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04-01-2009, 04:12 PM   #1
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Konica, Minolta, etc. lenses conversion

Following the request of Hin and OregonJim, I create a new topic on the lens conversion to PK mount. Hope it will be useful for the others who interest the lenses conversion. If it is not convenient in this section, mod or admin, please, move it to the convenient place.

Firstly, I introduce the conversion of Vivitar 70-210 S1, version 3 KONICA mount to Pentax K. Following Marks Robert, this one is the best among three versions.

The flange focale distance of Konica system is about 40,5mm, whereas the Pentax one is 45.5mm. Therefore, we must shave the lens about 5mm in order to focus to the infinity.

Here is the image of the lens before the conversion (sorry, because it from the seller)

Required things:
- An adapter M42-PK ~ 6$ (I bought from a seller on ebay)
- Some small screwdrivers
- A ruler
- A saw (A lathe will be better)
- A drilling machine

This conversion simply consists of two steps. Firstly, cut off 5mm and secondly replace the Konica mount by the M42-PK adapter.

1) Disassembling the lens and cutting away 5mm

Unscrew 4 cross-screws from the bottom of the lens to take out the Konica mount.

The M42-PK adapter is thinner than the Konica mount about 1mm. Therefore we must shave the other parts of the lens about 4mm.

This ring is associated with the aperture system of the lens by the trigger. I decided to shave the aluminum ring. Firstly, I sawed this ring, cut away 4mm. This ring screws on other part of the lens which has the thread as the image shown.


Secondly, I also sawed this part about 4mm as the below image. After that, I filed them, it would be better if I had a lathe instead of sawing.


The trigger were also cut away about 4mm in order to function correctly.


04-01-2009, 10:47 PM   #2
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2) Drilling the mount and reassembling.

The Konica mount is totally inside the aperture ring. Therefore, we must shave the aperture ring in order to place the M42-PK adapter above. If not, 1mm economized from the difference between two mounts is useless.

Throw away the ring with red dot (the thickness of this ring is about 5mm)

Drill 4 holes respectively on the M42-PK mount. Re-screw 4 cross-screws with 4 new holes.

Voilą, the conversion is done.

Here are the results of the quick test.

IMHO, its colors are beautiful.

I have not yet converted to Pentax KA. I think it is more difficult and it needs more precise tool to convert. Every comments or other conversion are welcome.
04-01-2009, 11:59 PM   #3
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you should submit this as an article. Because otherwise it's going to get lost among countless other threads...
BR
04-02-2009, 08:04 AM   #4
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Thank you, very informative.
Regards.

Pinwu

04-02-2009, 09:41 AM   #5
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Thanks, vietlh81! Very informative - now I have a use for the "cheap" flanged M42->PK adapters.

Yes, I agree, you should submit this as an article.
04-02-2009, 11:17 AM   #6
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You are the Man. Please submit this as an article. A very welcome guide that Pentaxian need to expand our lens territory.

Much appreciation to you with gratitude.

Hin
04-02-2009, 05:26 PM   #7
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Great conversion! I'm wondering about something though, after the conversion, does the diaphragm actuator / trigger of the lens perfectly match the body's diaphragm release? Or rather, does Konica's diaphragm actuator compatible with Pentax's?

The reason I ask is because I found the diaphragm actuator of my Nikon mount lenses work the opposite direction of Pentax lenses On Pentax lens you pull the lever down to open the diaphragm but on Nikon you pull the lever up..
I suppose there's no remedy for this?

I was planning to convert the mount but without the diaphragm actuator working I'm not sure to continue or not, since the Nikon lenses can already be mounted on my istDS (not perfectly of course)


PS:English is not my native, so in case I dont make myself clear enough here's the site where I got the terms (diaphragm actuator etc) kmp.bdimitrov.de K mount page (see picture)
04-02-2009, 05:57 PM   #8
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QuoteOriginally posted by axl Quote
you should submit this as an article. Because otherwise it's going to get lost among countless other threads...
BR
I concur with the others that have suggested you submit it as an article.

