Saturday, April 23, 2016

tried to control mirror

A long journey, this. And I'm still not clear about what I can or cannot do.

Decided to have a go at prototyping the camera control mirror lock-up cable. I wanted, at a minimum, to build a cable to go from the recently acquired Canon N3 adapter cable, with it's male sub-mini stereo plug, to ultimately connect to a box with the switching (and isolating) electronics. First, I'd solder up a female jack to a cable and with the loose ends do some testing.

Assembled parts and tools: MOSFETs, 10K resistor, N3 adapter cable, stereo sub-mini female jack, four conductor wire, digital multi-meter, jumper cables, sewing pin, side cutters, soldering iron, solder, small vice, helping hands, close-up glasses.

Did a battery of continuity tests to verify pin-outs. Created visual notes. Checked the adapter cable pins from the N3 to the sub-mini plug. Compared this to Michael Covington's notes. Confirmed. Looked at the Canon 40D DSLR N3 connector: the triangle is upside-down, that is, it points down; the bump in the connector is toward the lens. This appears to be opposite some other models. Used Peter Jensen's notes where he truly hacked the pins. Corroborated notes. Attached the female in-line plug and checked the wiring connection points. OK, ready to go!

Fired up the Weller, wet the sponge, stripped the wires, clamped the jack and wires in place, and soldered everything up. Screwed on the jack cover. Tight fit... Tested the connections. What?! A short! Removed the cover. Very tight fit... And found all the wires had twisted around one another, with one wire tearing free, and the extreme tension tearing out one of the posts! Crikey. Good for nothing.

Found another female jack from the parts bin: the last in-line connector. Whew! Stripped the wires. Soldered. Carefully installed the cover. Tested the connections. What?! No signal on the Focus circuit. Whiskey Tango Foxtrot?! I was not happy. Didn't even bother to open it up.

So upsetting.

Considered dropping the whole matter...

Grabbed a case-mount sub-mini female jack—to discover bad fitment. The plug did not seem to insert far enough (or it wasn't long enough) and would easily release. That would not be good in the field. Grabbed a panel-mount jack. Good positive fitment. Connected it with jumper cables. This would have to do for the balance of my prototyping.

Needed a female serial cable connector. Looked in the old computer cables box. Found a male. Looking in another old computer parts box. Ah. Old Psion stuff. And a gaggle of PC interface cables... with female ends. Grabbed one, cut it near the proprietary palmtop connector. Wow. Ten coloured, thin wires, not counting the ground strap. Checked the pin-outs noting the colours for pin 5 and 7.

Grabbed the Prolific USB-serial adapter and attached it to the netbook. Checked the assigned COM port: 4.

Grabbed the electronic experiment kit with breadboard and wired up the circuit, based on Covington's schematic.

Connected the DSLR to John Repeat Dance via the USB cable. EOS Utility woke. Did some quick tests. OK. Closed the EU app. Launched Backyard EOS. Dove into the settings, then Advanced Settings, and turned on the Virtual Mirror Lock. Tested Frame & Focus. Starting working on an image plan. Set the Mirror setting to 5 seconds. Set the Control Cable to COM4. Tried the Test Cable button... No error; but no positive message either. Started the imaging run... The Delay wound down... and nothing happened. Looked like the software froze. Tried again. No action. Huh. Wondered what was wrong.

Rebooted the 40D. Checked the camera settings. Found the Mirror Lock on... Is this causing a conflict? Now I was growing increasingly confused. Or unclear. And the awkward documentation with BYE wasn't helping. I felt the need to step back, review, gather my thoughts.

Reviewed my notes and thoughts from Aug 2015, as I tried to wrangle the camera. Where I was very confused for part of the evening. On that occasion I was shooting long exposures; earlier I had been shooting very fast.

Looks like I'm going to have to jump into the O'Telescope forums...

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