Converting spotting scopes to binoculars

On Tue, 27 Jul 2004 07:18:34 -0500, Beta Persei wrote
(in article ):


"Tony Flanders" ha scritto nel messaggio
...
Bill Tschumy wrote in message
m...

Has anyone here given much thought to constructing a pair of binoculars
from
a pair of spotting scopes? ...
The advantage of using spotting scopes over telescopes is that the
correct
image prism system is already in place.

Erecting prisms are a standard accessory for astronomical telescopes.
I predict that if you do a cost/benefit analysis, you'll find that's
an easier and cheaper way to proceed. With spotting scopes, you pay
a lot for ruggedizing and waterproofing, neither of which is an issue
for astro use. Also, if you're planning to use these only at relatively
low power, you can undoubtedly use astro OTA's that cost a lot less
than Pentax ED spotting scopes.

- Tony Flanders

Have a look on http://www.astromeccanica.it

Their solution doesn't yield a correct (non-reversed) image. That is a
paramount goal for this project.

Oh, another reason for using spotting scopes is that they already have the
image correcting prisms installed. With binoscopes, the image is generally
left-right reversed. I consider the correct image to be a major advantage of

binoculars.


Some considerations:

1. It seems that the image correcting prisms, no matter how good they are,
extract a price in image quality. Spotting scope generally do not go above
60x-80x, mostly because the atmosphere normally will not support that sort of
magnification.
My guess is that at 80x things would not be so great in the Pentax. Yes BVD
gives them a good review, but the needs of birders and astronomers are
different...

2. Have you tried left-right reversed binoculars or binoviewers? Personally I
don't have any problem with it on a telescope, if fact, if it is mounted on a
tripod, (and it yours will be) then I find correct image confusing...

jon

"Bill Tschumy" ha scritto nel messaggio
m...
On Tue, 27 Jul 2004 07:18:34 -0500, Beta Persei wrote
(in article ):


Have a look on http://www.astromeccanica.it

Their solution doesn't yield a correct (non-reversed) image. That is a
paramount goal for this project.

oops...may be I lost some part of the thread. I imagined that for astro
viewing a correct image was not really fundamental. But if it has to be used
for terrestrial viewing...


--
--
Beta Persei
45° 35' N
08° 51' E

Remove "_nospam" to reply

On Tue, 27 Jul 2004 08:05:19 -0500, Jon Isaacs wrote
(in article ):

Oh, another reason for using spotting scopes is that they already have the
image correcting prisms installed. With binoscopes, the image is generally
left-right reversed. I consider the correct image to be a major advantage
of

binoculars.


Some considerations:

1. It seems that the image correcting prisms, no matter how good they are,
extract a price in image quality. Spotting scope generally do not go above
60x-80x, mostly because the atmosphere normally will not support that sort of
magnification.
My guess is that at 80x things would not be so great in the Pentax. Yes BVD
gives them a good review, but the needs of birders and astronomers are
different...

You may be right and the only way I'll find out is to try one. However, BVD
says "it provides an amazingly bright, amazingly sharp, amazingly detailed
view from 20 to 60 power". This doesn't sound like the image is starting to
break down at 60x.

In any case, my primary use for this will be primarily for scanning the skies
at 20-30x. I imagine the only semi-high power use will be when I use it for
a travel scope and don't have my larger refractor available.


2. Have you tried left-right reversed binoculars or binoviewers? Personally

I
don't have any problem with it on a telescope, if fact, if it is mounted on a
tripod, (and it yours will be) then I find correct image confusing...

I have used several big binoculars on parallelogram mounts and I find the
naturalness and ease of use amazing. I have used binoviewers, but not a
binoscope. I feel pretty confident that I prefer a "correct" image for this
type of work. YMMV g.


jon

However, BVD
says "it provides an amazingly bright, amazingly sharp, amazingly detailed
view from 20 to 60 power".

My Pronto provides "amazingly sharp, amazingly detailed view from 20 to 60
power" as well.... It wasn't too long ago that BVD thought the Pronto was the
scope to beat....

In any case, my primary use for this will be primarily for scanning the skies

at 20-30x.

If you are going to work at 20-30x why limit yourself to 1.25 inch eyepieces...


I feel pretty confident that I prefer a "correct" image for this
type of work. YMMV g.

