It would look like heck, but using a rechargeable Nihm AAA or AA battery as a power source should get you 1.35 v, without any other diode or other electrical engineering.
The rechargeable Nihm batteries I use, all deliver about that exact voltage, when fully charged and last a long while.
You could make a black battery holder to mount with double stick or Velcro, on the FTn finder or better yet, the back of the F camera, 3D printing will give you what you need, and you will able to use that battery for years of shooting, and since you have to buy these in pairs or greater retail units, you'll always have a second backup, for added security, away on a shoot.
Any wires used to make the connection between battery and meter, will just add a 'steam-punk' look to your kit and you can use two black wires if desired.
Cheers.
The rechargeable Nihm batteries I use, all deliver about that exact voltage, when fully charged and last a long while.
You could make a black battery holder to mount with double stick or Velcro, on the FTn finder or better yet, the back of the F camera, 3D printing will give you what you need, and you will able to use that battery for years of shooting, and since you have to buy these in pairs or greater retail units, you'll always have a second backup, for added security, away on a shoot.
Any wires used to make the connection between battery and meter, will just add a 'steam-punk' look to your kit and you can use two black wires if desired.
Cheers.