CAN'T INF FOCUS: Hasselblad Distagon 40mm f/4 "C" Lens, Thoughts??

Discussion in 'Medium Format Cameras and Accessories' started by polymerase, Jan 19, 2012.

  1. polymerase

    polymerase Member

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    Hey Folks!

    I've got a headache of a focus problem that may be a simple fix. I'd love to hear your thoughts!

    I recently purchased a Hasselblad Distagon 40mm f/4 "C" lens with a chrome barrel. I snagged it for about $400. That's a very good deal, but was already out of my budget b/c med school is expensive.. I can't afford to send it to an official hassy tech, but I regularly repair/restore old cameras to help pay rent and figure this lens can't possibly be that complicated.

    That being said, I can't seem to figure it out...

    Despite the focus ring marking 19 inches to 50ft then infinity, the lens has a max focusing distance of about 7ft, and minimum focusing distance of about 10 inches. While the macro is kinda neat, I mostly shoot landscapes and large interiors, so I need infinity focus.

    I've tested this lens against my others on my 503CX body. This lens is the only one with a focusing issue, and it is reproducible every time I remove and re-mount the lens to the body (meaning the problem is consistent).

    The shutter fires correctly at all speeds, and all glass elements are clear, except for the front element. The front element has a decent number of scratches and cleaning marks, but no chips, fungus, or haze. I strongly doubt the front element is contributing much to this focusing issue. As far as I can tell, all of the lens elements are aligned and correctly oriented. I even cleaned each one individually to make sure no sort of strange invisible coating was causing the issue.

    I took the focusing ring off of the lens. I repositioned it on the barrel several times, each time setting the infinity at a different point. Unfortunately, the focus issue was identical every time I repositioned the focus ring, leading me to believe the problem lies elsewhere...

    Here are some photos of the lens I quickly/haphazardly snapped via my cell while I was messing with it earlier today:
    www.flickr.com/photos/51777251@N04/sets/72157628947330735/

    I'm sure the focusing problem is an easy fix involving something I've completely overlooked. I've never repaired a "C" lens before, and I don't have a service manual for anything earlier than the "CF" lenses, so I'm hoping you or someone else here can help me out.

    Thank you for your time!! I look forward to your reply.

    Cheers,
    Andrew
     
  2. keithwms

    keithwms Member

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    Put your glasses on. Can you see better now? :wink:

    Probably a dumb question but: is there some sort of macro limiter? And is the flange to film distance the same for all the hassy bodies? And is there any sign of a different rear mount, i.e. was it adapted, perchance?

    Just nutty thoughts....
     
  3. keithwms

    keithwms Member

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    Ah look at this, not the same lens but does it ring any bells?

    http://www.rob168.com/camera/Hasselblad.txt

     
  4. johnielvis

    johnielvis Member

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    maybe someone had it apart---and didn't put together right---like off 1/4 turn on the helicoid or something...if it was clad maybe that's what happened----
     
  5. Dan Daniel

    Dan Daniel Subscriber

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    I'll second this. Lens helicoids have multiple threads, and you can pick the wrong point to start the threads. Depending on the whole focus system, this could lead to jamming or reaching certain limiting parts, or everything could seem normal except it is shifted 'in space.' Although this is a different focus system, here's a Minolta Autocord's focusing block showing the variety of possible steps to be off when re-threading- http://www.flickr.com/photos/18067251@N04/5790473193/in/set-72157626869741228

    As to what it takes to get inside, and if it is worth even trying considering the risk, I can't help you. Unless I am prepared to lose a piece of equipment I don't poke around too much. And I consider the first time i go into a camera or shutter or lens, the most realistic thing I am doing is a dissection and autopsy, not a surgery from which the patient emerges alive.
     
    Last edited by a moderator: Jan 19, 2012
  6. polymerase

    polymerase Member

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    Keith, sadly this lens has no limiters. And I've got other "C" lenses that work great on my 503CX. Good thoughts though!

