Are you still considering wiring the clocks together? Seems if you are going for a button mod might as well go all the way.

Basically once I open'er up, I'll try the button mod and start poking around with my scope for clocks (I have some better ideas now where to look). But it seems to be a multilayer board with many SMD components, and that is tricky stuff without the right gear (that I don't have). It just depends which part(s) needs desoldering. And I'd like the option to get it back in if it doesn't work out, as I can't afford to trash a body.

I could use some expert advice for the clock hacking, so if you know any electronics whizzkids, ask them to drop by.

In the meantime I'll get AVR-based LANC sync measurement and record start/stop working to see if there's a non-invasive solution. Simultaneous record triggering will be useful anyway.

Can you try it without the m43 lens mounting? The delay might be the camera communicating with the lens.

Disregard all my previous CRT timings, I either did them wrong or it's my CRT - it's an ancient VGA monitor that only supports one resolution & refresh rate (badly), god knows if it even ran at the settings I thought.

(assuming LANC drift is directly related to sync) my new Pockets have 0.1ms / min drift. Worst-case sync (half a frame) @ 24p is ~21ms, it would take 3.5 hours to hit that (not that you want to be anywhere near it) - nice.

I'll check over time to see if it changes, temperature might have an effect. I'm also interested if both cams running off the same PSU/battery vs their own batteries/PSUs has any effect (slight voltage difference).

Timings are quite variable. I ran another test from cold over 15mins (same PSU for both as before), and got down to 0.68ms / min!

I then tried BM batteries over 5mins, back to my previous ~1ms/min. So it's fine to power from two different sources - but sharing power is probably safer for dual LANC control (depending on the LANC circuit) or if the clock gets cloned to the other body.

Record start/stop has no effect on the clock.

Interestingly, the new SD formatting function once reset the clock when I came out of it on completion, but now I can't reproduce it. I tried formatting empty cards and with recordings, neither cause it now - must be a combination of things.

I haven't got LANC working yet, somebody here already has though. I'll try when I have it running.

LANC signals seem to be synced to each video frame, so any delay between the two body sensors is also present on the LANC signal. That means you can't use it for syncing - any command you send simultaneously will be delayed on one body if there is a sync difference. But if there's another way to sync them, then you can at least start record simultaneously (for convenience and you can do it from a distance) + monitor sync from the signal delay.

LANC commands apparently have to be sent 5 times before they take effect (probably a workaround for unreliable signals). So there's potentially 5 video frames of latency in each command (~200ms @ 24p) which could explain the inc/dec focusing not being responsive.

Wait, it's open-collector so I'm not sending voltage, just draining it. Still, how much can I draw off the 5V? I want to run the micro (should be fine) + small OLED display (max. 40ma @ 5V, though less in practice). Safe?

You know that TV show where the obnoxious kid at the end shouts "I made this!"?

This is the LANC DRIFT3R:

Current features:

• controls one or two cams
• displays sync drift of two in real-time (+ record state & framerate)
• single touch-sensitive button for record (or testing other cmds)
• powered by LANC (no battery)
• colour OLED screen (just because)
• as tiny as I could make it.

For some early demo footage yes. But my plan is to try all available LANC commands next (which are unlikely to reset the clocks, record doesn't as expected), look for hidden ones, and failing that do a button mod to see if that will reliably reset the clocks. If a button mod works then I can verify its reliability with the drifter in the field.

There may be some randomness in the clock reset. If I use LANC record to get the cams out of play mode, I don't get a reliable sync difference (well, there sometimes is a pattern to it, but not always). That doesn't necessarily mean that a button mod won't work, there could be some variability in the LANC response that you may not get with a hardware button mod.

BTW, nobody responded to this

"Can someone reproduce? Just toggle in/out of play mode - in ProRes it should pause/blank & flash the screen & change the native lens' aperture (that's the clock reset). In RAW it just instantly goes in and out here, no pause or visual glitches."

Thanks @Pysco. It's running on an 8 pin AVR (Attiny) chip, code is straight AVR-GCC.

Yeah, LANC is in sync with the framerate, so any sync difference between the bodies is on the LANC signals as well.

I figured out that you could actually use LANC to sync the bodies genlock style, but it would require firmware additions. I know how it could be done - you'd then just wire the LANC ports together & set one cam to be the master. Apart from frame sync, you could even sync all the parameters (exposure, focus, iris, framerate, WB etc) in real-time aswell (that just requires extra LANC commands for each param, which are super-easy to implement).

If BMD would open up the firmware, it could be added fairly easily.

Which bit is giving you trouble? And don't say 'all of it' : ).