Newbie, first telescope Nexstar 8SE: need eyepiece recommendations

[nwink]

Hello.  I'm considering buying the Nexstar 8SE (SCT) for my first telescope, which comes with a 25mm eyepiece.  I hope to buy maybe two additional eyepieces, and I'd like pretty good quality eyepieces that also have a bit larger FOV (maybe 60-70 deg).  (While a multiple eyepiece kit would let me try a lot of focal lengths out, I don't want to spend money on cheap quality eyepieces...unless people on this forum would say the Celestron or Meade kits are alright, especially for an SCT...)

Any recommendations which focal length eyepieces I should get, and which specific brand/model eyepieces?  I'd hope to not pay more than $150 each.  Thank you!

[michael.h.f.wilkinson]

Nice scope. My Celestron C8 on its Great Polaris mount has the same optics, and has lasted over 19 years now. Great light gathering power in a very compact package. Much depends on your budget, but fortunately the F/10 optics are comparatively tolerant. For a wider FOV the 24mm MaxVision 24mm 68 deg is great, and would replace the 25mm that came with the scope (WELL within your budget, and great). If you do not wear glasses, the 16mm of the same series should be great for intermediate magnification (for me with my glasses the eye relief is too tight), and something like a 9-10mm is great for planetary work. The Pentax XW10 I have is great, but not cheap. You could get two Vixen SLV EPs for that money (excellent quality "only" 50 deg, but superb). The Pentax XF 8.5mm is well worth considering as well. The Celestron X-Cel-LX have a very good reputation, BTW.

For really wide views you would either need to invest in a 0.63x focal reducer (works fine, but screwing it in place is a hassle). Alternatively, you can replace the 1.25" visual back with a 2" type, and corresponding 2" diagonal. You can then use real wide-field EPs like the 40mm Aero (a clone of the TMB Paragon 40mm I foolishly sold).

With that visual back, any of the EPs in my sig also work, but they do not come cheap (collected over the lifetime of the scope; most were second-hand, which makes them a lot cheaper)

[Don Pensack]

I won't make specific eyepiece recommendations, as there are literally hundreds to choose from, but I will make recommendations of focal length.

That scope comes with a 1.25" visual back, and limits you to 1.25" eyepieces and a maximum of 0.76 degrees (a little over 45' field), but the 25mm won't get you there.

My magnification recommendations are for:

50X, 100x, 150X and a good 2X barlow to yield 200X and 300X (this one for double stars or planets in SUPERB seeing)

That's a 40mm, 20mm, and 13-14mm eyepiece.

40mm in a 1.25" doesn't have any wider true field of view than a 32mm 50 degree Plossl, so I'd replace the 25mm with a 32mm Plossl to get the largest field you can and get closer to 50X.

At 50X, a lot more star clusters look like clusters instead of random field stars.

A 24mm widefield with a 68 degree has exactly the same true field as the 32mm Plossl, but the extra magnification is a little too high for a lot of star clusters.

So that'll give you the magnifications you need (and exit pupils).  The 20mm and 13-14mm could be a wider apparent field so the fields don't narrow too much.

That scope has a tight clearance for the star diagonal, so there really isn't any point to converting to a 2" visual back and 2" star diagonal  (which can widen the field of view a lot at low power) because the 2" diagonal won't clear the base.  The plastic of the fork arm can be modified to allow the scope to be shoved farther forward, allowing the use of a 2" diagonal, but due to the slip clutch used on the altitude motion, this extra rear weight would have to be balanced with a front counterweight.  That, too, could be done, but then the scope shimmies for a much longer time, and this scope already has about a 10 second shimmy time and is particularly bad in a breeze.  That can be combated by keeping the tripod as low as you can that still allows you to use the scope (it is seated viewing, not standing) and by using anti-vibration pads under the feet of the tripod.  Those aren't a bad idea if you stay with a 1.25" visual back end, either.

So, why convert to a 2" back?  To jump from 0.76 degrees to 1.2-1.3 degrees of low power field.  That's a huge change.

Just remember:

--modify the arm to move the scope forward

--add a 2" visual back and 2" star diagonal

--add a counterweight on the front (or a heavy dewshield made of metal)

--lower the tripod

--add anti-vibration feet.

In the meantime, sub a 32mm Plossl for the 25 to gain field of view, and get a 20mm and 13 or 14mm eyepiece for higher power.  All those eyepieces will be usable every night.

Barlowing the 20mm to a 10mm  will be possible on many, if not most, nights.  Barlowing the 13-14mm to 6.5-7mm will be possible very rarely, but when you can, you'll be glad to have it.

Nice first scope, by the way.

[SacRiker]

Don - thanks for posting the info.  I'm going to get this scope as well pretty soon...will be sure to take your advice.  Also good to see another Californian.