correct image possible in newtonian?

Hello...Is it possible to use an erect image star diagonal (either the
90-degree type or the 45-degree type) on a newtonian reflector...to
get an upright, nonreversd image? I know it'll require an unorthodox
head position to look into it, but I won't mind that. I'm wondering if
it'll work optically. Thanks.

I suppose it is possible to work out some such arrangement. But why in the
world would you want to screw up the optical path with a bunch of junk which
would interfere with the image??

Clear, Dark, Steady Skies!
(And considerate neighbors!!!)

"Patrick" wrote in message
om...
Hello...Is it possible to use an erect image star diagonal (either the
90-degree type or the 45-degree type) on a newtonian reflector...to
get an upright, nonreversd image? I know it'll require an unorthodox
head position to look into it, but I won't mind that. I'm wondering if
it'll work optically. Thanks.

I don't think it would reach focus.


--
Clear skies,

Michael Covington -- www.covingtoninnovations.com
Author, Astrophotography for the Amateur
and (new) How to Use a Computerized Telescope

I suppose it is possible to work out some such arrangement. But why in the
world would you want to screw up the optical path with a bunch of junk which
would interfere with the image??


I agree, the beauty of the Newtonian is its simplicity. Let those SCT guys put
some more optical elements in the light path, 3 mirrors, a corrector plate,
maybe a focal reducer or two are only a good start on things. Let us see what
other goodies we can add....

:-)

jon

On 17 Sep 2003 21:04:14 -0700, Patrick wrote:

Hello...Is it possible to use an erect image star diagonal (either the
90-degree type or the 45-degree type) on a newtonian reflector...to
get an upright, nonreversd image? I know it'll require an unorthodox
head position to look into it, but I won't mind that. I'm wondering if
it'll work optically. Thanks.


Since the Newtonian employs two reflections to form the final
image, the relationship between top-bottom and left-right is fundamentally
correct. The final image, however, is often *rotated* with respect to the
observer's top-bottom axis.

To correct this, the Dove prism can act as an image rotator.
Unfortuntately, a single Dove prism will also reverse one axis.
To overcome this problem, two in series may be used.

See:
http://www.edmundoptics.com/IOD/Disp...Productid=2034

Or, if you are athletically inclined, you can orient the
eyepiece holder of the Newtonian to top-vertical, then
straddle the tube between your legs, and the view will be
fully correct.

Cheers,
Larry G.

What is the reason for the desire to have an upright image? Any additional
glass in the optical path will dim the view, decrease contrast, maybe not by
much, but on faint objects it prove crucial. On planets, it's simple enough
to LEARN to correct the view in your mind. It's been done that way for
hundreds of years.
--
----------------------------------------------------------------------
Pinprick holes in a colorless sky
Let inspired figures of light pass by
The Mightly Light of ten thousand suns
Challenges infinity, and is soon gone


"Patrick" wrote in message
om...
Hello...Is it possible to use an erect image star diagonal (either the
90-degree type or the 45-degree type) on a newtonian reflector...to
get an upright, nonreversd image? I know it'll require an unorthodox
head position to look into it, but I won't mind that. I'm wondering if
it'll work optically. Thanks.

LarryG wrote:

Or, if you are athletically inclined, you can orient the
eyepiece holder of the Newtonian to top-vertical, then
straddle the tube between your legs, and the view will be
fully correct.

This is known as an SPN (Slim Pickens Newtonian).

Mike Simmons

In message , David Nakamoto
writes
What is the reason for the desire to have an upright image?

Birds look kind of funny hanging upside down in the trees. :-)

Regards,
--
Martin Brown

On 2003-09-18, Patrick wrote:

Hello...Is it possible to use an erect image star diagonal (either the
90-degree type or the 45-degree type) on a newtonian reflector...to
get an upright, nonreversd image? I know it'll require an unorthodox
head position to look into it, but I won't mind that. I'm wondering if
it'll work optically. Thanks.

You don't have enough in-focus to do it on most newtonians. The
image in a newtonian is not mirror reversed.

--
When the fog came in on little cat feet last night, it left these little
muddy paw prints on the hood of my car.

Hello...Is it possible to use an erect image star diagonal (either the
90-degree type or the 45-degree type) on a newtonian reflector...to
get an upright, nonreversd image? I know it'll require an unorthodox
head position to look into it, but I won't mind that. I'm wondering if
it'll work optically. Thanks.

I assume you wish to use your Newt for terrestrial objects? You'd
have to use an image erecting prism in the focuser. I'm not sure what
commercial models are available. In addition, you'd probably have to
move your primary mirror up to allow your eyepieces to come to focus
with the prism in there.

Ritesh