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04-15-2012, 10:48 AM   #1
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Converting an OM mount Vivitar Series 1 to Pentax K?

Hi guys!

I've been reading the forum for about three months now, and have been really enjoying the great advice and sense of community. But I've finally got a question I can't seem to find a definitive answer for, so time to emerge from the shadows!

I've just bought this Vivitar Series 1 105mm f/2.5 1:1 Macro lens on eBay, having read some of the great reviews of it and its ilk. However, as you can see from the description, it's got an Olympus mount.

I know Leitax does an OM to PK converter, but they only have instructions (and therefore 'support') for Olympus Zuiko lenses, which this obviously isn't. So the question is, does anyone have experience converting this lens - or other Vivitar Series 1 lenses with Olympus mounts - to Pentax-K?

I'm preferably looking to do this in a non-destructive way. I guess if I can't find some means to attach this to my camera, I'll sell the lens on again.

Any advice? Thanks in advance!

Tristan

04-15-2012, 01:28 PM   #2
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There are several items in play here. I am assuming that its a Olympus OM mount that you are asking about. In theory an adapter should be possible. This is because the Olympus OM registration distance is a bit larger than the Pentax K distance.In this way you would not need to change mounts on the lens. Changing mounts on the lens gets in to the distances between the rear element and the flange, so as to keep the same relative distance.

Overall, not knowing a lot about the OM mount other than the Zuiko lenses are very good, I do not understand why there are not any adapters available. It may be due to the relative diameter of the OM mount to the K mount, the in ability to have sufficient material in an adapter to structurally hold the lens (note that for the M42 to K adapter, the M42 fits inside the K mount and therefore it has some structurally integrity).

Rico (and his Dremel) is the reigning authority on mount conversions here. Hopefully, he will drop by....

... from:
QuoteQuote:
- OLYMPUS: The OM mount is the most stable of any MF lens mount, there were never ANY changes in the manual focus series. There are 2 Olympus autofocus systems: the OM77 could accept OM lenses, but AF lenses did not work properly on manual focus OM bodies; the Olympus digital SLRs have a totally new, incompatible mount. Although no manual focus lenses can be used directly, the Olympus DSLRs are the most versatile of all in terms of accepting older lenses via adapters. There are adapters for OM, Nikon, Pentax (both screw mount AND bayonet), Leica R and Minolta MD lenses to fit Olympus DSLR cameras.
It does not appear that there really is any adapter that would provide the mechanical conversion, and trying a mount change would probably be even more difficult.
Your best bet may be to get a Pentax Q body....
hope that helps....
04-15-2012, 01:34 PM   #3
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I have modded several OM lenses to PK mount. My method is non-destructive in that the lens may still be used on an OM camera, but it does require some slight metal work which could diminish the lens' value. Also, I don't recommend my mod with lenses that weigh more than 450g / 16oz -- 400g would be even safer. With those caveats, here goes:

I start with a cheap PK macro tube set. I use the female mount piece as a test-bed. I insert a first-fime candidate lens into that mount and note where the lens and mount obstruct each other. OM and similar C/Y mount bayonet blades are slightly too thick to fit under the PK mount lugs. Solution: thin those blades a little.

I use a Dremel metal cutting disc (sorry, I don't have the number at the moment) to taper the lens bayonet blades. I taper the leading edge of each blade back about 10mm. The OM lens will now force-fit onto a PK mount. For security, I cut a retaining slot or hole for the PK lens locking pin to engage. The hole would be about 1.5mm wide and deep. The slot would be about 1.5mm wide and deep, and 6mm long.

For non-destructive conversion, I use metal tape to hold down the aperture stop-down button on the lens' side. For destructive conversion, I jam or glue that button down. I have various Vivitar and Olympus OM lenses, as well as a number of similar C/Y lenses. Haven't lost any yet!

If lens value is important to you, DO NOT attempt this mod. If you intend to keep the lens forever and don't mind the disfigurement, then have at it. Good luck!

EDIT: I only got in a few minutes late. Such is life.
QuoteOriginally posted by interested_observer Quote
Rico (and his Dremel) is the reigning authority on mount conversions here. Hopefully, he will drop by....

Last edited by RioRico; 04-15-2012 at 01:56 PM.
04-16-2012, 07:10 PM   #4
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Mount replacement is about all I know to do if you want it completely non destructive. I have done a few vivitar though the only one that I can think of that was a series 1 and om mount was a series 1 70-210mm 3.5. I used a donor mount off a damaged lens, a spacer made from a step ring if I recall right, and a second spacer for the aperture ring (I temporarily used a piece of plastic for the second one and never got around to doing a better one as it works fine). An adapter such as a pk-macro adapter or a pk-m42 adapter would work too though you would have to drill and countersink holes for the screws. Operation on that one would up being m42 type operation (you have control of the aperture via the aperture ring only).

