Plossl Eyepiece Query

Hi Guys,

I recently bought a Celestron firstscope 90mm refractor. I'm quite happy with it, I knew the eyepieces were failry basic (Kelner). I have decided to invest in a Plossl 9mm eyepiece anyone had any experience with upgrading eyepieces like this, should I expect it to make much of a difference to the quality of image or will it be a small improvement at best ? My interests are purely visual I have no interests in photography. I particularly I want to see detail on the planets I ordered a filter set to which might help this.

I have seen a nice bit of detail on jupiter last month (considering I live in an urban area). Mars I cant see much but judging from the Mars thread on this forum today people with much bigger scopes are having problems viewing details on Mars with current conditions.

regards,
PatC.

Hi Pat,

Kellners are perfectly respectible eyepieces... for low magnification. When used for high magnification (the shorter focal length eyepieces, say 20mm down to 4mm or shorter!) you will see that the stars are no longer round except at the very centre of the field of view. You may also notice some colour fringing on brighter stars and the moon - again more so towards the edge of the field.

Plossls are a more sophisticated design and do a better job of correcting these aberrations even at higher magnification. Other eyepiece designs will do a better job than Plossls and will give you a wider field of view... but you start to pay big bucks for those monsters.

Magnification is worked out by dividing the focal length of your telescope by the focal length of your eyepiece.

Phil.