Hello to all!
Sorry guys, a long time since I have not written. And now I would like to introduce you a final version of my project. Presenting Canon EF/EF-S compatible solution for external iris & focus drive. This adapter supports all lenses compatible with Canon EOS protocol (Tamron and Sigma too). You can control it by ASCOM Platform tools (Maxim DL, FocusMax, etc) or use simple desktop utility. But first things first!
The device looks like it's shown in the picture below.
On board. SBIG STF8300 + Canon 200L
QHY5 + Canon EF200L
Electronic parts haven't changed significantly. The device housing is made of metal (aluminum) and it surface is black anodized. Symbols are laser engraved. The powerful solid state laser is a really cool thing! The text is clear and well detailed, even small letters! The controller has 2 inputs: USB for connecting to a computer and DC IN 5V for huge lenses with large power consumption. POWER and SIGNAL LEDs is needed for user convenience. SIGNAL LED will be light on when transmitting the packet.
The most difficult part is a mechanical lens adapter.
I decided to make 2 types of this part: for M42 cameras with a small chip up to APS-C format and Full-Frame solution with 36x24 sensor and M54 thread interface. When designing I used the documentation from popular QHY/ZWO cameras. Back focal length of the Canon EF lens, as we know, is about 44 mm. Mechanical drawing is shown below.
Moreover, I implemented a standard filter socket on a rear side of the adapter. It was done because the full-sized filter wheel is not applicable in this assembly. There is no place for it. Bayonet parts, PCB with spring contacts, wire connection occupies a lot of space. I don't know if it's possible to make an adapter with a smaller thickness.
You can use round unmounted 36x2 mm filters for M42 adapter or 50x3 mm for M54 Full Frame adapter. Filters are clamped by a special lock ring. This ring has a thread with a little bit smaller diameter than the external adapter mounting thread. This way the filter can be changed at any time. Not as convenient as the filter wheel, but it's better than nothing.
Assembly diagramm is shown below. You can see both types of adapter. Simple system that can be used with a wide range of cameras and lenses. No additional external parts required.
To be continued!