Eyepiece confusion

[ottoman]

I have decided to get back into stargazing again as I have alot more time spare.

I am still relatively inexperienced at the hobby, I used to stick any old eyepiece in my scope and if it looked ok I assumed that I had the correct eyepiece.

I have spent most of this afternoon setting up my Skywatcher Explorer 130m making sure that its balanced and ready to go.

I have also read "The Warthog's eyepiece thread" and have worked out what I think are the eyepieces I should be using. Great thread by the way Mr Warthog!

F=900

D=130

900/130 = 6.923

5.175, 8.625 , 13.8 and 20.7

Am i correct? I know that eyepieces are not these exact sizes so do I buy the nearest ones? I have some meade eyepieces and also the standard ones that came with the scope, The meade ones are so much better on viewing quality. Any advice would be greatly appreciated!

Here is a pic of the pieces

[nightfisher]

ottoman, your correct that the eyepieces that came with your scope are not so good, your meade 26mm is a strong one, also the telescope house 7mm is an orthoscopic and very good, but only on nights of very good "seeing" a 12-15mm would be well worth getting, there is a GSO 12mm on ebay at the moment

[ottoman]

Is this correct nightfisher? Thanks for the advice!

GSO 12mm super plossl | eBay

[Capricorn]

With the scope the sizes would about match what you list:

Say 6mm, 8mm, 12mm (or 15mm) and a 20mm.

As to make the TMB planetary's come in 6, 8, 15, 20mm at Sky's the Limit.

The BST's come in 5, 8, 12, 18 or 25mm again Sky's the Limit.

TS have much the same but the cost appears to work out a bit more.

Above these in cost come the Celestron X-Cel's at 7, 12, 18mm £69 from FLO.

Meade Super Plossl's Series 500 are a bit more.

As all the ones you have are plossl's you could get more of those although at 6mm or 5mm the eye relief will be minimal.

[nightfisher]

Is this correct nightfisher? Thanks for the advice!

GSO 12mm super plossl | eBay

thats the one

[rwilkey]

Ottoman, your theoretical ep sizes are spot on, but choose quality carefully, as you have plossls already, I would look at others with more elements and better eye relief at the higher mags, unless you go for the Vixen plossls, which are really good quality.

[ottoman]

Thanks so much for the help rwilkey, nightfisher and capricorn. I am still a little confused about what eye relief is, and the word plossl. I know that plossl is two lenses in a eyepiece but why would you choose a plossl over a different type, im not sure what other types are called.

Thanks for your patience and help!

[ottoman]

Ottoman, your theoretical ep sizes are spot on, but choose quality carefully, as you have plossls already, I would look at others with more elements and better eye relief at the higher mags, unless you go for the Vixen plossls, which are really good quality.

When you say look at others with more elements and better eye relief at higher mags could you give me some examples?

I have been out this evening and I enjoyed my 26mm meade 4000 super plossl the most. It seems to give a really wide field of view and is comfortable to use. My 7mm orthoscopic one is blurry and doesnt seem to have a wide field of view. Its not very comfy either. I have noticed that my mirror is dirty and dusty so I wounder if it could be affecting the quality, or it could be that its just a cheaper model scope.

[jfox61]

Eye relief is the distance from the eyepiece that your eye can be, and still see the full field of vision. The further away, theoretically speaking, the better, as this means less eye strain.

[jfox61]

A little dust or dirt shouldn't affect it, but obviously if it is heavily soiled it will. If it is loose dust you can try using a camera blower bulb, one of those rubber bulbs wtha brush on the end, you'll need a large one, to dislodge it. But don't wipe it or use any liquids to clean it as this will kill your mirror

[ottoman]

I have posted a mirror cleaning topic in the scopes bit. Thanks for the explaination on eye relief jfox61.

[rwilkey]

Hi Ottoman, I have posted an article on eyepieces, plossls and eye relief here: Robins Eyepiece Guide Multiple element eyepieces tend to be a bit more expensive, but are better corrected and often give better eye relief, the trouble with high power plossls is that you have to get your eyeball up really close to the eyepiece to get the full field of view, with better quality eyepieces with a large eye lens, it makes for much more comfortable viewing.

[ottoman]

Ok Robin I will have a read of your eyepiece guide! If I have anymore questions I will ask.

Thanks alot!