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rwg

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Everything posted by rwg

  1. I've been waiting for someone to build a sensor that does this *at the pixel level*. Just like we have microlenses and (for colour cameras) filters on each pixel now, imagine a camera where each pixel had a prism arrangement splitting the photons between 3 separate detection sites.... Once camera, one shot colour, no 66% loss of photons. It might seem far-fetched, but the sort of features built into camera pixels now were pretty far fetched only 15 or 20 years back. cheers, Robin
  2. My trick is to wrap Zinc Oxide tape round each part to be unscrewed - the coarse fabric surface of the tape gives you plenty of grip, even on a narrow spacer ring, then the tape peels off nicely. You can pick up the tape cheaply from any chemist or probably sports shop (as it is used for strapping sports injuries). cheers, Robin
  3. I had a quick word with the organisers to point out that they had neglected to mention the opening time on their web site The site has now been updated with the show times of 9am to 5pm. I also remember there being a good sized queue outside last time before 9am. Of course it makes sense to only hand out talk tickets on the day to avoid problems with people reserving tickets and then not showing up... Anyway, very much looking forward to it cheers, Robin
  4. I recorded the missing bit later and you can find it here
  5. Check out the troubleshooting guide https://www.sharpcap.co.uk/sharpcap/features/polar-alignment/polar-alignment-troubleshooting If that doesn't help then capture a couple of images by using the 'snapshot' button and share them with me and I will have a look to see if I can work out why they are not working. cheers, Robin PS. At the IAS show this weekend, so may be able to look in detail until after the weekend.
  6. @Atreta until yesterday there was a donation button on the SharpCap web site. I've removed that because with the release of 3.0 in the next week or two there will be a 'Pro' option available for those who wish to support SharpCap. cheers, Robin
  7. Hi @Atreta, you need to be able to see the region around the pole (north or south) for the polar alignment to be able to work. I have an idea for a version that will work without seeing the pole, but have had no time to even test out whether it works yet, so it's a far while off even if it does work. cheers, Robin
  8. The solve status for the most recent frame is there - in Stage 1 and Stage 3 it's to the right near the 'Next' button and in Stage 2 it's to the left (I think that was the only space for it in stage 2). The actual plate solving procedure is fairly quick (fraction of a second usually) as it works over such a limited area of sky. Actually the first solve can take a few seconds as it builds it's search index at that point, but subsequent ones are fast. Anyway, as soon as the exposure finishes the frame gets passed to the plate solver and only when that is done does it get displayed on screen - if you see only stars on a frame and no NCP circles then that means the frame has already failed to solve, not that it's waiting for the solver to run. cheers, Robin
  9. @frugal Are you using the 2.10 beta? That has improved star detection and more tweaks to it too - it seems to have fixed issues in 2.9 with faint stars not working well for a number of people, particularly with lodestar cameras which seem to have no gain control Set a digital gain of 2x if you have no camera gain control and see if that helps. With a camera gain control (QHY, ZWO, Altair, etc) I'd usually advise exposures in the 1-4s range and a high gain. cheers, Robin PS. Don't forget to use the trial license key with the latest versions of the beta to unlock the adjustment phase!
  10. Personally I've never tried PE correction and just relied on guiding. cheers, Robin
  11. Look at the PHD guide logs - if it's mostly RA corrections then it's almost certainly periodic error. Polar misalignment would show up as DEC drift being corrected. cheers, Robin
  12. Are you sure that isn't periodic error? Two reasons I suspect this - 1) the trails are stronger at each end, suggesting it's spending longer with the star near the end than with it in the middle of the trail - that doesn't fit with a PA problem which should be a straight line 2) The trails look like they are almost due E-W (see http://nova.astrometry.net/user_images/1569527#annotated ) so it looks like you are getting trailing in RA, not DEC. Again this doesn't fit with a polar alignment issue, but does with periodic drive error. cheers, Robin
  13. Ah, good point - I didn't think of the auto-upgrade path when putting the license on the download page. I *think* I put something in the release notes that you see when you install a new version of SharpCap, but very few people read those I suspect... cheers, Robin
  14. If you look on the beta download page there is a license that you can use with the beta for now. This will continue to be available and updated during the beta period. So yes, you can still use the features for the beta period, but we've got to the point that the license entry/checking code needed to be turned on to make sure it didn't have bugs in it! cheers, Robin
  15. PHD does a strong stretch on every frame before displaying it which can make it's brightness onscreen misleading. There is a way to turn this off somewhere in PHD, but can't recall where. cheers, Robin
