eyepiece set??

hi, i have a question regarding ep's, now im very new at this hobby, have just bought a well used scope (cave 8" F/6) made in 1974,and it came with 3 old ep's, now ive got the scope all set up and collimated, have had it out 6 times, now, the ep's that came with it are a 40 mm kelner, and 2 ortho's ,a 4mm, and a 6mm.

to cut to the chase, the orthos look like they were dissasembled at one time, i am getting blurry views with them. i was looking at a budget set of ep's and was wondering what you more experienced thought of my selection? its a full 9 piece set(from 4mm-40mm) there Super Plossl and made by GSO (i think)

heres a link:
http://www.dbaastronomy.com/DSO%20Plossls%20Ep.htm

should i invest in these with maybe a 2x barlow. would i get a better idea what my mirror is capable of with such a set? the price seems alright. i want to recoat my mirror, and maybe get it refigured, but want to see what it does with new ep's first.....and i cant afford 100$+ ep's!

thanks for reading this.

Doug:

You will want some more eyepieces to be sure but I would not invest in the entire set.

With your 8 inch F6, the 6mm eyepiece provides 200x, the 4mm eyepiece provides 300x.

Unless the scope is well collimated, has cooled down and the seeing is quite good, those high power images will most likely be blurry. It takes an hour or more for a mirror that size to come to thermal equilibrium and until it does, it will produce tube currents and other effects that degrade the image. If the seeing is not good, ie the atmosphere you are looking through is not stable, then the image will not be sharp.

So, it is likely that any 4 or 6mm eyepiece would have provided similar images. If the scope is well collimated and you have waited for the hour or more that it takes for the scope to cool and you still have to wait for those moments when the atmosphere is stable... Turbulence in the air column you are looking through is like looking through a mirage...

Plossls are good eyepieces in an F/6 Newtonian. Personally I think something in the 25mm range, maybe a 32mm, a 15mm, a 10mm and something around 6mm plus a barlow are good choices. Look around for used eyepieces, most often you can save real money and get some good eyepieces at the same time.

The recent thread here about selling eyepieces that were not up to snuff is completely atypical of my experiences here.

Every eyepiece I have purchased here used has arrived and appeared to be essentially new though the seller just said it was in "good condition."

Jon

It's a good deal in some respects, but I think it's a better idea to get fewer eyepieces than it is to get tons of closely-spaced focal lengths.

You just won't get much use out of all of these eyepieces. The 32mm Plossl will be better than the 40mm, so skip the 40mm. A 4mm or even 6mm Plossl will be very uncomfortable to use - you have to hold your eye even closer than your 4mm and 6mm Orthoscopics. You'll want to get a barlow to achieve short focal lengths. 12mm and 15mm are very close together in magnification, and 32mm and 25mm are too close in my opinion as well.

So, just pick and choose:

32mm, 20mm, 12mm, 9mm. That's $116. Then get an Orion Shorty-Plus Barlow, which is as nice of a barlow as you'll ever need, for about $80. You've spent less money, AND you'll be happier.

Or you could get by with 2 or 3 more expensive eyepieces and a barlow, especially if you buy used and are willing to go a little above the $200 this entire set would cost.