    John and Dan, I thought the same thing, but the helicoid seems to be a part of the barrel.. or at least I didn't see an easy way to alter its height. The other perplexing thing about the helicoid is that regardless of what point I screwed on the focus ring, the focus would still be off by the same amount. Also, the distance between the focus ring and the DOF scale when the ring is at infinity is correct. This all makes me think the helicoid might not be the issue.. :/

    There are a few pictures of the focus assembly in the link I posted above. It's somewhat similar to the Minolta setup, but doesn't seem to be adjustable.

    Thanks for your thoughts! Please keep em coming.
     
  7. ic-racer

    ic-racer Member

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    Lens element turned around from prior tampering?

    I have this but I think it applies to the later 40mm.

    [​IMG]
     
    Last edited by a moderator: Jan 19, 2012
  8. Dan Daniel

    Dan Daniel Subscriber

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    Well, all I can suggest is to compare your lens to another lens to see if the elements appear similar. Meaning if, for example, it is one single unit for focusing, the the rear element appears to be in the same spot in relation to the mounting flange. Do a search for images of your model? Hard to imagine how what appears to be a single unit in your snaps can focus at incorrect distances except by being mis-mounted, but there might be internal elements moving or such.

    Most such lenses have multiple helicoids. I have re-assembled lenses for 35mm cameras where everything looks fine, markings fall into place, etc., but I have obviously mis-indexed something.

    Or maybe the outer rings, with focus markings and such, have been re-assembled out of position?
     
  9. MattKing

    MattKing Subscriber

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    This behaviour seems similar to what you would get if you used a very short extension tube, which makes me think there is something wrong with the mount.
     
  10. polymerase

    polymerase Member

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    I added 10 new photos to my flickr set. They show all of the innards of this lens assembly.

    IC, thanks for the diagram. Sadly that is for a newer version of this lens and does not apply.

    Dan, I'm suspecting more and more that it's not a mechanical issue and is more likely a problem with one of the lens elements possibly being somehow inverted? After taking the lens apart again, I found that the helicoid is locked in place by screws in a specific orientation, so the focus issue can't be due to a wrong turn. Regardless of where I attach the focus ring, and regardless of where the distance label is, the max and min focusing distance are still ~7 ft and 10 inches. Even if I screw the focus ring on in a way that lets me twist to the point of the ring being stopped by the VXM lever, the max focus is still ~7ft..

    Matt, I completely agree. But there's nothing extending the barrel, no tube attached, and nothing seems to be missing.. A mount issue would make a lot of sense, but I stripped it down to essentially the chrome frame and didn't see anything out of the ordinary.. Maybe you can see something I'm missing (via my flickr link.)

    Obviously, this is driving me slightly crazy. All of your help is greatly appreciated. Please keep the ideas flowing!
     
  11. Dan Daniel

    Dan Daniel Subscriber

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    One thing I notice on the photos is scratch marks at the two spanner wrench holes on the back lens group. Not sure if that is from you or from a previous owner. If previous, it might give a hint as to where people have been mucking around? It's one thing I'll look for, signs of previous dismantling, etc. Maybe the helicoid, which appears locked, has been unlocked, rotated, then re-locked in the wrong orientation. Marks from set screws can hint at this, true 120 degree tapped holes allow for mistakes in re-assembly, etc. Study screw heads for signs of previous disassembly. Well, looks as if these are things you are comfortable with already. I don't know if David Odess (sp?) in Boston area is helpful, but maybe he has ideas.
     
  12. RalphLambrecht

    RalphLambrecht Subscriber

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    i tried it and have noissue with mine
     
  13. John Koehrer

    John Koehrer Subscriber

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    Is the focusing ring threaded to fit a helical? I ask only because I don't remember a link between the focusing ring and helicals.
    It does sound as though the helical was assembled incorrectly
     
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  15. ic-racer

    ic-racer Member

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    Are you sure you understand about the helicoid? It just unscrews. But unlike a standard screw and bolt, there are multiple sets of parallel threads. It can "start" at different locations. Only one of them is correct. Usually there is no mark or any help what so ever. Getting it correct is trial and error if you did not put a mark on the two pieces when it was disassembled. (Sorry if you know all this).
     