My guess is that after a short time, the reversed image would seem natural and
you would be happy.

jon

On Tue, 27 Jul 2004 11:43:20 -0500, Jon Isaacs wrote
(in article ):

However, BVD
says "it provides an amazingly bright, amazingly sharp, amazingly detailed
view from 20 to 60 power".

My Pronto provides "amazingly sharp, amazingly detailed view from 20 to 60
power" as well.... It wasn't too long ago that BVD thought the Pronto was
the
scope to beat....

In any case, my primary use for this will be primarily for scanning the
skies

at 20-30x.

If you are going to work at 20-30x why limit yourself to 1.25 inch
eyepieces...

Do you know of any correct image spotting scopes that take 2" eyepieces??



I feel pretty confident that I prefer a "correct" image for this
type of work. YMMV g.

My guess is that after a short time, the reversed image would seem natural
and
you would be happy.

Jon, I've been using refractors almost exclusively for 25 years. I'm about
as comfortable with the reversed image as I'm going to get. Please believe
me when I say that TO ME there is a big advantage in a correct image for
sweeping the skies.


jon

Bill Tschumy wrote in message m...

But erecting prisms leave the image left-right reversed. To me this is a
major disadvantage and eliminates the "naturalness" of binoculars. If I was
content with that I'd just use a binoviewer.

No, no -- that's a standard star diagonal. I'm thinking of a free-standing
inline Porro prism. See, for instance, TeleVue's unit at
http://www.televue.com/engine/page.asp?ID=167. There are also 45-degree
erecting prisms if you prefer that angle, but the inline Porro prisms will
provide better help with the interpupillary distance.

- Tony Flanders

On Tue, 27 Jul 2004 16:01:17 -0500, Tony Flanders wrote
(in article ) :

Bill Tschumy wrote in message
m...

But erecting prisms leave the image left-right reversed. To me this is a
major disadvantage and eliminates the "naturalness" of binoculars. If I
was
content with that I'd just use a binoviewer.

No, no -- that's a standard star diagonal. I'm thinking of a free-standing
inline Porro prism. See, for instance, TeleVue's unit at
http://www.televue.com/engine/page.asp?ID=167. There are also 45-degree
erecting prisms if you prefer that angle, but the inline Porro prisms will
provide better help with the interpupillary distance.

- Tony Flanders

Yes, you're right that this would be an option worth looking into.

Thanks,

"Bill Tschumy" wrote in message
m...
On Tue, 27 Jul 2004 11:43:20 -0500, Jon Isaacs wrote
(in article ):

My guess is that after a short time, the reversed image would seem
natural
and you would be happy.

Jon, I've been using refractors almost exclusively for 25 years. I'm
about
as comfortable with the reversed image as I'm going to get. Please
believe
me when I say that TO ME there is a big advantage in a correct image
for
sweeping the skies.

but.... but... there's no upside down (or rightside up) in space. g

"Paul Lawler" wrote in message k.net...

"Bill Tschumy" wrote in message
m...

On Tue, 27 Jul 2004 11:43:20 -0500, Jon Isaacs wrote
(in article ):

My guess is that after a short time, the reversed image would seem
natural
and you would be happy.

Jon, I've been using refractors almost exclusively for 25 years. I'm
about
as comfortable with the reversed image as I'm going to get.

If I may interject, I don't know if I could ever be completely
comfortable with reversed images, either. Even if we put aside how we
relate the motion of the telescope to what we see in the eyepiece, the
image is just not what the object looks like (from the vantage point
of the Earth). Even if I would never view it any other way (fat
chance), I'd still *know* that it's backwards, and that bugs me a
little.

Please
believe
me when I say that TO ME there is a big advantage in a correct image
for
sweeping the skies.

but.... but... there's no upside down (or rightside up) in space. g

I'm fine with image rotation (at any angle)--it doesn't bother me one
bit, and never has, because the images are accurate representations of
the objects. I don't mean to put anyone off, especially beginners who
might be reading this--I just wanted to share what might be a peculiar
perspective on image orientation in telescopes.

Generally speaking, I'd still choose a good star diagonal over an
erecting prism for telescopes (for quality reasons), which should
illustrate how minor this "problem" is for me. However, with that
said, I agree with Bill in the context of what he's trying to
accomplish in this thread.


- Robert Cook