Hasselblad 553 ELX Inaccurate Focus.

[henry_finley1]

<p>OK, I've buttoned up the super cheapo 553 project and the camera is working again. Now I have noticed a very large discrepency in the infinity focus as compared to my other Hass bodies. That being said, like the man who owns 1 watch always knows the time. Wen he owns 2 watches, he never knows what time it really is. So it is with Hasselblads and their focusing accuracy. Infinity rarely agrees. That's why there are professional technicians.<br /> That being said, I am having a hard time even conceiving how focus could be so far off infinity in the finder as this one. We're talking 50 feet on the lens dial is infinity on this camera. Focuses WAY past infinity. Something is not right here. Yes, the original Accumat screen (or whatever... Interscreen, maybe); is installed correctly. This is my first experience with the gliding mirror. I've taken a couple pictures. The adjustment for the mirror stops are suspiciously close to one end of their range. Why, I ask. And the screen does not sit up on flat chrome-looking pegs. It rest on 4 pegs that look like cheap brass rivets. Maybe Hass changed the design from the C/M days.<br /> But something very strange is up. I wonder if that gliding mirror design is prone to get out-of-whack, or what.</p><div></div>

[thirteenthumbs]

<p>Is there a discrepancy between object focused on and the point of sharp focus in the image?<br>

If the focus screen is mispositioned then the mirror may be adjusted to compensate for it.</p>

<p>The reason for the difference between infinity on different bodies is the infinity target used and the person adjusting the camera. While I have not worked on Hasselblad cameras I have worked on medium and large format SLR's, rangefinders, and large format cameras.<br>

1. Establish an infinity target that is at least 5000 feet away. If you have a collimator use it. The Moon, Mars, Jupiter, or the Sun if you use the proper filter to protect your eyes, make excellent infinity targets. From your location use any online map service and identify a building or tree line that is a mile or more away.<br>

2. Identify where the exact film plane is on the camera you are servicing.<br>

3. Place a temporary piece of ground glass at the exact film plane for the camera you are servicing.<br>

4. With the shutter open and lens aperture set to wide open, focus infinity on the ground glass using a good loupe.<br>

5. Lock the focus once infinity is set if possible.<br>

6. Position the reflex mirror or focusing screen as needed to match the film plane focus.</p>

<p>In the case of your camera I would set the reflex mirror adjustment(s) to their mid point then adjust the focus screen.</p>

<p>When I set infinity using the coastal hills 3/4 nautical miles away the planets and stars are .001 off in focus movement. When using the Genentech building 1 1/4 nautical miles away as an infinity target there is no focusing discrepancy with the celestial objects.</p>

<p>Some technicians use a target 100 to 500 feet away as the difference between infinity and 100 feet will be covered by DOF at normal shooting apertures. </p>

[henry_finley1]

<p>Thank you. But what I'm wondering is how a Hasselblad made in 1996 could be so far out of whack. It's not like it's had an extra 30 years for people to be tinkering with it. And I know nothing about the "gliding mirror" mechanism--whether it could be prone to getting out of adjustment. So lacking the proper Hasselblad workbench and fixtures, I'm doing some forensics to get a handle as to why or how this could be happening. I'm hungry to learn these cameras, and have so little resources to glean knowledge from.</p>

[q.g._de_bakker]

I don't know the answer to which camera is out of whack (you can test running film through them, but it will be the 553), but to the question why: it doesn't take 30 years of tinkering to get one to be in that state. Tinkering with one only once should suffice.<br><br>There are three things (unless i forget some) that can throw focus off: body length, mirror position, and focussing screen position.<br>You haven't touched the mirror or screen (though someone before you quite possibly has), but have removed the chassis from the body. So it could be body length. (But since you were not the first to take the camera apart, it could be one (or both) of the other two, as well.)<br>One way to take the mirror and screen out of the equation would be using the ground glass back. If you can't get infinity focus on the image projected straight onto the ground glass back, it will not be because of mirror and/or screen misalignment (though it will not tell you whether those two are well aligned or not). So that would be a first diagnostic test.<br><br>But i gather that when the lens is at the infinity stop, the visual focus on the screen is not at infinity. So there must be something wrong with the optical path length from lens to screen. You said the upper frame of the shell was broken? And in your repair, did you touch the mirror mechanism? And then there is that stop you posted a picture off...

