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02-09-2010, 01:16 PM   #1
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adjustment of infinity focus on Kiron lenses

following a response I posted in a thread, regarding changing the infinity focus on Kiron and Vivitar (by Kiron) lenses,
https://www.pentaxforums.com/forums/905419-post64.html
I was contacted by a forum member for information on how this was done, so I decided to post the instructions here.

the lenses in question are 24mm F2 vivitar (kiron) and 28 mm F2 Kiron wide angle lenses, that I converted from nikon AI and Minolta MD mounts respectively to K mount using the flanged M42 adaptor.

I don;t know whether approach this applies to other makers as well

On the outside of the lens barrel of the optical group, just below the filter threads, there is a small set screw in the side of the barrel.

this locks the outer cover of the barrel to the ring with the makers name on it, under the filter. This outer cover is just that, it is not part of the lens itself structurally, it is just a hollow tube.

see image 2 the set screw visible on the collar (removed from lens)

If you remove this one set screw, you can thread the outer collar off and see the 3 screws that hold the focusing ring to the focusing helix

look at image 3 bottom right inside the lens, just below and to the right of the 1:2 marking. The second is under the A of wide angle

if you undo these screws slightly the focusing collar is now independant of the helix,

to set infinity,

- you tighten one screw a little, and focus to infinity, then
- slacken the screw, and
- turn the collar to the infinity mark and
- retighten, the focusing is set,



I have no idea how other makers do it.

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Last edited by Lowell Goudge; 02-09-2010 at 01:28 PM.
02-09-2010, 01:32 PM   #2
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anyone else who has made infinity focus adjustments on a lens is welcome to post here, as a repository for focus adjustments on MF lenses
02-09-2010, 10:11 PM   #3
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Lowell, thank you very much for your explanation and pictures! My Vivitar 28/2 is a Kiron after all. I don't know what I was thinking earlier. So, it looks just like yours. I had converted it from a Konica mount to a K mount by following the instructions in the Articles section here. However he converted a 70-210 which has places to remove the extra 5mm difference in the registration distance. My 28mm doesn't. But, using Lowell's method, I was able to readjust the infinity focus stop (by quite a ways) and now it works great! I owe you a beer or three .
Now if I can figure out how to make the aperture mechanism work, I'll be set.
02-10-2010, 05:45 AM   #4
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QuoteOriginally posted by slick100d Quote
Lowell, thank you very much for your explanation and pictures! My Vivitar 28/2 is a Kiron after all. I don't know what I was thinking earlier. So, it looks just like yours. I had converted it from a Konica mount to a K mount by following the instructions in the Articles section here. However he converted a 70-210 which has places to remove the extra 5mm difference in the registration distance. My 28mm doesn't. But, using Lowell's method, I was able to readjust the infinity focus stop (by quite a ways) and now it works great! I owe you a beer or three .
Now if I can figure out how to make the aperture mechanism work, I'll be set.
glad this helps.

the nice thing is you don't really have to worry about the shims at all, there is so much movement

I had "to go the other way" on the nikon mount, since the nikon register distance is evern further and due to the difference in mounts between the stock nikon and the flanged adaptor, I had the lens focusing to infinity half way through the rotation of the focusing collar.

The minolta mount lens was easier, because between one shim and the lens mount differences I was only dealing with about 0.12mm (.005 inch for the metric impared)

02-10-2010, 07:03 AM   #5
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I recently stripped and cleaned a K mount Kiron 28mm f/2.8 (oil on aperture blades). This was assembled the same way as the 24mm shown in Lowell's photos. I have also repaired a fair number of ther lenses (I have lost count now). Most of them have the same 3 screws holding the focus ring to the focus helix but the method of accessing these screws is different on many (quite often remove the trim ring - lenses such as super takumar 50mm f1.4 and 55mm f1.8). However other than the Kiron lens I have not found any to have enough adjustment to accomodate a change of registration distance.

QuoteOriginally posted by slick100d Quote
Lowell, thank you very much for your explanation and pictures! My Vivitar 28/2 is a Kiron after all. I don't know what I was thinking earlier. So, it looks just like yours. I had converted it from a Konica mount to a K mount by following the instructions in the Articles section here. However he converted a 70-210 which has places to remove the extra 5mm difference in the registration distance. My 28mm doesn't. But, using Lowell's method, I was able to readjust the infinity focus stop (by quite a ways) and now it works great! I owe you a beer or three .
Now if I can figure out how to make the aperture mechanism work, I'll be set.
I have made the aperture mechanism work on my Vivitar 55mm macro converted from Konica to Pentax mount. I just needed to make a bit of metal which I attached to the aperture mechanism inside the lens which acts as a normal aperture lever. I can meter using the green mutton in M mode and the aperture is open untill I take release the shutter. The photo bellow shows the conversion and the aperture lever. This lens did not have anywhere near enough adjustment to acomodate the change of registration so I had to machine 4.8mm off the back. The contacts were an attempt to make the lens work as an A lens, as usuall without sucess.

