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Tele Vue Genesis vs 8" SCT

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#1 asaint

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Posted 08 October 2003 - 06:38 PM

Tele Vue Genesis vs 8" SCT Article

#2 jrcrilly

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Posted 08 October 2003 - 07:55 PM

I agree completely with the author. I currently own a TV Genesis SDF and larger SCT's and have previously owned sveral 8" SCT's. I held off on trying to write a comparo because I never used both at the same time so I'd be comparing different views on different nights and I hate to do that. My impressions do match his precisely, though.

#3 Oldfield

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Posted 08 October 2003 - 08:19 PM

I've a Ranger, a C8, and a Sky90 (co-own with my friend). I only bring out my C8 for observation, and photography of the planet. The other two left were always left at home.

I bought my setup out by public transportation, 3 hours round trip including some walk, taxi and train. So, even the portability of the C8 is not as good, but it offers more light.

The Sky90 will be used only for deep sky imaging, and casual scanning, the Ranger? A bigger finder/guide-scope.

#4 Ron B[ee]

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Posted 08 October 2003 - 08:40 PM

I think it was a very interesting and very well written article. I like the fact that the author tried to go into more objective comparison (like when he mentioned the festoons).

However, I'd have like to see more objective comparisons of the features: eg. craterlets or rilles on the Moon that could be seen in one and not the other, white ovals in one and not the other. On Saturn, were there more bands on the planets that could be seen in one and not the other? Furthermore, since both scopes were clearly limited by seeing (i.e. 160x-170x), the larger aperture of the SCT was well, handicapped by the ability to achieve higher magnification and possibly bring out more details (or resolve the Cassini Division as wider gap). For instance, on excellent seeing nights, my 4" TV-102 APO could easily achieve 293x on Saturn with crisp details and I wonder what features 300x through the SCT would reveal on these sort of nights. Furthermore, at this high magnification, the SCT might have revealed the Encke Minima or even the spokes (which might also be possible with a 4" APO :question:).

After reading the article and if I may be so bold as to draw my own conclusion that both scopes were simply seeing limited, an important point for many observers who are not so fortunate to live in excellent seeing condition.

Lastly, both scopes have long been discontinued. It would have been very interesting to see a comparison of the recent SCT vs recent high quality 4" APO. I'm grateful however that the author has taken the time to writeup his comparison.

Ron the 4-inch Tall Evangelist B[ee]


#5 Oldfield

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Posted 09 October 2003 - 02:06 AM

Photographically (I mean high power), no 4" can beat a 8" SCT on the moon/planet.

#6 rboe

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Posted 09 October 2003 - 09:18 AM

I started out with a TeleVue Pronto, fairly quickly realized I liked faint fuzzies; and the Pronto's operative word is 'faint'. So I bought a NS11. It fills the bill, but I prefer the image of the Pronto for the most part. If I'm ever treated to a night of very high quality seeing the NS11 may give me something to drool over (OK, there was that first night at a dark sky site and I got see M42 in all its' glory: That was a drool momement). The eleven gives me those faint fuzzies in spades, just wished it weighted 50lbs less.

#7 summitlake

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Posted 09 October 2003 - 07:45 PM

Not yet having even looked through a serious refractor, just wanted to say I sure appreciate Chuck Zdeb's article, which was an eye-opener for me in many ways, and thanks for taking the time to compose a really thoughtful comparison.

In computer graphics I tend to be a contrast freak. I guess I'd warm to a TeleVue quickly! We are still learning our LX-90, and Cloudy Nights certainly has been a huge help with both general knowledge and specifics.

Picking up Chuck's analogy in a different way, which motorcycle is better, a 650 or 1300cc? Depends whether you're whipping through mountain curves, or touring the Interstate.

#8 Oldfield

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Posted 10 October 2003 - 01:40 AM

Visually, a refractor is more enjoyable and eye-pleasing.

#9 Guest_**DONOTDELETE**_*

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Posted 16 October 2003 - 01:42 PM

Hi Ron,
Thanks for the compliments. Your comments about both scopes being seeing-limited most of the time are pretty perceptive. I’ve long noticed that in bad seeing, most scopes perform about the same, and only when seeing gets really good do you see big differences between them. In bumping up magnification in good seeing with these two scopes though, my feeling was the Genesis ran out of steam due to lack of aperture, while the C8 was limited more by optical quality (I was never impressed with images in it over about 220X)(in fairness, by personal preference I don’t often use over 250X in anything, including my TEC 8” Mak). Whatever the exact cause, the result was that the C8 didn’t have a big advantage on planets even under really good seeing. Never saw the Encke Minima nor white ovals with either of them.

So far as comparing late-model scopes, if you’d lend me the famed Light Cup for a year or so, I promise to write up a comparison with the 8” Mak ;-)

Chuck






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