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BlueAstra

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About BlueAstra

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  1. I'm going on Saturday and hope to attend some lectures
  2. OK I have it now. You gently rotate the top plastic cover with the Fastar plate on it. I think the lower finger holes are for removing the mirror.
  3. I have a Celestron 9.25 SCT, but I can't see any collimation screws at the secondary mirror. The manual shows the screws clearly visible, but mine appear to be under cover, as shown in the photo. I know this mirror is removable to fit a Fastar system so I don't want to turn the wrong thing and see the mirror drop out. What precisely do you do to access the collimation screws and not remove the mirror?
  4. Camera Upgrade?

    I currently use a DMK 21 AU 04.AS mono camera (640x480, 8 bit ICX098BL chip, 5.6um pixel, 3-60 FPS) with a ZWO 1.25" FW and a Celestron 9.25" SCT for planetary and lunar imaging. Technology has moved on and I'm thinking of updating the camera for a better frame rate and maybe resolution, or even trying colour, but not sure which way to go. What would be good recommendations for a mono camera upgrade? Is it worth thinking about colour and if so, which ones are flavour of the month?
  5. The Evo 9.25 tripod is much larger than the Evo 6/8 tripod. I'd seen your solution before and tried it, but the 9.25 HC bracket is too large (the tripod legs are larger diameter) so its a sloppy fit on the handle. I believe this one is 3D printed, and the designer has put the drawings on the web, so if you have a 3D printer you can make at home! I also have a wedge and Starsense but not used them yet. I know about the bug so I'll be following your method!
  6. I didn't like the tripod leg HC bracket since the cord would wrap around the mount as it rotated. The 9.25 HC bracket was too big to clip to the mount handle, and go around with the mount, so I found this simple bracket on the Starzonia site. They ship to the UK so got one and it works a treat! No more wrapped cables.
  7. I can see two Celestron wedges, a NexStar Evolution 6/8 wedge and a HD Heavy Duty PRO wedge. I would assume that the HD Pro wedge is required for the Evolution 9.25, but the description for it only mentions the fork mounted SCTs up to 11". Does HD Pro wedge fit on the Evolution 9.25 tripod and take the Evo mount? Alternatively, does the Evolution 6/8 wedge fit on the Evolution 9.25 tripod? The Celestron website lists the Evolution 6/8/9.25 for the Evolution 6/8 wedge, but doesn't mention the Evolution 9.25 in the HD PRO page. So I'm confused now as to which wedge to use for the Evolution 9.25. I'd like to use the 6/8 wedge, but should it be the HD PRO wedge?
  8. C6 v C9.25 for Planetary Imaging?

    So from this analysis, the optimum sampling of the Airy disc is with an F/Number of about 5 x Pixel Size (microns). So from Michael's post, his sensors would work best at 5.3um = F/26.5, 3.75um = F/18.75, 2.4um = F/12, all of which ties in with his experience. However, this just states the optimum F/Number for Airy disc sampling, so on the face of it both the C6 and C9,.25 would work optimally at say F/30 with a 5.6um pixel (DMK), since both work at F/10 (done with a x3 barlow). However, I think the key thing is Michael's comment on image scale. With the longer focal length, the C9.25 will always put x1.5 more pixels on the object than the C6 for a given camera.
  9. C6 v C9.25 for Planetary Imaging?

    The C14 and C11 have slightly lower obscuration ratios, but similar F/Numbers, so would produce similar spot sizes. The lower obscuration would make the central peak of the spot slightly brighter.
  10. Considering a Celestron C6 or C9.25 for planetary imaging with a CCD camera. At first I thought its obvious, get a C9.25. However, that may be true visually, but is it true with a CCD camera? The Rayleigh limit for the C6 is 0.92 arcsec, and for the C9.25 is 0.59 arcsec. So the C9.25 has better angular resolution. However at the CCD plane the spot size is the same for each scope, 6.7 um (focal length x angular resolution, also proportional to wavelength x F/Number). So the same F/Number gives me the same spot size in the CCD plane. Both scopes are F/10, so both give the same spot size. I guess the C9.25 may be a bit brighter because of the larger aperture, but the C6 samples less 'atmosphere' so may give a steadier image. Both have about the same obscuration ratio. If the C9.25 has a better aberration correction, that may help, but for a price factor of x2 it would have to be good. So, comments please, which one for CCD imaging?
  11. Sold-Lunar and Planetary coloured filters

    Can you tell me the total height of the filters, and the thread height, to see if they will fit in my FW.
  12. Looking at getting a small USB filter wheel (x5) for my 6" SCT for a bit of colour planetary imaging with my mono DMK. I've seen SX , ZWO , and Xagyl wheels. The ZWO wheel is £175, the SX is £280 but includes a guider port and looks a bit bigger. The Xagyl is £199. Any opinions on these wheels, or possibly other ones? Also what would be a decent LRGB filter set to go with the wheels?
  13. Jupiter with 6" SCT

    Jupiter last night. From left to right, Jupiter, Io, Europa,Ganymede, Callisto. 6" SCT & DMK, about 1500 frames at 1/30s, processed in Registax.
  14. I've read about the Starsense Camera for alignment, and I'm thinking about one for use with my Evolution 6. I know they work by automatically looking at different parts of the sky and plate solving to find position. Fine if you have a clear sky. But what happens if it is partially cloudy, and the camera chooses a cloudy patch? If the plate solve fails, does it keep looking until it finds a clear patch, or does it fail after two or three attempts?
  15. I'm looking to spend up to about £350 or so on a lunar/planetary imaging camera. Not sure whether to go mono or colour, but if I went mono the colour wheel would be a separate purchase. Just want to get the best out of the scope. Its a good few years since I got a DMK mono (21AU04AS) but I'm thinking the technology would have moved on a bit by now. If it has I will sell the DMK to help fund the new camera, if not maybe keep the DMK. The scope is a 6" SCT, 1500mm focal length, with x2, x3 barlows. Any opinions welcome.
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