04-18-2012, 03:50 AM   #5
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Thanks everyone for your advice!

I've decided that at this early stage in my photographic hobby, meddling with lens mounts is probably a step too far, so I'm going to put it up for sale again. Really appreciate the advice though.

Tristan
04-18-2012, 08:30 AM   #6
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QuoteOriginally posted by interested_observer Quote
. . .

Overall, not knowing a lot about the OM mount other than the Zuiko lenses are very good, I do not understand why there are not any adapters available. It may be due to the relative diameter of the OM mount to the K mount, the in ability to have sufficient material in an adapter to structurally hold the lens (note that for the M42 to K adapter, the M42 fits inside the K mount and therefore it has some structurally integrity).

. . .

Leitax makes and adapter for Zuiko OM to K-mount.

Olympus OM lens for Pentax cameras
04-18-2012, 08:42 AM   #7
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Hi Blue, they don't do an adapter but a complete mount replacement. However as they are designed for Olympus Zuiko lenses rather than any OM mount third-party lens, and as they don't even support all Olympus Zuikos, I'm not inclined to risk it. It's €65 for the replacement mount and it looks like quite a bit of surgery is involved.
04-18-2012, 10:09 AM   #8
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QuoteOriginally posted by goldbug Quote
Hi Blue, they don't do an adapter but a complete mount replacement. However as they are designed for Olympus Zuiko lenses rather than any OM mount third-party lens, and as they don't even support all Olympus Zuikos, I'm not inclined to risk it. It's 65 for the replacement mount and it looks like quite a bit of surgery is involved.
If you were to try it I think you would have better chances with the mount off a junk vivitar lens that has the same screw pattern than with that adapter. I'm guessing it would not fit without modification too which defeats the purpose of an expensive custom mount.

04-18-2012, 10:15 AM   #9
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QuoteOriginally posted by goldbug Quote
Hi Blue, they don't do an adapter but a complete mount replacement. However as they are designed for Olympus Zuiko lenses rather than any OM mount third-party lens, and as they don't even support all Olympus Zuikos, I'm not inclined to risk it. It's 65 for the replacement mount and it looks like quite a bit of surgery is involved.
Well, the mount from Leitax is reversible. That is the big selling point of them. An adapter in the strict sense isn't possible due to the registration distance being very close to that of Pentax. On the other hand, that makes a mount replacement more straight forward.
04-28-2012, 02:44 PM   #10
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FYI, I've managed to on-sell this lens (for a 30% profit!) on the 'Bay.

Keeping my beady eyes peeled for a K mount version.
01-26-2014, 05:38 PM   #11
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I've just got me a pristine om 200mm prime which I intend to convert with macro tube. Wish me luck!!

01-28-2014, 02:57 PM   #12
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QuoteOriginally posted by Tarragon Quote
I've just got me a pristine om 200mm prime which I intend to convert with macro tube. Wish me luck!!

Update: it works! But I can't focus to infinity, which makes it quite limited. Nice lens though. I am considering getting an old olympus pen to mount this lens on (with their suitable om to 4/3 adapter!). Apparently it really increases the focal length of the lens dramatically. So my 200mm lens would be a super telephoto monster!!
01-29-2014, 07:46 AM   #13
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QuoteOriginally posted by Tarragon Quote
Update: it works! But I can't focus to infinity, which makes it quite limited. Nice lens though. I am considering getting an old olympus pen to mount this lens on (with their suitable om to 4/3 adapter!). Apparently it really increases the focal length of the lens dramatically. So my 200mm lens would be a super telephoto monster!!

Did you cut the lugs back or did you replace the mount? I assume if you are not getting infinity you replaced the mount. To get infinity you need to move the lens closer to the camera so you need to thin the new mount. If you still have the original mount, you could put it in place and measure from any point on the lens to the original lens mount face. You are going to have to be at that same point with the new mounts face (actually it can be 0.5mm longer as om is 46mm and pentax is 45.46mm but if you get the mount a little too thin, it should go past infinity and you will loose a little macro range which is usable).


