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About ACross

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  1. Happy to report that 18 months on and the rollers are continuing to work very well. They are a lot quieter than the nylon bushes too and I recommend having a go at it before your dome is assembled in its new home - it’s a long way up to the top of the dome.
  2. That is useful to note Tomato, on the size of van needed. One further small point to note from my own experience: the fully assembled dome top is fairly heavy (and difficult to move on your own). Try to keep it flat on its base lip whilst in the van and not propped on an edge. Mine was transported only 3 miles but propped up and the outer edge became fractured, despite the layers of blankets under it. Post some photos if you get chance to take some. Good luck!
  3. It will depending on how dismantled it is (and how much you want to dismantle on site). I only had to split the base in half to get it all onto an open, flat trailer and would have managed with a long wheel-base transit with the dome in to pieces. If you split the base and the dome into four I am sure you could get it all into a transit. As Tomatobro says above, take plenty of coverings - raid the airing cupboard.
  4. Yes, the pier is still available but due to its weight you should be able to collect from Suffolk. Edit: If you were wanting this before Christmas, I am around today but not available after that until 30th Dec.
  5. You are absolutely right. A few weeks ago I was getting so despondent, the whole lot nearly went onto AstroBuySell and my wife was starting to question my sanity. Then, while imaging this at the weekend, everything fell into place and it was thrilling to see it come together at the processing phase; very satisfying and reminded me why I get into astronomy in the first place. Thank you to everyone for their help and comments. Wishing you all clear, calm, dark nights and a Merry Christmas.
  6. Aha, success! With the very helpful advice on here I took the whole lot apart and started again. Starting with the scope collimation, re-positioning the coma corrector, cleaning sensor, cover, filters and corrector. After re-assembly and a lot of cloudy nights, I finally managed to get a good go at this last night and the results are so much better. I have almost eliminated false dark marks and those that remained were removed by the flats. This is my first attempt at processing with Pixinsight and although it is not perfect, I am very pleased with it.
  7. Hi David. Well I had a good look at the whole imaging train and also found a M42 male to male connector in the box of the filter wheel. This means that I can now fit MPCC directly to the filter wheel, the M42 connector and then the camera, giving me 54.5mm from the MPCC flange to the sensor. Excited to try this out if only the weather would clear!! Thanks for your help with this aspect, it has been a troubling point for some time.
  8. Well I have just had a good look into the sensor chamber with a strong light and a magnifying glass. There were dust motes on the outer surface of the glass and after blowing these away I could see a tiny speck on the sensor and another on the inside of the glass. Nothing for it but to open the chamber. Inside there are four desiccant tablets and it could be that the small specks came from those. After some careful use of the air pump (the tablets are very light) and reassembly it looks like I have eliminated most of the marks; certainly the prominent ones at least although there is a small one remaining in the middle of the image. Now I must wait for some dry weather to have another go at imaging and producing a new set of calibration files but I am much more optimistic, especially after Gavins efforts which confirmed I wasn’t doing everything wrong. Cheers, Anthony
  9. I have a steel pier for sale. This was purchased along with a pulsar dome and believe it is an older Pulsar model. The pier sat in a yard, exposed to the elements for a few years before I purchased it so there is some surface rust and flaking paint but will clean up nicely. £250 and buyer will need to collect from Suffolk.
  10. Thank you Gavin, that is actually very encouraging; this is my first foray into "proper" LRGB imaging, first use of SGPro, first use of Pixinsight and one of the first uses of my re-configured observatory too. If we are both getting similar results that shows me my processing and basic understanding is good and that the problem lies somewhere physically in the system. I have not yet had chance to take a detailed look at the camera but having done some elimination work I am certain that it is an issue with the camera, either on the surface of the glass or inside the sensor chamber - this would explain the droplet look to the small mark at the lower edge. If the rain eases up a bit I will bring the camera in and have a good close look at it. I remain baffled as to why the flats do not resemble the defects in the lights but the ultimate answer has to be to remove the defects in the first instance, before capturing anything and this has to be my focus (pun intended). I appreciate all the comments and assistance posted in response, thank you. Anthony
  11. Thanks @Demonperformer Yes, have setpoint cooling and normally keep this at -15. Do you update the masters at all? I guess over time there may be changes in the sensor such as dead pixels?
