eyepieces Help?

Ok thanks for that info John, I will research the Hyperion 21mm and 13mm eyepieces for future reference. Now can anyone do anything about the weather please? There should be some better weather for us from Sunday, because there will be an artic airflow pouring over us and it will either snow (Yay) or if not will be nice and clear albeit cold.

Sorry to bother you guys with this kindergarten stuff but, As I mentioned, I have a C8N 1000mm F5 reflector, Which I now know would have an average mag of 225x here in Ireland, to realise the high magnification with comfort I should get a Planetery HR eyepiece and not use barlow, the thing is if I get a 5mm eyepiece, the mag will be 200x, if I get a 4mm the mag will be 250, which probably wont be usable. I would need a 4.5mm, but this doesn't seem to exist in this long eye relief lense. If I stay at the 200x I am losing 11% of the mag potential. Should I be concerned about this of just be happy with 200x and not be greedy? hope that makes sense!

Rayman

The maximum magnification is usually 50 times the aperture of the objective mirror which in your case is 400x. So your 200x and 250x and even 300x are quite usable.

However the problem is finding an eyepiese of the right size to get to these powers and so you will need to use 2x barlows or even 3x barlows.

It is seldem that you will be able to use the highest mag. of 400x however and usually only on very bright objects like the moon or maybe on a bright planet. Sometimes the seeing will be so bad you wont even be able to use 200x without the view boiling and bubbling away:D

Also the higher the magnification that you use, then the less of the overall light gathered by the main mirror will be used by the eyepiece to form the image that you see. Thus the inage will be fainter, and atmospheric fussiness will be magnified as well to show you just an indistinguishabel grey blob.

So as regards whether you should go for 225x or a 200 x I would think that there would be no appreciable noticable difference in the views you would get as a casual observer from either eyepiece and some nights you would be saying i wish i had a lower mag. Other nights you will be saying i wish i had a higher mag.

I guess i would therefore suggest you could get a 5m which will give you 200x and 400x with your barlow. Or mayby get a 6m which will give 166x and 333x with barlow. I personally think that the second combination would give you by far the better usage fo the same reasons given above. Then later consider the 4.5 afterwards to fill the gap.

The main thing to consider is that the higher mag. that you have the less nights you will be able to use it although those nights will be ones to remember. So it is not worth your while trying to get the absolute last possible iota of magnification out of your scope. I dont think it works that way.

hey this was only ment to be a short post

Rayman,
One of things that really surprised me when I started observing, is that high magnification is not be all and end all. Lots of objects such as Nebulae, galaxies, and open clusters, are more pleasing in low magnification rich field views, my favourite eye piece is a wide angle 15mm which give me x66 and 1 deg FOV . Though high magnification also has its place, eg planets and binaries.

Another thing to watch for, I have 6 eyepieces and a x1.5 and x2 Barlow, this gives me 15 different magnifications I can use. Personally I can find this very confusing and waste time that could be spent viewing dithering over which combination of eyepiece and barlow to use.

Thanks David, Thanks Martin, Your points are well noted.
I think I will get the TS 32mm as my lowest eyepiece, a 6mm plossl which I can 2x barlow - this should lengthen the eyerelief, I think, though I will lose light & I will also get the 5mm planetery HR eyepiece. I think that will cover most situations for now.
:shock:

The beauty with buying decent equipment is that if it doesn't suit you or you don't like it, you can always flog it off in astromart or the for sale section on these boards.