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#51
September 30th 05, 03:02 AM
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"Stephen Paul" wrote in message
... wrote in message oups.com... If you want to see more deep sky objects a 10" or 12" dob makes more sense. To you maybe Three simple words..... who knew? Wow! I just had a BRILLIANT idea!!! Let's talk about off-axis reflectors for awhile, for our NEXT diversion... -- Jan Owen To reach me directly, remove the Z, if one appears in my e-mail address... Latitude: 33.662 Longitude: -112.3272 
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#52
September 30th 05, 04:21 AM
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"Jan Owen" wrote in message news:801%e.84531$DW1.20091@fed1read06... "Stephen Paul" wrote in message ... wrote in message oups.com... If you want to see more deep sky objects a 10" or 12" dob makes more sense. To you maybe Three simple words..... who knew? Wow! I just had a BRILLIANT idea!!! Let's talk about off-axis reflectors for awhile, for our NEXT diversion... Well, I can speak to the off axis aperture mask, on an SCT.
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#53
September 30th 05, 04:45 AM
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"Stephen Paul" wrote in message
... "Jan Owen" wrote in message news:801%e.84531$DW1.20091@fed1read06... "Stephen Paul" wrote in message ... wrote in message oups.com... If you want to see more deep sky objects a 10" or 12" dob makes more sense. To you maybe Three simple words..... who knew? Wow! I just had a BRILLIANT idea!!! Let's talk about off-axis reflectors for awhile, for our NEXT diversion... Well, I can speak to the off axis aperture mask, on an SCT. Hell, I WEAR one most of the time... -- Jan Owen To reach me directly, remove the Z, if one appears in my e-mail address... Latitude: 33.662 Longitude: -112.3272
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#54
September 30th 05, 05:02 AM
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Doink wrote:
Unless you have a very well trained eye, the difference will be disappointing----you are chasing small increments of "improvement". From your 8", the next real step upwould be a 18" DOB. Doink "Mark D" wrote in message ... The one thing to remember, is an 8" compound scope (of mostly any type note), is not technically a 8" scope due to secondary obstruction. The 11" will show you more detail, nebulosity, fainter stars, and split closer doubles under virtually any sky conditions, urban, suburban, and dark sky. Naturally, aperture will truly shine, and have the advantage under dark, transparent sky conditions. Also to remember, the larger the aperture, generally, the longer the cooldown period. There are ways around this. Lymax cooling fans, setting scope up prior to an observing run, etc. Dark sky conditions are not needed to do serious Planetary-Solar-Lunar observation-imaging. What is needed is a steady calm atmosphere, and equilibration of the scope. With Solar Imaging-Observing, there probably wouldn't be much gained between the 8"SCT, and the 11" SCT with white light filter. Mark Money, weight, portability and commitment wise also. JS
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#55
September 30th 05, 05:03 AM
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decaf wrote:
Actually, I don't think it makes any difference at all to the brightness of the moon. This is true in a telescope of any size. Surface brightness cannot be increased by a passive optical system as it would be a violation of thermodynamics. The Moon, or ANY luminous object will look brighter in a larger telescope than a smaller one for a given magnification, or the only gain would be resolvimg power. Actual surface brightness does NOT need to be increased for an object to appear brighter; the distribution of availible light energy increases the brilliance of an object for a given magnification. The larger the aperture, the more light energy is gathered and availible to spread over a given expanse of image plane. This is not the same as claiming that any telescope will show the Moon brighter per unit area than it actually is, or looks to the naked eye ( which it can't). Nor did I imply that. DC Any one buying an 11" SCT for looking at the Moon is an idiot! JS
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#56
September 30th 05, 05:07 AM
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#57
September 30th 05, 05:11 AM
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John Deer wrote:
I used to own a C11 after selling the C8. The C11 needed a lot of work to set up for one person. A semi/permanent housing is a solution but adds quite a bit to the cost and requires extra space. Then again your limiting yourself to your own backyard skies. Motorized drives are great when they work reliable, But dobs can have electronic setting circles that are just as useful for locating objects quickly. More important to me is aperture and quality. After selling the C11 I got a 16" dob. Given the choice of only the C11 or C8 I would take the C11 for optical reasons, but I sure would hate setting it up and taking it down alone. JD "Stephen Paul" wrote in : If you want to see more deep sky objects a 10" or 12" dob makes more sense. To you maybe. Mines C-11 OTA only 30LB, not that heavy. I'm 5'6", medium built. Use it on a GP with SS2K, works like charm for visual use. I entertain DOB guys when they give up finding things on star parties. JS
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#58
September 30th 05, 05:25 AM
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Any one buying an 11" SCT for looking at the Moon is an idiot! JS
---------------------------------------------------------------Perhaps true, but not for imaging the moon. Mark
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#59
September 30th 05, 02:12 PM
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Stephen Paul wrote:
Well, I didn't really forswear wide-field views, I just made a choice to use smaller exit pupil. My mistake; I should have said "rich field" or "richest field" instead. I'm sorry this discussion came up within this thread, since it's nearly irrelevant to the original question. But let me press you on it anyway, because I really do think it's important. Let me give you an analogy. When I was young, I was a voracious reader. About 15 years ago, I realized that I hardly ever read books any more, and wondered why my interest had waned. Then, after visiting an optometrist, I discovered that I needed reading glasses. After buying reading glasses, my reading returned to its childhood level. And I realized that my apparent loss of interest was, in fact, due to a simple physiological problem that could be fixed at negligible cost. Now I enjoy wide-exit-pupil viewing through telescopes as much as the next guy. But like you -- and probably the overwhelming majority of all serious observers -- I spend the lion's share of my time at a 3mm exit pupil or smaller. If I were prohibited from ever looking through a telescope again at wider exit pupils, I would adapt -- it wouldn't break my heart. Same cannot be said for binocular and naked-eye viewing. Those are really, really important to me, and they're all done at exit pupils of 3mm or larger. If deprived of that, I really would be desolate. So I'll ask again. If your wide-exit-pupil problem is really primarily due to astigmatism, then it can be fixed at negligible cost with eyeglasses. And you might find out that you like it far more than you expect once that trivial obstacle is removed. - Tony Flanders
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#60
September 30th 05, 02:22 PM
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"Jan Owen" wrote
Well, I can speak to the off axis aperture mask, on an SCT. Hell, I WEAR one most of the time... Who WAS that masked man??? Wha -- it wuz Off-Excess Appyture Man!!
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