Saturday, January 7, 2017

When Lens Conversion Goes Wrong, or Why Lenses with Auto Aperture Control Suck

I was somewhat encouraged by the semi-successful conversion of the Vivitar 40mm f1.7 from the Vivitar 35ES, so I ventured on to start another rangefinder that did not have aperture control: the Minolta Electro Shot.  This camera has a 40mm f1.8 lens but much larger than the Vivitar 40mm f1.7. Well, things didn't turn out as well as the Vivitar conversion.  The Electro Shot does not have separate shutter and aperture blades, like pretty much all other rangefinders from that era, but it employed a single shutter/aperture system. I didn't know this until the very end.

Lens Conversion Gone Bad

As I assumed the shutter and aperture blades were separate, and from experience that I gained, the shutter mechanism is usually accessible from the front. But when I disassembled the whole front, there was nothing.  All the controls are from the rear of the lens.  Long story short, in the process of trying to find the mechanism for aperture control, I mistakenly loosened three screws on top of the lens from the rear, and this caused the aperture/shutter blades to fall out of the lens :(  The timing and shutter/aperture control system is very complicated and I decided to just give up on aperture control. After some more thought, I further decided that I should make another Borg lens, with a Steampunk look.  Incidentally, my first Borg lens was also a Minolta.

From now on, I will stay away from rangefinders that have no manual aperture control on the lens. It's just not worth the trouble, unless the camera is dirt cheap or is unusual.  Of course, this could change if I gain enough skill to make more complex parts to enable the aperture in the lens.

Wilted Rose - Minolta Rokkor-QF 40mm f1.8 & Sony A7


  1. I love your "Borg" lens outcome. You could always machine a thin plexiglass donut to cover that section if you desired.


  2. Thanks John! The only thing I need is to machine an adapter so that I can put a hood on this thing. It flares like crazy.

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