i tried it and have noissue with mine
Originally Posted by keithwms
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
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).
Originally Posted by polymerase
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.
First, thanks for everyoneís 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, hereís what Iíve 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, Iíve 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 havenít mentioned is that the lens is very soft, even at f/16 on a tripod. Iím hoping a fix for the focus might somehow fix that too..
All in all, Iím 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 weíre on the same page, and that I havenít completely overlooked something important. Thanks!
Steven, can you please elaborate on the ďsliding lockĒ and tell me which photos you see it in? Iím not sure if I see any sort of locking mechansim anywhere.
Thank you again to everyone for your continued help! I really appreciate it!
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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.
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.
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 havenít mentioned is that the lens is very soft, even at f/16 on a tripod. Iím 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 Dan Daniel; 01-21-2012 at 12:32 PM. Click to view previous post history.
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.
Originally Posted by polymerase
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
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 darkprints; 01-21-2012 at 06:04 PM. Click to view previous post history.
Reason: for clarification