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#41
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To Refract or to SC
"Robert Geake" wrote in message ... My quandry is this, i cant seem to find any decent refractors above 4" without going for meade or celestron. Nothing wrong with either, as long as you avoid the Goto toys. I have a Celestron 150 6" f/8 achromat. It yields views just as sharp as any APO, although with a not insignificant amount of false color. Whether you find the purple halos objectionable is a matter of personal taste. But for £650, I feel it is money well spent. |
#42
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To Refract or to SC
Mark McIntyre wrote in message . ..
On 8 Oct 2003 11:26:16 -0700, in uk.sci.astronomy , (andrea tasselli) wrote: If any 4" scope beats constantly a 10" one something is deeply wrong with the latter. There is no known law of physics to allow for such a difference in aperture not to win hands down. You're assuming both are perfectly figured, aligned etc. AFAIR refractors are easier to figure right, and stay aligned better. That, plus other bits to do with the actual optical design, means they tend to produce sharper images for a given aperture. Sure, you might gather 6x the light from a 10" buf if that is spread out over a larger area, the result might be worse. Well, yes, the usual caveat applies: "all things being equal". Sad truth is that often things are nowhere near to being equal. Nevertheless I would expect that a 10" at about f/5, if figured properly, well acclimated and kept in tight collimation would still yield far better images than a 4" would do, expecially if one thinks about going the planetary imaging route. Me think that if one wants to go down that route he/she better have a big newtonian at f/6 or slower of fairly good size (8" or above) instead of spending nearly or more money on a 4" APO for however good this might be. Of course a MN or a MCT is even better :-). Best Andrea T. My Astronomy Pages at: http://www.geocities.com/andreatax/index.htm |
#43
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most fighting talk (or hot air) on any one thread?
This thread has really cracked me up!
Twelve quotes most likely to get the fists flying: 1. I understand that refractors are very good for planetary / binary / cluster observations from experience(The little tal eats the Europa for brekkie when it comes to that kind of observing). 2. SCTs are, IMHO must better than refractors if you intend to *use* them and not just sit and admire them as penis substitutes. 3. .... and a 5" to 8" SCT blows away an equivalent refractor easily, in terms of performance. 4. An SCT of an equivalent aperture (to apo refractor) is cheaper, and more easily used and has almost the same performance, 5. ive looked through where actually worse than the TAL 4" refractor. Including a 10" meade LX, a celestron 8" and an Orion Starmax. It will take a lot of perswading to make me buy a Schmitt of any kind! 6. this happen with a goto SCT? I don't know because I have resited the hype and have never owned one. 7. I must admit that I have been suckered in by the look of these units from time to time. However, I get the impression that you have to look a bit deeper than the glossy appearance. 8. Me think that if one wants to go down that route he/she better have a big newtonian at f/6 or slower of fairly good size (8" or above) instead of spending nearly or more money on a 4" APO for however good this might be. 9. To date, the refractor has performed brilliantly in comparison to the reflector and it has certainly given a number of it's bigger cousins in the Meade and Celestron arena a damn good run for their money 10. It's only 80mm. That's the problem. (this one also works in the bedroom) 11. Hard to see why you'd want to buy a rinky-dink el-crappola short-tube refractor to go with your apparently sub-standard reflector 12. I have a Celestron 150 6" f/8 achromat. It yields views just as sharp as any APO, |
#44
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To Refract or to SC
Morgoth wrote in
: On Wed, 08 Oct 2003 23:43:07 +0100, Mark McIntyre inscribed in blood upon a parchment: On 8 Oct 2003 11:26:16 -0700, in uk.sci.astronomy , (andrea tasselli) wrote: If any 4" scope beats constantly a 10" one something is deeply wrong with the latter. There is no known law of physics to allow for such a difference in aperture not to win hands down. You're assuming both are perfectly figured, aligned etc. AFAIR refractors are easier to figure right, and stay aligned better. That, plus other bits to do with the actual optical design, means they tend to produce sharper images for a given aperture. Sure, you might gather 6x the light from a 10" buf if that is spread out over a larger area, the result might be worse. Only if the 10" is horribly miscollimated, dirty, misaligned, smeared and so on. Nah. Reflectors are just smoke and mirrors without the smoke. Get a REAL telescope, a refractor! Klazmon. Best, Dave Author of the TalkOrigins Supernovae and Supernova Remnants FAQ http://www.talkorigins.org/faqs/supernova/ Visions of Light, Visions of Darkness - Photography of Wessex http://www.valinor.freeserve.co.uk/visions.html Conception 2004 - the South Coast Gaming Convention http://www.wessexgaming.org Musings from Thangorodrim - A livejournal http://www.livejournal.com/users/mrmorgoth |
#45
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most fighting talk (or hot air) on any one thread?
