M-Lens vs M42 type

Big Dave · 11-02-2008, 12:59 PM

Hello.
Yesterday I took my trusty FA-80-320 to the airshow here in Alamo City,Texas,USA. since my lens has stopped commicating with the camera, I had to use the AEL exposure lock and manually adjust the correct exposure. Needless to say my results were inconsistant. This is a big disadvantage of the M-type lenses. The M-42 type gives up auto diapharm for AV mode auto exposure with exposure compenation. Since I use long lenses in bright light, auto diapharm isn't a big deal to me. I didn't want to invest big bucks to repair my 80-320, so I decide to modify it to work in both M42 and M modes. I carefully taped off all lens openings and drilled and milled a new detent hole in the mount flange. It is located 6mm before the standard detent hole. In this position the camera diapharm actuator doesn't contact the lens lever. See photo. Now I can use it both ways, but I really prefer the M42 position for better ease of use. After testing it around the house, I am a happy camper. I'm leaving right to go shoot the Blue Angeles this after noon.

Dave

Big Dave · 11-02-2008, 04:30 PM

Well, I got the shots that I wanted and it was much easier using AV mode.

Dave

Big Dave · 11-07-2008, 12:30 PM

I seen a thread recently, where people actually cut off the diapharm lever on their M series lenses to allow AV mode. Well, my solution of drilling an extra latch hole in the bayonet allows you to still have both options. The new hole allows AV mode and the original hole gives auto diapharm with AEL(green button) exposure fuction. If you decided to change back later, a drop of solder or JB Weld will fill the new hole.

Dave

Voe · 11-07-2008, 03:26 PM

This is a very geniuos solution to a problem that was drawing me away from M lenses. Thanks for sharing!!

stevebrot · 11-07-2008, 11:15 PM

Initially, you lost me Dave, but after re-reading your message the light finally came on. You modified your mount so that the lens is not fully seated. Cool idea.

Steve

nixcamic · 11-08-2008, 10:19 PM

Brilliant! I think I'll be doing this to several of my M lenses, then I can use AV on my MG and my GX-10.

Big Dave · 11-09-2008, 06:17 AM

Hi,
I'm glad that you guys like the dual detent idea. It sure makes life with my manual lenses more enjoyable. The only time that I need to open the appeture to focus is in low light with a flash. In those cases I usually use a fully auto lens anyway. Of course this idea won't work with lenses that lack an appetture ring.

Cheers, Dave