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What can we say about 14" orion reflector.

Started by ref68, 11/06/2009 04:21AM
Posted 11/06/2009 04:21AM Opening Post
Hi,I have 10"lx200 i'm suffering with mising light!
in a satr party I was looking though 18" obsession m42 was beatifulle I now I canot affort that 18"
for better than nothing 14" could be better .
any one has one.to tell me the defferance in the optics.
compare to (18" VS 14"), (14" VS 12"), (12" VS 10"lx200)
clear skies.
Posted 11/06/2009 08:41AM #1
Hi Refet,
I have owned 8,10,12.5,14.5,15" Dobs and in my opinion a 12 vs. 14 is pretty close really. The 12 vs, 10 SCT however, there is a pretty good difference due to central obstruction and perhaps optical quality. 18 vs. 14, well the 18 is brighter, but unless you go to a much larger scope, say 20-22" the differnce is not that big.
Aperture is king, but there are other factors as well. Transporting and setup of a large scope can be a problem, unless you have the proper vehicle. Then there is optical quality, where a smaller scope may produce a better image on a good night due to the better optics. Plus, height at the EP, do you have to use a ladder and do you want to use a ladder? Many things must be considered when you decide to move up in aperture and design.

[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue grin
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Posted 11/06/2009 08:41AM #2
refet dehari said:

Hi,I have 10"lx200 i'm suffering with mising light!
in a satr party I was looking though 18" obsession m42 was beatifulle I now I canot affort that 18"
for better than nothing 14" could be better .
any one has one.to tell me the defferance in the optics.
compare to (18" VS 14"), (14" VS 12"), (12" VS 10"lx200)
clear skies.

refet: I find M42 beautiful in any scope, certainly a 10 inch is enough to provide wonderful views of M42. Before you giving up on your current scope, I suggest first considering the exit pupils/focal ratio/brightness issues, what you are likely missing is the possible with a faster scope.

I don't know what your current configuration for eyepieces but an F/10 telescope without a reducer corrector and without a 2 inch diagonal will generally be limited to something like a 3.2mm exit pupil while a typical DOB, 10 inch or 18 inch will be capable of operating at the maximum 7mm exit pupil, this is because of the F/5 and under focal ratio.

For a bright target like M42 for a fixed exit pupil, one can consider aperture only determines image scale, not brightness. Your 10 inch with a focal reducer and/or a 2 inch eyepiece could provide you with a exit pupil in the 5mm range, that would be about two and a half time brighter...

I don't quite know where to put the 14 inch Orion, my own collection includes 10 inch, 12.5 inch and 16 inch DOBs as well as a 12.5 inch on a GEM. I like them all and on any given night I am happy to use any of them though each has particular advantages. These scopes are generally a question of choosing size and awkwardness vs aperture. If you really want to grab the most light, I think a used 16 inch Lightbridge would give you the most bang for the buck...

The Orion's are new so a used one is out of the question and list at about $1800 plus shipping. Orion has a way of nicking the buyer for an extra hundred or so on the shipping... Herb has the 16 inch Lightbridge new for $1849 and I'll be that when shipping and handling are added it would actually be cheaper.

http://www.buytelescopes.com/Products/11470-16-lightbridge-truss-tube-dobsonian-deluxe.aspx

Of course the Lightbridge doesn't include DSCs/Intelliscope, that would be extra if you felt that was necessary.

Also beware, I would suspect that when you were looking through that 18 inch Obsession, it was very likely that there was a Paracorr and some rather expensive eyepieces in the focuser. A fast Newtonian can provide wonderfully clean and sharp views right up to the field stop but it takes a real investment in eyepieces to make it happen.

But first, if you are using 1.25 inch eyepieces without a reducer corrector, I suggest further investigation along those lines.

Jon