Eye Pieces and some advice

[vyeshaun]

Hello again.

Now I've read through the stickys regarding eyepieces. Im still a little confused though. Just if Im getting the hang of it.

I've just purchased a Skywatcher 130RA with a aperature of 130mm and focal length of 900mm. Which I have worked out gives me a F/6.9.

The trouble Im having is that I am trying to work out what EP's would be better suited for general viewing.

My Reflector comes with a 25mm & a 10mm EP

So far if I've worked things out correctly Ive got:

900mm / 25mm gives a x36

900mm / 10mm gives a x90 ( I really hope I've got this right?)

With my barlow x2 my max magnifications are x72 & x180.

So are there any other EP's you guys could recommend that I WILL need?

I hope Im working this all out right. I've read until my eyes bleed lol. Im looking at replacing my barlow with a meade one. But want to know how much of a difference it would make? Are the x3 Barlows any good? I appreciate that magnification isnt always important but would just like to see what I can squeeze out of a reflector under £150.

Thanks again. Will await your ever helpful replies and continue to read up.

[stick]

Hi mate

I've got the skywatcher 130 PM so my 10/25 eps are prob same as yours.

The stock eps are ok but you'll be suprised just how much better

You'll find it with some better eps.

I recently got some BST Explorer EDs (5 & 15mm).

They are a a big improvement. Far brighter and clearer.

Check out the "skys the limit" web site. About £40 quid each.

Lots of others recommend the TMB clones as well.

Hope this helps.

Stick

[david o]

I'd be tempted not to buy anything for now, just use what came with the 'scope. With eyepiece time under your belt you'll know what needs replacing or if there's a gap that needs filling.

The ins 'n' outs of choosing EPs can seem quite daunting but with a bit of experience with the 'scope and some general reading about astronomy it'll start to come clear. Honest

[nightfisher]

if you want to add one more ep, look at gso plossl in 15mm then on nights of really good seeing you can barlow it but 15mm is a good working size

[vyeshaun]

Thanks again

I have just ordered myself a 15mm and a 6mm plossl. Hopefully get some good viewing just as soon as my explorer arrives. Im buzzing I cant wait!

[John]

I'd be tempted not to buy anything for now, just use what came with the 'scope. With eyepiece time under your belt you'll know what needs replacing or if there's a gap that needs filling.

The ins 'n' outs of choosing EPs can seem quite daunting but with a bit of experience with the 'scope and some general reading about astronomy it'll start to come clear. Honest

That's exactly what I would have advised as well - accessory purchases need to be informed by some experience at the scope

[GazofCorra]

Spot on advice from David, as EP selection is an area that will take up quite a bit of time, which is better spent learning other things but reading the post from Warthog is a superb insight into eyepiece selection. Click here

Gaz

[vyeshaun]

Thanks chaps. I realise I might be jumping the boat a little here. Think Im going to invest in some good reading too. Just want to take in as much info as I can and Im alot better with practical learning.

[GazofCorra]

A good starting book which gets praise from quite a few members is "The Backyard Astronomer's Guide" as this book covers nearly all the bases you will ever need without going into too much depth.

Once you have your scope and start using it the book you would really benefit from is 'Turn Left at Orion" most people have it or have read it at some stage.

Later on you will decide what you want to concentrate on and can choose more detailed books which best match your interest in astronomy as there are many.

HTH

[ronin]

I would not try anything smaller then the 6mm eyepiece. Think that the scope has a spherical mirror and I would suspect that the aberations will become more significant if you tried for much more magnification.

The problem is that at the small end you will end up with eyepieces that go in 1mm increments. Some nights a 6mm will be fine another it will be a 7mm or an 8mm.

[Adz]

Also worth mentioning about a wider field eyepiece for the future. With a slower f ratio, you can get some great views from less expensive brands ie skywatcher panaview

[vyeshaun]

Awesome advice, thanks guy!

As for a Wider FOV with a slower f/ratio on the EP's how Would I go about working that out? Or am I being really stupid?

[GazofCorra]

The f/ratio is quoted by the manufacturer for each and every scope, fast scopes are f/6 and lower, slow scopes are about f/12 and higher.

The focal ratio of a scope is worked out with this simple formula (focal length / aperture) so if the scope has a focal length of 1200mm and an aperture of 200mm (1200/200 = f/6) the focal length is the length the light has to travel from the lens, mirror or both to the eyepiece.