Which eyepiece for the planets?

[kerrylewis]

My new scope (Celestron 9.25 SCT) has a longer focal length than my other one so my pride and joy eyepiece - a Televue Radian 6mm - gives a magnification of almost 400x . This is a bit much unless the seeing is excellent so I think I need one at about 10 or 12mm. Radians don't seem to be available any more in these sizes although other Televues are. A further consideration being that I have the Dioptrix fitting for my astigmatism which would fit other Televue eps but this is not essential - to be honest I'm not sure that it really helps.

Budget is not necessarily an issue because en eyepiece is for life! So - recommendations?

Cheers

Kerry

[fredster]

The TV Delos range are the replacement for the Radian. Good range of sizes to choose from now.

[Stargazer_00]

12mm Nagler in my opinion

In a 9.25 (2350mm focal length) this is basically 200x. Perfect planetary viewing magnficiation in my opnion. The 82' of AFOV gives wonderful context on planets and on the moon it would show alot of surface all at once. Perfect in this scope in my opinion.

[John]

I would say a Delos as well. They are about as good as it gets for contrast, sharpness and light scatter control which are critical for planetary viewing. I'd also suggest a Pentax XW as they are superb too but they don't do a 12mm. The 10mm XW is an absolute gem

Naglers are great but I reckon the Delos and XW's are better for critical planetary viewing.

[Stargazer_00]

I just thought Nagler because I didnt see an auto tracking mount in kerrylewis' signature so it'd be a bit less manual tracking. I guess with an EQ the slow motion controls aren't a real hardship for tracking though. I just love the greater AFOV.

[kerrylewis]

Thanks for the suggestions. My HEQ mount is upgraded to Goto so,tracking isn't an issue

kerry

[Stargazer_00]

Delos for sure then. Or pentax xw

[John]

I just thought Nagler because I didnt see an auto tracking mount in kerrylewis' signature so it'd be a bit less manual tracking. I guess with an EQ the slow motion controls aren't a real hardship for tracking though. I just love the greater AFOV.

That makes sense for an undriven scope - I use ultra / hyper wides because my mounts are all alt-az and undriven. I love expansive fields of view too

[E621Keith]

Since you are using Dioptrix for astigmatism, you should go for TV eyepieces. As others said Delos is the replacement for Radian.

If you don't need dioptrx, Kasai Orthos/BGO is an other good candidate. If money is no issue, the Leica zoom from APM Germany gets really good review on CN.

[allen g]

have you thought about the televue delos

[KaStern_Former_Member]

Hi Kerry,

A further consideration being that I have the Dioptrix fitting for my astigmatism which would fit other Televue eps but this is not essential - to be honest I'm not sure that it really helps.

the smaller the part of your eye you use for observation the lesser the effect of your eye's astigmatism.

It may be bad with 5mm exit pupil, but it won't be bad with 1mm eyit pupil.

So if you use an eyepiece with 10mm focal legth or shorter the exit pupil at your f/10 scope will be 1mm or less

and your eye's astigmatism will no longer effect the perceived image negatively.

For your 230mm f/10 scope would recommend an eyepiece with about 10mm or 9mm focal length.

This may be a good orthoscopic or a good ww like a Pentax XW or a useed Pentax XL

or a TV Delos.

Cheers, Karsten

[Naemeth]

Hi Kerry,

the smaller the part of your eye you use for observation the lesser the effect of your eye's astigmatism.

It may be bad with 5mm exit pupil, but it won't be bad with 1mm eyit pupil.

So if you use an eyepiece with 10mm focal legth or shorter the exit pupil at your f/10 scope will be 1mm or less

and your eye's astigmatism will no longer effect the perceived image negatively.

For your 230mm f/10 scope would recommend an eyepiece with about 10mm or 9mm focal length.

This may be a good orthoscopic or a good ww like a Pentax XW or a useed Pentax XL

or a TV Delos.

Cheers, Karsten

I was just about to suggest that, you took the words right out of my mouth .

I normally wear glasses all the time (and have done since I was very young!) because of astigmatism etc. But, my astigmatism is such that at an exit pupil of less than 2.5mm, it's invisible, thus I don't need my glasses for short FL eyepieces (anything below 12.5mm an F/5)

[E621Keith]

Hi Kerry,

the smaller the part of your eye you use for observation the lesser the effect of your eye's astigmatism.

It may be bad with 5mm exit pupil, but it won't be bad with 1mm eyit pupil.

So if you use an eyepiece with 10mm focal legth or shorter the exit pupil at your f/10 scope will be 1mm or less

and your eye's astigmatism will no longer effect the perceived image negatively.

For your 230mm f/10 scope would recommend an eyepiece with about 10mm or 9mm focal length.

This may be a good orthoscopic or a good ww like a Pentax XW or a useed Pentax XL

or a TV Delos.

Cheers, Karsten

Good point. Televue has a graph showing you when astigmatism becomes a problem.

In my own experience, they are right. I am 1.0 and I begin to see astigmatism when exit pupil was around 2mm.

http://www.televue.com/engine/TV3b_page.asp?id=54&Tab=_Choose

[kerrylewis]

The Delos has arrived! Can't wait to try it

Thanks for all the info about astigmatism. I hadn't realised that exit pupil size made a difference. But as I said in my original post I have not noticed much effect with the 6mm - now I know why

Kery

[Moonshane]

I doubt that you'd be disappointed with any of the options mentioned. i have never looked through a Delos but believe based on comments of others that they are quite superb.