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Cosmic Geoff

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About Cosmic Geoff

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  1. Jupiter -23 April

    The image below was taken with Celestron C8, ASI120MC, ADC. It's my best effort so far but not as great as some other folk's images. This was taken near S. transit and for the first time using a ZWO ADC. I'm not sure why exactly it turned out well.
  2. I took the image below on the morning of 23 April using: Celestron C8, ASI120MC camera, ADC. It shows more detail of the belts than my previous efforts, but while processing I thought that the image seemed on the dim side. I had set the exposure for maximum apparent contrast on the raw live image. I think there is some histogram thing in Smartcap for this but it's hard to recollect that sort of thing when out in the dark. Ditto the focus - I adjusted for what looked sharpest and hoped for the best. Also the ADC - I tried it out on Venus a few hours earlier with a different telescope and dropped it into the C8 with the same setting (and the same way up). Absence of fringes looked okay so I left it like that. Is there some 'best' way of setting it? BTW I have calculated the angular sizes of Jupiter's principal moons and got results of 2" or 3" of arc. So they should resolve with good equipment. Right?
  3. I think it depends on where you want to concentrate your effort. If you mainly aim at doing DSO imaging, according to all comments you need a heavy duty GoTo equatorial mount and a small APO refractor. If you want to concentrate on lunar & planetary imaging then what the people producing great images mostly use is a SCT on an equatorial mount. If you want to do visual to start with, consider a SCT instead of the cheaper but heavier and bulkier Dob GoTo. I have found that my 127mm Mak SLT and C8 SE work well for visual and are also adequate for basic lunar and planetary imaging (on a windless site). The C8 SE is popular and it is easy to find them second-hand at substantially cheaper than new. Note that Alt-Az GoTo (and alt-az mounts in general) are much less of a bother to set up than an equatorial GoTo.
  4. Celestron 11049 NexStar 4 SE: Lost :)

    I doubt very much that there is anything wrong with the telescope. The range of focus of a Maksutov is very large, and there is only a very small range of adjustment in which it is in or near focus. As another poster suggests, try it in daylight with the scope aimed at a distant tree or TV aerial. If you don't start by aiming at a bright and/or high contrast object, it can be very difficult to find the focal point. A good trick is to aim at a brilliant point of light in the night sky (such as Sirius or Jupiter). You should see a broad circle of light with a dark hole in the middle (like a doughnut) . Then it's easy - just adjust the focus in the direction that makes the doughnut smaller. Eventually it should turn into a planet or a point of light.
  5. If you mean the Starsense, that's a matter of opinion. At its current price it probably costs nearly as much as your 130 SLT outfit. I have one on my C8 SLT and I like it because it simplifies the setup. I don't have to fiddle about doing alignments, and I don't have to level the tripod. I can just lug the outfit outside and turn it on (actually I still have to connect a battery, enter the time & date, remove covers and fit a dewshield, but these are not exacting tasks.) Doing a 2-star align is not hard once you are used to it, but if you can avoid it I always found the 3-star align was a lot of work, and it's only needed if you can't identify the stars.
  6. Mix and match tripod and mount?

    That's what we'd all like, but alas it ain't gonna happen. The difference between the faint fuzzy blobs seen visually and the amazing images obtained by some people with small aperture telescopes is such that it is obvious (to me at least) that if you want 'great views' of galaxies, the best, and most cost-effective way of getting them is to image. (Or to try EAA). Even with the planets, I am finding that imaging results tend to surpass what I can see with my eyes through the telescope. Re resolution, I would suggest that aperture is not the only thing that affects (image) resolution. Atmospheric conditions, guiding accuracy, focus precision and mount vibration will also play a part. The fact that a lot of people use 80mm refractors for deep-space imaging suggests that they are satisfied with the resultant resolution.
  7. The question I am always tempted to ask about a Newtonian is "Why?". Yes, they are cheaper than an SCT, and you can have a shorter focal ratio, which may or may not be useful depending on what you want to do with it. But you have to mount it... and they are long, heavy and the eyepiece can get into awkward positions. Likewise with an equatorial mount: "Why?" If you only intend to use the telescope visually, an alt-azimuth mount will be less of a bother all round. But if you have (planetary) astrophotography in mind, an equatorial mount will be worth having. Also the alt-az GoTo mounts tend to be made for portability rather than stiffness. Dew - SCTs require a dew shield. Cooling - not a big issue especially if you can plan ahead e.g put it outside to cool, or do low-resolution tasks first.
  8. The Celestron 4SE mount

