a 80mm lens and i can't seem to notice the problem on that one. so that might lead me to think that the problem is the lens itself... so, in case the lens is defective, is there a chance that what i see in focus in the screen is not what is being registered in the film?

as well: you know of any place i can bring my camera for a check in london (uk)?

thanks a ot for your answers, i really appreciate

all the best,
 

ttam

New Member
> Hello Carlos,

If your camera body functions properly with other lenses known to be good, then what you see is what you get (WYSIWYG) on the film. I can't think of a situation where the focusing screen image would NOT AGREE with what the film see even if the lens is 'off' as say, when someone disassembled its helicoid and did not reassembled it correctly or in case cases, lens elements may be reversed or replaced 'backward' during reassembly. Some lenses may use shims to calibrate and position is optical lens cells - upon reassembly, these may be mixed up or left out completely! In any case, WYSIWYG if the camera has proper focusing and lens flange/film plane register - as someone has noted previously, the tolerances are only a very few hundredths of a millimeter - in some cases, optical means are used to assess these dimensions (especially for parallelism of the respective parts).

Unfortunately I haven't a clue about whom to recommend in the UK except for the official UK Hasselblad agency.

Here in the US, there are many that I would recommend (not in order of preference): Hasselblad USA, David Odess, and Essex Camera Service. Unfortunately for us camera users, Professional Camera Repair ceased to exist shortly after Marty Forscher retired and Bill Maxwell stopped repairing cameras - he STILL makes a hell of a great focusing! I use them in all my Hassy's!

Hasselblad in the US were very accommodating (and provided me with EXCELLENT service before the moved their HQ to the west coast) when I needed my equipment inspected. They checked out my lenses and bodies while I waited. It was a bit of a schlep to drive there - about 60+ miles round trip. I should hope the the small repair/parts office they maintains on the east coast is as good - only problem is that this office only handles analog equipment, so digital user will STILL need to send thei goodies to their west coast HQ for checking and service.

Good luck and I hope you get your problem resolved satisfactorily! In any case, watch out for those pesky little mirror foam cushions - they DO REQUIRE periodic replacement!!!

Happy snaps, Tsun

>
 

gjames52

New Member
Hasselblad in the US were very accommodating (and provided me with EXCELLENT service before the moved their HQ to the west coast)>

V service is still in New Jersey.

Regards:

Gilbert
 

uaiomex

New Member
Hi Wilko:
You said right. I bet David's 500Cm's issue is caused by that.
The tropical (hot&humid) weather does funny things to some materials. Years ago, I bought a pair of bose 901 speakers and after only 3 years the suspension (made of some kind of syntetic rubber, I believe) came to a dusty mush. Luckily, the speakers had 5 year warranty, so they sent a set of 18 new drivers! That say something about a company honoring a warranty! - The new set never had any of this problem after 20 years.

On the gliding mirror. If this mechanism eliminates this eventual problem, it is a big plus. Posibly enough reason to upgrade my camera to a newer model. hehehe


Happy trails
Eduardo
 

wbulte

Active Member
Hi Eduardo,

Well, the mechanism of the gliding mirror does not depend on foam (mushy or not ;-) It looks more mechanically 'polished' compared to the classical mirror mechanism. That said, I took both my 500C/M on the road (holiday), not the 500ELX. That one has the gliding mirror, but I don't like the added weight when traveling.

Wilko

NB: as for my trails, todays trails in the Black Canyon of the Gunnisson National Park (in Colorado, US) were fine. I'm a bit overexposed myself from the sun, currently cooling my neck with a wet towel. Hopefully the shots sofar are OK. Specifically a couple earlier ones, made in Victor, CO (sic...) that I hope will come out well.
 
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