AMcD

Many thanks Louis, I am most grateful for the advice.

Is anyone using one of the older versions of these with the Crayford 2.5" focuser? If so, are you able to assist with the precise nature of and the size of the OTA to focuser adapter? The new rack and pinion versions are described on the TS website as M109x1 female, M95x1 female, but mine does not look like a screw fit adapter. Instead, it appears held on with three small grub screws. I can take it off to see the precise nature of the fixing and measure its size but thought I would ask before I get the tools out 😂 Thinking of upgrading to a TS 2.5" or 3" rack and pinion focuser as the Crayford is struggling with the QHY268M and filter wheel. Lost a moonless night of remote imaging last night due to slippage (one of the drawbacks of remote operation is not being able to pop down the bottom of the garden when things go sideways 🙄). Many thanks.

This is my first attempt at an HaRGB image. It comprises 9.5hrs of 360s integrations in Ha, 4hrs of 120s integrations in red, 4hrs of 120s integrations in green and 2hrs of 120s integrations in blue of the Cygnus Wall in NGC7000. A total of 19.5hrs. It was taken with a QHY268M on a TS152 achromat mounted on a Losmandy G11. Acquired using SGP, stacked in DSS and processed in PI and PS. After 20 years with a OSC camera, I am finding the learning curve in mono imaging and processing very, very steep indeed. There is more wrong with this image than right, but it's a start I think...

I attended an event at the Royal Society tonight for work. During the reception prior to the event I spotted this. It is an objective lens by Huygens, presented to the Society in 1691. The label says the lens results in a focal length of 122 feet. Too big for my observatory.

The sense of depth created by the dust against the background is stunning. Amazing work.

Whilst not an exact analogy, I had a similar experience recently when I upgraded the worms and motors on my Losmandy G11. The guiding became much worse for a period before settling down to being better than previously. I think the brand-new parts just needed to break in a bit. In particular, for a while I had significantly increased DEC backlash. Your DEC backlash results do appear similar to the ones I was initially getting, and I believe do show some DEC backlash. I found that if I nudged the DEC axis north to clear the backlash before using the Guiding Assistant, I got a more accurate picture from the Assistant as to what adjustments would assist. You may well already have seen them, but the PHD2 Good Practice guide is very helpful for trouble shooting, as is the Analyzing PHD Guide Logs document. I have attached both in .PDF format in case you do not have them. If all else fails, you can upload your guide logs to the PHD2 Forum at Open PHD Guiding - Google Groups (having followed the steps for making a baseline guiding log in accordance with the third and final document I have attached) where expert advice is available on what steps will assist. Apologies if I am teaching my proverbial grandmother to suck eggs.🙂 PHD2_BestPractices.pdfAnalyzing_PHD2_Guide_Logs.pdfHow to create a baseline for guiding results using OpenPHD2.pdf

I use the 2" Antlia 3nm Ha and am looking to get the Antlia 3nm OIII and SII when I can afford them. I am very pleased with the Antlia Ha filter. The Antlias are still very expensive, at least from my perspective, but they seem to strike a good balance between quality and price in the crazy world of narrowband filters. For RGB I use Baader 2" CMOS optimised filters. Again, I am pretty happy with these (although I strongly suspect the "CMOS optimised" thing is a gimmick).

Great image. I am intrigued as to where the phrase “greased watermelon in a pool” comes from 😂

Beautiful images. I too prefer the second (previous) image. It looks very skilfully processed to me and not at all ‘overboard’. I have just started with the QHY268M. You will love it!

I think it will be useful during periods of very high humidity. I ran the camera tonight at -5C over a period during which the AAG Cloudwatcher recorded a rise in humidity from 60% to 72% and there was no sign of condensation. I would have continued the experiment and waited for the humidity to hits its forecast of 94% later, but I really need to get some sleep tonight😂 The humidity last night touched 98% according to the Cloudwatcher and 100% according to the PPBA environmental sensor and, as you noted, I had the camera cooled far more than is necessary. As such, I suspect if the risk of condensation on the outside of the sensor window is at its greatest at very high humidity readings and that an argon purged imaging train may assist in those situations, if reducing the cooling target does not eliminate the issue completely.

