I'll be more specific about my concerns re long-term use of Leica M motors: as there are no electrical interfaces, the system depends on constant torque to operate. The way the motor operates is a bit like putting pressure on the advance lever while pushing the shutter-button. Maybe the shutter-linkage is different in the M-6, but I know, from an old M-2 that I took apart, that there is a cutout at the top of the wind-spool that a pin fits into to secure the frame location. This pin moves when the shutter is pressed to allow the spool to wind when the advance lever is moved, after each exposure. If pressure is kept on the wind-lever as the shutter is pressed, the release-pin rubs hard on one side of the aforementioned cutout. I would think that doing this repeatedly could create a serious wear situation, perhaps leading to framing inaccuracies, or even a complete failure of the shutter/wind-mechanism linkage. Am I being overly concerned? As stated, I really like the motor for certain situations, so much so that I would accept that its use might shorten the useful life of the camera in general. What I would find unacceptable is sudden mechanical failure. Are there any tech-folks out there who've looked at the guts of an M-6 to know if I should lose any sleep over this?

-- John Layton (john.layton@valley.net), December 29, 2001

Answers

The M winders have a switch which is activated mechanically by a shaft, when the shutter is pressed , and which winds the film after the shutter trips. When you take your finger off the shutter button the shaft retracts and the motor switch is disengaged. There is no constant torque applied to the winding pawl. Wear on mechanical parts is mostly caused by friction, not pressure. The pressure on the winding mechanism stop is not greater with the motor than without. What causes the most wear-and-tear on motor-driven cameras is the increased number of shutter cycles and the speed at which the transport is driven. The latter is not a concern with the M winders, the former is a function of the photographer.

-- Jay (infinitydt@aol.com), December 29, 2001.

The winder that Jay is describing is the very first version of the Winder M4-2. The later versions of the winder use a different system. When the shutter is fully wound, the winder's motor shifts in its mounting and activates a switch which reduces the amount of torque the motor is producing. When the shutter is released and finished its travel, it frees up the winding mechcanism which allows the winder's motor to shift back and start working at full power again. So a wound camera is not subject to the full torque of the winder. The winding mechanism of the M4-2 and up cameras was beefed up with steel gears and other improvements so I do not think you need to worry about the cameras not being up to the task.

The only problem seems to be with winder/motor-camera synchronisation. SOME cameras allow the winding mechanism to start working before the shutter has finished its cycle. This causes uneven exposures (very similar to when a the curtain brakes fail)and can damage the shutter as well. I do not recommend that you use a Winder or Motor on a M camera at a shutter speed slower than 1/50.

-- John Collier (jbcollier@poersurfr.com), December 29, 2001.

My 2 Winders are a late M4-2 (M6-compatible) and a Winder-M, the model just prior to the latest (small profile + grip) version. Both my winders are triggered mechanically by the shutter release in the M6, there are no electrical contacts that I can see. My M4-2 winder had an awful kickback when I first bought it, but someone on the 'net published an adjustment procedure and since I did that it's as soft as the later Winder-M. If there's any torque on the transport when prior to releasing the shutter, it certainly isn't evident.

-- Jay (infinitydt@aol.com), December 30, 2001.

http://www2.bitstream.net/ ~campbell/

There is the link to the page you mentioned Jay. As you can see the motor torque is used to control the winder. The early Winder M4-2 had a mechanical switch that was activated by an extra shaft attached to the shutter release found only in the M4-2 cameras and early M4-P cameras (it can be added to those M4-P cameras that do not have it but not to the M6. This early winder is of a completely different design to the later winders and was a great deal more problematic.

-- John Collier (jbcollier@powersurfr.com), December 30, 2001.