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Hi Voitty,
As Erick said on your other thread, better do some reading.
I just downloaded some specs on what I believe you have:
Optical Design: Reflector
Aperture: 130 mm
Focal Length: 650 mm
Focal Ratio: 5
Eyepiece 1: 20 mm
Magnification 1: 32.5 x
Eyepiece 2: 10 mm
Magnification 2: 65 x
calculating Eyepiece 3 (4mm) would be 162.5 x magnification.
Thats a big jump from the 10mm.
And to be able to get a clear image with that much magnification is going to require a very clear sky with good conditions.
So this is why your 4mm is fuzzy.
The general rule is higher magnification for planets, less for the moon if you like, and lower magnification for Deep Space Objects like Clusters and nebulae.
I read on a thread here the other day that the best sort of magnification one can expect is around a factor of 1.2 time the aperture.
So that would be 156. So the 4mm is right on the edge of the best you could expect (and that is on a good night.)
the other thing about plossls in the 4mm range is that the exit pupil is so small, its like looking through a straw.
So you may be advised to buy an ED. they are much bigger image, easier to look throufh and you can get a 5.2mm one which may better suit you.
I have a 5.2mm ED that I bought new, think I paid $80 for it on special.
I have since changed my scope and dont use this much now.
It is probably just right for you.
Let me know f you are interested and we can work out a deal, depending on where you are. (Something like current retail by half, and PP).
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