[ap-gto] Which Camera?

LKDodd <lkdodd@...>


I have a ZWO ASI6200C with ZWO off-axis guider. The off axis guider has some design deficiencies imo. The off axis mirror/guider housing is 1 unit and cannot be locked firmly into the body of the OAG and hence some flexure is possible. Despite tightening the lockscrew as much as I dare you can still move the guide camera sideways relative to the OAG body.

I also have a QHY600M with QHY filter wheel and QHY OAG. Quality of construction is better imo. The OAG is well designed.  The guide camera housing is built into the body of the OAG and the off axis mirror moves as a sub assembly in the body of the OAG.  Also the QHY has a helical focusser built in, where it's an option on the ZWO. Albeit the QHY is more expensive. 

Re camera differences , I like the fact that the power cable has a lock screw on the QHY, also I believe there are internal and chip grade differences in comparative cameras. I have found issues with the USB cables supplied with the QHY, had some strange download issues and had a sequence stopped for no reason on 2 occassions and camera disconnect with NINA. I replaced with aftermarket quality cables and have had no further issues.

I have attached my latest project QHY 600M , Astrodome filters, Tak 105FSQ. Needs more work only curves using masks to date. But you will no doubt be aware of many superb images taken with the QHY600M.

Regards Luke Dodd 

------ Original Message ------
From: "Kenneth Tan" <ktanhs@...>
To: main@ap-gto.groups.io
Cc: "main@ap-ug.groups.io" <main@ap-ug.groups.io>
Sent: Friday, 2 Jul, 2021 At 5:47 PM
Subject: Re: [ap-gto] Which Camera?

I have quite a few zwos . The 6200  is great . I would not get the 2400. The 2600 are ok.
Zwo Filter wheel design acceptable and convenient if you intend to use their system with the asi air pro. But not what i would say the best. A little rough around the edges in implementation. 
OAG best to avoid the zwo


On Fri, 2 Jul 2021 at 04:09, Roland Christen via groups.io <chris1011=aol.com@groups.io> wrote:
I've been looking long and hard at full frame mono CMOS cameras as a next purchase for our AP observatory. So the question is - which camera - QHY or ZWO?
Which has the better accessories such as filter wheel, off-axis guider etc...
Any and all thoughts welcome.



-----Original Message-----
From: Dale Ghent <daleg@...>
To: main@ap-ug.groups.io
Sent: Thu, Jul 1, 2021 12:44 pm
Subject: Re: [ap-ug] Questoin for Roland: Waited too long to buy 175TCC (discontinued) for my 175EDF....is QUADTCC is as good of a solution.


> On Jul 1, 2021, at 01:54, ROBERT WYNNE <robert-wynne@...> wrote:
> Based on what I've read on this and other venues I remain unconvinced in CMOS chip technology's ability to capture an equal amount of photons compared to an CCD, in focus and without tilt at the pixel well level with 0 or near 0 noise in reasonable time frames. I would not underestimate my desire to obtain the largest Sony CCD available if the notion caught my interest nor a CMOS chip if the advancement in CMOS quality presents itself in the next year which could easily exceed a 67 mm circle. Thus my push.

With all due respect, but none of this makes any sense.

Current CMOS sensors have QE in the high 80's, pushing 90%, and approach 1e- read noise in typical operating modes. 5, and even 3 minute long narrowband exposures at circa f/5 are normal... no more 15-20 minute exposures that can be ruined by a passing cloud or other interference.  On top of that, you don't need to endure the comparatively glacial readout speeds that CCDs have, which eats into total integration time when you sum up the 15-20 seconds it takes to pull each frame off a CCD camera.

You sentiments would have made more sense perhaps up to 2 years ago. But the current generation of CMOS sensors, namely the IMX533 (1", color), IMX571 (APS-C color+mono), IMX455 (FF, color+mono), and IMX411 (150mp medium format, mono), have performance characteristics that make choosing them over CCD almost a no-brainer. They also have such low dark current that chilling them below -10C is very firmly in the territory of diminishing returns, making these sensors more warm-climate friendly top operate.

I will say that there seems to be a lot of sentimental or emotional attachment to CCDs; perhaps more so now that stocks of them are running on fumes. There are *plenty* of compelling reasons to adopt modern tech, however.

Roland Christen