P.S. The condensation was definitely on the outside of the window, as I was able to blow it away and dry the window with a bulb blower.

It was! Bloody button batteries and grub screws. The focuser tensioner on the TS152 is a giant grub screw and the battery holder in the Gemini I is not user friendly. Always fun to fiddle with those in the poor lighting of my observatory. Many thanks as always to you and @teoria_del_big_bang for your sage advice regarding -5C. I will try that. It is not a big issue to re-do the darks given the number of cloudy nights forecast for the next week 😳 If the issue remains, I can add in a dew heater on the imaging train and I will look to purging the area in front of the CMOS window / in the filter wheel body with argon, which is a method I see was mentioned on Cloudy Nights for this issue and that also seems to have worked. Thanks again.

@teoria_del_big_bangThanks Steve. Will the desiccant tube make a difference when the condensation is on the outside of the CMOS window rather than the inside? I think the CMOS chamber is OK. I believe it is the area in front of the CMOS window / in the filter wheel body where there are high levels of humidity, causing condensation to condense on the front of the CMOS window. I will also check the position inside the chamber with EZCap.

I had one of those astrophotography nights last night that seems to be an endless exercise in problem solving. First, the battery in my Gemini I was low, causing strange slewing behaviour, and had to be replaced. Second, as the autumn temperatures decrease the focuser tensioner on the TS152 became looser, causing slippage when pointed at the Zenith, and had to be tightened. Finally, following the heavy rain, and with humidity at 98%, it would appear that the heater for the window in front of the CMOS chip on the QHY268M was overwhelmed, as condensation formed on the outside of the window (presumably once the temperature gradient between the inside and outside of the window became too acute) ruining my red frames... I suspect this may be consistent issue for me as the camera / filter wheel are kept permanently in the observatory, which is dry but unheated; at least when there are very high levels of humidity and I attempt to go for a low CMOS temperature (last night -20C). Does the dew strap solution work consistently @Richard_? I also wondered about purging the filter wheel and remainder of the imaging train in front of the CMOS window with argon. I have also read that keeping the camera temperature at parity with the ambient temperature resolves the issue but, of course, at the price of increased noise.

I am no physicist, but I suspect it all depends on what is the most efficient means of transferring energy from the method used to deflect the asteroid to the asteroid itself. I suspect, but don't know for certain, that with a small body impacting the asteroid you get a very efficient energy transfer which can be targeted at the point of impact most likely to result in that transfer of energy altering the orbit in the required manner. I think it would be more difficult to achieve these twin goals with a nuclear warhead detonated at a distance. Then again, it is now some 36 years since I failed my physics GCSE. 😂

Dr Becky is pretty good on that question 😀

The G11 does have PEC. I have always wondered whether the PEC would compete with PHD2 but I can see how they might in fact complement each other. I will give it a go 😀

I am slowly progressing with dialing in the QHY268M, with the inestimable help of @Richard_, @ollypenrice, @teoria_del_big_bang, @Starflyer and others, to whom I am very grateful. Last night I managed to get some further data at shorter exposure lengths as part of a test to see if I can address an issue with my star shapes. This image now represents 9hrs and 50minutes (4 hours 10 mins of 600s frames and 5 hours 40mins of 360 frames) taken through an Antlia 3nm h-alpha filter on a TS 152 achromatic refractor mounted on a Losmandy G11. The data was captured with SGPro guided with PHD2, stacked in DSS and processed using PS and Starnet. I am particularly pleased that the camera has managed to split the two stars of what I believe is ES 1451 on the shoulder of the wall. I am hoping to get some RGB over the next few clear nights (whenever that maybe) and try my first HaRGB image. TIFF: NGC7000_9hrs_50mins_H-Alpha_268M.tif