[henry_finley1]

<p>Here's where I don't get you. Though I removed the chassis from the shell, I did not disassemble any of the chassis panels. The lens hooks to the chassis and doesn't even touch the shell; the same for the back. So how could I have possibly made it a long camera? The camera does not even need the shell at all to be useable, strictly speaking (aside from needing the shell to be a holder for the screen). But on that count, when you tighten the screws under the tripod socket base, everything is as it was.</p>

[henry_finley1]

<p>Yes, the thin cross-beam of the shell was broken on one side, The thin cross beam at the top rear of the shell. But the broken edges match up and the top edge of the chassis rear window frame keeps it in place nicely.<br /> I might note again that on any other of the C, C/M, EL, ELM class camera I've worked on, infinity never agrees perfectly. But I attribute that to probably the pads under the mirror being rotten.</p>

[henry_finley1]

<p>A not so good picture of the screen pegs.</p><div></div>

[henry_finley1]

<p>No to fooling with mirror mechanism in any way. Now that I think about it, when I got it last week, the upper left front leather piece was missing--a sure sign of tinkering or repair. In fact seeing there was an adjustment screw (presumably) underneath was m first introduction to this feature, since my learning has been limited to the C, EL class. I also wondered why the bottom of the shell was not solid like the C/EL class. It was a cut-away, or maybe spring load place to tighten the bottom of the chassis to. I wondered what was up with that, and if it is in conjunction to the [adjustment screws?] on the upper front of the shell. Perhaps this is where screen adjustment is done on a 553. Speculation. Perhaps to allow to "cock" the chassis in the body shell? Wondering out loud. Thank you.</p>

[thirteenthumbs]

<p>At this point you need <strong>A</strong>. A service manual, <strong>B. </strong>another body that is functioning correctly to use as a guide, or <strong>C. </strong>an experienced tech to guide you.</p>

<p>If these options are not viable get a digital P&S capable of 15-20 inch macro shots and take pictures of an assembly before and after disassembly and verify they are in focus enough to be usable for reassembly.</p>

<p>I would start with establishing infinity at the film plane then a) shim the focus screen to match the gg if the screen requires the lens to be moved forward to achieve infinity or b) if the screen needs to be lowered as the lens needs to come inward into the body to focus infinity on the screen then adjust the mirror adjustments in 1/8 to 1/4 turn increments and evaluate the results of that adjustment. Focus should be judged at the center of the gg or screen.<br>

Keeping good record and having good pictures you can return to this state. <br>

Looking at your screen post picture I'm betting the other educated fingers lost/left off the pads that should be on the posts or they deteriorated and they had nothing to make new ones from then tried to reposition the mirror to compensate for them missing.<br>

Now, as for taking the mirror assembly apart, no unless the mirror will not operate or operates incorrectly and its obvious.</p>

<p> </p>

[thirteenthumbs]

<p><strong>P.S.</strong><br>

<strong><br /></strong>If my speculation is correct the pads will be 1mm (.040 inch) to 2mm (.080 inch) thick.</p>

[henry_finley1]

<p>Charles Monday--if you are still reading, you have shed light on some clues I was getting but not written of here. I do not have time to chronicle the whole repair. Suffice it to say I never lose in the end, in re-working a difficult camera, and 2) I repair "repairs", and have corrected quite a few "repairs". But I'm not a paid service tech; I'm an offset printer who would love to change careers. OK, background done.<br>

Thank you for your help. To recap, you are saying that the mirror pegs should be smooth and flat, and silver colored just like on the C/M's?. And that these are actually just caps that are on top of the indented-looking copper/brass colored posts in my photo? This explains a lot.<br>

So, to further speculate, I am now believing that the focusing screen accuracy adjustment is actually on the bottom of the chassis in relation to the shell casting. Along with the [adjustments?] on the top front corners, underneath the leather. <br>

It is obvious I need to buy a good dial caliper for the flange-to-pressure plate measurements. Then fabricate a groundglass to insure infinity. Then, proceed with a strong magnifier to adjust the screen, via the screws at the bottom of the casting, under the tripod plate. <br>

I have never seen any shim in a Hasselblad. I'm convinced the engineering used adjustment instead of shimming.</p>

[q.g._de_bakker]

I checked my cameras, and the mirror stop position is nothing out of the ordinary. So it's not that.

