AMcD

It turns out the people of TS were taught well. This 10-minute subframe suggests that 88mm (plus 1mm to account for the filter) seems about right. Now, if I can just solve the DEC backlash that is playing havoc with my guiding...

This is a single ten-minute sub with my QHY268M. On the face of it, it looks OK but zoom in and you see the stars are egg shaped with the same orientation across the entire field. It turns out that one of the cables to the DEC park sensor on the mount was snagging and pulling against the mount. Bad cable management has been but one aspect of the comedy of errors I have committed in setting up this new camera 😟

Hold the phone! I have just found this on the TS website: Connecting a camera to the TSFLAT 2,5: For best results, a correct distance to the camera sensor is necessary. This distance is measured from the female M69 thread of the corrector. The thread itself does not count. ♦ Focal length up to 500 mm ... 106 mm ♦ Focal length 510-600 mm ... 101 mm ♦ Focal length 610-700 mm ... 96 mm ♦ Focal length 710-800 mm ... 91 mm ♦ Focal length 810-950 mm ... 88 mm I could have sworn I read somewhere that for the f5.9 TS 152 the correct back focus was 106mm. But the TS152 has a 900mm focal length, which the table equates to a back focus of 88mm. I'll get my coat 😂

It is certainly a learning curve! But what I love about this hobby is the willingness of its adherents to give their time and help to others. I want to get full SHO filters eventually but will stick with HaLRGB for now (or at least until my bank balance recovers!) I am still having trouble dialing in the back-focus. Having been plainly in error in using the generic 55mm figure without regard to the requirements of my field flattener, I went to 106mm per the TS recommended back focus for the flattener. However, I now appear to be too far from the first optical element having regard to the star pattern, although I only managed 15 minutes between the clouds: So, I guess that back-focus is somewhere between the 55mm I incorrectly commenced with and the 106mm that TS says it is, and which worked with the QHY8. I will just have to achieve it by trial and error - unless @vlaiv knows some Ninga maths for this 😂

Many thanks, I will add in 1mm to account for the filter as the 2" Antlia 3nm Ha is 3mm thick I believe. There is a lot to learn with mono imaging. Looking at your images I realised I had left the OSC settings on in DSS, so was producing an RGB Tiff file 😳. Now corrected...

Well, here is first light on the QHY268M with the Antlia 3n Ha filter. I managed 1 hour of 360s integrations under high cloud, before the clouds moved in completely. I have stacked it in DSS with dark frames and stretched the result in PS. Compared to the QHY8 I am blown away 😃. I used the 5m USB3.0 cable last night but the 3m Lindy Chromo USB3.0 cable is coming today. It is clear from the stars in the corners that my back-focus is off considerably. I have set the back-focus to 55mm per the QHY recommendation. However, the information for my TS 2.5” Field Flattener states as follows: “The 2.5" flattener offers generous back focus: Like the smaller 2" version, we have designed this flattener with a long back focus distance. So it is not a problem to add Off-Axis-Guiders, filter wheels etc. The recommended distance between the flattener's M69 thread and the focal plane is 91.5 mm for lenses with f/7 and slower. For f/6, we recommend a distance of 106 mm. For f/5.5, we recommend a distance of 111 mm” Within this context, I note the following extract from the OPT guide to setting back-focus: “My Camera Says I Need 55mm Back Focus. Is This Correct? Let’s get one thing out of the way: back focus is a property of optics, not cameras. That being said, 55mm is an industry-standard length of back focus for many optical correctors and focal reducers. So, while 55mm is usually correct for most setups, we always recommend double checking the manuals and diagrams for your corrector/reducer or telescope (if it has a corrector built in) to be sure. These can usually be found on the manufacturer's product page. If it's not listed, contact the manufacturer.” Having regard to the above, with the field flattener I had the back-focus for my QHY8 set at 106mm for my f5.9 TS152 and had round stars to the edges. I am wondering whether I should do the same for the QHY268M? Many thanks again for all your assistance @Rob_Jn, @Richard_, @teoria_del_big_bang and @Starflyer

Thanks @Starflyer I have this afternoon unbundled the USB3.0 cable from the power cables to eradicate noise / interference. The image misalignment remained. I then checked each of the USB connections for looseness and contact problems. It would appear increasingly likely that the culprit is the patch panel USB3.0 connector where the USB cable enters the server cabinet, and another short cable goes then from the connector to the computer. The patch panel connector connection was very loose. If I bypass the patch panel connector by plugging the cable from the PPBA directly into the computer I get consistently good data transmission from the camera and I get this even over the 5-meter long USB3.0 cable. This suggests to me it was the patch panel connector that is in fact the culprit. I will try for first light tonight and if that goes well will forego the voltmeter. Thanks again for your kind assistance.

