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Archive 2009 · FD 85L f/1.2: a real gem
  
 
JimBuchanan
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p.7 #1 · p.7 #1 · FD 85L f/1.2: a real gem


pengland wrote:
Jim,

Even if you use a smaller diameter element holder, don't you think there could still be contact? This looks to be more a problem of depth than diameter.

Nick


Yes, I agree the main problem is depth, but every little bit helps. I was thinking also in terms of the viewfinder housing on the top side.



Oct 15, 2009 at 07:16 PM
kf_tam
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p.7 #2 · p.7 #2 · FD 85L f/1.2: a real gem


ronchappel wrote:
Hi kf_tam,well done on taking the plunge!
From those numbers i'd say you will get almost identical focus distance as the 5D -about
25 meters maximum.Still very worthwhile considering this type of lens is mostly used for close subjects



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.



Oct 15, 2009 at 08:06 PM
trifox
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p.7 #3 · p.7 #3 · FD 85L f/1.2: a real gem


Hi there ...

We do carry out conversion FD lenses to EF mount with measuring equipment.. All rear parts are in black color to avoid any internal reflections ...

We believe that the infinity focus is worth of shaving the mirror -- but inifinity may be adjusted, of course..

the pricing is: 150 EUR including shipping back within EU, 170 EUR incl. shipping back to the rest of the world - USA, ASIA and others ...

We have done FD 85 f1.2 L, FD 135 f2, FD 50 f1.2 and starting doing teles

If any questions, please ask ... info@cameraserviceone.com

or visit our site .. www.cameraserviceone.com

thanks

trifox



Oct 15, 2009 at 09:41 PM
ronchappel
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p.7 #4 · p.7 #4 · FD 85L f/1.2: a real gem


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
...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...



Oct 16, 2009 at 04:10 AM
kf_tam
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p.7 #5 · p.7 #5 · FD 85L f/1.2: a real gem


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 .



Oct 16, 2009 at 04:28 AM
ronchappel
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p.7 #6 · p.7 #6 · FD 85L f/1.2: a real gem


Well that's a nice surprise.I've never even held one of those beauties let alone used one


Oct 16, 2009 at 10:39 AM
Alf Beharie
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p.7 #7 · p.7 #7 · FD 85L f/1.2: a real gem


I've just bought an FD 85mm f1.2 L on ebay for just 310!...Heres a link to the auction page:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=110443436022&_trksid=p2759.l1259

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?



Oct 16, 2009 at 10:15 PM
pengland
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p.7 #8 · p.7 #8 · FD 85L f/1.2: a real gem


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



Oct 17, 2009 at 12:26 AM
cogitech
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p.7 #9 · p.7 #9 · FD 85L f/1.2: a real gem


I noticed immediately that the rear element was missing.

So sorry to hear that you've had such bad luck, Alf.



Oct 17, 2009 at 01:39 AM
kf_tam
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p.7 #10 · p.7 #10 · FD 85L f/1.2: a real gem


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.

Edited on Oct 17, 2009 at 10:03 AM · View previous versions



Oct 17, 2009 at 08:13 AM
 

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Alf Beharie
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p.7 #11 · p.7 #11 · FD 85L f/1.2: a real gem


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.


Oct 17, 2009 at 08:52 AM
kf_tam
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p.7 #12 · p.7 #12 · FD 85L f/1.2: a real gem


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.



Oct 17, 2009 at 09:36 AM
m-a-x
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p.7 #13 · p.7 #13 · FD 85L f/1.2: a real gem


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.



Oct 17, 2009 at 09:41 AM
ronchappel
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p.7 #14 · p.7 #14 · FD 85L f/1.2: a real gem


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.



Oct 17, 2009 at 11:29 AM
ronchappel
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p.7 #15 · p.7 #15 · FD 85L f/1.2: a real gem


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

Normal lens


Rear element moved forward 1mm


Normal lens,edge crop


Modified ,edge crop








Oct 17, 2009 at 11:45 AM
Alf Beharie
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p.7 #16 · p.7 #16 · FD 85L f/1.2: a real gem


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:

http://www.luciolepri.it/lc2/marcocavina/articoli_fotografici/TEST_85mm_f_1,2/02.jpg

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.



Oct 17, 2009 at 03:33 PM
m-a-x
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p.7 #17 · p.7 #17 · FD 85L f/1.2: a real gem


It is not bi-convex. The picture is not 100% accurate.
I would say it is slightly concave on the camera side, similar to the others.

If it helps: it could be exactly the same element like employed on the FD50L.



Oct 17, 2009 at 04:15 PM
JimBuchanan
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p.7 #18 · p.7 #18 · FD 85L f/1.2: a real gem


m-a-x wrote:
If it helps: it could be exactly the same element like employed on the FD50L.


Nope, not the case.



Oct 17, 2009 at 05:52 PM
SoundHound
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p.7 #19 · p.7 #19 · FD 85L f/1.2: a real gem


Wow! Really quite so simple!! If so one of you guys should buy up all the 85 FDs, convert them and resell the result for $500. Huh??


Oct 18, 2009 at 02:23 AM
Leon Noel
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p.7 #20 · p.7 #20 · FD 85L f/1.2: a real gem


And make a loss of $200-300 each?



Oct 18, 2009 at 02:32 AM
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