Synta ED refractor versus Firt class refractor.

Hello,

For a specialized refractor in the work of splitting doubles, what is best, for example, a Synta ED of 4" or 5" , or First class(Televue,Takahashi,TMB...)of smaller aperture,2.5" or 3"?

Anyone have proved this question, side by side?

Thnks,
Paul

Hi Paulo,
Well, larger means higher resolution, which on tight doubles is good. I have a Meade 127ED f/9 APO that splits doubles very well. They sell for a reasonable price when you can find them. I have had as much luck with it as a very high quality APO of the same or larger size. But I have not tried too many times with my 80mm APO, which is a high quality APO objective, so not sure whether it would have compared on the same night.

Paulo martin said:

Hello,

For a specialized refractor in the work of splitting doubles, what is best, for example, a Synta ED of 4" or 5" , or First class(Televue,Takahashi,TMB...)of smaller aperture,2.5" or 3"?

Anyone have proved this question, side by side?

Thnks,
Paul

In my experience, splitting tight doubles is very dependent on the aperture of the telescope. A good 4 inch will split something down around 1.15 arc-seconds or so and a 3 inch is going to have problems with it. False color is not such a problem with doubles unless they are significantly different in magnitude so a good solid achromat or a newtonian are good tools for splitting doubles.

jon

Having high performance optics is not a requirement for splitting most doubles. Aperture is the main criteria. A 1/4 wave optic will split equal mag doubles as well as a perfect optic. When splitting unequal doubles, aperture plus high correction is a requirement.

Rolando

Hi Paul,

I was able to get better splits on every double tried with a 12" Orion Newtonian with an off-axis 4.25" mask than with my FS102 set up right next to it. My Discovery 8" F7 Newt is the best double star instrument I've ever used bar none. I had an MN56 that was excellent on doubles as well. My point is that you don't necessarily need an Apo for doubles. The short focal length of many Apos is, IMHO, a detriment for doubles due to the need for Barlows and very small exit pupils.

Hope This helps,

Steve