02-10-2010, 07:27 AM   #6
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QuoteOriginally posted by MattGunn Quote
I recently stripped and cleaned a K mount Kiron 28mm f/2.8 (oil on aperture blades).
this seems to be a common problem of Kiron lenses, both mine had the same issue, which is why I decided to do the mount conversion. one lens was free, the other cost the extortionate sum of $5.00.
QuoteQuote:
This was assembled the same way as the 24mm shown in Lowell's photos. I have also repaired a fair number of ther lenses (I have lost count now). Most of them have the same 3 screws holding the focus ring to the focus helix but the method of accessing these screws is different on many (quite often remove the trim ring - lenses such as super takumar 50mm f1.4 and 55mm f1.8). However other than the Kiron lens I have not found any to have enough adjustment to accomodate a change of registration distance.
I suspect, and this is pure guess work on my part, that third party manufacturers that use this technique have all the range they need, and this is where they make the adjustment so they can keep the same mechanics and machining between all possible mounts, there is no need for pentax, nikon, or any other manufacturer to do this because they don't need to make the lens work on multiple regestration distances.
QuoteQuote:


I have made the aperture mechanism work on my Vivitar 55mm macro converted from Konica to Pentax mount. I just needed to make a bit of metal which I attached to the aperture mechanism inside the lens which acts as a normal aperture lever. I can meter using the green mutton in M mode and the aperture is open untill I take release the shutter. The photo bellow shows the conversion and the aperture lever. This lens did not have anywhere near enough adjustment to acomodate the change of registration so I had to machine 4.8mm off the back. The contacts were an attempt to make the lens work as an A lens, as usuall without sucess.
the aperture modification is interesting, but in the end it comes down to most cameras having different movements, nikon's lever goes the other way, and so does the minolta MD. Konica works in the right direction not sure about the range of motion or linearity of aperture etc. that is why I remove the linkage all together and use them in stop down mode.
02-10-2010, 12:01 PM   #7
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QuoteOriginally posted by Lowell Goudge Quote
I suspect, and this is pure guess work on my part, that third party manufacturers that use this technique have all the range they need, and this is where they make the adjustment so they can keep the same mechanics and machining between all possible mounts, there is no need for pentax, nikon, or any other manufacturer to do this because they don't need to make the lens work on multiple regestration distances.
I had come to much the same conclusion. The vivitar macro had a removable rear section which was quite long on the Konica version, this was where I removed the 4.8mm of material. I suspect that the pentax version of the lens just has a shorter version of this section with a K mount on the end.

QuoteOriginally posted by Lowell Goudge Quote
the aperture modification is interesting, but in the end it comes down to most cameras having different movements, nikon's lever goes the other way, and so does the minolta MD. Konica works in the right direction not sure about the range of motion or linearity of aperture etc. that is why I remove the linkage all together and use them in stop down mode.
Olympus mechanism also workes the wrong way, I've been trying to figure out if I can reverse it in a 50mm f/3.5 macro I got for conversion.
The aperture mechanism on the Konica mount Vivitar macro does appear to have a linear displacement with area as required for A type lenses (although I haven't tried measuring it properly). However the range over which it operates is a bit larger than KA lenses so the exposure is still wrong but if gets further out linearly as you stop down (over exposing).
02-10-2010, 12:13 PM   #8
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QuoteOriginally posted by MattGunn Quote
Olympus mechanism also workes the wrong way, I've been trying to figure out if I can reverse it in a 50mm f/3.5 macro I got for conversion.
The aperture mechanism on the Konica mount Vivitar macro does appear to have a linear displacement with area as required for A type lenses (although I haven't tried measuring it properly). However the range over which it operates is a bit larger than KA lenses so the exposure is still wrong but if gets further out linearly as you stop down (over exposing).
the only "reversing" mechanism I have seen is on a tamron adaptall mount for a spotmatic, where there was an idler gear. this was for the couopling deleted by the FA-J mount (crippled K mount) and I bet it would be too massive for the reaction time needed here.

as I said, I have just given up and use the lenses as stop down lenses. I was more after the F2 maximum aperture any way, for night shots.

If I combine the best and fastest out of my M42 kit and K mount kit, the line up looks like this at present

24, 28, 35 mm at F2
50, 85 mm at F1.4
105mm at F2.8
135mm at F2.5
200 mm at F3,5 (i love my preset tak, but would also love a 200F2.5 in the future)
300mm at F4
400mm at F5.6

this is just about as fast as you can get in primes

02-10-2010, 12:54 PM   #9
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QuoteOriginally posted by Lowell Goudge Quote
the only "reversing" mechanism I have seen is on a tamron adaptall mount for a spotmatic, where there was an idler gear. this was for the couopling deleted by the FA-J mount (crippled K mount) and I bet it would be too massive for the reaction time needed here.
I considered something like a gear mechanism but decided it was too much hastle. I now intend to convert the lens so that the DOF preview button that the Olympus Zuiko lenses have will still work. I can then use this to manually stop down for shooting.

