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About woodblock

  • Rank
    Star Forming

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  • Interests
    Painting, Printmaking, Astronomy, Growing Vegetables and Fruit
  • Location
    Shropshire UK
  1. I've used both Registax and Autostakkert for stacking pictures of the surface of the moon with some success. I wondered what criterion they use when you ask them to select the alignment points. Almost always you can see that many of the points appear to have no discernible feature. I would have expected that they would select points where there's a distinct gradient. First of all why would they pick points like that and secondly how can it align points on two separate images when there is no feature there to align to - if you see what I mean? Cheers Steve
  2. I understand the principle of PEC but I'm a bit hazy on some of the details. I've recorded a PEC profile using EQMOD. The output txt file has three columns - time, motor and smoothed PEC. What do the numbers in the smoothed PEC column actually represent? What units do they have and how are the numbers actually used when PEC is active? Cheers Steve
  3. Thanks, it seemed a bit odd. I've got a skywatcher scope and I've bought various other bit of skywatcher stuff, eyepieces and barlows and so on but they all just said 'skywatcher'. The one I was looking at was in Rother Valley Optics and I wondered why that particular item was identified with OVL. Does all Skywatcher kit come into the UK through OVL?
  4. I was looking for a x3 Barlow and came across some called OVL which I think means Optical Vision Ltd but they were also described as Skywatcher barlows. Is OVL a part of Skywatcher? What's the story there?
  5. You can do it with EQMOD. I just got a game console to make it easier to manually guide and I tried last night. You just call up the PEC facility on EQMOD, click on record and guide on a star. You have to do it for quite a while depending on how many cycles you are recording but it is quite doable. Steve
  6. I suddenly realised last night that a newtonian on a equatorial mount like mine is a perfect system for oscillation. A light weight tube with a heavy mirror at one end and a heavy DSLR and finder at the other, pivoted in the middle. It's a classic oscillator. Steve
  7. I've got the HEQ5 with a SW200PDS. Although it's well within the specified maximum payload I would say it's at the limit for stability for astrophotography. I use it for that but it's a bit shakey. It's ok for visual use though. Cheers Steve
  8. Is there a way to record a pec curve while manually tracking and without using a guide scope? I use APT and EQMOD. Cheers Steve
  9. During the winter I got into the habit of switching on the dew heater on the secondary mirror of my Newt and it worked - no more problems with dew. A few days ago I was playing around with star collimation. I was actually using APT and then zooming in at x10 and it seemed to work except that I could see wavering heat trails coming from the secondary mirror. Last night I did it again without the dew heater on and the heat trails were not there. I have a controller but I'm only using one channel which I had wound right up which was obviously a mistake. In future I shall have to just turn it up a little and only use it when dew is a problem. I was taking pictures of the ring nebula using APT, just 30 second exposures. I have no guiding on the scope just normal tracking. I noticed as I stepped through the pictures I could see that the stars at the edge of the frame were creeping across frame by frame. Just a tiny amount. At first I thought it was due to poor tracking because of poor polar alignment but then I found that they started stepping across in the opposite direction so over a period they would drift across in one direction but then turn around and drift back the opposite way. I think this might be due to periodic error. I'm not sure if that's a symptom of PE but that's my next port-o-call. Cheers Steve
  10. APT has a collimation aid. According to the general descriptions about star collimation you have to use a high magnification. I was wondering if I'm using APT and I use the x10 zoom feature is that the same as using a high magnification through an eyepiece? I'm not quite sure how you'd calculate the equivalent magnification with a 1000mm focal length telescope and a canon 450d at prime focus. If that was equivalent to say x20 and I use the x10 zoom then I suppose that would give me an overall magnification of 200 which is what's suggested for this kind of collimation but is that the same as having x200 through an eyepiece? Cheers Steve
  11. I'm just getting to grips with APT which is a great piece of software but I have a few of questions. I have a SW200PDS and a canon 450d. 1. In the tools there is a thing called DARV. I thought great, an easy way to do drift alignment with polar alignment. I tried it but all I got was a straight line. I'd done the polar alignment the usual way and then deliberately adjusted it out. So I was expecting to see a V shape. When I looked closely at the line I realised that it was slightly thicker one end than the other so it was a very narrow V shape. I came to the conclusion that it was probably because there wasn't enough magnification. I put a x2 barlow in and tried again but the result wasn't much different. I tried different exposure times but still no luck. Has anyone got any tips for using this tool? 2. I use Live view a lot which I'm sure everyone does. But it only shows up the bright stars. I tried playing around with the controls under the histogram tool including autostretch but all I got was a huge amount of fuzzy noise like an untuned TV. Any help on that would be great. 3. Also with live view. I wanted to use the x5 zoom but all I got was the untuned TV again. 4. I was trying to find the settings for live view but all I could find under tools/apt settings was the number of stacked images. I thought I'd seen reference to an exposure time on one youtube video but I couldn't find the setting. Cheers Steve
  12. I used to have a 14 inch SW dob and I often used it with their 7mm UWA eyepiece. That would give me a magnification of 235 which I found very comfortable when looking at the moon or Jupiter. I'm 68 and my eyes are not brilliant and I found the high magnification useful. Sometimes when you watched say Jupiter it would shimmy about with the atmosphere but every now and again there'd be a second or two of brilliant clarity, same with the moon. Just sit there and look. Cheers Steve
  13. Thanks John, I did read that before. It only says that it recommends you wait for at least one cycle before taking a photo. I assume that is to ensure that it passes the index mark at least once. One book I have says that some mounts do a PEC initialisation when you turn it on. I'm hoping to use the PEC built in to EQASCOM rather than the scope itself. Steve
  14. I have an HEQ5 mount. As far as I know it doesn't have an encoder on the RA axis so for the purpose of PEC I assume that it must have some kind of index mark. I haven't tried PEC yet I'm just looking into it. So when you turn on the mount and want to turn on PEC the mount has to see the index mark before it knows where the motor shaft is. So I wondered if it does some kind of initialisation where it rotates the RA axis until it sees the mark before kicking off PEC.
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