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John C

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Everything posted by John C

  1. The Atik 460 EX gives a pixel scale of 1.9 arc secs and the 490 EX is 1.5 arc secs per pixel with my Equinox Pro 80 (focal length 500), so presumably the 490 would be a better match for photometry assuming average seeing is 4 arc secs. However FLO says the 490 has a larger dynamic range https://www.firstlightoptics.com/blog/atik-460ex-v-atik-490ex.html Any advice?
  2. Thanks. That’s helpful. I’ll match the CCD to the refractor. I suppose I could always use binning 2x2 if the pixel size was too small for the SCT.
  3. I would like to start photometry of variable stars and eventually would like to be able to contribute to the AAVSO . I am going to buy a CCD camera and need to match it to one of my two scopes. I understand that for photometry the FWHM of a star should cover 2-3 pixels. I’m not sure which scope is best for photometry. I have a Celestron 8 Edge HD and a Skywatcher 80 Equinox Pro. Which scope is likely to give a big enough field of view to pick up comparison stars yet also capture enough light to give scientifically useful data?
  4. Thank you everybody for your advice. I'll have a go with my 300 mm lens next time. Sent from my iPad using Tapatalk
  5. I must add that 4th January at 3am was very humid and I wonder if that affects the seeing. Sent from my iPad using Tapatalk
  6. I've had two attempts at imaging this comet. I'm using a Canon 60d and a 8Edge HD with a 0.7 x focal reducer. I'm not able to guide very well at this focal length so tried using short exposures of 30 secs at ISO 3600 and stacked 41. This is the result, but there are no tails. Would I be better to use my 300mm lens instead of the telescope and go for long exposures? Sent from my iPad using Tapatalk
  7. The Astronomik clip filter system for Canon EOS cameras is an alternative. http://www.astronomik.com/en/clip-filter-system.html. It fits just inside the camera. You can use different lenses or a telescope with the same filter. To quote "Almost all Canon system lenses (with the exception of the EF-S series) and all M42 and T2 lens adapters, can be used with the Astronomik Clip-Filter System" . Anyway, I've started using one and like it though it seems to have increased my exposure time dramatically. Sent from my iPad using Tapatalk
  8. Thanks, that's very helpful. I realise I need to take a lot more subs. Sent from my iPad using Tapatalk
  9. Thanks, that's very helpful. Sent from my iPad using Tapatalk
  10. I forgot to ask what mount you used, anything you can tell me about how you imaged the whirlpool galaxy helps me to get the best out of my SCT so thanks for any information. Sent from my iPad using Tapatalk
  11. I'm in the same position. I must say that's an amazing image using a finder guider and 90 sec subs. How many did you use? What SCT do you use? Which mount do you have? I've found the same limitations. Like you I don't want to spend a lot of money for a new guide camera that would work with an OAG. Also the Celestron OAG doesn't easily work with a focal reducer on an 8 Edge HD, it requires all sorts of extra adapters besides the ones that come with it, and I haven't read of anyone who has made that arrangement work so so far. My next experiment will be guiding with a Star Travel 80. Sent from my iPad using Tapatalk
  12. Very impressive! How did you guide your SCT? I'm having difficulty guiding my 8 Edge HD with 0.7 reducer. Thanks. Sent from my iPad using Tapatalk
  13. Thanks. Are you saying that if you convert the FWHM into arcsecs that is the seeing or is it not that simple? Sent from my iPad using Tapatalk
  14. I've seen threads mentioning that the seeing is such and such a value in different places and on different days, but how can you tell? I'm asking this because I've seen recommendations on PHD guiding settings based on the seeing. Thanks. Sent from my iPad using Tapatalk
  15. Thanks, I may try an OAG. Sent from my iPad using Tapatalk
  16. Thanks for the advice Ray. If imaging scale means arcsecs per pixel, mine works out at 0.63, so looks a tall order for this set up. I wonder why Celestron promote it for astrophotography? Anyway, I'll keep trying for now. If it doesn't work out I've still got a nice set up for visual use. Sent from my iPad using Tapatalk
  17. I run my mount and camera from a laptop 10 metres away in our garden summer house, through USB extension leads with built in amplifiers (made by Blue Rigger). I power the mount and dew heaters from transformers in a big plastic storage box next to the scope. They are powered by an extension lead with RCD. The storage box doubles up as a table for the laptop when I'm doing drift aligning and focussing the camera, but after that I move the laptop into the summer house. I do worry about my DSLR though and one night it got really wet with dew. Next time I might put a plastic bag over the camera. I don't know what other people do. I might go indoors to make a hot drink, but feel I need to keep an eye on the guiding. Sent from my iPad using Tapatalk
  18. I am new to autoguiding my AVX mount with a 8 Edge HD and a 0.7 x focal reducer. I'm using a 9 x 50 finder guider with a QHY5 II L. I know I have a lot to learn and am experimenting with PEC, drift alignment and balancing the telescope in different ways. I don't know what is a reasonable expectation for the guiding accuracy of this set up. I sometimes get RMS values for RA under 1 arc second and a bit better in declination. I realise this mount has limitations and that imaging at this focal length is difficult for a beginner but I enjoy a challenge. This is a recent image of the pinwheel galaxy. Only 4 x 10 min subs with a Canon 60d. On this occasion guiding in RA was nearer 1.4 arcsecs RMS. Sent from my iPad using Tapatalk
  19. Thanks everybody. I'll experiment and see what happens. Sent from my iPad using Tapatalk
  20. What I mean is, doesn't a digital zoom keep the same resolution as the original image? Sent from my iPad using Tapatalk
  21. Is the 5x zoom a digital zoom in Backyard EOS? If so, wouldn't it be better to use an optical method of increasing the image size. I'm not sure what the BYE feature is. Sent from my iPad using Tapatalk
  22. I hadn't seen your post when I said it was too complicated, perhaps it's not so complicated as I thought. Celestron make a universal Barlow with a T adapter attached so perhaps I could try that? Thanks for your post Sent from my iPad using Tapatalk
  23. I've found another thread on this subject. It looks rather complicated and unsatisfactory . What about using the eyepiece projection kit made by Celestron? http://www.celestron.com/browse-shop/astronomy/astroimaging-accessories/other-astroimaging-accessories/deluxe-tele-extender Sent from my iPad using Tapatalk
  24. I imaged Jupiter for the first time this week. I used a canon 60d DSLR and a Celestron 8 edge HD. The canon was set on movie crop mode which is 640 x 480 at 50fps. The exposure was1/500s at ISO 800. I don't think the seeing was good, there was some haze. The trouble is Jupiter is only 60 pixels across, so how could I attach a Barlow and camera to the telescope? I don't want the expense of a powermate. Sent from my iPad using Tapatalk
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