[thirteenthumbs]

<p>I looked at http://www.cameramanuals.org/hasselblad/hasselblad_553elx.pdf after my previous post.<br>

Does the camera have the/a correct focus screen? Fine thread adjustments would be better than pads on the post.</p>

<p>Yes, there are digital readout calipers for $20 from many sources that are worth their weight in diamonds.</p>

<p> </p>

[henry_finley1]

<p>Frankly, the more I think about it, the more I think I did a sloppy job of reassembly. These 553's apparently do not just go in their shell and tighten up the screws and that's it, like the EL/ELM machines.I think a lot of the screen adjustment has to do with the way you put the chassis in the shell and how you tighten it. THEN, and only then, do you proceed with any screen peg adjustments. And upon close examination, the screen pegs are actually hex screws, not the flat-top pegs like the EL's. I think I need to take this camera back down and start over.<br>

My main question all along has been to learn about the gliding mirror, and whether it was prone to get out-of-whack. So far, I haven't fooled with any adjustments ordinarily done with the official fixtures and jigs, and I am trying very hard to not foul things up to where only ta tech with the proper fixtures could get it right again. What I am pretty sure of is that I am fighting a previous knucklehead-boob's work, and have some problems from that to correct.</p>

[thirteenthumbs]

<p>When one fights me I sit it aside until I can look at it with a fresh point of view and not continue with the same mistake making/mind block state of mind I was in before.</p>

 

[q.g._de_bakker]

The hex keys are what they should be.<br>It's very well possible that the body length is off. That would not necessarily be the result of what someone before you did. It needs to be checked every time you put the chassis back into the shell. From the front surface of the front bayonet to the rear surface of the rear plate the length should be 71.40 mm. Using an 80 mm lens (the shift in focus depends on body length error and focal length), the body length being 0.1 mm short moves focus from infinity to 65 m (213 ft). If 0.2 mm off, you're already at half that, 32 m (106 ft). So try to check body length (without the jig Hasselblad provides to repair shops).

[q.g._de_bakker]

Uhm...<br><br>When the body length is too short (as i said in my examples) focus would move beyond infinity. I meant that when it's too long, focus moves to somewhere between the camera and infinity.

[henry_finley1]

<p>That's it. I'm buying a decent dial caliper. Anything less is just tinkering and getting things all fouled up. I'm a good worker--I have a good record of repairing "expert repairs". I've seen enough boob work from camera service shops to know I'm an attentive worker, even if I don't actually make any money off it. But if you guys are so kind to answer my questions, it's incumbent of me to cut the mustard and be deserving of your trouble. Stand by till my equipment comes. I have lots more questions. Thanks, men.</p>

[henry_finley1]

<p>Well I got my dial caliper. It's a used Mitutoyo I got off fleabay for 25 clams. I spent last night sanding and re-polishing the crystal that was all scratched. Then I miked various things that I KNEW were thus-and-so, and it checked out sweet. I've measured the 4 corners of this ELX chassis, and the worst measurement was 71.39. Pretty impressive. Now I can start getting to the bottom of this situation.</p>

[henry_finley1]

<p>OK, if anybody might want to hear further of this trek to pin down the measurements and track down the dirty culprits, here's what I've got. Now mind you, this is with a metric dial caliper--inferior to the Hasselblad-approved jig. I'm getting 71.44 on the left side and 71.38 on the right, with the chassis buttoned up and screwed back into the shell. Because of the use of a caliper, you have to take many measurements, to fined some sort of consistency, because of angling, which can throow off your measurements by a pile. I'm using a 1.56mm drill bit against the back panel of the chassis to take the edge of the shell out of the picture, and subtracting the diameter of the bit. On the front, I'm measuring from the face of the ring on the shell, and measuring down to the face of the bayonet, and subtracting that.<br /> Next item on the agenda is to fashion a ground-glass stand-off for the back rails, so I can do a little view-camera-style checking under the cloth of what my infinity looks like, to see where I stand on the infinity stop in the lens. I've set myself a tentative final error standard of .04mm.<br>

Sorry about the poor pic. Was holding the caliper in one hand and digital camera in the other, just to show. Notice the wood block from a letterpressman's furniture cabinet for squaring, and the drill bit taped to the camera back plate.</p><div></div>