Deep Sky Camera advice

FF would be vignetted and uncorrected unless you opt for a 3" focuser and CC that allow 44mm imagining circle. Not many out there and non inexpensive.

Marco Grisolia:
I already have the Skywatcher Quattro CC and I don't want to be mistaken but I think it supports full frame imaging train, for the 3" focuser I never looked for it, thanks! 
Any other particular advice on particulars that I could be missing ?

I have the same CC and there is no way it can support a 44mm imaging circle* as it is far too long to illuminate that far (and in fact much less). You really need a 3" focuser and a 3" CC to achieve a decent illumination beyond APS-C radius. Also, the secondary must be sized to match so neither the standard secondary nor the support are adequate.

(*): @ f/4

Marco Grisolia:
It is really helpful, thanks again
So as I understand, in order to not change all my imaging train starting from my secondary mirror, I am forced to move on ASP-C if I don't want major vignetting...
Maybe it's not a smart question but couldn't I just crop or bin the image but still have a greater resolution than an ASP-C ?
Any great combinations with my setup on OSC / APS-C sensor ?
I am thinking about:
- 2600MC from ZWO
- Poseidon-C from Player One
- Any QHY that outperforms the ZWO ones ? 
- Also any other good camera that matches those specs ?

Image scale gives the resolution not the area covered by the sensor, all other things being equal. You are going to pay a premium for a FF sensor and then you just crop it? Not sure how much sense this does unless you are going for the distance and plan to update the various bits and bops in order to image with a FF one day. Fair play to that but the headache is only postponed at best. Binning with CMOS doesn't make much sense to me (or as much as it does with CCDs) but it doesn't address the issue of illumination and you can always do that in post-processing (the gain to do that on the camera is marginal).

Any camera with the IMX571 sensor is bound to perform well so maybe is a matter of preferences (and costs). Personally I'd go with the ASI solution but it is just my experience with the maker (compared to others). If you have the money then go for a really high end solution such as the Moravian Instruments C3-26000, that's my advice.

Marco Grisolia:
It is really helpful, thanks again
So as I understand, in order to not change all my imaging train starting from my secondary mirror, I am forced to move on ASP-C if I don't want major vignetting...
Maybe it's not a smart question but couldn't I just crop or bin the image but still have a greater resolution than an ASP-C ?
Any great combinations with my setup on OSC / APS-C sensor ?
I am thinking about:
- 2600MC from ZWO
- Poseidon-C from Player One
- Any QHY that outperforms the ZWO ones ? 
- Also any other good camera that matches those specs ?

Hi Marco, I own an ASI2600MC-Pro since a couple of years, and I can only recommend it. It is extremely reliable and I never had any problem (i.e. ice formation on the sensor in the transient cooling phase). I recently bought a second color camera with the same sensor, the TS-Optics TS2600CP,  that costs significantly less (1000 €) and has the same Sony sensor as the ASI2600. I used it on a different scope and for the time being I am satisfied with it. This is an image taken with it. Hope this helps. Ciao.

One thing to watch out for…

if company b is claiming a higher full well using the same sensor company a, company b is using some deceptive marketing.

Marco Grisolia:
Thanks a lot,
Yes I know this camera is one of the best on the market actually and is currently on my main choices.
The only thing that really make me think about it is that, compared to its competitor from player one, it has a less Full well capacity and I also heard people saying that the poseidon goes at delta 30/35 at only 20/30% of power resulting in less overload on the peltiers...
What is your experience on the power usage of the 2600MC?

Hi Marco,
I never had issues with cooling and dew heating power with the ASI2600. I noticed, as expected, higher consumption in few exceptionally warm summer nights, but I never made specific measurements, because this was never a critical point to me. Let me add that the ASI circuitry is also self setting the cooling speed, without need of external control. And, as I previously said, I never had ice on the sensor, that is something I experienced with other cameras like the ASI071 for instance. All in all it has a very good cooling setup in my experience.
As regards the FW, I would suggest to check that the measurements on the two cameras are taken at the same gain value given in electrons/ADU.
I made a precise comparison among ASI2600 and the TS2600, and they show exactly the same FW when the gain (in e/ADU, not the gain control parameter, that is conventional) is the same.
Lastly, let me say that I agree with the remark of @Brian Puhl regarding exposure time. The downside of the monochrome is rather additional complexity and additional cost because you must, as a minimum, use RGB filters and mount a filter wheel, and maybe at the beginning you do not want this. In 3-band narrowband (e.g. SHO) the advantage of monochrome is evident (not so if you make 2-band (e.g. HOO) with dual-narrow-band filters on OSC).

