Eyepieces for planets and DSO

yanyewkay · Post by **yanyewkay** » Mon Apr 23, 2007 10:44 am

After reading Canopus Lim eyepiece review http://www.singastro.org/viewtopic.php?p=37503#37503

I went to look up for more info on the different types of eyepieces. I noted the eyepiece application said "Lunar and planetary observing - best possible on-axis sharpness is required"

So what properties do I look out for to determine an eyepiece is good for planetary and/or DSO?

The only other reference I found said Plössl was suited for both planetary and DSOs.

Meng Lee · Post by **Meng Lee** » Mon Apr 23, 2007 10:58 am

High contrast: exotic glasses used, internal baffling, internal blackening, edges blackening.

High throughput: Fully multi coating.

Sharpness: lens design such as Orthoscopics and their variants

yanyewkay · Post by **yanyewkay** » Mon Apr 23, 2007 11:58 am

so much parameters.. so which is meant for what?

Meng Lee · Post by **Meng Lee** » Mon Apr 23, 2007 12:26 pm

Actually if an eyepiece has all the qualities above then it is good for planets and DSOs.

For planets, there is more emphasis on 1st and 3rd quality.

For DSO, the emphasis is a little more on the 2nd one + wide field of view

Post by **weixing** » Mon Apr 23, 2007 12:27 pm

Hi,

So what properties do I look out for to determine an eyepiece is good for planetary and/or DSO?

The only other reference I found said Plössl was suited for both planetary and DSOs.

Basically, any planetary eyepiece will be good at planetary and DSO especially if you have a motorized mount... just that you won't have the "spacewalk" effect. Also, IMHO, unless you are a true specialize planetary observer, you basically won't "see" the difference between various planetary eyepiece... unless that eyepiece is really lousy.

Anyway, I have been using mainly ortho and now a 8mm BO/TMB planetary eyepiece for observing DSO and I don't have any problem with it... in fact, I'm able to see more details in objects through our serious light pollution sky due to the high light transmission of the planetary eyepiece.

Have a nice day.

Meng Lee · Post by **Meng Lee** » Mon Apr 23, 2007 12:35 pm

Also, for wide angle eyepieces, many manufacturers do make them, but they do it at the expense of field curvature uncorrected and so on.

IMHO, wide angle eyepieces are the eyepieces that follow this statement the most: "you get what you pay for"

yanyewkay · Post by **yanyewkay** » Mon Apr 23, 2007 12:54 pm

oh i see..am I right to say planet viewing have higher requirements than DSO so any suitable for planets will most likely fit DSOs?

Meng Lee: The spacewalk effect is the "rolling your eyeball within the eyepiece"?

Canopus Lim · Post by **Canopus Lim** » Mon Apr 23, 2007 1:11 pm

Actually buying eyepieces is very PERSONAL. It depends a lot on what telescope you are using and your preferences (whether you like small FOV or large FOV, eye relief, sharpness etc) and how much you are willing to pay.

As what Weixing said, the UO ortho, Circle T orthos are good and cheap. If you are more 'perfectionist', the quality of these eyepieces may not meet your demand. If you are not so 'perfectionist', these eyepieces are very value for money. Also, the BO/TMB planetary eyepieces are not bad for its features (16mm eye relief, 60 degree AFOV, price of 99usd). I am keeping my 5mm BO/TMB for globular cluster use, lunar and wider field.

About differences seen..... the differences between a top quality planetary eyepiece and that of the UO ortho is SLIGHT. Do not expect a big difference in the quality. There are differences though but you need to look for it. So it boils down on how much you are willing to pay for that slight increase in performance. For optics, a slight improvement can mean more than a double increase in cost!

Post by **weixing** » Mon Apr 23, 2007 1:16 pm

Hi,

oh i see..am I right to say planet viewing have higher requirements than DSO so any suitable for planets will most likely fit DSOs?

Higher requirement in almost every category, except Apparent Field of View (AFoV). If you don't miss the "spacewalk" effect (the AFoV is so large that you need to roll your eye ball or even turn your head to see the edge of the FoV) and you got a motorized mount, planetary eyepiece is quite good for DSO observation.

IMHO, BO/TMB planetary eyepiece is quite good for DSO observation... the AFoV (60 degree) is not too small and not too expensive compare to other wide angle eyepieces.

Have a nice day.

Meng Lee · Post by **Meng Lee** » Mon Apr 23, 2007 1:52 pm

IMHO, spacewalk is like, you look through the eyepiece, but you don't see the edges of the eyepiece (field stop), is like you are floating in outer space, looking at the stars!

Just to add, Good Diagonal, (for planets, no diagonal is the best), top barlow, and spot-on collimation and stable mount are also factors to achieve good planetary views. Eyepieces are just one part of the story.