Difference between lenses

[bob4026]

Hi all,

I will be upgrading the cheap lenses supplied with my scope and was wondering if anyone could explain the differences between the Celestron Omni and the X-Cel LX ranges? Is it just simply a quality / price thing?

Thanks for all and any help...

ATB

Bob

[Ricochet]

The Omnis are a common 4 element eyepiece design known as a Plossl that gives a 50 degree apparent field of view but at short focal lengths can become uncomfortable to use as the eye relief becomes very short. In years gone by a Plossl would have been a prized possession.

The X-Cell LXs are a newer 6 element design giving a larger 60 degree apparent field of view and much improved eye relief. They are commonly recommended as a step up for anyone looking to upgrade from the eyepieces normally supplied with a telescope or from Plossls. A similar performing eyepiece is the BST Starguider/Explorer which is available from http://www.skysthelimit.org.uk/ for £50.

[Putaendo Patrick]

If you're in the market for secondhand EPs, it's worth mentioning there was an earlier version of the Celestron X-Cel without the LX suffix. These have an AFOV of 55 degrees and incorporate one or (I think) two elements of ED glass. When they came out they had generally positive reviews. Compared to the LX version, some say they are better, some worse and others say there is little difference! Certainly some of the older 18mm's had quality control issues. I have two (25mm and 18mm) of the old X-Cels, but have never had the chance to put them side by side with the newer LX version.

As Ricochet says re Plossls, modern EP design has come a long way in the last decade or two!

[happy-kat]

This is a very good read

http://www.swindonstargazers.com/beginners/eyepieces.htm

[John]

I've used a couple of the older Celestron X-Cel and the newer X-Cel LX's and there was quite a difference to my eyes in performance with the older X-Cel being optically outclassed by the newer X-Cel LX. The differences are light scatter and ghosting which are really quite annoying when using the X-Cel on bright objects.

The Meade HD-60 series are rumoured to be the same eyepiece as the Celestron X-Cel LX.

Personally I reckon the BST Explorer / Starguider's are as good as the X-Cel LX's and quite a bit less expensive.

[laudropb]

As you can gather choice of eps is a very personal matter. I much prefer the XLs over the BSTs.

[Ricochet]

Out of interest what do you prefer about them?

[John]

As you can gather choice of eps is a very personal matter. I much prefer the XLs over the BSTs.

Agreed on the personal choice. Neither are actually my favourites but when I compared them I could not see any differences that justified the additional cost of the X-Cel LX's over the BST Explorer / Starguiders. The X-Cel LX's have a heavilly curved field lens that is bang on the focal plane of the eyepiece so any sort of dust shows up sharply and can't be removed with any amount of cleaning plus I found this lens causes some off-axis glare.

For what it's worth, at longer focal lengths I think the Maxvision 68 is a superior eyepiece to either and that is also a sub-£100 eyepiece.

I ought to add that none of these are in any way poor eyepieces - these differences are minor really but I'm a bit fussy over eyepieces I guess

[Owmuchonomy]

As above.  Just to say that the Cel 40mm Omni is an absolute steal for use in long focal length scopes.  If you search around you can sometimes get it less than £20.