Wanted:Planetry EP

[Andrew*]

This is a brilliant thread, and so many replies since just yesterday. I'm in the same boat as blinky. I have a 1000mm f/5 scope and need a good ortho to get the highest mag out of my scope for planets. I've been thinking a 9mm that I can triple with my barlow, but the general consensus seems to be that's too much power to work with. I now think 3.5mm is about as high as I can go. What do you think?

I was even considering getting the 3-6mm nagler. That would make planetary observation a doddle. Frame it at 6mm, and zoom as high as you can. But at £300, needless to say, it's way over budget. One guy sold one on SPA recently for £100 :shock:

Blinky, whatever you go for, I'll be right behind you!

Andrew

[Andrew*]

This is a little on the steep side for me, but it seems to be a fab EP. RRP is around £100, and if it's really worth it and going to give me worthwhile views, £55 is alright!

http://www.astrobuysell.com/uk/propview.php?view=10302

Or would I/we be better off with an ortho?

Andrew

[GordonCopestake]

I tend to work out my highest magnification not by the magnification but by the exit pupil. 0.5mm is as small as I'd like to go with any scope/eyepiece combination and 1mm is much more comfortable IMO

Don't forget that seeing limits you to about 250x on a good night and you will rarely get to use 300x effectively.

[Brass n glass]

I've used a 4mm Vixen lanth for a long time and it's an excellent high-power eyepiece with a built-in Barlow and a relatively narrow field of 50 or 52 deg. The Vixens are the grandaddies of all the modern Chinese LER clones and like all medium-range Japanese eyepieces IMHO offer top value for money. The 4mm never kidney beans on me even though it has 20mm eye relief and I don't wear glasses

[GazOC]

I tend to work out my highest magnification not by the magnification but by the exit pupil.

A lot of people plan their whole eyepiece collection by exit pupil rather than magnification.

[Andrew*]

right. You've confused me again. I know I've asked this too many times, but what significance does exit pupil have?

I saw one thread where steve said aperture/magnification=exit pupil. Right. So if I want, as Gordon suggests, a 1mm exit pupil with a 200mm scope, I shouldn't go for anything much below 5mm, giving 200x. Right? Does that suggest that I won't comfortably be able to use a higher mag than 200??

How disappointing!

Andrew

[GazOC]

Exit pupil is the size of the image that a scope/ eyepiece combination produces, if your dark adapted pupil is, say, 7mm then anything larger falls outside the pupil and is lost. So some people will have their lowest power eyepiece to give an image the same size as their dilated pupil, their highest power eyepiece with whatever the smallest exit pupil is that they are comfortable with and stagger the other eyepieces at intervals inbetween based on exit pupil.

The theory is sound at low power but at the high power end its very subjective and of course you can only really plan your eyepiece collection for one scope/ eyepiece combination as soon as you have another scope with a different focal length it all goes to pot.

[tom.yates]

The Baader orthos are top notch as well as i have just bought a set from Steve looking through them the other night i was amazed at what i could see.

[Macavity]

The Baader orthos are top notch as well as i have just bought a set from Steve looking through them the other night i was amazed at what i could see.

Well, I must admit I am tempted (Thanks for info). Having sold all my "shorter" Vixen Lanths (I am still having difficulties coming to terms... ) I did wonder. As a (sometime) glasses wearer, the eye relief question is always moote - but not totally prohibative? Sometimes I can press the old "wireframes" against the plastic and, even at 12mm (eye-relief) and notably narrower fields, they are still usable. It seems reasonable, in light of the thread, to consider the possibilities of volcano (you'll 'ave your eye out!) tops too. Ta! As ever, I begin to sense that physical parameters don't always dictate personal experience. Even first-glance (sic) "dogs" should be given a chance...