Author Topic: ultimate sub 100$ gift telescope  (Read 100 times)

Josh Rinderman

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Re: ultimate sub 100$ gift telescope
« Reply #30 on: February 09, 2018, 07:58:14 AM »
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In general I think 76mm reflectors are a bad idea. Even if they're well executed, 76mm refractors are too close in price and would certainly be better. 114mm reflectors suffer a bit from this as well, except the dobs (because a dob will have a good, stable mounting and are ultra-portable, while a 90mm refractor is starting to really need a good mount).
Long tube (f9 or f10) 76mm Newtons are BETTER than cheap 70mm f10 refractors.I have used both.[/quote]

I'm curious about this. Which ones?

I would not expect a 76mm newtonian to beat a 70mm f/10 refractor of equal quality, if both were decent instruments. The extra 6mm aperture is not going to cancel out the refractor's inherent advantage. At 70mm and F/10 the chromatic aberration is not going to be a significant problem, either. However, differences in quality could easily turn that around.

erenlinra

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Re: ultimate sub 100$ gift telescope
« Reply #31 on: February 09, 2018, 09:08:55 AM »
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<p class="citation">Mitrovarr, on 29 Nov 2015 - 9:15 PM, said:<a href="https://www.cloudynights.com/index.php?app=forums&amp;module=forums&amp;section=findpost&amp;pid=6916600" rel="citation">[/url]<blockquote class="ipsBlockquote built" data-author="Mitrovarr" data-cid="6916600" data-time="1448824514">
In general I think 76mm reflectors are a bad idea. Even if they're well executed, 76mm refractors are too close in price and would certainly be better. 114mm reflectors suffer a bit from this as well, except the dobs (because a dob will have a good, stable mounting and are ultra-portable, while a 90mm refractor is starting to really need a good mount).
Long tube (f9 or f10) 76mm Newtons are BETTER than cheap 70mm f10 refractors.I have used both.

I'm curious about this. Which ones?

I would not expect a 76mm newtonian to beat a 70mm f/10 refractor of equal quality, if both were decent instruments. The extra 6mm aperture is not going to cancel out the refractor's inherent advantage. At 70mm and F/10 the chromatic aberration is not going to be a significant problem, either. However, differences in quality could easily turn that around.

I agree that if the quality were equal, the refractor would be the better scope. The recent 60 mm and 70 mm refractors I have looked through/owned from Meade and Celestron are not up to the quality of the old Japanese scopes, maybe the Orion is better, a quality 70 mm F/10 achromat could show some nice views of Jupiter, split some close doubles.. The Orion 76 mm I looked through, seemed to have better optics but that is by memory.

The Newtonian has an advantage in that the tripod legs need not be extended so far since the eyepiece is at the sky end of the scope, a real plus for these undersided mounts.

Jon

Chris Young

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Re: ultimate sub 100$ gift telescope
« Reply #32 on: February 09, 2018, 10:12:48 AM »
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<p class="citation">Mitrovarr, on 29 Nov 2015 - 9:15 PM, said:<a href="https://www.cloudynights.com/index.php?app=forums&amp;module=forums&amp;section=findpost&amp;pid=6916600" rel="citation">[/url]<blockquote class="ipsBlockquote built" data-author="Mitrovarr" data-cid="6916600" data-time="1448824514">
In general I think 76mm reflectors are a bad idea. Even if they're well executed, 76mm refractors are too close in price and would certainly be better. 114mm reflectors suffer a bit from this as well, except the dobs (because a dob will have a good, stable mounting and are ultra-portable, while a 90mm refractor is starting to really need a good mount).
Long tube (f9 or f10) 76mm Newtons are BETTER than cheap 70mm f10 refractors.I have used both.


I'm curious about this. Which ones?

I would not expect a 76mm newtonian to beat a 70mm f/10 refractor of equal quality, if both were decent instruments. The extra 6mm aperture is not going to cancel out the refractor's inherent advantage. At 70mm and F/10 the chromatic aberration is not going to be a significant problem, either. However, differences in quality could easily turn that around.

A Tasco 3" az-el reflector with 1.25" eyepieces ($30 used) versus Celestron 70AZ refractor ( $36 Amazon special green tube ,1.25" eyepieces..BUT with that mediocre erect image diagonal),I also have several Meade 70f10 bought used.Still think the Tasco reflector is better.

A 114az-el is even better. and not much more $$$