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)
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.
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.