  12. @tomato Good point about the usb speed, I am not sure if I checked this and will have a look at the settings. The capture was done in SGPro and I think that the speed is setup in the equipment profile and this was used for both light and flat capture; worth checking again though.
  13. Hi David Your comment is extremely helpful as this is something I have struggled with a lot. Yes it is the MPCC, purchased nearly four years ago for my first VX8 on the advice of Orion Optics but could not understand where to fit it. Unfortunately not long after I had an accident and replaced the scope and mount as part of an insurance claim. The second VX8 was purpose made (upgraded to 1/12 pv) and colimation seemed much better so stars were more round but still not ideal so I dug out the corrector again. I read about the 55mm spacing but it was not clear whether this was from the sensor surface, the glass front, flange or what. I took it to be 55mm from lens to sensor and then guessed as to how it should fit. I am going outside to have a look at this and see if I have enough bits to make it work as you suggest. Cheers, Anthony
  14. Hi Gavin. Rather sheepishly yes, took 20x darks for each filter and also took 50x bias for each filter too! Thought it might have been overkill but dont think it did any harm other than using up a chunk of my NAS drive space. Is it ok to have a master bias and dark and how often should it be updated? As regards flats, I had seen a Pixinsight tutorial which talked about a master or universal flat but was not entirely convinced; your comment is heeded, flats each time. Your comment on exposure of the flats is encouraing, I had read about ADU and didnt understand it but selected an exposure that showed the peak approximately in the middle of the histogram. I will have a closer look at this before the next attempt. I appreciate your offer to have a go at the processing and have copied the original capture data into Dropbox but caution that the folder is almost 1.4Gb. It can be access by this link: https://www.dropbox.com/sh/l6cydc3lirz083i/AAADMKS3AziIdqMUvIG9DChua?dl=0 Cheers, Anthony
  15. Thank you for your replies. After posting I realised I had missed some detail out so to fill in and answer a few questions posed. Firstly as to LRGB, I took 20x each for darks and lights and 50x each for bias. I knew this was overkill but the Pixinsight BatchPreprocessing script didn’t bat an eyelid and produces me a set of master calibration files (this was the first time I had used PI). I have a permanent setup so the scope was left in place while the darks were taken, immediately after the lights using the same SGP sequence but with the end caps on and lights (and pc monitor) off. @PhotoGav & @tomatoThe flats were done the following day with absolutely nothing moved, including focus. I set up a lamp and diffuser and took the flats using the same camera temperature of -15 but the ambient would have been higher, not sure if this is enough to have made a difference. Now here’s something: the exposure of the flats was only 40ms due to the amount of light from the lamp, could that be it? Should I be trying to get the light down to a level where 30s exposure is not blown out to white? After taking the flats I figured I had nothing much to lose and so experimented to find the source of the doughnuts. Image train is as follows: Into the 2” eyepiece I have a new filter wheel (and new filters). Connected to this is a Baader coma corrector that is screwed onto the front of the camera. Firstly, altering the focus did not alter the doughnut shape in any way. Nor did changing the filters or rotating the camera&wheel. With everything attached I then slightly unscrewed the camera from the corrector and still no change or rotation; this tells me the dust is on the camera. There is a glass screen over the sealed sensor although I cannot see anything on it I am hoping the debris is only on the outside as I do not relish the idea of opening up the sensor to the air. Agreed that it is better to clean the imaging train and not have to correct for these and I like you suggestion @david_taurus83 of the light pollution filter, this could attach to the thread at the end of the focus tube and seal the whole thing. I am still puzzled as to the difference, as you say @Demonperformer the doughnuts do correspond in location and intensity to the marks in the lights but I am baffled as to why they are a different shape. In tapping this reply out I am beginning to think it is connected to the exposure and perhaps I should try exposing flats with a much lower light level and aim to get nearer to 30s exposure, perhaps a single LED And a couple of diffusion sheets. I would be interested to hear how others do this and what exposures. Than you all for your comments. Will be spending some time today cleaning up the camera as this is the ultimate answer. Anthony
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