Hi,
I passed throught the same question the last few months.
My main camera is out for maintenance.
Since will be a long wait for the camera to return back I decided to take one of these Panasonic CMOS in the meantime.
So I made my considerations (DDR buffer, heat windows, usb-hub etc.) and took a QHY163, and the story began:
[Assumption: I already had both the ZWO and QHY filter wheels. And 31mm filters].
My first issue was the size of my filters, 31mm unmounted. The QHY filter wheel by default works with 1.25 mounted filters.
QHY and the italian dealer make a great job provided a very good solution by drilling 3 mini-holes for each filter hole and provided me the screws to mount the filters.
Let the guide camera (QHY) come in focus with the OAG (QHY) was tricky task. This was related with the model of the QHYCFW I had that was the US model (Ultra Slim).
I had to remove the very last part of the guide camera, the one with a protecting window. No a big deal but not so nice though..
At the first light, despite I used 31mm filters, I had vignetting at F7.
I knew about this possibility, but I also knew that QHY provides adapters to reduce the backfocus of the camera, changing the way it connects to the filter wheel.
So I looked for their small and big screw adapter solutions.
Then, thinking about that I realized that the OAG will never come in focus if I would reduce the distance between filters and sensors further more (my backfocus has to be 55mm total, so what I remove between camera and filters I have to put back at the beginning of the train).
Looking for a solution I saw QHY sells a set of spacers to put between the OAG and the filter wheel..
Problem is that QHY uses connections with screws. This provides a stiff connection but is out of standard.
I order the set of those spacers but they come without screws (which has to be of a precise length and, of course, thread size)..
I think I could have use also standard M54 thread extender between OAG and FW but then I would have to left the screw holes of the FW empty, that would led problems of light leaking..
At that point I gave up, I had the feel that I was falling in a money-drain loop and also my setup, with all those screws, was becaming less confortable to store and travel with.
So I tried with the counterpart and ordered an ASI1600MM.
In 5 minutes I had the camera, filterwheel and OAG mounted together with 55mm of backfocus out of the box and maybe 7/8mm (camera itself have 6.5mm bf) distance between sensors and filters, with no extra adapters/extensions in addition the ones provided with the camera.
Until now I tried it only with a 135mm DSRL lens (but without the OAG) and I had a bit of vignetting, at F2.
I sold the QHY things.
[ Here is the link to thread I opened to QHY forum, there's some drawings I made that explain my issue better than my sloppy English:
https://www.qhyccd.com/bbs/index.php?topic=6878.0 ]
I don't know what will be your setup, and I know mine maybe is a 'borderline case' but consider the above if your plan is to use and OAG and save some money for the filters getting 1.25/31mm instead of 36mm.
Regards,
Stefano.
PS: I don't want to blame/advice-against QHY company in general.
They are a good company and sell quality items.
I think the problem I had was only due to the QHY163 and aftermarket solution they provide to solve particular issues with particular setups (they advice 36mm filters in fact, but I didn't wanted to replace my 31mm ones) and the integration of those solution with their stiff but not very flexible standard.
So probably if you stay with the standard you will be fine with them.