kf_tam wrote:
Initially it certainly focuses less than 50m. It is a bit dispressing .
I tried to bite the bullet, and screwed the M39 adapter inwards to the point that when the M42 adapter was mounted to the camera, the top of it wouldn't stay flush to the EOS flange and tilted downwards. But the lens did focus further away. And the camera still would fire with the mirror going up and down without any collision.
So I decided to trim down the M39 adapter, allowing the M42 adapter to stay flush with the EOS flange as the M39 adapter go deeper into the EOS throat. And voila, the lens now focus close to infinity....Show more →
Mmm there is something odd going on.If i remember rightly it was impossible to achieve infinity with the 5D body.Even with the two rear elements touching it couldn't be done!
The answer must be that your 1Dmk II has a more mirror clearance than a 5D.I'll see if i can find the measurements and notes i kept...
ronchappel wrote:
Mmm there is something odd going on.If i remember rightly it was impossible to achieve infinity with the 5D body.Even with the two rear elements touching it couldn't be done!
The answer must be that your 1Dmk II has a more mirror clearance than a 5D.I'll see if i can find the measurements and notes i kept...
Hi Ron,
That most likely to be the case, as judging from the fact that the 1D series has less troubles in adapting Contax and Lecia lens (see Compatibility lists). Well, 1D series users are cursed with heavy weight, inconveniently big size and unimpressive battery life (maybe the Mk3s are better), so at least we are blessed with a better behaving mirror .
I'm not worried about the mount being seperated from the lens as I wont be using the FD mount anyway...The plan is to convert it to SA mount.
Whilst I wait for it to arrive (which could be a week or more away) the only thing that really worries me about it is that the outer diameter of the rear element holder tube may be bigger than 48mm...Because thats the biggest rear element diameter that the SA mount can take.
Does anyone know the diameter of the rear element tube?
I wondered why that one sold for so much. I saw that one and I hate to be the bearer of bad news....but I asked the seller if the fixed rear glass element was in place (it sits in the FD mount assembly) and he told me this:
I see no glass attached the rear mount assembly.
I don't know that it has a glass, I bougth it from a little store in Thailand, then it can not be mount with my camera so I have to sell it.
- kobkik2007
I told him he should edit the listing to let people know this important detail. He kind of covered himself though because the description says he didn't know if anything was missing and he sold it 'as-is" If the rear element is really not there you have yourself a soft-focus lens.
Sorry, Alf, for the missing rear element .
But I did measure its diameter to be 36.15mm (glass + metal ring). I think the metal ring is permanently fused to the glass, and the whole thing screws in its carrier in the back plate of the FD mount. The diameter of that carrier is 37.4mm.
Anywhere, I noted that the quality of my images focused at infinity is a bit softer at the right side. Given that I centered the rear element and the M42 adapter by simple eyeballing, this may be the cause. I measured at 0.2mm out of center for the M42 adapter relative to the main lens.
Therefore I stripped them down, and recentered carefully with caliper this time, and this showed more even image quality at the different sides of frame.
There is haze overall at f1.2, which is largely gone at f2.0 (At very long distance there does have some real haze due to air pollution in Hong Kong.) Notes that the depth of field does not cover the entire image!
At f2.8 the whole image is reasonably sharp. It continues to improve at f4.0.
I forgot to add:
I also tried to increase the protrusion of the rear element towards the mirror. I have removed the original metal plate and just glued the rear element (with its metal ring) to the M39 adapter, with careful centering. Then the M39 adapter ring is filed down 0.8mm. Now if I screwed in the rear element too much the mirror would hit the edge of the element's metal ring.
I finally settled to 1.3mm protrusion over the M42 mount, making the total distance of element to EOS flange to 6.96mm. Thus it is just 0.5mm off from its original FD configuration.
Obviously thats very bad news but I'm not totally glum about it...The chances of finding a replacement rear element for such a lens may be next to zero (though it might still be worth ringing Canon just to check) but I have an assortment of lens elements which I removed from various lenses over time and I'm hoping that among them is one that might do the job...If not I'm hoping I can resell it without losing any money.
Alf Beharie wrote:
Obviously thats very bad news but I'm not totally glum about it...The chances of finding a replacement rear element for such a lens may be next to zero (though it might still be worth ringing Canon just to check) but I have an assortment of lens elements which I removed from various lenses over time and I'm hoping that among them is one that might do the job...If not I'm hoping I can resell it without losing any money.
Alf,
I've just very crudely measured the focal length of just the rear element, and it is about 28cm. Because I was just hand-holding the element with one hand, a milky semi-transparent plastic with another, and tried to hold a ruler at the same time, it was as crude as it could be.
If you find a 30cm fl lens or slightly longer you can give it a try. Using a longer fl lens should also give you a bigger clearance for the mirror. I knew that someone in China is converting the FD85L this way.
I destroyed my original rear lens element during conversion.
I could kick myself, but then luckily I found it as a spare part in the bay.
In beween these days I called and emailed Canon (Europe) but they did not have any parts for that lens any more.
Alf: I can send you my heavily scratched rear element against shipping costs.
There will be loss of IQ, though. Send a PM for a better description, if you are interested nevertheless.
Oh thats a shame Alf-that lens looked quite nice otherwise! the lens is a complete dud without a rear element.But like others say,there may be a solution!
If all else fails it may even pay to have one made to measure.One of use can give the dimensions and approximate curvature
I hope it turns out well.
Well here are some more example crops,this time at about 20m focus distance.I'm now convinced that moving the rear element 1mm forward INCREASES image quality a little.It may not be by much but it's noticable at 100% magnification,especially nearer the edges.
Note this test was not perfect-i had to move forward slightly to focus one of the edge crops(was too lazy to start all over again).This gives that shot a slight advantage but not enough to account for the huge improvement it shows.
As you can see the center crops show the modified element lens to have a very slight advantage,while at the edge the modified lens is noticeably better
ronchappel wrote:
Oh thats a shame Alf-that lens looked quite nice otherwise! the lens is a complete dud without a rear element.But like others say,there may be a solution!
If all else fails it may even pay to have one made to measure.One of use can give the dimensions and approximate curvature
I hope it turns out well.
That may be possible but it should also be possible to find a similar lens element to replace it with...A look at these lens diagrams of three 85mm f1.2 lenses and luckily its seems that the FD is the only one to use a simple bi convex rear element:
I have plenty of them to try...Most will probably have a deeper curviture than the original and that could effect the registration distance and/or cause some noticable distortion but it will be fun trying.
I have a couple of questions about adapting this lens to an EOS DSLR.
First, has anyone looked into the cost of having an adapter machined that would allow the rear element of this lens to be screwed into an M42 to EOS adapter? Kind of like an M39 to M42 adapter ring, but with the inside threaded to accept the rear element from the 85.
Second, is there any consensus about which cameras allow infinity focus with this lens?
I know it won't with an unmodified 5d/5dII. But how about the following.
1. 5d/5dII with shaved mirror.
2. 1d or 1ds series cameras.
3. Canon APS-C cameras.
.
.
