Eye Piece Choice

[SJC03]

Eye piece choice for planets with 80mm 550 FL refractor

I have not upgraded my eye pieces since my 80mm 480 FL refractor and as such my Vixen 5 eyepiece is my most powerful ocular.

For general viewing this is not a problem but for planets the image size is just to small in view.

I experimented with a Hyperion 8 eye piece adding tube rings to get 4.3 and looked at Jupiter.

I liked the view and larger image size so this is my planet view for now.

The question really is would a/ Hyperion 3.5 be better

b/ A barlow

C/ Powermate

I do not use Barlows and a powermate is expensive, out of choice I have Vixen LVW & Baader Hyperions.

My other scope is a GSO 8" astrograph.

[Ags]

A common guideline is that you can use an EP with a focal length equal to half your scope's F ratio. I know many owners of quality refractors push the magnification even further than that... Your scope is F7 so a 3.5mm EP should be usable.

I can't see your sig but I am assuming your scope is an apo.

[great_bear]

A common guideline is that you can use an EP with a focal length equal to half your scope's F ratio.

Hmmm... but only if its got great optics!

On many (most?) scopes, about 75% of F-Ratio number is the smallest focal length in mm that you can achieve before the image dissolves into mush...

i.e. for a F5 scope, that's 3.75mm

[Ags]

I'm assuming the scope in question is an apo with quality optics. The maximum 'good' magnification is also highly personal.

I've been told for example that my scope has a max useful mag of around 130 but I strongly disagree - I use 220x on a regular basis. It all depends how you look and what you are looking for.

I'm pretty sure almost any scope, except a fast achro, can get up to 150x on certain targets, which is what the 3.5mm hyperion would yield.