StuartJPP

An awesome image Maurice....up there with your usual high standards....

I bought my MGen II off eBay a couple of years ago at an absolute bargain price but to be honest I have hardly used it. I did get it all working and it seemed to be pretty good on the times that I did try it out. I coupled up to the QHY miniGuideScope on my Avalon M-Zero mount. I did briefly have an LVI Camera Smart Guider 2, but just couldn't get on with it. Compared to the MGen II it was severely lacking, especially when it comes to focusing as there's no "live view" like there is in the MGen II. I bought both mainly so that I could go PC/Laptop free, but after getting a small Netbook and being able to run it for the entire night I have parked it for now. I do still intend on using it when I go on holiday to minimise the amount of things I need to carry so it will hopefully get some use in the future. But to be honest I have been spoilt with fast Polemaster polar alignment and plate solving that is not possible with just the MGen II. Also reviewing images and doing quick stacks in PixInsight and APT makes me quite reluctant to change my current setup....plus PHD2 is so much easier to fault find..... Of all the stand-alone guiders I found the MGen II to be well ahead of the rest (at a premium price).

Caused by a cosmic ray. See them often when stacking many subs and looking at what sigma clipping rejects.

I am happy with it, however compared to Olly's it looks like I need to keep at it for a few more outings 😁 Anyway, I was in Lincolnshire, ~4 miles outside of Horncastle. Milky way is visible but it isn't super dark there. Broadband LED street lighting. I do have a Unihedron SQM and it was reading roughly 20.87, temperature of about 18C. Whatever that equates to on the Bortle scale I'd have to investigate...hang on....Bortle 4...heading towards Bortle 3 according to Wikipedia.

Thanks guys...👍

Love it Olly, makes mine look quite pathetic in comparison....

It's been a long time coming...I have been absent from the DSO game for approximately 18 months due to various reasons (mostly weather!). So this bank holiday weekend looked ideal to dust the kit off and make sure that I can still get my equipment up and running. It wasn't ideal from a temperature point of view as it was a bit too warm, but have to take every opportunity as it comes along and if I didn't capture anything useful at least I could refresh my memory. I didn't have too much trouble getting all set up and then subsequently imaging, mostly due to the fact that all my kit is labelled and ready to go, all the cables are cut to the right length, all the accessories are ready to be attached and my imaging netbook is left well alone. I have no desire to change any kit so my setup is stable and ready to be used when the opportunity arises. Friday night was a bit of a waste as there was quite a bit of thin cloud about but last night was decent. The moon rose half way though my session but I was imaging away from it so it didn't have too much of an impact, though each sub was getting a bit brighter than the previous after a while. Guiding was good and I achieved well below 1" RMS, though not a very tricky target in that respect. Processing is a bit rubbish as I have forgotten so much in this time! Need to practice a bit more often. I have wanted to image the Ghost Nebula alongside the Iris ever since I saw it, but just never got the opportunity. Anyway, enough waffle. Baader modified Canon EOS 6D Canon 500mm f/4 L IS Lens @ f/4 Avalon Instruments M-Zero Mount 50x 5 minute subs @ ISO400 20x Bias 20x Flats No Darks APT for Data Acquisition + Dithering + Framing PHD2 for guiding Thanks for looking.... Iris and Ghost Nebulae (NGC7023 and VdB 141) by Stuart, on Flickr

Haven't had the opportunity to image for the past (circa) 18 months until tonight. Well (touch wood) things have gone quite smoothly and I am surprised how quick I managed to get things up and running again, despite the grey matter fading quickly. Hadn't even switched on my netbook since April but a fresh charge and everything is still there ready and waiting. Need to label a few cables as I was pondering which USB cable went into which slot, but other than that no real problems. Polar alignment was a doddle (DIY Polemaster), guiding (PHD2), goto (Stellariumscope), image acquisition (APT), dithering (PHD2 and APT) and plate solving (APT) all worked fine...first time. I do have all my bits in a single box so if the box isn't empty after setting up I know something isn't connected. I Lso don't update any software on the netbook except for critical updates every now and then. So the question is.....what has gone wrong that I haven't spotted yet 🤣😂

Yes, this is a working farm and you could say that the cows are free-range as the fences have been flattened years ago. As a consequence their range is very far, luckily not around on this particular night. Occasionally there's some horses in this field, there was the last time I went. All a bit unnerving for a city boy like me, they can be a bit daft these animals 🤪

It kind of amuses me that I am on the top of a cow pat filled hill at midnight taking a photo of a fairly spectacular noctilucent cloud display and probably 99.9% of the people in the houses captured are totally unaware of it. Taken on 11 July 2019 @ 23:25 Canon 5D Mark III Canon 70-200mm f/4 L IS @ f/4 and 70mm in portrait mode 5 Second Exposures @ ISO 100 6 Frame Panorama Stitched With Hugin. Noctilucent Clouds by Stuart, on Flickr Headingley Stadium can be seen on the horizon (the row of lights). Original file is here (10,018px × 3,448px): Thanks for looking.

The thing is that if you have a 24MP full frame sensor and a 24MP "crop" sensor there will be more pixels on the Horse and hence more detail (all else being equal). Making the sensor smaller without making the pixels smaller as well just gives you a smaller FOV with the same detail.