  16. snederhiser

    snederhiser Member

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    Hello Ralph;
    I looked at your jpeg's and saw on your focusing mount that there was a sliding lock. Usually on most lens assemblies there are two. Slide these out and see if the rear mount will screw in one turn. Reinsert the slides and reassemble and see if this helps. Steven.
     
  17. polymerase

    polymerase Member

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    First, thanks for everyone’s continued help!

    I added a more photos to clarify how the focus rings work. I also uploaded 3 photos taken with the lens to show the focus issue directly (taken after I dismantled/reassembled the lens for the other photos).

    Before I answer specific questions, here’s what I’ve recently found:

    The lens focus ring can only attach to the barrel in the correct orientation if it is set to infinity focus with the helical completely compressed. Any other arrangement will not align correctly, will cause the focus ring to only be able to rotate a few centimeters in each direction, or will cause the focus ring to fall off the barrel. There is only one correct orientation of all of the focus rings.

    The adjustable helical within the focus ring has threads but is also on a track with a screw serving as an endpoint. Because of the track and screw, this is not an adjustable part.

    Furthermore, I’ve re-checked the orientation of every lens element and all things seem in the correct position. There is no room for a different order or orientation of any of the elements.

    Then lens continues to have the same focusing issue. Also, something I haven’t mentioned is that the lens is very soft, even at f/16 on a tripod. I’m hoping a fix for the focus might somehow fix that too..

    All in all, I’m stumped.

    Now for specific answers:
    Dan, John, and IC, I may be missing something important. I repair camera bodies regularly, but I have never repaired a Hasselblad lens before. I understand how a helical threaded set of screws work, and how helical focusing works, but maybe I am calling the wrong part a helical in my description? Have I photographed the helical/helicoid/heli-etc. that you are each referring to? I want to make sure we’re on the same page, and that I haven’t completely overlooked something important. Thanks!

    Steven, can you please elaborate on the “sliding lock” and tell me which photos you see it in? I’m not sure if I see any sort of locking mechansim anywhere.

    Thank you again to everyone for your continued help! I really appreciate it!
     
  18. mdarnton

    mdarnton Member

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    The Helicoid referred to is when you have fully disassembled the focus mount, and are holding three very greasy parts with giant square threads in your hands. The focus ring is screwed onto the middle of the three rings, the lens elements hang in the front threaded part, and the mount at the back is connected to the third. It does not sound like you have gotten anywhere near to disassembling the lens this far.

    As others have said, when you get these back together wrong, the zone of focus is off. In most lenses, the scale as marked will be off by exactly 1/6 of a full turn of the focus ring, or possibly a multiple of that--check yours to see if this is the case. This is deep surgery, probably worse on a Blad, though I've never had one apart, and it's common for people to get it wrong, not understand the problem and give up and sell the lens as it is, messed up. It's not hard to fix, but may not be an at-home job for you.
     
  19. snederhiser

    snederhiser Member

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    Hello Ralph;
    In photo #4 & #5 you have the back of the lens disassembled. On the barrel there are usually 2 slots machined into the barrel. The sliding locks fit in the grooves to prevent the barrel from turning when you focus the lens. These look like a T with two small holes in the top. This is a common feature on every lens I have worked on except front mounted lens cells. Not easy to fix a camera or lens by description, Steven.
     
  20. Dan Daniel

    Dan Daniel Subscriber

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    Before you spend much time on the focusing distance issue, I'd like to return to something you sort of just dropped in there-

    "Also, something I haven’t mentioned is that the lens is very soft, even at f/16 on a tripod. I’m hoping a fix for the focus might somehow fix that too."

    If this lens moves all elements as a single block, and you can't get a clean image at what appears in the viewfinder to be the best focus spot, I wonder if this is worth continuing. Seems to me that the helicoid we are all focused on is simply a device to move the lens block back and forth, nothing more all in all. And if this lens block is junk, who cares if it won't reach infinity? Infinite junk is still, well, junk?

    Have you studied the lens block to see what could have happened? If it isn't a single block in motion, I'd suggest that your problem lies in how these parts are assembled and moving, not in the overall focus helicoid.

    I think it's time for some emails to people like David Odess and other Hassy repair outfits. I don't know much about him beyond what I read hear and elsewhere. I've had some repair people be very helpful in emails in response to questions. Maybe there is another Hassy person who is known for being helpful?