    For this task you should either persist with the Dob and star-hopping, or replace it with a telescope of 8" or larger aperture which has GoTo. For looking at galaxies you need dark skies, and if you have to travel, you may appreciate the time-saving GoTo. Tracking is not essential, as manual Dobs are much used for looking at DSO's but don't track.
  9. The Celestron 4SE mount

    People have tried imaging with a Dob, but people have also rowed across the Atlantic. It's still not clear why you want to buy more kit. Seems you want a travel setup, but what for exactly, and why won't your existing kit do?
  10. The Celestron 4SE mount

    A small widefield scope matches well with an alt-azimuth mount which I suspect you have anyway. 80mm is really a bit small for visual observation of DSOs. I have a 102mm widefield scope and I have put it on a EQ-5 tripod to image the Moon, & M42, and put it on a GoTo mount to find and image Ceres (all with a planetary camera). Visually the 102mm + GoTo was useful as a travelscope to view some galaxies from dark skies sites.
  11. The Celestron 4SE mount

    I've only seen these instore. AFAIK the mount is also used on the 5SE, and is sturdier than the SLT mount & tripod. As you say, it has a built in wedge. You don't need the wedge for planetary imaging, and the 4SE would at least be good for trying out some basic planetary imaging. As for deep-space imaging, check out what other people use. As for mounting a refractor, AFAIR this has a vertical arm (like my 8SE mount), so suited for mounting short telescopes (like the MAK) and not good for a refractor unless it is equally short. And yes, the dovetails ought to be compatible.
  12. You will get a variety of answers. There has been considerable discussion in the past about which design is 'best' for planetary viewing. Apochromats, Maksutovs, long focus Newtonians and SCTs are all somebody's best choice. Also consider the mounting. Something that tracks will make planetary viewing much more pleasurable. Also consider that you might want to try basic planetary astrophotography, in which case you will want a setup that will readily convert for this.
  13. Finderscope for ST80mm

    I have a Sky-watcher Startravel 102mm achromat, a size bigger than the ST80. It has a red dot finder on it. I have a 6x30 finder and a 9x50 finder that I could swap onto it in moments, but I have never found any reason to do so. IMHO the red-dot is a widefield finding device, and matches with a widefield telescope.
  14. What screw to SCT 8"

    Some Celestron C8 are metric, others are not. If it isn't metric, note that the front and back rings have different size threads. On mine the back ring has several holes of thread UNC 8-32, 5/16 deep, and the front ring has one usable hole threaded 10-24, 5/16 deep. (in addition to the existing dovetail fixing) I hope this helps.
  15. turning an old spy lense into a telescope?

    I am puzzled by the repeated references to f1.2. The primary mirror of my SCT reportedly has a focal ratio of f2 or f3 but the focal ratio of the primary-secondary assembly is f10. The latter is more to the point for the user, and the lower power of the OP's cheapo eyepieces should work in my telescope. A common feature of Schmidt-Cassegrains is that by moving the primary mirror the secondary (useful) focal point can be moved in and out through a wide range - demonstrably at least 10cm in the case of my telescope. Assuming that the spy camera optics resemble a Schmidt-Cassegrain, one can speculate that as a telescope it might not require exotic eyepieces, and that if the makers wanted the secondary focus to be several inches or a foot behind the unit (the most useful position?) there would be no problem in having it where they wanted.