The rule of thumb I hear most often is that you can get 50x per inch of aperture. That means you should be good up to 600x. A lot of factors need to be weighed in though: Seeing conditions, optical figuring, optical allignment and focus sensitivity are some of the factors that will affect the amount of usable magnification you can get out of your scope. You have control over two of the factors I listed. Optical alignment and focus sensitivity. If you don't have a laser collimator I highly recommend getting one. I was able to identify quite a few misalignments in my newtonian system the first time I used a laser. A misaligned system is even more noticable in short F ratio scopes like yours. Since your scope FL is 1460 your 9mm gives you 162x. You have a lot of room for more power if you want it. I have gone up to, believe it or not, 800x on my 8" F6 on the planets and moon using a 3mm Radian and a barlow. The seeing conditions were perfect, I had just laser aligned my system and it took a while to get the focsing right but the views of jupiter and especially saturn were amazing. It's cool to see the planets take on a true 3D sphere look.

Once again the best advise is to try what ever you want with your system. See what works and what doesn't. See what you like and what you don't. If you can get to a star party, try as much as you can in your system. Another way to try items out is by purchasing them used. I bought and sold quite a few eyepieces on Astromart over the four years I owned my current scope and I'm just now settling down with a few eyepieces that are keepers. If you don't like the way an eyepiece works in your scope you can usually sell it for about what you paid. I look at the shipping cost a a rental fee. If you don't like what you tried you pay the rental fee and get something else.


Bottom Line:
(1) Check and adjust your system for optimal performance.
(2) Try out different eyepieces in your scope and get the ones you think you'll use the most.
(3) Adjust and try someting else if you feel like it.

Astronomy is a hobby of patience. The moon changes on a monthly cycle, the sky changes on a yearly cycle and other celestrial events take even longer. Enjoy the ride this hobby provides. I know I do.

• 50x apperature rule - djmccrady - April 29, 2002 - 17:39 UTC
  • 50X rule - bobsal - April 29, 2002 - 21:26 UTC
    • 50x Rule - djmccrady - April 29, 2002 - 22:51 UTC