#Arkive SQ: Thoughts about a smart FD adapter

Started Apr 16, 2019 | Discussions thread
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SQLGuy Forum Pro • Posts: 10,375
#Arkive SQ: Thoughts about a smart FD adapter

Canon FD mount allows for communications and actuation from the body:

1. There's a pin whose length is read by a sensor in the body so that the body will know the maximum aperture of the lens.

2. There's another sensor in the body that senses the position of the aperture ring, so it knows the currently set aperture or whether the lens is in program mode.

3. There an aperture stop down lever in the body that closes down the aperture when getting ready to release the shutter, so composition and focusing can be done wide open.

I think it would be really cool to build an E mount adapter that implemented these features. Besides making FD lenses easier to use, it would also make them easier to mount (no Open/Close nonsense).

It's certainly feasible. The LA-EA3 has such an aperture lever, as does the Nikon smart adapter. Zeiss Loxia lenses have aperture rings, so E mount does support the lens telling the camera the aperture.

The main missing piece would be the focal length(s) of the lens. One option that occurred to me is to allow the adapter to be programmed (probably over Bluetooth or BLE) to recognize specific lenses by max aperture. For people that only have a few FD lenses to use on the adapter, this could make use really easy - e.g. the 2.0 is 35mm, the 1.4 is 50mm, the 2.8 is 24mm... However, if there are multiples at the same aperture, then things get trickier, and a button and maybe an LED or two on the adapter may be needed to switch between lenses. For zooms, I think the best behavior would be to disable IBIS (configurable through the programming).

One other option that occurred to me is little bar code stickers for the breech ends of the lenses and an optical reader in the adapter, ala Leica's 6-bit encoding, so that the lenses could be recognized unambiguously. This would still require configuration of the adapter for the lenses a particular user has, but it would get rid of the need for buttons and LEDs on the adapter. In fact, it could obviate the need for the aperture pin reader.

What do you guys think? Would an FD adapter that allows lenses to work like they do on an FD body, plus EXIF and automatic configuration of IBIS, be a compelling product? I don't think there's enough market for this to be a money maker, but it would be something I'd like to have.

As for my skills in this area - I'm a developer by trade - mostly Java these days. I have some experience with custom solutions based on Cypress PSoC and PRoC microcontrollers. My formal training was avionics and computer engineering. I have a mini lathe and some fabrication skills... some of which come from a hobby in watch repair and restoration. I know nothing about the E mount protocols. Clearly they have been made available or reverse-engineered by Techart and Conurus, but I don't know how available this information is. The FD side of things should be pretty easy to figure out, just by measuring lenses, even if the details are not available somewhere.

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A7R2 with SEL2470Z and a number of adapted lenses (Canon FD, Minolta AF, Canon EF, Leica, Nikon...); A7R converted to IR.

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