double filter wheel in MaxIm

[George A Silvis]

Here's a good one!

We (Arne and the AAVSOnet) have coupled two filter wheels together in the optical path. FW1 will have photometric filters. FW2 has various diffusers and ND filters; we're going after bright stars.

FW2 is connected to the guider camera in MDL and there are MDL properties to move the guider FW.

Where can we hook into the ACP/Focuser/MDL code stack to intercept a move to filter "V_Dif1" to a MDL command to move FW1 to V and the guider to Dif1? I'm assuming MDL does the actual work of controlling the FW, not FocusMax or ACP.

Do we need a FilterWheel driver that wraps the existing driver?

Always looking for fun problems to solve!

George

[Colin Haig]

George, I work at Diffraction Limited (makers of MaxIm DL Pro), and this is ringing a bell. I think we did something to stack a pair of filter wheels. I'll see if I can find it.
BTW which wheels are you using?

[Colin Haig]

Ok, it's TRIVIAL because we solved this ages ago.
See attached screen shot.

MaxIm - Camera Control Window - Setup Tab
Filter

First, you need to set up each filter wheel and it's filters.
In my example, I used an SBIG filter wheel and a DL filter wheel.
SBIG got Clear, OII, Ha, SII.
DL got Clear, U, B, V, R, I.

After you set up the filters for both, then you need to set up the synthetic Dual Wheel, and name its filters.

Select "Dual Wheel" as the option.
Then hit advanced.
Then you get to select what the first filter wheel is, and then what the second one is.
Then you set up the filters.
Effectively you get a "Synthetic" fliter - so you could even combine two filters.
You might do a clear or empty slot in FW2 and overlay that with the Clear UBVRI set in FW1, and then combine that way.
In the MaxIm manual, search for "Dual Wheel" - its around page 264.

[Colin Haig]

One more thing: You could create a synthetic filter named "B_ND1", "B_ND2", "V_ND1", "V_ND2" which combines an ND filter in wheel 2 with a Bessel / JC / Sloan filter in wheel 1.
Then in ACP or MaxIm, you just select the filters you want from the dual wheel, and no special coding or anything required.

[George A Silvis]

Colin,

We, ie Arne, has been trying this to get this to work, with no success:
==
I'm still having problems with the dual filter wheel plugin. I can select filter wheel for both camera1 and camera2, and they both work. If I select the dual filter wheel option and follow the manual instructions, only filter wheel 1 turns.

The filter wheels are the same make and mode. The problem appears to be that the two filter wheels are using the same driver?
===


Any suggestions on how to get this to work?
George

[Colin Haig]

George, do NOT use a filter wheel for camera 2. This is wrong.
Arne needs to think about this differently.

See the attached diagram.
dual_wheel_and_guider.png

Here's the two scenarios:

On the Guide or Expose tab, Filter Wheel 2 is associated with the guide scope and guide camera, and should NOT be used, unless you have a small filter wheel associated with the guide camera. Almost ZERO people use that. I know a couple of people that have a light pollution, Halpha, clear, and IR pass filter for their guider in a small FW2 for Camera 2. It's rare.

Filter Wheel 1 is set to Dual Wheel which is the COMBINATION of FW1A and FW1B. In my sample, I had provided 2 different filter wheel types just to make it clear, but I guess since they are called Filter Wheel 1 and Filter Wheel 2 in the example and in MaxIm and this naming convention can be confusing. I suppose you could call them 1-1 and 1-2, and the a rare guider fw is 2.
So the three are:
FW1 = FW1A or FW1-1 cascaded with FW1B or FW1-2.
FW2 = Guider's filter wheel FW2


In more detail:
Main Camera is always Camera 1.
Guide Camera is always Camera 2.
Main camera has a Filter Wheel 1.
Guide camera on rare occassion has its own filter wheel, known as Filter Wheel 2.
This would total up as 3 PHYSICAL filter wheels; but MaxIm calls the pair on Camera 1 "Filter Wheel 1" - a virtual filter wheel only when using Dual Wheel.
MaxIm calls the optional small filter wheel on the guide Camera 2 "Filter Wheel 2".

Feel free to call me at the Diffraction Limited office to discuss/debug. 613 225 2732

To get FW1A and FW1B to move to different slots, you need to define the virtual filters so that they are drawn from each separate wheel, FW1A and FW1B.

When defining the wheels, there needs to be a way to differentiate between them.
I don't know whose wheels you are using or what models.
The old Apogee Dual Wheels use 1 driver, but in the advanced settings for the driver, you picked which of the two USB devices.

[Bob Denny]

Thanks for the detailed info Colin!! I would never have known how to address this.

I'mm move this to the non-ACP issues section.

[George A Silvis]

Thanks Colin!
George

[Colin Haig]

BTW I am not quite following your idea of the FW on the guider. We treat the FW associated with Camera 2 (the guider in normal situations) as a separate FW. eg some folks use a small FW for their guider with a clear, ND, and Ha filter. This is separate from the dual wheel main FW on the main imager.

[Bob Denny]

Colin -- Thanks from the bottom of my heart for this!!!