Brian Puhl:
This comment I see far too often and it bugs me.    You can gather more data with mono in the same amount of time.

The OP may be meaning  convenience when they said time.  Yes, you can gather more data with mono in the same amount of time, but some people prefer not to go through the expense of purchasing expensive filters, dealing with 4 sets of subs with associated calibration etc.

Thanks for all the responses, 
I can consider also to have an ASP-C Mono setup of course, but I really don't know whether I would be in the price range I initially set… but probably yes. Also when I was talking about time, is not only the imaging acquisition, but also all the time involved behind to process and deal with the data… Clearly it will not be simple at the beginning, but maybe by improving and learning I could also try that…
Also if I were to go for a Mono setup, what kind of narrowband filters do you advice ? Antlia 3nm?
 
Another sort of problem in using a filter wheel is that in this particular moment I can't put too much weight on the front of my tube because when balancing I have to lower the center of mass in the Dec axis and, by doing so (have the mirror much further back), I hit my mount limits (set near hitting the tripod legs) when I'm placed before and after meridian…The tripod pier extension is not an option cause I can't lift the tube that much in the air…
Any other advices ?

As for the Mono Calibration it isn't an issue since I have a light panel, flats are much much easier, surely less complicated than taking darks all the time because the sensor isn't cooled down ^^

Filters entirely depend on budget. I would consider an Antlia 3nm set to be on the expensive side, but if you have the funds, they are a heck of a deal compared to the other 3nm options. There is also the Antlia 4.5nm set for considerably less and the performance should be pretty close and may actually be better at f/4 and below. Antlia actually make a separate high speed set of the 3nm for scopes below f/3.6. I have the budget option, I bought a set of used ZWO LRGBSHO 31mm 7nm and a set of used ZWO SHO 36mm 7nm. They work surprisingly well for a "budget" option. The Oiii has a touch of halo but nothing compared to some other filters I've used. Antlia also has a 7nm set for a very reasonable price (less than half the 3nm price).

I have compared some images made with 3nm filters vs the 7nm and there is a noticeable improvement in contrast but $200 for my used set of SHO 36mm vs $930 for a set of Antlia 3nm SHO.

My two cent is not to save too much money on filters. I happened to have reflections issues with a mid-priced dual narrowband (I shoot with an OSC), that disappeared when I adopted an Antlia ALP-T. You would regret chosing cheap filters in the future. 2nd hand is an excellent option, but I never found the right place in Europe, surely there are some.
If you go for a mono camera, you would need a set of broadband filters, that is R+G+B+ optionally Luminance and a different set of narrowband filters Sii + Ha + Oiii. Do not go for Hb filters that are in my opinion useless, as they gather a weaker signal from the same source as Ha.

To summarize, in the case of monochromatic solution, you should need
- a mono APS-C camera
- 7 filters (2" framed or unframed 36mm) LRGB + SHO
- a 7 position 2" filter wheel compatible with the camera
- a focuser motor
- an automation SW to control filter change. I use NINA, that is free (!) and is in my opinion complete and reliable.
Go to a shop that can offer you support, in order to be sure you are fine with the backfocus distance and all the details.

With NINA you can program a flip when you approach the meridian. Better to trigger it 20 to 30 minutes past the meridian.
For the narrowband filters, 5nm are enough. Buy S,H,O of the same brand and bandwidth to have the parfocal and star size balanced, respectively.

With NINA you can program a flip when you approach the meridian. Better to trigger it 20 to 30 minutes past the meridian.
For the narrowband filters, 5nm are enough. Buy S,H,O of the same brand and bandwidth to have the parfocal and star size balanced, respectively.

I have tried that but as soon as I get near the meridian flip (before) my mount would stop tracking and so no more plate solve ruining all the remaining hours of night time. The problem is if I perform the flip before I can't track on the west side and if I flip after the meridian I can't track on the est side... I think the only solution would be as @andrea tasselli mentioned adding some magnetic weights (which I really don't know how to find) to shift the tube up and modifying my mount limits... (In the hope that my cq350 35kg payload won't cry for that extra weight on the guiding as I consistently get 0.4" and below ^^)