  16. @al-alami Have you turned up the gain? That's usually necessary to see a decent selection of stars with 2-3 second exposures. cheers, Robin
  17. Other possible causes of error that I am aware of * Bad plate solve on either the first or second stage - this could throw out the whole process - I think this is very unlikely and haven't encountered a case yet * Atmospheric refraction - only significant below 30 degrees of latitude, probably not going to be a problem in NE Essex! I would advise that if you are having problems, then at the end of the PA process (once adjustment complete), spin the RA axis again and watch the screen - the stars in view should appear to move around the point marked as the NCP. If none of this helps, then I am (for now) baffled. It would be helpful to have an image captured (saved using the snapshot button in SharpCap, not a screen grab) for each orientation of the PA process and also if possible an estimate of the PA error from an independent measurement such as PHD drift alignment. cheers, Robin
  18. One case where there was a similar problem was tracked down to a mechanical problem causing the view to shift as the scope is rotated - this led to inaccurate results. The user's view of polaris as they rotated the mount was like this As you can see at a certain point in RA, something shifted which then ruins the calculation of where the telescope's axis is pointing. Another (unconfirmed so far) suspicion is that there may be flexure in some mounts due to weight distribution changes when moving the telescope from the pole pointing position used for alignment to a more ordinary position for imaging. This might be a particular problem if you are using a tripod on soft ground. cheers, Robin
  19. @Crose01 I think it ought to work - a side offset of a few inches (or feet for that matter) isn't going to make any difference as the stars are effectively infinitely far away... @spillage 2.10 (in beta) is better at picking up faint stars than 2.9, also there are tweaks to the star detection parameters that may help. Much more info here. cheers, Robin
  20. Hmm, once you have polar aligned with SharpCap, you have your mount axis well aligned with the pole. If you then set the correct orientation of the polar scope and then adjust the polar scope collimation to put Polaris in the circle I would have thought that you have then successfully aligned the polar scope correctly with the mount. Was that what you were thinking of? cheers, Robin
  21. @SkyBound I think it should be fine with a wedge - it doesn't care about what mechanical setup gets the RA axis pointing near to the pole as long as you can rotate about the RA axis and make adjustments of Alt/Az. @mountainmadman No, there is never a 'Next' button enabled in Step 3. I have made this clearer in the next version of SharpCap (2.10 beta) which gives a guide as to the quality of your PA and I think I removed the button too. It's up to you how close you want to get, but for most purposes 1 minute of arc is good enough! cheers, Robin
  22. @DuncanM There is currently no correction for atmospheric effects in the polar alignment routine - I don't think that would be too difficult to add as long as I knew the observer latitude and longitude. The lat/long is most likely the cause of the adjustment directions being out too. I estimate your longitude based on PC time zone - so if your TZ is EST (UTC-5) then I estimate your longitude at 75 west (and your latitude as 45 degrees). This gives me the info I need to convert a difference in RA/Dec to a differences in Az/Alt. If your PC isn't set to your local timezone then my guess of longitude will be wrong and the offsets will be wrong, although I think you'd have to be out by 30 degress+ to see a big problem. I will try to find some time to put a way to set Lat/Long in the 2.10 version (and show the estimated values) cheers, Robin
  23. I suspect that the frame rate you were seeing under the old directshow code wasn't real - if you look at the specs for that camera, it's rated for only 22fps @ full resolution and only hits 220fps @ 320x240 crop, so 500+fps isn't going to be a true rate! cheers, Robin
  24. Kev, just install the ZWO drivers from their website or the CD and also SharpCap and you should be fine. Your guide scope has a 5.7 degree FOV with the eyepiece it comes with, but it will be nearer 1 degree with the camera, which is spot on for SharpCap polar alignment (which isn't really drift alignment - not sure if there is a name for it - perhaps photo polar alignment?). If you are going to be guiding then you will need PHD2 as well for the actual guiding. There are a number of programs for DSLR control - APT and BackyardEOS for Canon, both now have a Nikon version or some Nikon support too I think (APT Nikon might still be in beta). Robin
  25. Great to hear that people are getting good polar alignment results I think I have an idea for another polar alignment technique that would work when you can't see the pole - basically accelerated drift alignment with the same sort of guidance for the adjustment stage that you get with the current polar align in SharpCap. This would require a view of about 120 degrees of RA at some particular declination and plate solving software (like Astrotortilla). Just an idea at present, so it won't make it to the next version of SharpCap, but maybe later in 2017. cheers, Robin
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