[AZ-Observing] Re: Refractor Comparison


Jeff Hopkins wrote:

>Back to Stan's dilemma, I think if he want to attend events where 
>solar system objects or double stars re view, a refractor will be 
>great. If he wants to use the telescope at dark sky star parties, a 
>larger DOB would be a better choice.
>
>  
>

Well, actually my dilemma is not whether I want a telescope to attend 
events where solar system objects or double stars are viewd vs. a 
telescope at dark sky parties, but instead to determine which of the 
various makes, f-ratios, objective sizes, and optical design of 
refractors would give me the most all around satisfying image. I am sure 
others would be interested in the same thing. For example, an RR (which 
I doubt anyone in Arizona has) is reported to have a much sharper image 
than a Synta, but just how noticeable is it? We all read Jack's report 
of his new 100mm ED, but just how does it compare to other refractors? 
We not know, and written descriptions are difficult to visualize. What I 
want to use it for is not the issue. Whether it should be an issue is 
valid, but I am already aware of this and am not seeking advice on 
whether to get a refractor or reflector.

It is a given that I will get a refractor. Determining which refractor 
would give me the best all around image can only be truly determined by 
a comparison of various refractors at the same time on the same object 
or part of sky. Would a Asto-Physics be best? I do not see how the cost 
can justify it. Would an f6 be good, or would an f8.3 give a 
significantly better image to justify a significant loss in field of 
view? How much does an f6 of the achromat design degrade the image of 
the the moon or planets compared to an apo? Yes, there is some color, 
but would I, or others, think it that objectionable to justify the cost 
of an apo? One might be able to make a statement, but individual case 
statements are difficult to visualize. let's see, for example, in 
actuality how an Orion f6 compares to an A-P (or other make) of the same 
f-ratio or near f-ratio. It may be stated that the figure on an A-P 
refractor is better than an Orion, but just how noticeable is it on the 
actual image? One may be able to make a statement, but statements are 
hard to visualize. It may be that after using a refractor extensively I 
may be very unhappy with one, but that is another issue. However, I must 
say that the dark sky view through Jacks 80mm Orion refractor at the 
last Messier marathon was great.
Stan

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