Your ideal planetary eyepiece

[chunkylad (David)]

Hi everyone

IF you had an f5 Newtonian, what would be your 'ideal' eyepiece/barlow combination for viewing the planets. Would you have several eps, and no barlows, or one or two eps and several barlows?

Or put this way: What would be your 'must have' eyepiece for planetary observation?

Cheers

Dave #17

[ausastronomer (John Bambury)]

Dave,

Unfortunately specifying an F5 scope is only specifying 1/2 the equation because we also need to get a handle on the scopes focal length. ie The same eyepiece that is suitable for planetary observation in Andrew Murrell's 20"/F5 is not suitable for planetary observation in a 6"/F5.

However, assuming an F5 scope with a focal length of about 1250mm (10"/F5), my 2 ideal eyepieces would be a 7mm Pentax XW and a 5mm Pentax XW. These perform exceptionally well at F5, have a wide and flat FOV for use in an undriven scope and are very sharp with high light transmission and have comfortable eye-relief of 20mm.

The Zeiss orthoscopics are the best planetary eyepieces I have used in terms of light transmission, contrast and sharpness but they are limited by the focal lengths they come in and their short eye-relief at short focal lengths. However, in a scope of about 1200mm focal length, the 6mm zeiss ortho is as good as it gets.

CS-John B

[Dave47tuc (David)]

I have looked through so many Ep's and looking for a high power can be a puzzle.

But with your Dob you would like wide field at high power. So as John has said the Pentax's are super. Also the Tele Vue Radians are nice as well as Naglers. Ortho's are very good and Plossll's are great with smaller fields.

With your new Barlow as i have you then get larger Images scales so 14 mm down to 7 mm work well.

For me I really like the Meade 8.8 mm UWA Barlowed, when seeing is good it is really nice and sharp. Still with a big field for a 4.4 mm

Good hunting.

[wavelandscott (Scott)]

As mentioned before, I'm becoming pretty fond of my Pentx 7 mm XW...it is as good as advertised at f5...

[gaa_ian (Ian)]

In my F5 10" Dob the TV 8mm Radian give superb planetary views
(on those rare good nights)
But it does not perform well in the 8" F10 LX-90 (to much mag. I think)

[Starkler (Geoff)]

I just wish that Pentax sold a 6mm XW

[ausastronomer (John Bambury)]

Originally Posted by Starkler

I just wish that Pentax sold a 6mm XW

I agree Geoff,

Thats the 1 missing hole IMO. However the 14mm pentax XW in the 2.5X TV Powermate comes pretty close to what a native 6 would do IMO.

CS-John B

[asimov (John)]

My favorite planetary eyepiece for visual & photographic work has a fairly small field of view ( If you have tracking a big FOV is not necessary ) not much ER ( I'm used to it ) It has only 4 elements ( more light transmission ) Off axis a bit seagully ( I don't care I keep the planet in the centre FOV ) It was EXTREMELY cheap ( 15 bucks second-hand or there abouts )

= .965" unitron orthoscopic 5/6/9/12.5mm The 5mm is the best of the bunch for up close & personal type viewing of planets IF the seeing is 7/10 & better.

I use these on planets only naturally.

[iceman (Mike)]

Hi Dave.

I started a thread a few months ago, here which discussed several alternatives I was considering at the time for a premium planetary eyepiece.

Of course you don't need to spend a lot - for some people, a short focal length (5-7mm) $150 televue plossl will be an excellent planetary eyepiece with great contrast and very sharp. Orthoscopics are in the same boat.

If you need extra eyerelief or prefer a wider field of view, that's when you can start looking at Radians, Naglers, Pentax's.

But if you're specifically looking for a good planetary eyepiece, stay away from the cheaper widefields or cheaper plossls - without tracking you'll be forever trying to keep the planet in the centre of the FOV and it will detract from the otherwise great view you'd get.

If you get something around the 6-7mm range (for when the seeing is "ok" at around 200x), combine it with your UO 2x barlow when the seeing is GREAT and you'll have outstanding views at 400x. Remember though, don't try it unless the seeing is great, or you'll just be disappointed with a blurry view that won't come to focus.

And make sure you know how to collimate your 12" newt! Planetary views will be most disappointing if you're not collimated properly!

[chunkylad (David)]

Originally Posted by ausastronomer

Dave,

Unfortunately specifying an F5 scope is only specifying 1/2 the equation because we also need to get a handle on the scopes focal length. ie The same eyepiece that is suitable for planetary observation in Andrew Murrell's 20"/F5 is not suitable for planetary observation in a 6"/F5.

CS-John B

John - my OTA is f5/1500mm

Last night I tracked down Uranus. The view through my GS plossls required constant nudging to keep it in the fov. I found that my 15mm barlowed allowed the best view, with the 6mm being optimum for the seeing conditions. I found it difficult to 'find' the planet when stepping up the mag, through my plossls.
As Iceman and others so rightly point out, a wider fov is more than a luxury when you don't have tracking.
cheers
Dave #17