Noctilucent Clouds - 21 June 2019 @ 1am by Stuart, on Flickr Definitely not as good as previous attempts but will keep my eyes open. By the time I got to the top of the hill they had started to disperse, hung around for a while but the display faded. 21 June 2019 @ 1am (Morning of the 22nd) Canon 5D Mark III Canon 70-200mm f/4 L IS @ f/4 and 70mm in portrait mode 4 Second Exposures @ ISO 400 7 Frame Panorama Stitched With Hugin. Thanks for looking

Nicely captured....and a very nice display.

If your OAG and main camera are now rigidly mounted then I am sure your issue will disappear. I used to have similar star trailing with my refractor and it turned out to be flexure of the lens (OTA) foot. The flex was undetectable by feel/naked eye. My trailing would happen if I guided or not and was eventually eliminated by securing my OTA in a much more secure manner at both the front and back of the dovetail. Your flexing will still happen of course but the guiding using the OAG will correct for it. See this thread for animation showing the star trailing I used to have before the issue was solved. Hope your new setup works out for you and you are able to find the source of your problem.

Looks quite interesting to me. Although it appears quite pricey if it delivers on its promise I think it will be a very good option for people on the go. Things that appeal to me is that it can break down into component parts making airline travel much easier. You have the option of using it as a tracker (single arm) or goto (dual) which again helps immensely for travel. No need to guide is a major plus if the tracking accuracy claims are true. What would also interest me is current consumption, if it can run off a small 12V power bank for an evening, it is a major plus for me. The original AstroTrac consumed very little power. Not requiring a PC has its benefits, but I am so used to focusing, polar alignment and plate solving that I am not sure I could live without one....plus you can view the quality of the subs straight away and no touching the mount at all... Will have to see how it performs, a lot of nice features that ticks a lot of boxes for the portable imager.

This was in Caleta du Fuste...I can PM you the actual place I used.... Certainly not an ideal imaging site....but not too bad when you get away from the promenade lights.

Another from a recent frosty session:

According to the specifications it is only 57.6W/h, at least it claims to use LiFePO4 batteries. I use one of these: https://www.amazon.co.uk/20000mAh-Multi-Voltage-Portable-Notebooks-Compatible/dp/B00BUJCMUQ/ref=cm_cr_arp_d_product_top?ie=UTF8 Which is a similar size but is 74W/h but I don't need very high peaks of power with my kit.

Rather pathetic that. I could stomach the excessive cost but 4 months? Nations have risen and fallen in less time.

I use the QHY miniGuideScope and a QHY5L-II-M for my 500mm OTA/lens. I already had the QHY5L-II-M camera before getting the little scope but I really like the combo, small and rigid. What is nice about it is that I can use the combo with SharpCap for polar alignment. And since I have got the QHY5L-II-M camera I can also use a cheap 25mm CCTV lens and use PoleMaster software as well if I need to. The miniGuideScope only has a 130mm focal length but with the small 3.75um pixels of the QHY5L-II-M (same as your ASI) I think it would be suitable for way longer focal length than what I use it for. I don't think you can go too wrong with your choice. One slight flaw that I noticed with it is that if you focus too far out (i.e. unscrew the barrel) and then try to lock focus, you can damage the threads on the barrel with the grub screw so be careful. It isn't normal to screw focus out much so it shouldn't really be a problem.

I had a similar problem a while ago and it was caused by differential flexure. I was using a large and heavy Canon lens as an OTA and the supplied tripod foot is only attached at one point (the rear)...Once I braced it at both the front and the rear of the lens my problem went away. Now if I don't dither I can get well over 45 minute subs with no trailing (I only do 5 minute subs anyway). In my case it was the actual lens/OTA that was flexing...In your case it is probably the guide scope itself if your problem is indeed flexure. You could point the scope in the opposite side of the sky and see if the movement is still the same direction with gravity acting on your setup in a different way. Just remember that the flexure can be totally imperceptible to the naked eye...We are talking tiny, tiny movements.

I have got a Canon 1000D (Rebel XS) with a spare sensor that I have been meaning to mono modify but I realise that I just may not get around to it so may be putting it up for sale soon for cheap...it is currently astro modified (front filter intact).

Regarding those with AstroTracs... I have yet to try the PoleMaster/SharpCap on my AstroTrac...it is on my TODO list. I peaked at 180 seconds at 500mm focal length using the supplied, but well collimated, polar scope. I was unsure if it was tracking error or polar alignment error that was the limiting factor, I suspect PA error as well as flexure. Flexure from the tripod foot as it is only one point of contact and with my 500mm f/4 lens it definitely flexes ever so slightly and is the reason I now fix it at the front of the lens as well. The speed of tracking of the AstroTrac changes over time (tangent function) so if it isn't granular enough you could end up with oblong stars. I did once measure the stepper motor frequency of the AstroTrac and it did change every so often in discrete "steps". These comments are from my notes... 228.581Hz initial frequency 228.414Hz after about 3 minutes 228.08Hz after about 10 minutes 227.914 after about 12 minutes So it would be good to put this to rest and figure out what was limiting me to 180 second (reliable) subs at 500mm focal length.

If your OTA/sensor had 0.5 degrees of rotation/pointing error in relation to the Dec axis and you then flipped Dec by exactly 180 degrees, would the error now be 1 degree off? I'd suspect so. Now also take into account tilt of the OTA (cone type of misalignment), then it will probably do the same thing when flipped. In other words the error is 1/2 the value measured. It isn't an error after flipping it is a cumulative error from before and after flipping. The good thing is that this can be tested during the day quite easily. My brain doesn't work in 3D so I can be totally wrong.

Thousands of posts, really? The AstroTrac polar scope is far from ideal but it is still very useable after some minor tweaking...well the two that I own are and probably "millions" of others.