Eyepiece Advice

[Mangleworsle]

I have just got a Star Traveler 102 / 600 Goto, and would be grateful if some of the more advanced members could give me some advice on eyepieces. It came with a 10 & 20 mm eyepieces.

I can't afford expensive ones, but if you could give me some idea of middle range models that will work well for Deep Sky observation and the occasional Planetary viewing.

Thanks

Jim

[Ricochet]

Do you have this Startravel? If so it has a focal length of 500mm not 600 making it ~f5. If so then I would recommend a 10-12mm eyepiece for DSO's and either a 24mm 68° or 32mm Plossl for wide views and as a finder. For planetary I'd look at something around the 5-6mm mark although a short focal length refractor is going to show a fair bit of false colour on bright targets. Alternatively, a 10-12mm eyepiece and the barlow that came with the scope could be used. You might also want to upgrade the 45° erecting diagonal for a 90° star diagonal as I understand the ones supplied with the scope aren't the best quality.

With regards to specific eyepieces what is you budget per eyepiece and do you need to wear glasses while observing?

[rwilkey]

Hi Jim, probably the best value ep's on the market are the BST Explorer/StarGuiders, highly recommended for both performance and relative cost, and they work well in all telescopes.  For deep sky you would need the 25mm and for planets I would recommend the 8mm, available from FLO here: https://www.firstlightoptics.com/bst-starguider-eyepieces.html

[ronin]

I would say the Vixen NPL Plossl range, presently £34 at FLO.

The 30mm will be good for wide although so will the 25mm. Medium try a 10mm or 15mm. For higher power it is likely to be the 8mm although that is not overly high. The 5mm will have very little eye relief., so not a good idea.

Greater cost (£50) try the BST Starguiders (FLO and Skies the Limit) maybe the 25mm for wide and the 8mm for more magnification.

Check Skies the Limit as they sell the BST's but they also have a line of premium plossls and cannot recall the cost, may be less then the Vixens and are likely to be good eyepieces.

Unfortunately a lot really depends on what your budget is.

[Dave In Vermont]

You can't really go wrong with good quality Plössl eyepieces in fast refractors - like yours. They work well on a variety of subjects, including getting close-up with planets. The only problem with Plössl's and fast refractors is with high-power needing the 6mm or lower 'mm' eyepieces. For this you'd be better off using a decent quality Barlow-lens - a 12mm Plössl and a 2X Barlow would give you the equivalent of a 6mm eyepiece, without causing you to need to squint and get your eye almost touching the glass of the lens.

This would make for a good place to start from. Time at the telescope will direct you to finding what would serve your interests best, and then you can save up and get better eyepieces as needed and/or afforded. You can also look into the 'Used' market. Us astronomy-folks tend to take excellent care of our gear, so you can get some really nice items for - on average - 2/3rds the price of new. Also a good way to sell off things you no longer need.

Hope this helps -

Dave

[Mangleworsle]

Thanks ever so much gentlemen.

I think I can now see where I am going, the range you have pointed out has helped and I will certainly be looking at the 12 & 30 mm and a quality Barlow.

I haven't looked at the Vixen range as I thought they would be way out of my price range. The BTS eyepieces  also must be on my list.

Thanks again, I have learned a lot from your responses.

Jim

[Cosmic Geoff]

From the lack of denial, I assume this is the 102mm Sky-watcher Startravel f5, the same OTA that I have.  It's primarily a wide-field instrument, but  with better eyepieces, a 90 deg star diagonal and the original Barlow it will give half-decent planetary views. The 10mm eyepiece supplied with it is not very good, and the 45 deg erecting diagonal is not very good either for astronomical use at high powers.

As it's a short focus achromat prone to some chromatic aberration, don't expect too much of it. Also note the field distortion if you point it at a TV pole.  Likewise I'll leave it to you how much money you want to throw at it for eyepieces. I have a Revelation Astro 20mm Plossl that does not work well at f5.

[Mangleworsle]

Thanks Cosmic Geoff,  I Don't deny anything, even less about a typo.

Could you let me know of your experiences with this scope as you must know it much better than me a ( only got it last week ).

Any help would be most appreciated.

Jim

[Cosmic Geoff]

I use my Startravel less than my C8 and Mak. It has had most use being taken on holiday to look for galaxies in darker skies (on a Nexstar GoTo mount). I also use it for projecting the sun, as at 102mm it's not too big an aperture and I can get a firm grip of the dovetail bar or 4" barrel to carry it outdoors. I've also taken it out at night when I wanted a really wide field, e.g. spotting a bright comet in the middle of the night.  But for targets requiring aperture or resolution of fine detail I pick up one of the other scopes. The highest magnification I've used is x100.

[happy-kat]

I would also get a star diagonal (90°) makes night viewing so much easier. Generally the supplied 20mmor is ot 25mm are ok to use but the 10mm is not a great eyepiece. Save some budget because you may soon decide you need better power these mounts don't run great on rechargeables.

[Mangleworsle]

2 hours ago, happy-kat said:

I would also get a star diagonal (90°) makes night viewing so much easier. Generally the supplied 20mmor is ot 25mm are ok to use but the 10mm is not a great eyepiece. Save some budget because you may soon decide you need better power these mounts don't run great on rechargeables.

Thanks happy-kat, luckily I have a 12 v 15A/h portable power supply duty I do like the idea of saving money. Any ideas on a good diagonal? 

Thanks

Jim

[Dave In Vermont]

A very good 90° diagonal, which is a keeper so get a very good one so you only need to buy once, is a 1.25" GSO Dielectric Diagonal. These can be found with many different brand-names on them. Ah! Eureka - here's one:

http://www.teleskop-express.de/shop/product_info.php/info/p1771_TS-Optics-1-25--TS-Optics-1-25--Star-Diagonal-with-ring-clamb---99----1-12-Lambda.html

See what you think.

Enjoy -

Dave

ps - the diagonal referenced above is a dielectric mirror-diagonal with 99% reflectivity. I have one, and it's excellent.

[Cosmic Geoff]

12 hours ago, Mangleworsle said:

Any ideas on a good diagonal

You don't need a 'good' diagonal for this scope. I bought the cheapest one I could find on Astroboot for my Startravel, similar to those supplied with sundry telescope kits, and it's perfectly adequate. If you look into the tests of diagonals you'll see that more money may buy you better build, less light scatter and longer coating life, but not more optical precision. You'll want a mirror diagonal, not a prism for a f5.

If you want to buy an expensive one with a view to re-using it in another scope later, that's up to you.

[Louis D]

2 hours ago, Cosmic Geoff said:

You don't need a 'good' diagonal for this scope. I bought the cheapest one I could find on Astroboot for my Startravel, similar to those supplied with sundry telescope kits, and it's perfectly adequate. If you look into the tests of diagonals you'll see that more money may buy you better build, less light scatter and longer coating life, but not more optical precision. You'll want a mirror diagonal, not a prism for a f5.

If you want to buy an expensive one with a view to re-using it in another scope later, that's up to you.

I found that the difference between a generic plastic body 90 degree mirror diagonal and the WO 99% dielectric diagonal were night and day.  The former couldn't even hold proper aligment with a heavy binoviewer inserted whilst the latter had no flexure at all under load.  The correction of the mirror also seemed much better at very high powers in the WO as well.