    And an exploded diagram. Oftentimes that shows you exactly what is backwards, missing, etc.

    (Is this thread referenced in the Camera Building, Repair forum at APUG? Just to be sure to reach anyone who might be able to help.)
     
    Last edited by a moderator: Jan 21, 2012
  21. john_s

    john_s Subscriber

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    If the lens was sharp at some focused distance, say 7 feet, I would be suspecting the mount. If it's not quite sharp at any distance, then that leads me to suspect an internal optical problem. It's quite a complicated lens and it doesn't take much to mess up such an optical arrangement. I have the same lens in Rolleiflex SL66 mount (i.e. no focus mechanism because it's in the camera, with the shutter too) and I can tell you it's quite a sharp lens.

    It's not uncommon to end up with a lens that someone's messed about with. I bought a nice collapsible Summicron (Leica) from a local dealer and it wouldn't critically focus. Evidence that someone had messed it up on very close inspection: it was found that he had left some of his lunch inside the lens. The basic problem was one of alignment. I got a refund
     
  22. darkprints

    darkprints Member

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    1. I've never seen a 40 with a chrome back half and black front half.
    2. The 40's minimum focusing distance was .5 meters (19.68"), not 10".
    3. The 40's smallest aperture was f/32, not f/22
    4. There was a click-stop at .9 meters - a reminder that focusing closer was not recommended.

    Maybe you have a Frankenblad lens.
     
    Last edited by a moderator: Jan 21, 2012
  23. ic-racer

    ic-racer Member

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    Just so we are all on the same page, my take on it is that in your pictures "EXTENDED" and "FULLY CLOSED" it is showing the movement of the standard thread that allows twisting of the lens, not the helicoid. You have to put the helicoid inner and outer pieces together with that standard thread somewhere between "EXTENDED" and "FULLY CLOSED." The helicoid threads will fit together in a number of different places and only one is correct.

    One way to tell which is the helicoid is to follow a groove all the way around. You will see that it will look like you are skipping some of the threads as you progress because there are multiple parallel separate grooves.

    600.png
     
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  24. polymerase

    polymerase Member

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    I haven't responded yet because I want to reply with something substantial. Sorry for the delay!

    Thank you to everyone for the help! And Thank you very much Ian for your detailed instructions. I'll reply later tonight or tomorrow with progress.

    In a nutshell, I'm still having the focusing issue, but.. as I stare at more and more photos of other 40/4 "C" lenses, I'm feeling stronger and stronger that I have 40mm glass, but have the 50mm "C" shutter assembly. Take a look on eBay or search google to have a look at the lenses and barrels for yourself. I think you'll see the same thing.. That'd explain a lot. But that would also be really sad, because I have no idea where I'd find a working 40mm shutter without the glass for any reasonable amount of money..

    In the meantime, I'm going to continue to attempt to focus with the lens as is.

    Thanks again! I'll keep you posted soon.

    Cheers,
    Andrew
     
  25. darkprints

    darkprints Member

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    In case you haven't deduced from my post #21, the lens elements behind the shutter (the chrome section) would also be from a 50mm lens. So, you have lens elements from both 40mm and 50mm lenses.

    Where did you buy this $400 "bargain"? If you don't end up selling it for parts, you could probably use it as a Holgablad lens.
     
  26. polymerase

    polymerase Member

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    I've been chatting with the fella that sold me the lens. He bought a bunch of hassy gear on the cheap from an estate sale and tried to flip it for more money, as anyone would (though I'd probably have kept the coolest of the toys for myself..). He told me he's going to extensively dig through all of the stuff he purchased in search of the correct lens body/shutter assembly. We'll see how that goes..

    Also, I've got horrible, terrible, downright no good, massive exams on Monday and Wednesday of next week.. so I'm taking a hiatus from messing with this lens/situation until after the exams. Hopefully by then the guy who sold this frankenblad to me will have helped sort things out.

    Thank you again to all of you wonderfully helpful people!! I will keep you posted as I find out more.
     
    Last edited by a moderator: Jan 24, 2012