Now for another EP thread

[Damienandwendy (Damien)]

This is such a broad and variable topic I know, but still thought I would post here to get a feel for things. I have read a lot of posts about this but I am trying to cover 2 scopes and not just 1

First thing first: I am not looking for an expensive single EP to kill all EP's - I am looking for 2 or 3 EP's that are significantly better then the standard 10/25mm plossls that come with Skywatcher scopes.

At the moment the only different EP I have is a 6mm Prostar :http://www.myastroshop.com.au/produc...sp?id=MAS-004I
As to telescopes: Primary will be the 10" F4.7 goto dob, Secondary : 5" F12 goto Mak.

My budget at this time is around the $150-$200 per EP. With that in mind I am looking at Hyperion's, Vixen NLV's, Orion Stratus and ES 82d. More than happy to consider cheaper EP's too if there is something you have or have used which you liked. GSO superviews is one that I have noticed that people seem to like even though they are fairly cheap.

I am not thinking of particular sizes at this time .... apart from covering low/medium/high magnification across the 2 scopes.
I have also been reading a bit about different EP's and their effect on fast/slow scopes. I know that I am potentially being unrealistic at being able to get 2 or 3 EP's that will cover the 2 scopes, but that's why I have posted in the hope that someone has some wisdom to share.

Thoughts/comments/ideas appreciated.

[dannat (Daniel)]

Of the ones you mention the lv & ES will be best at the edge at f4.7, your mak will take any ep's. One not on your list are the BST explorer (astrotech paradigm by another name) can be had for <$100 from telescopes astronomy in SA, good edge & comfortable to look thru. The lv are also comfortable, the ES less comfortable

[glend (Glen)]

I love my GSO Supviews in 30mm and 15mm. They are very good and my EPs of choice.

[casstony]

Probably easiest to pick from the ES 82 degree eyepieces; perhaps start with a 24mm and 11mm, and perhaps the 6.7mm if you are able to use 180x magnification reasonably often (I imagine you would have fairly stable skies up in Townsville).

Some of the ES 82 degree eyepieces get less favourable reviews: the 14mm is reported to have field curvature, the 18mm tight eye relief, and reflections in the 4.7mm.
I have the 30, 11 and 6.7 which I think are very good eyepieces.

[Astro_Bot]

The ES 68deg 28mm is very good. (I also have the 40mm that I quite like, but it's a bit long for your scope).

I concur with the above comments on the ES 82deg 14mm and 18mm, though, apart from the tighter eye relief, the ES 18mm is quite good overall - better than the Baader Hyperion 17mm, for instance, to which I compared it closely.

I also have the ES 82deg 11, 8.8 and 6.7mm and find them all quite good, though there's a bit of flaring on bright objects with the 8.8mm (that I don't notice with others).

I did extensive side-by-side comparisons with a Baader 8-24mm Mk III clickstop zoom - I found it slighter better than the ES 82deg 14mm at that F/L (although it was a close-run thing). In general, it wasn't quite as good as the other fixed length ES eyepieces at the same F/L, but it came pretty close, and considering the costs involved, that means it holds its own, IMHO.

I've also had the GSO Superviews and, whereas they're not bad for the money, they are no match for the other eyepieces I've mentioned.

[Damienandwendy (Damien)]

Hi to All that have responded and thank you for your replies.

I have been trying to focus mainly on EP's for the new dob and the mix of AFOV and focal length makes it interesting to get a feel for the view you might get.

I have been using the Scope+EP addin for Stellarium to get an idea of AFOV and EP focal length - does anyone know if this is a reasonable representation of what you might see through a particular scope and EP combo as far as TFOV goes ?

cheers

[Astro_Bot]

Originally Posted by Damienandwendy

I have been using the Scope+EP addin for Stellarium to get an idea of AFOV and EP focal length - does anyone know if this is a reasonable representation of what you might see through a particular scope and EP combo as far as TFOV goes ?

For TFOV, it's quite useful, but it's not the same as the real thing - you won't see astigmatism, coma, field curvature, flaring, or other aberrations that might be introduced or exacerbated by an eyepiece - Stellarium assumes perfect optics every time.

Also, the "Ocular" plugin doesn't show the limitation of the human eye, i.e. Stellarium gives you a flat disc on the monitor that is easy to see all at once but some eyepieces have an AFOV too wide to see in one "glance" and you never get a sense of that.

Stellarium can also simulate light pollution, but I find that of limited use overall, and no use with the "Ocular" plugin.

[Astro_Bot]

Try this as an eyepiece FOV simulator (though it has similar limitations to Stellarium):

Eyepiece FOV Simulator

[Damienandwendy (Damien)]

Thanks Astro,

I just happened to find a nice calculator with recommendations on exit pupil and magnification - http://www.stargazing.net/naa/scopemath.htm

Adding more maths but I have read on other posts people suggesting EP's based on exit pupil more so than actual magnification.

With that in mind, in my 10" F4.7 Dob:
ES 6.7mm 82d - exit pupil 1.4mm
ES 11mm 82d - exit pupil 2.3mm
ES 18mm 82d - exit pupil 3.8mm

I think those might do to start with ... VTI in Oz don't have other good sizes in stock atm.

The search and research continues ...

[Richard Gamble (Richard Gamble)]

Yes, I agree too, that the ES 82D are the ones to go for IMHO and the 6.7, 11 and 18mm are available from VTI in Oz.
I purchased my 6.7 from them.