QHY600m lite review

[Peter Ward]

The run of fine weather in Sydney has given me several nights to test the new camera.
My earlier reservations have pretty much disappeared.

A very impressive camera by any measure.

Full review is here (http://www.atscope.com.au/BRO/tutorials/QHY600.html)

[Andy01]

An impressive beast indeed, thanks for the comprehensive and informative review Peter! :thumbsup:

[Peter Ward]

My pleasure. Also fixed the page formatting :doh: ...now readable on an ipad

[niharika]

Thank you Peter. Was an interesting and informative read. Is the included power cable long enough to route through the mount?

[Peter Ward]

The DC power cable is a two part plug and socket affair, and while long enough would likely come apart if you tried to pull it through a PMEII.

It's a simple two wire arrangement , hence making a longer section would be easy, but if you are going to that much trouble, you'd be better off wiring up a proper din aux power-in plug and saddle-out cable, which the PMEII's are pre wired for.

[gregmc]

An interesting read, thanks Peter.

I have the QHY600 PH (Amateur Photographic Version)

some comments:

I only use one USB3 cable to the camera. I also use the thin QHY interconnect cable between the camera and the QHYCFW3 filter wheel (which has 7 x 50mm filters)

I also live in Sydney and also had weather issues. I've only had an initial test run which showed some vignetting issues with my SkyWatcher ESPRIT 120ED that has an M48 out which I've improved with a new adapter that plugs into the M54 of the CFW3. (so also a delay organising an adapter and getting it made)

I did a test run Sat night (10/10/20 at Terrey Hills) and have not had a chance to process them yet (or build flats & darks) but something I've noticed is the need for a bigger 12V fuse (all my leads are independantly fused from the 12v LiFePO4 battery) and that it often (maybe always but too soon to know) does not power up if I power up USB and 12v at the same time (ie. plug the 12v bat with all stuff cabled up). I fix this by repowering the 12v plug on the back of the camera which is a bit annoying.

I also note that finding the latest drivers can be an issue as they tend to number the all in one system package differently to the stand alone drivers. I now only use the all in one pack (https://www.qhyccd.com/download.html). (stable WIN version)

The installation video (https://www.youtube.com/watch?v=I7tNxzahlWM) shows the same annoying task that I also have is having to find the firecapture directory. The video misses the other annoying task of skipping throug a dialoge box about sending an email (that does not work if you try it).

https://www.qhyccd.com/index.php?m=content&c=index&a=show&catid=94&id=55&cut=1 (FYI - QHYCCD 600 spec page)

[DavidTrap]

Thanks for the review Peter,

I like your suggestions about some plumbers tape around the camera fitting.

As for the filter wheel - agree, the supplied screws and washers are sub-par. I've got a set of Filter Centering Masks on the way from these guys - LINK (https://buckeyestargazer.net/Store/FilterMasks.php) They were recommended on a thread from Cloudy Nights - might solve your artifact problem as well.

DT

[Peter Ward]

It's comforting to hear I am not the only one struggling with QHY's documentation/distribution system.

I am not sure how you get away with one USB cable for both the Camera and auto-guider...are you not using the OAG?

In any event, I can see how a M48 adapter would cause vignetting. I'll likely ditch the QHY M54/2" nosepiece and simply go for a M54 to AP2.7" thread.

Interesting times ahead!

[Peter Ward]

Those filter masks are the bees knees! Will definitely order a set.

[DavidTrap]

Dunno if they work yet...

Shipping with USPS is a little uncertain at present...

DT

[gregmc]

They work fine. I have the 50mm ones in my QHYCFW3

[gregmc]

I have my QHY600M on a SkyWatcher 120ED ESPRIT refractor and don't use an OAG. I use an ASI120 on an EVOGUIDE 50ED as a guide scope.

The one cable is to the camera / filterwheel combination and one cable to the guide scope (and a USB cable is also needed for the focus setup)

Even with my earlier setup, I needed two USB cables. The ASI1600MM pro has USB3 in and 2 x USB2 out. One of those USB2 went to Filterwheel. I could not use the other USB2 for guiding as I needed USB3 for the ASI120mm on the guide scope.

[gregbradley]

Thanks for the review. I am interested in this camera also. Perhaps in a month.

I was considering the ZWO version but QHY have a few benefits with the Photographic version that seem like they would be worth it. ZWO may be more compatible with their software though. I use an ASI183mm in the Sky X with no troubles at all.

The Cloudy Night's forums for these cameras are a great source of data.

