Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
  #1
Converting M series lens to manual
Posted By: GUB, 12-02-2014, 10:00 PM

There is an established trick of not clicking your M lens all the way home on its mount to achieve total manual control of the lens.
The camera can then be used in AV mode. I now drill a custom locater pin hole at the right point to achieve this.
I learnt this trick of creating a custom lens lock pin hole from people on this forum a while back. But I have not come across a thread showing how to do it. So apologies if there is one out there.
The chances are if you have some M lens then you have a sick SLR body to cannibalize.
Mark approximate top dead centre (A) on the lens mount of the SLR.
Mark which hole is the lock pin hole(B).
Take (unscrew the 3 little philips screws) the lens mount off the body.
Turn the mount over and remark those points on that side. (I used twink)
And also mark the screw hole (C)
Put your lens on the mount like you were putting on the camera and get top dead centre to the top.
Now when you drop a small punch (screwdriver) thru the pin lock hole (B) it should drop in and locate the lens in its pin lock groove.
Centre punch through the screw hole (C). This is where you need to drill the custom hole.
I use a 2.5mm drill in a drill press and drill just far enough that the full diameter hole is forming.
I then take another 2.5mm drill that I have ground the bevel tip off (see image) to mill the hole so it has a flat bottom.
The aim is to end up with a flat bottomed hole that is around 1mm deep.
This hole is just over 9mm from the old pin lock locater groove.
If you so wish you can create this hole 1 - 2 mm closer but you run the risk of the lens not totally stopping down.
Please note that my camera goes tramping with me , bounces around in my farm truck and getting generally abused but I sense no stability issues with the lens being only part way on.

Attached Images
     

Views: 3,782
12-03-2014, 03:27 AM   #2
Forum Member
Chris Stearns's Avatar

Join Date: Jun 2007
Location: Southern Illinois
Photos: Albums
Posts: 58
Cool M lens hack. Fortunately, I don't have access to a drill press at the moment. I've always just used a small strip of splicing tape on the lens mount where it meets with the contacts. Then it works like pre-M takumars in Av mode, and I can always remove the tape and use the lens on my film bodies.
12-03-2014, 07:14 AM   #3
Pentaxian
Rimfiredude's Avatar

Join Date: Oct 2014
Location: Washington
Photos: Gallery
Posts: 2,177
QuoteOriginally posted by Chris Stearns Quote
Cool M lens hack. Fortunately, I don't have access to a drill press at the moment. I've always just used a small strip of splicing tape on the lens mount where it meets with the contacts. Then it works like pre-M takumars in Av mode, and I can always remove the tape and use the lens on my film bodies.
Maybe I will give that a try before drilling the mount. Thanks for the tip.
12-03-2014, 07:52 AM   #4
Forum Member
Chris Stearns's Avatar

Join Date: Jun 2007
Location: Southern Illinois
Photos: Albums
Posts: 58
QuoteOriginally posted by Rimfiredude Quote
Maybe I will give that a try before drilling the mount. Thanks for the tip.
I believe it was tHoog that posted about taping the lens mount to fool the K-01 into treating M lenses like m42 lenses, but I couldn't find it.
I dug out my taped M50 1.4 and played around with it on my K10, K5ii, and K-01 and I could not get it to work an Av mode at all except wide open.

I've never been a fan of the green button method. I shoot a lot with m42 taks and am used to stop down metering, so it just isn't natural for me to compose, focus, stop down, hit the button, then shoot. I much prefer to compose, focus, stop down, and shoot.

I may try re-taping it, but for now I have decided to un-tape it and place it on the ME that I bought it with. At least that way I can enjoy its true focal length on a genuine Pentax full frame camera.

12-03-2014, 08:08 AM   #5
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 27,294
Am I correct in concluding that all this hack does is to provide lens lock with the lens barely mounted?


Steve
12-03-2014, 09:51 AM   #6
Pentaxian




Join Date: Oct 2011
Location: Savannah, GA
Posts: 5,002
Someone mentioned a way to remove the aperture lever entirely in a reversible manner? I have taken a couple old lenses that were semi-broken but useable (not worth anything) and just hacked off most of the lever so I can use them that way -- something easy & reversible would be nice. Or I could just buy that Sony full-frame mirrorless and they will all work that way, eh?
12-03-2014, 10:09 AM   #7
Pentaxian
aleonx3's Avatar

Join Date: Jul 2007
Location: Brampton, Ontario
Photos: Gallery | Albums
Posts: 3,888
I did successfully remove the aperture lever linkage from a Porst 55 f1.2 lens; it becomes a k-mount MF lens behaving like m42 lens so I can use stop-down metering. The whole process is completely reversible without damaging any part of the lens. I have not tried on M lens yet although I think it would be very similar.
12-03-2014, 10:13 AM   #8
Pentaxian




Join Date: Oct 2011
Location: Savannah, GA
Posts: 5,002
QuoteOriginally posted by aleonx3 Quote
I did successfully remove the aperture lever linkage from a Porst 55 f1.2 lens; it becomes a k-mount MF lens behaving like m42 lens so I can use stop-down metering. The whole process is completely reversible without damaging any part of the lens. I have not tried on M lens yet although I think it would be very similar.
I think there was an old and newer version of the Porst, but I could be mistaken. I have the Revuenon 55 1.2 (Cosina-made) -- might be the same lens. Maybe I could see a photo of yours?

