Metrogon in an unusual shutter

[Sam_PNW]

No markings on the shutter housing. Lens appears to be a Metrogon, and is marked 2-7129 and EFL153.35mm. Fixed (round) aperture. One solenoid sets either “bulb” or “instant” mode. In bulb mode the shutter remains open as long as the second solenoid is activated. In instant mode, the shutter opens and closes with minimal delay, perhaps 1/250 - but I have not measured it. Shutter is set manually by winding a knob connected to the long arm, which also resets the first solenoid to instant mode.
The shutter blades were taped down with some sort of thick paper tape, and the main spring was removed from what appears to be the correct attachment point. I removed the tape and reset the spring and I can now manually operate the shutter. It shows very little sign of wear internally. I have not probed the solenoids yet to determine how to drive them. If anyone has additional data, please let me know.

 

[138S]

In bulb mode the shutter remains open as long as the second solenoid is activated.

The two solenoids configuration is interesting... When a single solenoid is there two different voltages may be used, a higher voltage pulse is used for a fast operation but for long exposures (bulb or seconds) the voltage driving the solenoid is soon decreased to the level that is able to hold the shutter open, this prevents reheating the solenoid or ultimately burning it, and it saves battery when system running on that.

In your case the second solenoid should not rehead too much with a long activation, while the first one perhaps it may reheat if activation is too long. You may mesure ohm in each and use an IR thermometer, but be careful because a solenoid can reheat too much before the heat reaches surface and can be read with the thermometer.

 

[Dan Fromm]

Hmm. OP, does the lower solenoid in fig. 4 open the shutter when retracted? If so, does the shutter stay open when the solenoid is released?

I ask because it appears that the upper solenoid releases a ratchet when retracted, and that the ratched hold the shutter open.

If I got this right -- very probably didn't -- this is the exact opposite of the AGI F.135's electronic shutter. That one has a lever that protrudes from the shutter and two opposed solenoids that extend, not retract, when energized. When the open solenoid whacks the lever, the shutter springs open and stays open until the close solenoid whacks it and it springs back to the closed position. Fewer moving parts that your monster.

 

[Sam_PNW]

I made a short video to demo the shutter, which might be more helpful than explaining it in text form. I can do a write up later, just short of time today.

 

[Dan Fromm]

Thanks for the video. As I feared, I got it wrong. I understand why it works, find what it does incomprehensible. Bulb makes little sense in an aerial camera, and so does a single instantaneous speed.

There are some aerial cameras, all, I think, French, with fixed speed venetian blind type shutters. Several models of shutter, each with a different instantaneous speed. Want a different shutter speed for a mission? Put the right shutter in the camera before putting it in the aircraft.

 

[Sam_PNW]

I agree - the thought occurs to me that perhaps it is not from an aerial camera. Was the metrogon used for anything else? The shutter is obviously professionally done. It does looks somewhat similar on the outside to an example I find on google “f6.3 Viewlex Inc. Aerial camera”.

 

[Dan Fromm]

I didn't know that Viewlex made cameras for USAF. They certainly made lenses for USAF, years ago I had a Viewlex 6"/6.3 Metrogon. It came in a shutter housing but without the shutter, which inserted into the lens.