04-02-2009, 06:00 PM   #9
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good stuff ... worth the effort? any lenses worth adapting ... besides the 58 1.2 of course :P
04-04-2009, 09:22 AM   #10
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Hi there,
I've submitted this as an article as you suggested. Thanks for encouraging me. I've posted the way how to convert Minolta lens mount to Pentax K.
I converted three lenses: The legendary Rokkor 58 1.2, the Rokkor-X 50mm 1.2 and, the Kiron 28mm f/2.
Here is the link

@sajah: This Vivitar has the automatic diaphragm as the same one of Pentax. Firstly, I intended to convert to Pentax KA, but it is quite difficult and need some other things to convert successfully.
The diaphragm actuator behaves the same way as the Pentax one. Therefore I put the diaphragm actuator in the position as the same one as the Pentax KA lens in the above photo.
Everything seem Ok. No auto aperture, the lens needs to stopdown to take the photo.

For Nikon lenses, instead of converting to Pentax K, I mount it directly on Pentax. There are no problem with the mounting.
04-04-2009, 02:52 PM   #11
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I see, then I suppose I'll just keep my nikon mount.. I have no problem with stopping down / no auto aperture lenses, it's just I dont like the viewfinder getting darker as I close down the aperture.
Anyway, thanks for answering.
04-09-2009, 03:08 PM   #12
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QuoteOriginally posted by vietlh81 Quote
Thanks Hin,
I usually read your blog and I am impressed by your knowledge. I read your review about this lens before having bought it. I've created a new thread to introduce how to convert it to PK mount.
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/56002-konica-m...onversion.html
@OregonJim: I converted some Minolta lenses and Kiron in Minolta. It is more simple than the conversion of Konica. If it is possible, I will show the steps how to convert it.
I want to thank you for the write up on the article. And your alternation inspires me. I am never a handy man but your article has given me some incentive to try modification on a 300mm tele lens in K/AR mount, I am naive in mounting, is the K/AR the mount name in your conversion in your Vivitar Series 1 zoom for Minolta or Konica. I am unsure if Minota and Konica mount such as K/AR are similar. I should have a picture when my K/AR lens arrived. I am going to PM you as well and please allow me to add you as my "friend" in PentaxForums.

Thanks,
Hin

Last edited by hinman; 04-09-2009 at 03:16 PM.
04-10-2009, 01:37 PM   #13
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The mine is Konica K/AR version. Before buying this lens, maybe I were very optimist to think that it is possible to convert it because the Komine also made it for Pentax mount.
Another factor to contribute to the successful conversion is that the focal length of the lens (70mm) is long enough to not hit the mirror of the K100D. I think your tele will be the same.
Of course, the conversion of Minolta lenses is easier because of the difference of register distance.

Very pleased to be your friend.
Regards,
09-13-2009, 02:50 AM   #14
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Minolta MD lens to Pentax KA lens

I've recently received the legendary Vivitar 100mm f2.8 (Kiron 105mm f2.5) for Minolta MD mount. So I intended to convert it to Pentax K mount to take the macro photos.



The conversion to Pentax K mount is quite easy, but comparing to the last conversion, this one has the Auto Aperture function. I observed that the Minolta MD mount is nearly the same with Pentax K's one. Therefore, this time, I put the diaphragm actuator in the location as the other Pentax K lens (as the image below).

Combining with the Pentax K-M to KA conversion, finally I have a Vivitar KA 100mm f2.8

Here some results on my K100D:



@f22 & f32: the photos are a underexposured, but with a flash, this won't be important.

Last edited by vietlh81; 09-13-2009 at 07:18 AM.
09-13-2009, 07:16 AM   #15
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Here is a macro photo with flash at f/11:
.

Thanks for your reading.
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