I should have mentioned this was without the fixed rear element at just over 3 feet from a subject with the lens set to minimum focus distance.
I have tried the fixed rear element fitted on the back of an M42-SA adapter...It produded so far I could'nt mount the adapter.
Then I remembered some have said that the rear moving element must be only 1-2mm away from the fixed rear element and this would mean mounting it onto the front of the M42-SA adapter...I tried this and it makes no noticable difference to the closest focus distance.
I tried the fixed rear element touching on the tube that holds the moving rear element and the rear of the lens is still at least 30mm from the mount on the camera at closest focus distance.
This is'nt bad news though as with the large registration distance there is the possibilty of the lens being used as an ultra fast tilt/shift lens.
Are you sure you have the proper fixed rear element? It sounds like what you have is not working properly in the "optical formula" for the FD85L. Could it be that you have the element for some other lens?
Nick
Its supposed to be, but I cant be 100% sure...I obtained it for the just price of postage from an FM forum member who saw that I needed one.
I'm hoping that the moving rear element has'nt been tampered with...It could have been taken out and replaced the wrong way round.
The seller I got it from lives in Malaysia and he said he obtained it from a "repair shop", so anything could have been done with it and I would'nt have a clue.
The rear element has scratches but it is the right one. I am the mentioned FM member, and I took it out from my FL85/1.2 before I mistakenly damaged it.
I was so fortunate to find a new rear element (an old original replacement part) for my lens :-)
Alf, the convex side is facing the other glass elements of the lens. The concave side is facing the camera. In other words, the most protruding part of the rear element is the rim, not the center.
Hi Max, yes thats the way I have tried it, just cant work out why its not doing much.
I read some replies stating the moving rear element and the fixed rear element should only be 1-2mm apart at infinity but that would place the fixed rear element within the dished rear plate that holds the aperture dial on and I would have to make something to hold it in place...not easy.
Also the moving rear element it not right at the end of its holding tube, the edges of the element, which is noticably concave towards the back of the lens, are 5-6mm down from the rear tip of the holder tube and therefore it would actually be impossible to get the rear of the moving element closer than 4-5mm say away from the front face of the fixed rear element...Perhaps I have 1 element missing?
Mmm this is getting more curious!I'm certainly confused
To clarify... the rearmost element is a single piece of glass(not any kind of group).It's slightly convex on the front and slightly concave on the back.It's quite thin!-the total thickness is only about 3.5mm (a quick guess)
When completely bare it will be just the glass part with a thin metal threaded surround.The thread is 0.5mm pitch and about 35.5mm diameter
It shouldn't be mounted in any kind of holding tube! If you balanced a ruler across the rear of the element it would touch the outer edges of the glass
Don't rely on infinity working if the gap is over 0.5mm (i hope it wasnt me who told you 1-2mm.If so maybe it was a generalization..?)
The convex surfaces of the last two elements should be virtually touching if you want to be sure of infinity focus!
Here is how to be sure:
First,make sure the lens is focused as close as it will go.Take the focus ring right off and check that the infinity stops are removed ,that the helicals completely bottom out and there are no gaps anywhere .
Now,stick a small piece of tape sticky tape directly in the center of the second last element (paper type tapes/post it notes are best)
With this small bit of protection you can safely rest the last element directly on the 2nd last element.
Hold it there with some small bits of blu-tak ,etc around the edges.
Now hold the lens against the camera mount -the bare lens chassis points must touch the camera mount-if not you must remove some lens parts.
-Aim at a distant subject and take a test pic.
-Keep taking shots as you gradually move the lens away from the camera.
Don't worry if the sticky tape on the elements gives the pics an odd colour cast,etc.All you are trying to do is check focus
The first shots should be out of focus because the elements set that way will allow the lens to go PAST infinity.
If some of the subsequent shots are in focus then all is well !
Well, I sent the rear element to Alf, expoxied inside a "tube" (holder with M42 threads).
But Alf mentions a protruding tube around the rearmost MOVING element.
Furthermore, he mentions that the rearmost MOVING element is concave.
Both is clearly not the case in a standard configuration.
I think you are right, Alf. What you see is probably the second element of the moving group (which is the third element in total, seen from the camera side).
I assume that not only the rear FIX element was missing in your purchase but also the rearmost MOVING element.
Sorry Max, I just realised I got a bit mixed up with the terms concave and convex...The moving rear element is actually convex toward the rear of the lens.
In light of this do you think the rearmost moving element is still there?
The rearmost part of the floating assembly should be glass....only glass....no tube. There should be no metal protruding beyond this element whatsoever. The rearmost point in this assembly would be the center (because the glass is convex) of the rearmost moving element. In other words the closest metal in the floating assembly (looking from the side) would be the holder for this moving element and would be a few millimeters forward of the rearmost point on this element.
Oh no...So it looks like I really do have TWO elements missing!...That explains the extra long registration distance.
I still want to use this lens so I dont want to give up just yet...I wonder if there is a solution to this problem
A slightly drastic solution that might possibly work would be to add the rear element from another fast (ish) 85mm lens...My Helios 40 could be a likely donar as it has no Iris in it and I never use it since getting my CZ 85mm f1.4 Planar T*.
What do you think?
I think you are veering far away from the original design of the lens. You are going to end up with a "frankenstein" FD85L. What you will end up with is guaranteed to be as unlike an FD85L in terms of performance as virtually any other lens.
You have to ask yourself what you expect from this lens.
The engineers very carefully designed the lens with consideration to lens glass, materials, shape, position etc... When you start introducing "foreign" materials into the equation it is anyone's guess what you will end up with.
Think of all the times you have read about drastic differences in picture quality produced by different copies of the same lens. In this cases these lenses were identically engineered and manufacturing differences are "micro-negligible" compared to what you are considering doing. What are the chances that you will "accidentally" come up with something good as compared to the likelyhood of creating a total abomination?!
If you want to experiment with "hobbling" lens parts together to see what happens, I would suggest doing it with a couple of cheap lenses. I know you didn't pay a low price for this "deficient" FD85L so I would hate to see you lose even more money.
Personally I think you should resell the lens for parts provided the barrel and remaining elements are in good condition. At least this way you can get out of this while you still can while salvaging some of the money from your investment.
Blimey...You make me feel like Dr Frankstein meddling with the laws of nature!
At the end of the day its just a broken lens and I have nothing to lose by trying to get it work but potentially everything to gain if I can get it to work.
I can always fall back on your idea of breaking it down for seperate parts which can be sold to recoup at least some of my losses but that will be the very last resort.
Please excuse my analogy. I just thought it was a good one to describe what you will end up with if you start introducing elements from other lenses. Would you put different lens elements in your eye glasses just because they "looked" about the same size and shape?
You know what would happen.
If you are determined to resurrect (there I go again ) your lens so that it is a functional FD85L you will have to be patient and search for another FD85L as a donor or use yours as a donor to resurrect the other and sell off what is left.
I reckon finding broken FD 85mm f1.2 L with intact rear elements going very cheap is probably going to be nigh on impossible so till then I'll just have to give the "Helicon" or "Canios" a go.
You never know. You might find one with a bad front element and/or damaged focus ring or barrel. It could indeed be a long waiting game.
Whatever you do with what you have needs to be easily reversible. You have to be careful not to damage or irreversibly modify something specifically in an attempt to make the lens function with non-stock components. Think of what you are planning to do as strictly "experimental". If not, you will further devalue what you have or possibly even render it completely worthless.
Well I had a go at it with the Helios 40 rear element...OK for macros only...Also tried various other elements taken from miscellanious lenses over time, again best for macros.
