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03-19-2015, 06:38 AM   #436
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Hello guys,

I get trought e(vil)bay a FA28-70/4, but all the rear part of the lens is eated by fungus and have balsam separation.

I was wondering, if you had some kind of idea to use the good part of the lens ? Like creating a new lens with some other part laying around ?

Here is the 28-70/4 diagram :
The last two group (on the right) are unsalvageable.

I might have a old 100mm f6.7 lens somewhere, covering 6x6 - probably a triplet.

A Pentax A50/1.7 too can be used.

My idea was to create a frankenlens. the bigger the format covered, the better. Any idea ?

03-19-2015, 08:30 AM   #437
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QuoteOriginally posted by aurele Quote
the bigger the format covered, the better. Any idea ?
If you ever see an "Oscillo" lens, just put your wallet away and walk on, because it really is Impossible!
The lenses were intended for about 1:1 or 2:1 use on 4x5 Polaroid.

Here is my attempt to use the lens, reversed, on 6x7 format when focussed at infinity.
The first image below is sooc (a positive of the C41 neg)
Note the severe radial pincushion and color distortion.
https://app.box.com/s/4tnhnaytrml2vtfpbxxg

The next was an attempt to clean it up using 2nd order radial corrections in ImageMagick
https://app.box.com/s/gl0zrlu7aohiwdj8k395
Uh-Oh, Still no good
03-19-2015, 08:41 AM   #438
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Thanks guys for your answers !

To get the hand on the middle element that has balsam separation i had to unscrew everything possible, litteraly.



Now that all the parts are spread, i think i'm gonna change the middle group with a single lens from a triplet and the rear group with one of a Zuiko 50mm 1.8.

The shape of the correction remains in the same ballpark, but i can say using my phone as a projector that the whole thing can be sharp in the middle if well adjusted, and uber soft in the corner !

So let's rebuild this and see what happened !

I bet however that the thing won't focus on the body without modification, though.
03-19-2015, 08:43 AM   #439
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What frame size are you going to try?

03-19-2015, 10:49 AM   #440
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QuoteOriginally posted by wombat2go Quote
What frame size are you going to try?
i'm staying sur 35mm so far.

I've encouter a big problem when rebuilding the lens : the front group part isn't screwed to anything hence when i'm returning the lens, all this part, well, fall apart.

i've no piece missing, no screw hole on the parts ... i just don't even understand how the hole thing is suppose to hold together


EDIT :

If i don't put back the front group (the two first glass) and reverse the lens (with only the the glued group change - last group have been put back even if it's full of fungus on the side) i can have a 40mm (more or less) lens, aperture unknow, probably f5.6 so far ( blades are blockd -grrrr).

I just don't know what to do with the forst two curve elements.

Last edited by aurele; 03-20-2015 at 02:33 AM.
03-20-2015, 02:40 AM   #441
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QuoteOriginally posted by wombat2go Quote
What frame size are you going to try?
So far i cover a bit more than 24x36, probably 40mm x 40mm.
03-20-2015, 05:55 AM   #442
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QuoteOriginally posted by aurele Quote
So far
Here is a real simple and free lens modeling app
OpticalRayTracer Home Page
It gives results including image circle and chromatic abberations etc

If you have unknown positive lenses, you can approximately measure the thickness and radius simply.
But for a negative element, like front elements on an old zoom, you would have to just guess and use trial and error

06-12-2015, 06:22 AM - 2 Likes   #443
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For many years now I've had a 1947 vintage Kodak 35RF rangefinder sitting on a shelf as an ornament, unusable because of a seized-up rangefinder mechanism and a crack that lets light leak in. So last weekend in a fit of boredom I decided to convert the old camera's Kodak Anastigmat 50mm/3.5 lens to K Mount and see how it worked on a DSLR.

It's a rough-and-ready conversion using superglue to attach an M42 to K Mount adapter to the Kodak lens, and amazingly (thanks to the quirky design of the Kodak 35RF) the registration distance is just right to allow infinity focus. The lens's built-in leaf shutter still works, but for the purpose of these initial test shots I've set the lens to T and used the DSLR's shutter. Next time I'll experiment with setting the DSLR to time exposure and allowing the lens's leaf shutter to take the shot.

These first test shots are just quick snaps in bad light, but I'm encouraged enough to keep trying with this 68 year old uncoated lens. I'm convinced that there's a hint of a vintage Kodachrome look in the way it renders.











(Xposted in the K10D Club.)
06-12-2015, 09:36 AM   #444
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QuoteOriginally posted by Dartmoor Dave Quote
For many years now I've had a 1947 vintage Kodak 35RF rangefinder ...
That's great !

