cannot get focus /astromaster EQ 130 MD

[juleznz]

KiaOra everyone from a Autumny New Zealand ok ive just purchased a 2nd hand Celestron astromaster 130 EQ MD......Pristine condition 6,mths old and seller highly recommended showed me his pics he had taken with scope all seems good there...I set scope up followed instructions to a T...waited for clouds to clear Milky way is out and clear aim and focus on jupiter just a white blob...im turning focus knobs looks to be getting sharper then just when its going to get in focus nope other side of out of focus ..tried the 2 eyepieces 4mm and 10mm has a barlow with scope nothing at all thru that nothing thru the 4mm at all just out of focus and cant get into focus on the 10mm...any suggestions plz?

[Knighty2112]

Have you tried focusing on a distant object in the landscape in the day time at all? Try to see if it is Ok first like this before you try again at night time. If you still can't achieve focus then either the secondary mirror might have moved or been moved previously. I have this scope too and once moved the secondary mirror to what I thought was the right place for collimation, but could not achieve focus with any of my EP's after doing this, so had to move it back to the previous place, which on this scope is off centre when looking through the focuser hole. 

[brantuk]

The 130 has a focal length of 650mm so the 4mm eyepiece is giving you 162x magnification which should give a well focused view of some sort. But it depends on many things - quality of the lens, seeing conditions on the night, height of the object above the horizon, humidity, transparency, light pollution, dark adaption, etc, etc. You need to have all of these come together at the same time to get the best view.

My guess is either a "not so good" eyepiece, or collimation problem - but really it could be any of a number of factors. I'd suggest starting by borrowing a good quality 4mm eyepiece from a friend, or colleague at your astro soc, to eliminate that from the investiation.  

[happy-kat]

The Moon would be a better target for testing focus on.