Celestron 127slt: Help with recommended eyepeices

[Dragko]

Hi folks,

As Christmas approaches I would like to add a couple eyepieces to my wish list . I was wondering if there are any MUST haves for this scope. I am also looking for advice on the best Barlow that is still reasonably priced. I understand 4mm would be overkill with this scope. What is your most used eyepiece with this scope?

Thanks for any suggestions!

-Dragko

[Ruud]

Hi Dragko,

if I'm right you have an f/12 Mak with a 1.25" focuser. If you want an apparent field of view of 50° or larger you can use eyepieces from 32 mm to 6 mm, giving magnifications from 47 to 250 times. Here re are just a few suggestions. Your telescope, by virtue of being a slow telescope, is not finicky about eyepieces. These eyepieces would all work fine in a slow scope

	focal length	afov	magnification	tfov
GSO Plössl	32 mm	52°	47 x	1.07°
ES 68° / Meade 5000 SWA / Maxvision SWA	24 mm	68°	63 x	1.04°
Skywatcher Nirvana / WO UWAN	16 mm	82°	94 x	0.84°
Baader Hyperion	13 mm	68°	115 x	0.59°
Celestron Luminous	10 mm	82°	150 x	0.55°
Baader Morpheus	6.5 mm	76°	231 x	0.33°

afov = apparent field of view (how big it seems to your eye) and tvof  = true field of view (how big it is in the sky). 

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1.1° is about the largest field of view you can get from your telescope. Slow, small telescopes are very good for smaller targets like the Moon or planets, but there may come a day that you want wider views. That probably means buying a second telescope like a Dobsonian, with faster optics.

Not all eyepieces work optimally in both slow and fast telescope. For a fast telescope I would not recommend the GSO Plössl, Baader Hyperion or Celestron Luminous. They'll give fine views in a slow telescope, but not nearly as fine in a fast one. 

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When you activate the Oculars plug-in of Stellarium you can get an idea how eyepieces frame different targets, and how the apparent field of view impacts the viewing experience. Both eyepieces give about the same true field.

If you haven't already downloaded Stellarium, do so now. Set it up for your home town, and set up the Oculars Plug-in for your telescope, the eyepieces you already have, and any new eyepiece you consider buying.

 

 

 

[Northern Soul man]

Hi Dragko, a very warm welcome the the SGL - Hope your enjoying the 127 - I Have one and find it a very nice scope to use and transport around my garden.

Ruud Has pointed out (very well) what sort of EP's to look for - My scopes have focal lengths of F10 and F 12 ish - so are great for the cheaper EP's - I've got nearly a full set of the Hyperions and find they work very well with both my scopes - I don't think you can really test an EP at these focal lengths, but you get what you pay for these days, with the exception I think of the Explore Scientific's - I have a few of the 82 degree, and find them very nice to use - but i look at the bigger picture - not just what the maths tells me.  Its fine to get a grip of the formulae and charts, but I find that you just need to try as many as you can before buying - I hope that your in this position and you have friends or know of other Astronomers or clubs where you can have a look through or borrow EP's - this would be my best advice to see if you can try before you buy - when I first started out I collected over a few months, a set of Meade 4000 Plossl's - I used these for such a long time - if you can get over the very short Eye Relief and you don't wear glasses at the scope, this would be a good introduction, the longer focal length EP's are much more comfortable to use - this is a point with the Ex Sci 82's I have - they are well corrected by all accounts - so with very little aberrations to deal with - but with very short Eye Relief - you really have to  get your eye in very close to the eye lens (the one you look into when its in the scope) and I have great difficulty "looking around" with my eye so close to the eye lens - this is where I like the comfort of the Hyperions - even at 5 and 8mm focal lengths - they give a very comfortable feeling when looking in - even with my glasses on, I can manage because the eye lens of the EP's are a lot bigger than most.

I hope you can try before you buy - but the most important point to make is that YOU need to know what feels right for YOU at the scope under the night sky - yes have a look and research the maths associated with Magnification, TFOV, Eye Relief and so on - but at long focal lengths - the "budget" EP's work just as well as the "premium" priced ones at F10. 

So with a little of the Maths, make sure you can use this by spending A LOT of time at the scope, using the EP's what you already have and assessing whats BEST for you - when your looking through these threads for advice - take it all in - then get around the back of the scope for a good clear nights observing - if you have light polluted skies - stick with the brighter Messiers/Moon - if your anything like me - I tend to forget all the Maths at the EP - even Magnification - you know the low power views always feel just that bit better for me.

Paul.