Hope to see more soon ... TFS, J
12-27-2015, 05:05 PM   #445
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Kool

info here
01-05-2016, 01:06 PM   #446
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Has anyone found any way to use old FD Canon lenses on Pentax even with extensive hacking? I have an 85mm f/1.8 SSC that was my moms and she no longer shoots film or even Canon. I am mainly curious since I already own the FA 77 f1.8 so the 85 isn't an essential bit of kit. I'm well aware the registration distance is too short on this lens to adapt conventionally to Pentax K mount without a teleconverter style glass approach which would not appeal.
01-05-2016, 02:30 PM   #447
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QuoteOriginally posted by UncleVanya Quote
Has anyone found any way to use old FD Canon lenses on Pentax even with extensive hacking? I have an 85mm f/1.8 SSC that was my moms and she no longer shoots film or even Canon. I am mainly curious since I already own the FA 77 f1.8 so the 85 isn't an essential bit of kit. I'm well aware the registration distance is too short on this lens to adapt conventionally to Pentax K mount without a teleconverter style glass approach which would not appeal.
Hi. I would suggest getting a Canon FD to Pentax K adapter and removing the correction lens element. It will work like an extension tube which should be interesting with your 85/1.8 ... or you can just sent it to me !!!

My FD 135/2.5 on the K-5 ...


01-05-2016, 02:45 PM   #448
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Canon-FD 55mm f 1.2

QuoteOriginally posted by UncleVanya Quote
Has anyone found any way to use old FD Canon lenses on Pentax even with extensive hacking? I have an 85mm f/1.8 SSC that was my moms and she no longer shoots film or even Canon. I am mainly curious since I already own the FA 77 f1.8 so the 85 isn't an essential bit of kit. I'm well aware the registration distance is too short on this lens to adapt conventionally to Pentax K mount without a teleconverter style glass approach which would not appeal.
Here is my setup with K-3 and Canon-FD 55mm f 1.2. This is a permanent conversion of the FD mount to the K-3 mount done in a way that allows complete focussing range and allows the lens to function as a Pentax-D lens. Forum member Brian Gohacky (forum handle dcshooter) can do this for you and silver the lens as well. Brian did this for my Canon-FL 55mm f 1.2.
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01-05-2016, 02:57 PM   #449
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QuoteOriginally posted by ivanvernon Quote
Here is my setup with K-3 and Canon-FD 55mm f 1.2. This is a permanent conversion of the FD mount to the K-3 mount done in a way that allows complete focussing range and allows the lens to function as a Pentax-D lens. Forum member Brian Gohacky (forum handle dcshooter) can do this for you and silver the lens as well. Brian did this for my Canon-FL 55mm f 1.2.
Brian has done a lot of work for me already but I never thought to ask about this. Do you end up with manual aperture (I assume so). I would assume some lenses might have issues based on where the elements fall and how much room for mount surgery there is. That's great to know. Thank you.
01-05-2016, 03:22 PM   #450
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QuoteOriginally posted by UncleVanya Quote
Brian has done a lot of work for me already but I never thought to ask about this. Do you end up with manual aperture (I assume so). I would assume some lenses might have issues based on where the elements fall and how much room for mount surgery there is. That's great to know. Thank you.
With the Canon-FD 55mm f 1.2 conversion, I have same aperture setup as if it were a Pentax-D lens. Works perfectly with the green button. The lens Brian actually did for me was the Canon-FL 55 f 1.2, and that is the one that he also silvered for me. With the FL the lens aperture shuts down entirely by hand, and if you have enough light to focus with the lens in the shut-down state, you can actually use Av Mode; or you can focus, stop the lens down, and then shoot using AV mode. He also set it up such that you can manually focus with the lens wide open, and then manually stop down before taking the shot using AV mode.

This is not a particularly cheap procedure, and probably only worth doing on rather valuable lens. The Canon 55mm 1.2's, it seemed to me, fit into that category, so I spent $200-300 each on them to be able to use them with Pentax cameras. The Canon-FD 1.4 is another lens that I own and which has a fairly fabled status, and which some might consider to be worth converting. I do not know much about the 85mm, although I own one. It might be worth going back and reading the reviews or testing it yourself to see whether it offers something not otherwise available.

The easier way to do all of this, of course, is to get one of the Sony cameras and an adapter, allowing you to fit any Canon-FD or FL on the camera . . . but I shoot Pentax, and look forward to using these two lens on Pentax FF when it becomes available later this year.
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