Geoff Smith wrote:
10. It's only 80mm. That's the problem. (this one also works in the bedroom) We'll defer to your more catholic experience here, Geoff. Best, Stephen Remove footfrommouth to reply -- + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Stephen Tonkin | ATM Resources; Astro-Tutorials; Astro Books + + (N51.162 E0.995) | http://www.astunit.com + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + |
#46
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most fighting talk (or hot air) on any one thread?
-- Remove XXX in address to reply "Stephen Tonkin" wrote in message ... Geoff Smith wrote: 10. It's only 80mm. That's the problem. (this one also works in the bedroom) We'll defer to your more catholic experience here, Geoff. Best, Stephen Is it the old "... is that an 80mm refractor in the bed or are you just pleased to see me..." Martin |
#47
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most fighting talk (or hot air) on any one thread?
On Fri, 10 Oct 2003 02:57:50 +0100, "Geoff Smith"
wrote: This thread has really cracked me up! Twelve quotes most likely to get the fists flying: We're all quite civilised now though. A few years back and a verbal war would have broken out. Perhaps it's a realisation that the "this scope is better than that scope" argument is largely pointless (with the obvious exception that apo refractors are better than SCT's and Newts ;-) ). If you want a fight these days, you really have to wade into the film vs digital argument on a photographic forum. Oh boy, do they fly. -- Pete Homepage at http://www.pbl33.co.uk CCD/digicam astronomy |
#48
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To Refract or to SC
On 10 Oct 2003 16:15:54 +1300, Llanzlan Klazmon The 15th
inscribed in blood upon a parchment: Morgoth wrote in : On Wed, 08 Oct 2003 23:43:07 +0100, Mark McIntyre inscribed in blood upon a parchment: On 8 Oct 2003 11:26:16 -0700, in uk.sci.astronomy , (andrea tasselli) wrote: If any 4" scope beats constantly a 10" one something is deeply wrong with the latter. There is no known law of physics to allow for such a difference in aperture not to win hands down. You're assuming both are perfectly figured, aligned etc. AFAIR refractors are easier to figure right, and stay aligned better. That, plus other bits to do with the actual optical design, means they tend to produce sharper images for a given aperture. Sure, you might gather 6x the light from a 10" buf if that is spread out over a larger area, the result might be worse. Only if the 10" is horribly miscollimated, dirty, misaligned, smeared and so on. Nah. Reflectors are just smoke and mirrors without the smoke. Get a REAL telescope, a refractor! Klazmon. Fiddlesticks. Those are just glorified (and unwieldly) toilet rolls with a couple of magnifying glasses stuck in at each end that give back and neck ache to anyone lunatic enough to want to use them.... Best, Dave Best, Dave Author of the TalkOrigins Supernovae and Supernova Remnants FAQ http://www.talkorigins.org/faqs/supernova/ Visions of Light, Visions of Darkness - Photography of Wessex http://www.valinor.freeserve.co.uk/visions.html Conception 2004 - the South Coast Gaming Convention http://www.wessexgaming.org Musings from Thangorodrim - A livejournal http://www.livejournal.com/users/mrmorgoth Author of the TalkOrigins Supernovae and Supernova Remnants FAQ http://www.talkorigins.org/faqs/supernova/ Visions of Light, Visions of Darkness - Photography of Wessex http://www.valinor.freeserve.co.uk/visions.html Conception 2004 - the South Coast Gaming Convention http://www.wessexgaming.org Musings from Thangorodrim - A livejournal http://www.livejournal.com/users/mrmorgoth |
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