Erecting Eyepieces

[Akyra]

Are these good for use with astronomy? Do they make life easier? - No more up is down, left is right business...

[GazOC]

They're pretty pointless IMHO. They just put more glass inbetween you and the object you are observing for no good reason.

[Andrew*]

i would agree. It doesn't take a lot to get used to the reverse directions, and of course there's no up or down in space!

I was wondering about these though: for terrestrial viewing (not that I'm planning it with my 8", mind) these are obviously very useful, but there don't seem to be any half-decent ones available. You always get one packed with dirt-cheap scopes, but otherwise they aren't very often sold by dealers. Is there a reason for this?

(Sorry, I don't mean to hijack your thread Akyra, but I think we've answered your question!)

Andrew

[themos]

"there's no up or down in space!"

That is actually not true. Spacetime is curved by the matter, matter is lumpy so there is (almost) always a preferred direction. And even if there was not, selecting one direction would make sense when it comes to comparing images. Cartographers figured that out long ago.

PS: I can see myself becoming annoying on this subject. Do tell me to shut up.

[Akyra]

Shall we just all agree on there being 4 directions, North / South / East / West?

[GordonCopestake]

The erecting eyepiece will help you whilst you begin, but it will only hinder you as you progress as they are not of the highest quality. It would be best to just to "learn to live with it". You will be suprised at how quickly you get used to the reversed directions. I try and think of the arrows buttons moving the field of stars and not the 'scope. The 'scope stays still and the stars move, if that makes sense.

[Astroman]

Themos, my new hero! I thought I was the only one buttin' in with "annoying" clarifications of esoteric minutae. I feel better now.

BTW, I agree with Gordon and Gaz re erecting EP's.

[mhc]

"there's no up or down in space!"

That is actually not true. Spacetime is curved by the matter, matter is lumpy so there is (almost) always a preferred direction. And even if there was not, selecting one direction would make sense when it comes to comparing images. Cartographers figured that out long ago.

IIRC, spacetime is curved by gravity, not matter per se As to a "preferred direction", surely that will be on a particle level case-by-case basis, given the effective randomness of orientations in space.

[themos]

Gravity IS the curvature of spacetime. What causes curvature is, strictly speaking, the "stress-energy tensor" (matter density being one part of it).

G_??=8?T_??

that will be on a particle level case-by-case basis

This is like arguing that earth maps should have no preferred direction because the terrain goes up and down in different directions at different places.

[Merlin]

Erecting eyepieces are gernally poor quality and they increase the magnification.

The best way to erect the image is to use an Amici prism erector,always assuming,of course,that there's enough movement in the focuser to bring the folded beam to focus.

[The Warthog]

Are these good for use with astronomy? Do they make life easier? - No more up is down, left is right business...

I would only use one for terrestrial observation. The only time I have trouble is viewing the moon. I have difficulty getting used to the difference in directinality when trying to find stuff through the refractor in the star diagonal. I am very used to the reflector view.

Whether there is an up or down in space is a theoretical discussion. It makes no difference for viewing through an amateur refractor.