Many thanks Steve. I think the problem is almost certainly my USB3 cable from the PPBA to the computer. In particular, and looking at in the cold light of day, it is clear I have done two silly things. First, I bundled the USB cable with the power cable to the PBBA, which probably does not help. Second, having now looked at the USB3 cable during daylight I have remembered it is a high speed USB3 cable but one that is 5 metres long! This caused no issues with the QHY8 but I strongly suspect the drop off in speed inevitably caused by a 5m long cable is far more significant for the QHY268M. I need some slack in the cable to avoid it cable snagging but God knows why I thought I needed a 5m cable when the server cabinet is only a metre from the mount 😳. The fact I have had to partly coil it because it is so long probably makes matters worse. Anyway, I have a ordered a 3m Lindy Chromo USB3 cable and I will see if that solves the issue. It will give me the slack I need, will not have to be coiled and is within the tolerance limit for USB3. It is coming tomorrow - by which time the clouds will no doubt be back! Thanks again to everyone for the advice and assistance.

Many thanks Richard. In light of the description of your set up, I suspect one of my issues might be that I run a long USB3 cable from my PBA to my server cabinet in the observatory. It never caused a problem with the QHY8, but it may be that the firmware / increased data with the QHY268M is too much for it. I have just done a quick test with the camera attached to the computer directly and it worked perfectly, including no buggy temperature readings. I will continue to test tomorrow to see if I can bring the PBA back into the picture. At least I know I do not have to send the camera back! Many thanks for your extremely helpful advice. A

Many thanks @Rob_Jn. I have just finished trying it with a direct connection to the computer and it works fine! Should have tried that before posting 😃 It looks like the Pegasus PBA USB hub is corrupting the communication as I have plugged it into the PC with a relatively long USB3 cable. Many thanks for your help, I am most grateful.

P.S. Every now and then it spits out a frame without lines (albeit a tad dusty 🤭) so I don't think it is the camera...

Hi @teoria_del_big_bang, @Richard_, @tomato and others on this thread. My QHY268M arrived today with the CFW3 filter wheel. I have spent a somewhat frustrating day wrestling with the QHY drivers. I have in particular struggled to get SGPro to recognise the camera. I then had a problem with SGPro persistently crashing after failing to download frames and giving nonsense temperature readings for the camera. I have finally managed to get SGPro and the camera and filter wheel talking to each other consistently after multiple driver reinstallations. The temperature readings for the camera make sense and SGPro is downloading fames. The only difficulty is that the frames downloaded by SGPro look like this and variations of this (and in Nebulosity the frames are the same): SGPro: And Nebulosity: Any ideas? I wonder if it is a data transfer issue as my USB3 to the camera at present goes through my Pegasus PBA as the set-up is remote controlled. I have upped the USB Traffic setting in the driver window to 50 but this did not help. Any ideas grateful received. AMcD

Me too. I have spent the entire afternoon trying to get SGPro to work with my new QHY268M but it keeps crashing. It might be something I am doing of course, but I think I will have a go with NINA and if it works, I don't think I will look back!

Are you running the 4.2 version of SGP.? Since that update I have found SGP to be less than stable. Last night the autofocus failed because SGP would not calculate HFRs. This was cured by downloading a further update (4.2.0.903). However, I was still getting weird behaviours such as the 'Take One Frame' function getting stuck and taking frames continuously. The denouement was SGP crashing in the early hours, putting an end to the session. If you have not updated to 4.2.0.903 that might help eradicate the odd behaviours but, as I say, it does not seem to cure all.

