TTL Metering for a Fedka or Zorki

[JX8p]

Evening folks,

I've just finished work on the third revision of a TTL light meter for my Fed 5v. I've attached a photo of it below (note that I have yet to make the battery cable look nice. I was in a rush to test it):

If any folk are interested in how this was done then do let me know.

Thanks,
David

 

[zuiko85]

Interesting.
Just as a matter of FYI the acronym 'TTL' is short for 'Through The Lens' and in regard to on board camera meters refers to metering through the taking lens. Is this the set up you have or is it rather a 'built on' meter that measures light through a separate lens or window?

 

[JX8p]

Interesting.
Just as a matter of FYI the acronym 'TTL' is short for 'Through The Lens' and in regard to on board camera meters refers to metering through the taking lens. Is this the set up you have or is it rather a 'built on' meter that measures light through a separate lens or window?

It is through the lens, aye. I set up the sensor in the cavity between the lens mount and the shutter curtains, where it points at a dot painted on the shutter curtain.

 

[Joao]

David
Some more details on your work would be most welcome. And when you have results I would appreciate to hear about them.
Best regards
Joao

 

[David Hughes]

Hi,

Fascinating, I've often wondered if the blinds could be covered in a random pattern like the Olympus OM10 and just a sensor put inside to catch the reflection with the rest of the metering outside...

Regards, David

 

[zuiko85]

It is through the lens, aye. I set up the sensor in the cavity between the lens mount and the shutter curtains, where it points at a dot painted on the shutter curtain.

Well then that is doggone clever if you ask me. Quite a bit of work too I would imagine.

 

[CMur12]

I'm certainly impressed!

I would like to follow this project to completion and see some more photos of your work and the finished camera.

- Murray

 

[Ko.Fe.]

Keep us upgraded!

 

[Fuchs]

Oh yes, that's very interesting. Please share more details and keep us updated!

 

[Sid836]

Very nice. Would it be possible building something small and compact enough to mount it atop the camera, perhaps on the flash hotshoe? I'd love to have something like that I could add on most of my cameras that do not have meter.

 

[ForestCap]

Does the one who bought the FED-6 visit this forum?

 

[B-9]

Eat your hearts out guys,
http://www.rangefinderforum.com/forums/showthread.php?t=148622

If anyone attempts this, order me a copy of that PCB would ya 😉

 

[ForestCap]

Eat your hearts out guys,
http://www.rangefinderforum.com/forums/showthread.php?t=148622

If anyone attempts this, order me a copy of that PCB would ya 😉

I was dreaming of some sort of universal digital back that you can install on the film pressure plate of all those fixed-lens and system rangefinder cameras.

 

[David Hughes]

Hi,

There has been a lot of talk about them but nothing ever seems to come of them. I have often wonderd about the digital back Minolta made for their film cameras years ago but no one else seems to have heard of it. IT might have only been a prototype but the pictures of it I saw suggested otherwise.

Regards, David

 

[nikarlo]

I have a similar idea to put inside kiev 4 old selenium light meter.
Share with us your work!

 

[dee]

Fascinating .

 

[Ron (Netherlands)]

So did the OP ever finish his job?
He does not seem to respond to any of the questions here...

 

[hwntw]

Fake, Photoshopped

 

[B-9]

Can anyone elaborate on the controller used and how it would be programmed for this application?

It seems the rest of the parts are typical radio shack bits.

 

[JX8p]

So did the OP ever finish his job?
He does not seem to respond to any of the questions here...

I did and it works. I'll see about uploading some scans tomorrow. For the most part I'm just reluctant to show my work to others, lest it be judged harshly. I've shown it here in the hope it can inspire and help others who may wish to do similar.

Fake, Photoshopped

You're not very imaginative, are you?

 	 		 		Can anyone elaborate on the controller used and how it would be programmed for this application?

It seems the rest of the parts are typical radio shack bits.

It's an Atmel AVR. It is programmed to calculate the level of light by measuring how many interrupts are generated by a TSL235 light-to-frequency converter every second. The result of that is a value on a linear scale. This is rebased on a base-2 logarithmic scale and a constant (0.7 in my case) subtracted or added to bring it in line with the EV scale (the constant was calibrated by comparing same-aperture results on the Fed via my meter and a Canon EOS 5). The results are displayed on the OLED display.

Very nice. Would it be possible building something small and compact enough to mount it atop the camera, perhaps on the flash hotshoe? I'd love to have something like that I could add on most of my cameras that do not have meter.

It'd require a little fine soldering but is definitely possible. Probably a custom PCB and case as well.


Photo host seems to be down. Reuploaded below. A photo of the prototype as well, for the fun of it.