Eyepieces

JJLoke · Post by **JJLoke** » Fri Oct 06, 2006 2:18 pm

i was wondering whether celestron xcel series eyepiece, with FL 5mm is good for plantery observation.

what do u guys think ? or is that other better alternative ?

somehoe i find the prices in the Astro Omni Theater pretty expensive

pls guide me .. thanks

Canopus Lim · Post by **Canopus Lim** » Fri Oct 06, 2006 3:40 pm

Hi,

If you want cheap and good eyepieces for planetary you can consider University Optics (UO) orthos.

Others you can consider are Celestron Ultima and Televue Plossl (but I think shortest fl is 8mm).

However for the UO, Ultima and Televue Plossl, do bear in mind that the eye relief is real short and you have put your eyes very near to its small lens especially for shorter focal lengths. Also the field is not that large.

Or you may consider the Burgess/ TMB designed eyepiece which cost $99 usd. It has long eye relief (good for spectacles), wide 60 degree AFOV. It performs like a good plossl but more comfortable and wider views. It is a good deal.

jermng · Post by **jermng** » Fri Oct 06, 2006 4:02 pm

I think the most important question is what scope you're using.
The focal length of the scope itself determines how much magnification you get with different EPs.
The aperture (diameter of the objective lens/mirror) of the scope determines (to a certain extent) how much magnification your scope can take. Of course, atmospheric conditions play a large part too.

For example, in my case, a 5mm eyepiece would give me ~406x magnification in my C8 (fl 2032) which would be a little too high except in the best sky conditions. However in my widefield scope (fl 480), the 5mm EP would give me about 96x which might be a little low for catching much details in planets.

A general rule of thumb is to go for a maximum of 40-50x per inch of aperture, but atmospheric conditions normally limit magnification to 200-250x. Unless sky is superb AND optics on your scope are excellent.

Like what Yang Beng has said, orthos are great. The field of view is a small though, so unless you've got a tracking scope you might wanna look at something with a wider field like the TMB/Burgess series (also mentioned by Yang Beng).

Post by **acc** » Fri Oct 06, 2006 4:17 pm

The xcel series perform way below par when compared to the Burgess Planetary or Stratus eps. The Burgess is great for higher-power planetary work, while the Stratus is an excellent general-purpose ep.

JJLoke · Post by **JJLoke** » Fri Oct 06, 2006 4:57 pm

since im new to astronomy ... i dont want to spend one whole chunk of money at a go, rather buy efficient EP first, then continue the investment.

u guys did mention brands of EP i have not heard before.

is there other place in Sg to buy telescopic parts ?

i currently am a student and only have $200 budget to spend on the EP

Post by **acc** » Fri Oct 06, 2006 5:19 pm

Hi Loke
Welcome to singastro. What telescope are u using? This will help us to recommend an ep that is suitable for you.

jermng · Post by **jermng** » Fri Oct 06, 2006 5:19 pm

What scope are you using? The focal length and f/ratio of the scope are important before anyone can give a reasonable recommendation.

The Burgess/TMB EPs can be gotten online - www.burgess.com. www.astrobargains.com offers some budget EPs too and you can meet Joo Beng who's a great guy to deal with.

For $200, and without knowing what EPs or scope you currently have, I would recommend a couple of plossls and a barlow (doubles the magnification of the EPs you have).

JJLoke · Post by **JJLoke** » Fri Oct 06, 2006 5:38 pm

im sorry .. but im using my diy scope. the objective lens is from an old bino. 2" but only 180mm FL

the best pic i taken with the scope was a cluster of craters on the moon, very clear tho

Post by **weixing** » Fri Oct 06, 2006 8:21 pm

Hi,
Welcome to SingAstro!!!

im sorry .. but im using my diy scope. the objective lens is from an old bino. 2" but only 180mm FL

the best pic i taken with the scope was a cluster of craters on the moon, very clear tho

What eyepiece are you using now?? Does it have a focuser??

Anyway, I would suggest you save your S$200 now and get a better scope setup when you have save enough... you can always join some of our members observation session when the weather and that #@^&%$ haze clear up....

Have a nice day.

Have a nice day.

Canopus Lim · Post by **Canopus Lim** » Sat Oct 07, 2006 12:08 am

Yup, it will be great if you can join those obs. Then you can look through better scopes.