12-03-2014, 11:07 AM   #9
Pentaxian
Rimfiredude's Avatar

Join Date: Oct 2014
Location: Washington
Photos: Gallery
Posts: 2,177
OK guys, I just had something interesting happen. I have a Sears PK mount, not an "A" lens, think it was made by Cosina, with Fungus inside the rear element. Thought I would try to get at it from the rear of the lens with no success. I assembled the lens incorrectly, not catching the notch to make the auto diaphragm work automatically. Now my lens works completely manually, just like using a Takumar on Manual. HOORAY! Has anyone else had this happen and I wonder if it will work on my "M" and "K" lenses?
12-03-2014, 11:30 AM   #10
Pentaxian
aleonx3's Avatar

Join Date: Jul 2007
Location: Brampton, Ontario
Photos: Gallery | Albums
Posts: 3,888
QuoteOriginally posted by vonBaloney Quote
I think there was an old and newer version of the Porst, but I could be mistaken. I have the Revuenon 55 1.2 (Cosina-made) -- might be the same lens. Maybe I could see a photo of yours?
I have both versions of the lens, I will take some shots of the aperture linkage when I get a chance to share it with you.

---------- Post added 12-03-2014 at 01:34 PM ----------

QuoteOriginally posted by Rimfiredude Quote
OK guys, I just had something interesting happen. I have a Sears PK mount, not an "A" lens, think it was made by Cosina, with Fungus inside the rear element. Thought I would try to get at it from the rear of the lens with no success. I assembled the lens incorrectly, not catching the notch to make the auto diaphragm work automatically. Now my lens works completely manually, just like using a Takumar on Manual. HOORAY! Has anyone else had this happen and I wonder if it will work on my "M" and "K" lenses?
As someone already mentioned, if you don't turn the lens all the way until it clicks/catches the notch (at which position, aperture lever of the lens is not fully depressed), then you can close and open the aperture. However, in this position, the lens is not secured, but if you are careful with it, then it should be fine.
12-03-2014, 12:24 PM   #11
Pentaxian
Rimfiredude's Avatar

Join Date: Oct 2014
Location: Washington
Photos: Gallery
Posts: 2,177
QuoteOriginally posted by aleonx3 Quote
I have both versions of the lens, I will take some shots of the aperture linkage when I get a chance to share it with you.

---------- Post added 12-03-2014 at 01:34 PM ----------



As someone already mentioned, if you don't turn the lens all the way until it clicks/catches the notch (at which position, aperture lever of the lens is not fully depressed), then you can close and open the aperture. However, in this position, the lens is not secured, but if you are careful with it, then it should be fine.
You misunderstood. When I reassembled the lens, I did it wrong, not lining things up correctly. The lens mounts and locks on the camera correctly.
12-03-2014, 12:26 PM   #12
GUB
Loyal Site Supporter
GUB's Avatar

Join Date: Aug 2012
Location: Wanganui
Photos: Gallery | Albums
Posts: 2,469
Original Poster
QuoteOriginally posted by Chris Stearns Quote
I've always just used a small strip of splicing tape on the lens mount where it meets with the contacts
There are no contacts on a M lens.

---------- Post added 12-04-14 at 08:33 AM ----------
Sorry this is a response to stevebrot. For some reason it left the Quote off!!!
Part way on (read my last sentence)
You can drill the hole 1-2 mm closer and risk losing f11-f22.
No great loss but within a mm from there you lose all.

Last edited by GUB; 12-03-2014 at 12:34 PM.
12-03-2014, 05:24 PM   #13
Forum Member
Chris Stearns's Avatar

Join Date: Jun 2007
Location: Southern Illinois
Photos: Albums
Posts: 58
QuoteQuote:
There are no contacts on a M lens.
True, but the mount itself is conductive. The tape tricks the camera into allowing stop-down metering in Av mode. The downside is this technique seems to only work with the K-01. Why? I would assume it has something to do with the mirrors on my K10 and K5ii.

Another non-destructive way around the green button is to simply remove the aperture arm and spring. Then if you ever decide to sell or use the lens on a film body, you can just put the spring and arm back on.
12-03-2014, 05:36 PM   #14
Pentaxian




Join Date: Oct 2011
Location: Savannah, GA
Posts: 5,002
QuoteOriginally posted by Chris Stearns Quote
True, but the mount itself is conductive. The tape tricks the camera into allowing stop-down metering in Av mode. The downside is this technique seems to only work with the K-01. Why? I would assume it has something to do with the mirrors on my K10 and K5ii.
Yes, none of the models with mirrors will stop down the aperture ever with a manual lens when the camera is not on (M)anual mode.
12-03-2014, 05:59 PM   #15
Pentaxian
aleonx3's Avatar

Join Date: Jul 2007
Location: Brampton, Ontario
Photos: Gallery | Albums
Posts: 3,888
QuoteOriginally posted by vonBaloney Quote
Yes, none of the models with mirrors will stop down the aperture ever with a manual lens when the camera is not on (M)anual mode
Not because of the tape (or conductive material) but the aperture linkage is pushed wide-open by the camera (so stop-down metering is not possible unless in M mode).
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
aperture, camera, centre, contacts, custom, diy, do it yourself, drill, happen, hole, lens, lock, mark, mm, mount, notch, pin, position, yourself
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
For Sale - Sold: Pentax A series 28mm f2 manual focus lens 17dew Sold Items 7 08-26-2014 04:09 PM
Converting an OM mount Vivitar Series 1 to Pentax K? goldbug Pentax SLR Lens Discussion 14 01-31-2014 05:41 PM
For Sale - Sold: SMC Pentax K series 28mm 3.5 manual focus lens 17dew Sold Items 4 10-23-2013 09:50 PM
weather sealing manual K or M series lenses Naturefreak Troubleshooting and Beginner Help 20 11-29-2010 02:03 AM
m series manual? iasonis Troubleshooting and Beginner Help 7 07-05-2009 03:28 PM



All times are GMT -7. The time now is 08:36 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top