After over ten years of faithful service, my venerable QHY8 is bowing out to make way for a QHY268M that arrived this morning. A clear night last night allowed me to use it for one last time with my TS152 achromat to add some data to my image of NGC6888. The image now comprises 9 hours of 300s integrations taken through an Optolong L-Extreme filter and guided with PHD2 on a Losmandy G11 under Bortle 5 skies. Looking forward to trying my hand at mono...

@Jannerland The motor assembly is pretty compact. I have marked the dimensions of the area occupied by the motor with mount and pinion on the photo below. The box with the electronics is likewise modest, with dimensions in cm of width 24, height 19 and depth 9. Hope this helps.

I’m with Nigella 😂

Indeed! I have always wanted to learn Python, but I suspect this old dog is too old to learn that new trick 😃

Just to say that the Talon etc. does require a degree of DIY in that it required me to adapt Talon system, rack etc. to my particular ROR observatory, which in turn required some re-engineering of the observatory rood before I installed it. It also requires building and wiring up the server cabinet / to all of the individual components of the system, mount, camera etc. in the observatory. I think in total it took me about two weeks of working every day to get it installed and up and running😃 This post records the process:

For my ROR observatory I have used the Talon roof system, integrated with the Lunatico Cloudwatcher AAG and the Lunatico Dragonfly relay box to ensure that the system responds to the weather and ensures the telescope is out of harms way when the roof closes. It has worked flawlessly so far and will sometimes open and close the roof multiple times during an imaging session if the night is one with only intermittent clear periods. The system also allows me to control the observatory online so it can be used from the house, or indeed anywhere in the world. The major drawback of this route however, is the cost. The Talon, Cloudwatcher and Dragonfly, together with the associated power transformers, cabling, ethernet hub, UPS power supplies (to allow the roof to close in the event of a powercut) and server cabinet were rather expensive. As was the Starlight Xpress All Sky Camera that allows remote confirmation of the imaging conditions. That said, it has allowed me to go from using my observatory perhaps four of five times a year to using it four of five times a month depending on the weather. Pictures of the set up below.

It would appear that the problem was something to do with the image I was working on. I restacked the integrations and re-processed the image, on which Starnet++ worked fine. I suspect I accidentally 'pushed a button' when processing the original image that led to Starnet giving the results it did.🙄

I have added a further four hours of integrations to this image. I have also tried processing each channel separately in PS, having watched a video on Astro Backyard about the technique. The image now comprises 9 hours of 300 second integrations taken with a QHY8 OSC and an Optolong L-Extreme filter through a TS152 achromat on a Losmandy G11 guided with PHD2. The image was acquired using SGPro, stacked in DSS and processed in PS. This version did not use the freestanding Starnet ++ GUI as, for some reason, it has decided to stop working on my 16bit TIF files and is now simply spitting out black images with artefacts 🙄

Thanks for the quick response Martin. Something very strange is going on. I am using Starnet ++ as a freestanding application to process 16bit TIF files produced in PS. It works on the small test TIF that comes with the Starnet ++ GUI download. It also works my older 16bit TIF files from earlier in the year. It suddenly refuses however, to work on 16 bit TIF files from yesterday! I have looked at these new 16bit TIF files and cannot see that I have done anything to them that I have not done to the older files on which Starnet works fine. Very weird...

Yesterday Starnet++ worked as expected, in the same way it has since I downloaded it. Today it produces only black images with vertical artefacts. 🤔 I have made no changes to my system between yesterday and today (although I shut the computer down last night and turned it on again this morning. Is anybody able to suggest what might be going on (on CN there is a suggestion that installing the NVIDIA CUDA package (the one that is meant to speed up Starnet significantly) solves the problem, but it does not seem to). Any assistance gratefully appreciated.

I have an eight hour layover at Miami International Airport on the way back from a work trip. It is a lovely clear night in Worcester so I have fired up the observatory from the airport lounge and am collecting integrations on NGC6888. I am sorry if this sounds a little like bragging (which I guess it is) but I (a) am quite proud it works and (b) cannot believe, when I think back 40 years to using a small Tasco refractor in the garden, that this is even possible.😊