Spooky - I am doing that very test as we speak! I still see some "eggyness" at 360s, albeit it is less pronounced than at 600s. Strangely, the scope has just done a meridian flip and the stars look slightly better with the scope on the east side of the mount than they did on the west. I no longer seem to be getting the more peculiar features of 'doubling up' and 'kidney beans'. I re-cabled the set up today so that the collected cables now drop from the top of the counterweight bar per @ollypenrice's advice. I also checked thoroughly again for loose fittings and other potential points of flexure. I think it is coming down to an issue of either guiding or flexure or both. The G11s can be difficult to 'dial in' when it comes to guiding and I have recently upgraded the worm blocks and motors. I reseated the worms today, but I am going to send my logs to the PHD2 forum tomorrow. The last time I had an issue, Brian Valente was able to give me a solution. With respect to flexure, I have been looking at solutions today for mounting the guide scope with clamps rather than scope rings and attaching it to the side of the dovetail plate rather than on a plate on top of the main scope rings. The guide scope rings are tight, but I never fully trust them. I am also considering off-axis guiding but I understand that can have its challenges as well. I will solve it eventually... 😂

Thanks Olly, that means a great deal coming from you. The data is a joy to process.

Many thanks Olly, excellent tip. I feel a re-cabling day coming on for Saturday...

Many thanks. I think the focus is OK on the full frame subs. I was using autofocus in SGPro, which is generally pretty accurate. In addition to the steps I set out above, I will do a thorough check of the guide scope fixings and focuser with respect to possible flexure.

Many thanks to everyone for your advice and suggestions. I really am most grateful. Olly, the Guiding Assistant in PHD2 indicated last night that I had a very significant problem with DEC backlash and having checked the play in the RA axis, it feels greater than it did when I last adjusted it. I have recently installed Losmandy one piece worm blocks on my G11, which make adjusting the worms much easier. I will look to see whether I can better seat the worms as a first port of call and then will try your tips. Whilst I dealt last night with an obvious cable snag before taking the images above, I think I am going to have to consider the cabling again. My set up is remotely operated and I run all the cabling on the scope to a Pegasus PBA. From that I run a pretty heavy USB3.0 cable and a 12 volt power cable. The cables from the park sensors on the mount also drop to the floor. At present, they are fixed at one point to the scope ring and then drop straight to the floor. The wires are however, quite heavy between them and might be pulling on the scope. I suspect it will be better for me to have two drops, the first to the top of the pier, with sufficient play to allow the scope to move fully in RA and DEC, and only then a drop to the floor. I suspect my old QHY8 allowed any number of quiet issues with respect to backlash, flexure and cabling issues to pass unnoticed. It may be the QHY268M is revealing a multitude of sins 😀 Many thanks again to all.

Last night I managed to get my first extended run with the new QHY268M. This image represents 4 hours 10 minutes of 600s integrations taken with a TS152 achromat through an Antlia 3n h-alpha filter under Bortle 5 skies with some passing high cloud. Stacked with darks in DSS and process in PS. The stars leave a great deal to be desired as I am having peculiar issues with my mount/guiding, about which I have posted separately (and any ideas gratefully received):

Yesterday evening I did a four-hour imaging run with my new QHY268M. The initial frames were not successful due to a cable snag, which I eradicated. Guiding was also initially an issue due to DEC backlash, but I addressed that also. However, the images below represent the beginning, middle and end of the run. I am almost certain there were no more cable snags and guiding was around RMS 0.60 for the session. Notwithstanding that, the stars seemed to move from round(ish), to 'doubled' to 'kidney bean' shaped over the imaging run. Does anyone have any ideas on a possible cause. I am wondering whether this is flexure at the focuser as my QHY268M and filter wheel is considerably heavier that my QHY8. However, the frame with the doubled stars perhaps does suggest a cable snag that came free during the exposure.