Controlling multiple imaging cameras with one asiair (or anything that allows sync/snap/shutter type interface)

[powerlord]

So..I wiser man would have testing this first, but I wanted to get stuck into CAD, electronics and software, so went ahead and built this before I knew if it would work:

The plan was to several fold:

1. I hoped that an asiair would be able to be setup with a guide camera which I'd swap over to use as a main camera just for plate solving gotos and PAing (this bit does work), but then when ready to image, have it set to guide with the camera, tell it to use the DSLR 'snap' remote to take pics and not worry about the fact a main camera wasn't connected (since my M100 doesn't support remote wired control).

2. Also be able to use the same gadget to 'piggy back' on another imaging session, by using the DSLR interface to shoot with the M100 as the same target or a different one at the same DEC with maybe different FL, etc.

3. be able to set up the M100 with a traditional intervalometer and use for unguided stuff (no asiair) or even fixed tripod.

The good news, was 3 works fine with the gadget. 🙂

1 however is a non starter - the asiair it turns out will simply not function unless it thinks there is a camera installed, so my plans to add PA and goto plate solving plus guiding to a more basic AZ GTI EQ setup are foxed there.

So lets talk 2: My (untested) expectation was that the 'DSLR' remote on the asiair was 'live' all the time. i.e. whenever it was taking an image - whether via something like my asi2600mc, or via my canon 6d (though the USB not remote interface), it would still be operating it - pulling the shutter pin low when taking an image, high when finished.. I mean - why would you NOT design it like this...

Well.. yeh.. ZWO designed to ignore the design paradigm - 'a design is not complete until you cannot take anything more away), and in fact make this interface conditional on a bunch of stuff. This is a right pita - and I'll raise with ZWO though won't hold my breath for a change..

So the DSLR connection ONLY works in the following conditions:

1. you have attached a 'DSLR' (i.e. a supported camera recognised as a non zwo supported canon or nikon)

2. you have selected the toggle that says to use the DSLR remote trigger interface to take photos

If these conditions are met, though the USB connection to the camera is used for live view, and the connection must be active, when it comes to taking an exposure ASIAIR uses the DSLR remote trigger INSTEAD of the USB. The idea here is that some cameras have a max 30 sec exposure via USB control, and this gets around that. Which is all well and good, and certainly you need a way of selecting that it should or should not use the USB for taking an image - but there is NO situation where having the DSLR trigger simply working ALL THE TIME would be a problem and would have been the simpler design!

This also means that if your main camera is an ASI2600, etc you are also stuffed - the DSLR interface does nowt.

At this point then, I was pretty miffed off.. however then I thought - well.. hold on... the 6d doesn't need it, but would it work with it if I set it (and connected a remote line to the 3 pin remote on the 6d) ? The answer is yes, it does. Exactly the same as it does over USB.

So, at this point I rigged up a new cable:

On one end is the 2.5mm plug to plug into the asiair. It then splits into 2 cables - one has a 3.5mm pin for my M100 remote gadget, the other has the round 3 pin connector for the 6d on it. And I plugged it all in.

I set the asiair to use the 6d as main camera, but use the DSLR for shutter. And I then tried taking a sub... both cameras fired as expected!

In fact, you can even just press the shutter on the 6d, and it will press the shutter on the M100 (asiair doing nowt here) - since the interface is really basic - all it does is connect the ground (ring) the the tip to activate shutter. Hence, both cameras see this as continuity when asiair does it - both fire... and since the wiring internally in the 6d also connects it's interface when it takes a pic, that makes the M100 shutter go too!

I imagine this could be extended to many cameras if you were particularily mental.

So.. going back the the original wish list, 2 is a 'sort of'. Yes it has lots of caveats

- It will only work if I have a rig setup with the canon 6d and canon m100

- they must be set to take the same exposure length

- the targets must be at the same DEC for guiding to be working right for both (I think?? correct me if I'm wrong)

So it is I grant you, very much and edge case... and I won't be surprised if I remain the only person in the world wanting to do this. However, it would be possible for someone as an example, to setup 2 identical canon 6ds with the same lenses, etc - and have one be shooting NB with a filter, and one shooting WB RGB with no filter of the same target all night.

So - in summary - sorry for long post. The gist is:

1. asiair use: yeh can do 2 with caveats - just make that lead up

2. making that lead up will also work for any other intervalometer or remote trigger (e.g. the ones on azgti, SW EQ5/6 mounts, most adventure style AZ mounts, etc) and allow you to control multiple cameras at once.

Here's a pic of the imaging rig I'll be trying sat night (on a modified EQ5 rather than the azgti shown here):

 

Edited October 13, 2023 by powerlord

[Elp]

Whenever I've done this I've used an intervalometer with the second camera and just left it to continue taking images, if you're imaging 2 minutes or less with the main camera you don't loose too many subs whilst the first is dithering etc. For easier setup (ie focus routine) use a second air, even if it's the gen1 version but you still loose subs when it's dithering.

[powerlord]

Yeh good point, I should have mentioned that.