Peter Drew
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Everything posted by Peter Drew
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I've never tried an annular silicone secondary attachment, the suggestion came from a very respected optical expert. đ
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Maksutov Cassegrain vs Dobsonian
Peter Drew replied to bluesilver's topic in Getting Started Equipment Help and Advice
Having both would be ideal, is the 180Mak available for a "try before you buy" arrangement? đ -
Hello Dave. Welcome to SGL. Come over and see us sometime at the Astronomy Centre. đ
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Cellestron 114az
Peter Drew replied to Stacey caley's topic in Getting Started General Help and Advice
Hello Stacey. Welcome to SGL. When first starting with a telescope it's best to try it in daylight to get used to focusing. If you then can't get an image it maybe that an extension piece on the focuser needs to be removed or added. The red dot finder may have a strip of clear plastic between the battery which prevents accidental switching before sale, the red dot will not appear until you do, it will also be faint in daylight. đ -
Herschel wedge do I need one
Peter Drew replied to Steve Clay's topic in Getting Started With Observing
Not a significant gain but a worthwhile one and a more long lasting accessory. đ -
A full disc might not be possible with a Quark as it uses a 4.2x Barlow in the system. The Evoguide at 242x4.2 would work at 1016.4mm focal length. đ
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Yikes!, it could be a close run thing.
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I was building an astronomy centre at 61. 78 now and still not finished! đ
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Good luck in your new location, lots to look forward to. đ
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I think where this issue falls down is the emphasis on "competition". There are of course established advertised competition where the reader should expect to see the best on offer. Other than that, in the main, imaging should be only a "competition" between the challenges and the imager's personal desire for improvement. đ
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Considering how much space is devoted to the best images I would have thought half a page at least could show inexperienced efforts as an encouragement to others. đ
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The best way to reduce the time/cost of equipment is to share it. I have more telescopes than I can use but being part of an outreach facility, thousands of people have benefited. That's what I call good value. đ
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I used Dow Corning silicone on the successful mountings which were maximum 90mm minor axis. It has been suggested that an annulus of silicone between the rear of the mirror and its backplate with a small hole in the silicone to release air might be a better method than the commonly used silicone blobs. đ
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Fifty thousand telecom satellites will make astronomy impossible!
Peter Drew replied to Jkulin's topic in The Astro Lounge
On the brighter side, a meteor shower every night ! đ -
Fifty thousand telecom satellites will make astronomy impossible!
Peter Drew replied to Jkulin's topic in The Astro Lounge
Get some shares in solar equipment. đ -
The outcome of this will be of interest to me. I have two secondary mirrors for my 30" Dobsonian, one as a spare. Both are 150mm minor axis and 12mm thick. I have mostly "glued" secondary mirrors to backplates with success so did the same with these. The telescope then showed astigmatism and knowing that the primary was ok I suspected the secondary, and the spare one when fitted for a comparison. The secondaries were independently tested and found to be good when unmounted so I subsequently remounted one in a "hung" arrangement. The astigmatism disappeared. At least it's a simple thing to experiment with. đ
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Yes, this is the usual comparison and can be difficult to justify the cost of a binoscope other than to those who are binocular enthusiasts. A large binoscope is usually larger than a conventional binocular and carries a similar impression to a large refractor. The odd thing, is that a 6" F8 refractor is perceived as being huge whereas a 6" F8 reflector is considered small. đ
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Interesting design. What stops the rolling roof from lifting in wind whilst open or rolling? Not obvious from the photos. đ
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Mercury Transits Sun - 2019 NOV 11
Peter Drew replied to CentaurZ's topic in Celestial Events Heads Up
No luck here despite our considerable preparation. A couple of gaps were so transient there wasn't time to even focus properly. Fortunately an internet live stream entertained the visitors. âšī¸ -
A binoviewer halves the light from a single telescope although this is mitigated a bit by having a signal to both eyes. A binoscope provides a full aperture to both eyes and the general perception is of 1.4x brightness enhancement. đ
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I feel adequate as I have 150mm, 200mm and 300mm reflecting binoscopes already. Looking forward though to how this new one develops. đ
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Mercury Transits Sun - 2019 NOV 11
Peter Drew replied to CentaurZ's topic in Celestial Events Heads Up
I will have a C8, 150 SW refractor and 100mm Tal refractor with full aperture Baader white light filters and 150mm and 60mm Ha refractors ready for any gaps in the cloud. đ -
Mercury Transits Sun - 2019 NOV 11
Peter Drew replied to CentaurZ's topic in Celestial Events Heads Up
You can follow it on GONG solar if you have access to it. đ -
I have a pair of 20mm eyepieces of the same design and period. I use them on my 300mm reflecting binoscope giving 50x. The centre definition is excellent but falls away rapidly towards the edge, much less noticeable with binocular vision. The 84 degree apparent field is largely due to opening the field stop to the maximum possible. They seem to need more IN focus than my other eyepieces. One of them is branded "Fullerscopes" and the other "Mirador". đ