QuoteOriginally posted by Lowell Goudge Quote
If I combine the best and fastest out of my M42 kit and K mount kit, the line up looks like this at present

24, 28, 35 mm at F2
50, 85 mm at F1.4
105mm at F2.8
135mm at F2.5
200 mm at F3,5 (i love my preset tak, but would also love a 200F2.5 in the future)
300mm at F4
400mm at F5.6

this is just about as fast as you can get in primes
A nice selection of fast lenses. How many did you have to convert?
02-10-2010, 01:29 PM   #10
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QuoteOriginally posted by MattGunn Quote


A nice selection of fast lenses. How many did you have to convert?
only the 24 and 28, as mentioned earlier in the thread.

the 35 is an SMC tak
the 50, 105, 135 and 300 are all is an SMC-pentax
the 85 is a vivitar series 1 KA mount
the 200 is a tak - preset
the 400 is a vivitar MC by Komine in K mount
02-10-2010, 01:36 PM   #11
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Hi,

Up to now, i have fixed the infinity focus on my Super Takumar 24/3.5, and i have a Meyer Primoplan 58/1.9 waiting to be serviced ...

The full fix instructions are on my blog here ...

Cheers
02-10-2010, 09:48 PM   #12
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My Vivitar (Kiron) had oil on the aperture blades too. On my lens there's no direct connection between the aperture ring and the mechanism. There is a fork that is part of the mount that surrounds an arm on the mechanism. The ring pushes this fork but is not directly connected. I think I'm going to have to make a custom fork and attach it to the ring just to use it in stop down mode. Lowell, how did you connect the aperture ring to the aperture actuating arm (I'm making up these terms as I go!)?

The adjustment to the focus is really moving the entire focus range. I now have infinity focus but it doesn't focus as close as it used to (as expected). Now if there were a way to move just the close focus stop instead of the entire range. I don't know if it's possible but since there are some versions of this lens that are marked as close focus and I know the focusing helix has the range, it might be.
02-11-2010, 06:24 AM   #13
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QuoteOriginally posted by slick100d Quote
My Vivitar (Kiron) had oil on the aperture blades too. On my lens there's no direct connection between the aperture ring and the mechanism. There is a fork that is part of the mount that surrounds an arm on the mechanism. The ring pushes this fork but is not directly connected. I think I'm going to have to make a custom fork and attach it to the ring just to use it in stop down mode. Lowell, how did you connect the aperture ring to the aperture actuating arm (I'm making up these terms as I go!)?
on the 2 lenses I modified, I didn't, I use them as stop down lenses. this is partly lazyness on my part, and also due to the fact that the lever on the nikon AI mount and the Minolta MD mount goes the opposite direction, and I didn;t want to deal with that level of modification. If you find one that works in the same direction as a pentax, then you need a K mount with bearings that support the lever, or take the bearings and support off the lens you are modifying.
QuoteQuote:
The adjustment to the focus is really moving the entire focus range. I now have infinity focus but it doesn't focus as close as it used to (as expected). Now if there were a way to move just the close focus stop instead of the entire range. I don't know if it's possible but since there are some versions of this lens that are marked as close focus and I know the focusing helix has the range, it might be.
on the two that I modified, if you remove totally the focusing collar, you will find that it has the stops (or more appropriately the working range) notched into it. just extend the notch. I didn't bother with this but did see how it worked.
02-11-2010, 12:14 PM   #14
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Matt's Vivitar 55mm f2.8 macro mod is impressive. For my conversion of the same lens from Canon FD mount, I scratched my head for a while, then tried something complex that failed. I ended up soldering two brass rings together in the mount and removing everything else. Now the aperture ring turns from the f2.8 mark to just beyond the f8 mark. The blades go from fully open to fully closed. It functions like an M42 lens on manual. I probably should look for an infinity focus adjustment, but it's a macro so who cares that it only focuses to 4 feet.

To the original topic, here is another method for infinity focus adjustment. Two rings with square slots for a lens spanner surround the front element. Arrows mark the spanner slots. One ring is a locking ring, the other screws a carrier for the front element in or out. Sometimes lacquer locks the rings also. I've seen this on zooms only. Some examples are the Pentax-F 70-210 and its Takumar-F relatives, the Takumar-A 70-200/4 and its twins under Cosmicar and other brands, the Pentax-A 80-200mm, and the Pentax-F 100-300.

02-11-2010, 12:15 PM   #15
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QuoteOriginally posted by Lowell Goudge Quote
on the two that I modified, if you remove totally the focusing collar, you will find that it has the stops (or more appropriately the working range) notched into it. just extend the notch. I didn't bother with this but did see how it worked.
Thanks, I'll give it a try when I get home. Do you just remove the three screws and lift off the collar? I made the mistake of taking some close up test shots before adjusting for infinity focus and really liked how they came out. Here's one of my "tool of destruction", wide open, of course.

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