Forgot Password
Pentax Camera Forums Home

Show Printable Version Search this Thread
01-21-2012, 12:52 PM   #1
Veteran Member

Join Date: Dec 2009
Location: Ontario
Posts: 550
Auto m42 lens conversion


Just had a technical question about converting an auto m42 lens to a manual one. I know it is possible and very easy to do. Where all that need to be done is to hold the pin down via glue/paperclip or some mechanism. However, my question is will this constant pressure on the pin cause any problems or stress on other parts such as the aperture ring or blades? I know that there are two types of pin mechanisms the pentax version and the one adopted by Fujica and other companies; where half pressed moves the blades slightly.

The version I am looking to convert is the Fujica one where it must be fully depressed in order to move the blades. However, will the constant pressure on the pin cause problems long term wise?

01-21-2012, 01:02 PM   #2
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
No problem that I've seen. I stuck-down the pin on a Meyer Domiplan three years ago -- jammed a whisker-wireb eside the pin. I can remove the wire and the aperture still movers properly.
01-21-2012, 05:00 PM   #3
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,400
If you take the mount off you will find it possible to slip about 3/32 to 1/8 inch of plastic tube(cut from the end of a ball point pen refil) over the tube to hold the pin depressed. Somewhere on the forum is a photo I posted showing this in place on a tamron adaptall M42 adaptor

  • 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!
auto m42 lens, blades, cause, fujica, lens, m42, pentax help, pin, pressure, question, version
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
For Sale - Sold: Yashica Auto Yashinon DS-M 50mm f/1.7 m42 lens dcshooter Sold Items 3 01-23-2012 09:50 PM
Camera mount for Pentax M42 Auto Bellows? (NOT about M42-K adapter) baj Pentax Camera and Field Accessories 9 10-24-2011 10:42 PM
Another Ricoh: Auto Rikenon 35mm f/2.8 (M42) lens ChrisPlatt Pentax SLR Lens Discussion 4 09-05-2010 06:43 AM
How to fix a auto-only M42 lens so it becomes a manual one sterretje Pentax SLR Lens Discussion 5 05-16-2010 10:12 PM

All times are GMT -7. The time now is 06:24 PM. | See also:, 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?
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]