I would also use the camera at longer focal lengths and use 2x2 as with 60mp there are plenty of pixels left to create a high resolution image.

These sensors are also quite a bit more sensitive in narrowband than CCDs.

Greg.

[niharika]

Talking about documentation, I don't see any clear indication of whether the specified backfocus (17.5mm) is mechanical or optical(cover slip). How did you measure your back focus Peter? Will you be trying any different combination of gain settings and USB speed to see if noise for narrow band gets any better or not?

[DavidTrap]

Much to my surprise, the filter masks arrived today. After a bit of trimming around the lugs, they fit well. I wonder if the design of the filter wheel has changed since the manufacturer made his original design.

I also bought a set for a ZWO 31mm filter wheel and these fit perfectly, so I don't think it's a problem with the 3D printing.

DT

[Peter Ward]

Again, I am none the wiser due the lack of clarity in the QHY documentation, but looking at the CAD diagram, then 17.5mm looks to be the mechanical back focus distance.

I have tried a number of readout modes, but the high gain mode seemed to give the optimum result with NB filters. But my level of experience using the camera not extensive, hence as I try different filters, apertures and focal lengths, that may change.

[Camelopardalis]

The high gain mode in these modern sensors is almost win-win.

The dynamic range is only slightly crushed but the read noise is majorly crushed :D

While some worry about well depth, and I get that that's because of saturating stars too quickly with a fast scope, surely it's the dynamic range that counts?

Judging correct exposure length to keep it in the sweet spot is all the more important as a result.

[Martin Pugh]

Let me add a little bit to this.

both of my QHY600 cameras have had to be returned for one problem or another. According to my supplier, so many of these cameras have had to be returned that the backlog is significant. My OSC has now been away for 2 months and my mono camera even longer.

The ZWO6200 on the other hand has worked flawlessly out of the box.

Martin

[AnakChan]

Martin,

Can you please share what issues you had with the QHY600? I have the ASI6200MM and so far am ok with it although I've been following closely on microlensing & reflection issues. Whilst the thread started off as being ASI620MM specific, it's apparently a common problem across multiple CMOS/CCDs. Having said that, I've not seen any QHY600 samples exhibiting the microlensing/reflection issues.

Sean

[gregbradley]

That's a bit of a worry. What are the problems with the 2 cameras?

Greg.

[Peter Ward]

While I don't doubt Martin's experience, I've seen a few QHY600's now, with no QC issues. By the way I've updated the review with some more test data.

The only issue I am having with the camera is impatience: I'm waiting for some Precise Parts adapters to nail down squaring-on of the sensor.....I've decided compression fittings don't cut it. 60Mp shows even the slightest tilt.

But on the odd occasion when you do nail everything down perfectly with top-shelf optics in front, the amount of sky you cover using one of these puppies at the back end and with superb resolution to boot, is awesome.

[gregbradley]

I asked on Cloudy Nights if anyone had a problematic QHY600m. The responses were almost all that theirs was reliable with one that had some trouble.

One responder said make sure you have a 5 amp power supply separate for the cooler and a good USB3 cable as that can cause issues. I have read similar about the ASI6200mm about the need for an adequate power supply separate from other devices.

So it sounds like its not systemic.

61mp full frame does sound like a challenge to get square and all perfect. I saw posts about chromatic aberration showing up in FSQ images near the corners. The theory is that the 61mp small pixels are showing up aberrations not normally visible.

Greg.

[Camelopardalis]

Indeed, and this is to be expected with such a large chip with “small” pixels...with 9 micron pixels we were oblivious.

[Martin Pugh]

Earlier post edited following more clarification from QHY.

Hi.

thought I would add some more information that I gleaned over the weekend from Dr Qiu at QHY direct. As a relatively new CMOS user, I wasn't aware of this, and if you are reading the spec on the QHY website you may be misled.

So, bin 2x2, does not yield 18bit output as it states on the website. This is under development however, so if you use the on-chip binning function it outputs 12bit, so you need to do it through the driver which will then output 16bits. Of course, this is ONLY relevant to the mono camera. You cannot bin 2x2 the colour camera, hence you have to acquire data unbinned and do software binning thereafter. I have been toying with this over the weekend and I am yet to see any improvement in SNR. I find it quite interesting in the Maxim DL help file that after using the Bin 2x2 command, you should rescale the image by a factor of 4 in pixel math. Whereas in PI, you only have the option of average, median, min, max in IntegerResample, which outputs an identical ADU value to the unbinned image.

Martin