Its important to keep the mount the same thickness all the way around. If you don't have a machine shop (I don't) the only way I know to do it is with a file and sand paper with a flat surface (put the sand paper on the flat surface and slide the mount around on the sand paper to level things, measure often and work the high spots with the file). I have heard of some doing it with just sand paper but I could see that taking quite a while. If you are certain about your measurements and there is a lot to remove, you could alternate taking a little bulk off with a dremel and then use sandpaper/file to true things up and correct thickness.
01-30-2014, 11:24 AM   #14
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Wow! That's a lot of work! Nope, I just got an extension tube set for cheap, and whacked the om lens onto it (it just fit with a little encouragement!). I ended up with a 200mm that wouldn't focus to infinity, but worked ok for Closeup. I didn't do a permanent wedge onto the tube, as I have found out that this lens will fit onto a penax q camera, giving a x5.7 boost to the 200mm focal range! That appeals to me, so I have carefully put away the lens for use when I save up and get a secondhand q and om adapter...

My local camera shop is closing down, and I have picked up a lot of stuff very cheaply. I bought an old Bell&Howell 100-300mm lens for 10 so making the 200mm redundant really. Though, it's a big beastie to carry round all the time

My DIY skills aren't that great, so it's probably best I don't try and convert the om lens. I'm far to impatient and clumsy to get a lens mount ground down to 0.5mm accuracy!!!

My new lens has evidence of a bit of fungus round the edge of the front lens, which I didn't spot in the shop (the front lens needed a proper clean from being at the back of the cupboard). I have taken some test shots, and it doesn't mess with the picture at all. I'm now researching fungus, and I don't think I will be brave enough to try and clean the inside of the lens myself! I guess I will just keep the lens warm and dry, away from my other lenses, and just use it until I can afford a better one.

Thanks for the practical tips on how to convert the om lens, it is tempting to just have a go as the lens only cost me 10 too! I can't believe how cheap the old stuff is. I shoot manual and like to focus manually too, so I just don't have any problems using the old lenses. Maybe it's because I don't take photos of many fast moving objects??

I also picked up an old flash gun for 10 too... Pentax sure is value for money!! One of these days I will be able to afford a new camera(!!)
01-31-2014, 05:41 PM   #15
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I see. on the fungus thing about the only thing I have heard short of tearing it apart is using uvc light to kill the fungus. It won,t kill every thing in there but it will kill what the light can reach slowing the spread of it. Of course proper storage is important beyond that. I have heard of people leaving the lens in bright sunlight for several days to try and attempt this (in a window sill I assume). That wouldn't work too well where I'm at right now due to weather though. I recently read many cfl light bulbs emit a decent amount of uvc. They are not supposed to. The phosphorus coating on the inside is supposed to block harmful uvc light but apparently when they twist the glass it causes cracks in the coating which allows plenty of uvc light through. Yes that means they can contribute to skin cancer like the sun does. I would assume that it would also mean if you placed the lens near one in a lamp (close but not so close that it would heat up the lens) I'm guessing it might kill it too.



QuoteOriginally posted by Tarragon Quote


Wow! That's a lot of work! Nope, I just got an extension tube set for cheap, and whacked the om lens onto it (it just fit with a little encouragement!). I ended up with a 200mm that wouldn't focus to infinity, but worked ok for Closeup. I didn't do a permanent wedge onto the tube, as I have found out that this lens will fit onto a penax q camera, giving a x5.7 boost to the 200mm focal range! That appeals to me, so I have carefully put away the lens for use when I save up and get a secondhand q and om adapter...

My local camera shop is closing down, and I have picked up a lot of stuff very cheaply. I bought an old Bell&Howell 100-300mm lens for 10 so making the 200mm redundant really. Though, it's a big beastie to carry round all the time

My DIY skills aren't that great, so it's probably best I don't try and convert the om lens. I'm far to impatient and clumsy to get a lens mount ground down to 0.5mm accuracy!!!

My new lens has evidence of a bit of fungus round the edge of the front lens, which I didn't spot in the shop (the front lens needed a proper clean from being at the back of the cupboard). I have taken some test shots, and it doesn't mess with the picture at all. I'm now researching fungus, and I don't think I will be brave enough to try and clean the inside of the lens myself! I guess I will just keep the lens warm and dry, away from my other lenses, and just use it until I can afford a better one.

Thanks for the practical tips on how to convert the om lens, it is tempting to just have a go as the lens only cost me 10 too! I can't believe how cheap the old stuff is. I shoot manual and like to focus manually too, so I just don't have any problems using the old lenses. Maybe it's because I don't take photos of many fast moving objects??

I also picked up an old flash gun for 10 too... Pentax sure is value for money!! One of these days I will be able to afford a new camera(!!)
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