the refractor craze??

I think the buyers
of the SCT's are disappointed with these instruments and in someway regret
their purchasing decisions or at least long for another instrument with
complimenting features.

No disappointment.
No regrets.
No longing, except for more clear nights.

I recommend mid-sized SCTs specifically for the
combination of portability, ease of use/set-up, and good optics.
Visual or otherwise.

SSX

Aperture for aperture an f/6 (or there about) apochromat refractor is
the closest thing to an all-around-do-anything-telescope. Why?
(keeping in mind "aperture for aperture".)

1) For all practical purposes image quality is 'perfect'. The
aperture is totally free from any and all obstructions. It has the
highest (percentage) concentration of light within the Airy disk
that's possible. Scattered light is at a minimum. Contrast is at a
maximum.

2) equal suitability for low-power, wide-field work and high power
planetary or double star work. At equal apertures the apo isn't
likely to be bested in either area by any other telescope. It's
literally the best of both worlds.

3) For refractors in general: Thermal cool-down takes less time.
Tube currents are less of a problem.

4) Collimation is 'dead-on' when received and tends to stay that way
indefinitely. Minimal maintenance is necessary.

5) Mounting options are 'open'. The apo can be mounted in whatever
manner is necessary for whatever task the owner may desire to put it
to.

6) The only way it can be bested (in one way or another) is by
utilizing a scope of smaller or larger aperture; but that other scope
will not be able to best the original apo in all areas for all
purposes (portability is an important consideration for many
amateurs).

The above may not be reasons enough for all people to go with a high
quality refractor; but it's sufficient for some -- and that's all
that's needed to satisfactorily answer the original question.

Note: Not all of the above points apply to all refractors. OTOH, a
major component to any perceived 'refractor craze' *is* the fast, high
quality, apochromat refractor. The portability of small, fast,
achromats like the ST-80 provide another component to the perceived
craze. Many amateurs -- regardless of what kind of 'large' telescope
they use, also own a small refractor that bears at least some
resemblance to an ST-80.

Final (Personal) Note: For myself, under my relatively dark sky, a
small refractor can surpass the deepsky performance of larger
telescopes used under poorer skies. My largest refractor has a 13cm
aperture. Nevertheless I've visually observed Pluto, the Horsehead
Nebula (no filter used), and other objects (with my refractors) that
some people considered doable only with significantly larger
apertures.

Bottom Line: Aperture is *not* everything!

Sketcher
To sketch is to see.

Aperture for aperture an f/6 (or there about) apochromat refractor is
the closest thing to an all-around-do-anything-telescope. Why?
(keeping in mind "aperture for aperture".)


Inch for inch the APO F6 refractor certainly has a lot to offer.

Dollar for Dollar, well thats another story...


Final (Personal) Note: For myself, under my relatively dark sky, a
small refractor can surpass the deepsky performance of larger telescopes used
under poorer skies.

On the other hand, under a relatively dark sky, or under any sky for that
matter, a large Newtonian can easily surpass the performance of a small
refractor used under the same skies...

Inch for Inch or Dollar for Dollar??

Those 12.5 inch APOs at F4.5 are getting expensive these days...

jon

(Jon Isaacs) wrote:
[snip]
Final (Personal) Note: For myself, under my relatively dark sky, a
small refractor can surpass the deepsky performance of larger telescopes used
under poorer skies.

On the other hand, under a relatively dark sky, or under any sky for that
matter, a large Newtonian can easily surpass the performance of a small
refractor used under the same skies...

Undoubtedly, but if you only have two hours free and it's a 20 minute
drive to your local dark(er) skies site the ease of setting up a small
scope means you are more likely to actually go to the dark skies and
use the scope. For a grab-and-go or quick-look scope you want a small
OTA on a simple mount. If you're going for small and portable then
refractors start to look more attractive.

No point having a big newt if you never have the time or energy to use
the damn thing.


Tim
--
Foo.

Undoubtedly, but if you only have two hours free and it's a 20 minute
drive to your local dark(er) skies site the ease of setting up a small
scope means you are more likely to actually go to the dark skies and
use the scope. For a grab-and-go or quick-look scope you want a small
OTA on a simple mount. If you're going for small and portable then
refractors start to look more attractive.

No point having a big newt if you never have the time or energy to use
the damn thing.


Tim

I agree completely. I often make a 50 minute drive to the mountains for a
couple of hours observing. That is why my 12.5 inch Newt is F4.06 and sets up
more quickly than many small refractors.

Not too long ago I timed myself setting it up..

Sitting in the drivers seat of my 1992 Ford Escort Hatchback. Hit the stop
watch, pull the trunk release, open the door and go for it.

41 seconds late when I push the button to stop the watch, the scope is on its
mount, finders in place with a Starbound chair sitting alongside, ready to go.

12.5 inches is not big these days but its big enough for me to really see some
stuff...

jon

Sketcher wrote in message . ..
Aperture for aperture an f/6 (or there about) apochromat refractor is
the closest thing to an all-around-do-anything-telescope. Why?
(keeping in mind "aperture for aperture".)

1) For all practical purposes image quality is 'perfect'. The
aperture is totally free from any and all obstructions. It has the
highest (percentage) concentration of light within the Airy disk
that's possible. Scattered light is at a minimum. Contrast is at a
maximum.

2) equal suitability for low-power, wide-field work and high power
planetary or double star work. At equal apertures the apo isn't
likely to be bested in either area by any other telescope. It's
literally the best of both worlds.

3) For refractors in general: Thermal cool-down takes less time.
Tube currents are less of a problem.

4) Collimation is 'dead-on' when received and tends to stay that way
indefinitely. Minimal maintenance is necessary.

5) Mounting options are 'open'. The apo can be mounted in whatever
manner is necessary for whatever task the owner may desire to put it
to.

6) The only way it can be bested (in one way or another) is by
utilizing a scope of smaller or larger aperture; but that other scope
will not be able to best the original apo in all areas for all
purposes (portability is an important consideration for many
amateurs).

The above may not be reasons enough for all people to go with a high
quality refractor; but it's sufficient for some -- and that's all
that's needed to satisfactorily answer the original question.

Note: Not all of the above points apply to all refractors. OTOH, a
major component to any perceived 'refractor craze' *is* the fast, high
quality, apochromat refractor. The portability of small, fast,
achromats like the ST-80 provide another component to the perceived
craze. Many amateurs -- regardless of what kind of 'large' telescope
they use, also own a small refractor that bears at least some
resemblance to an ST-80.

Final (Personal) Note: For myself, under my relatively dark sky, a
small refractor can surpass the deepsky performance of larger
telescopes used under poorer skies. My largest refractor has a 13cm
aperture. Nevertheless I've visually observed Pluto, the Horsehead
Nebula (no filter used), and other objects (with my refractors) that
some people considered doable only with significantly larger
apertures.

Bottom Line: Aperture is *not* everything!

Sketcher
To sketch is to see.

Hare you obsrved, for example, the Perseus galaxy cluster with your 6"
refractor? How many galaxies can you see? How about NGC 6894? Or
NGC2371-2? How do these objects look in your 6" refractor?

Better on deep sky?

Give me a break!

Clear skies,
Shneor Sherman

"Shneor Sherman" wrote

Bottom Line: Aperture is *not* everything!

Sketcher
To sketch is to see.

Hare you obsrved, for example, the Perseus galaxy cluster with your 6"
refractor? How many galaxies can you see? How about NGC 6894? Or
NGC2371-2? How do these objects look in your 6" refractor?

Better on deep sky?

Give me a break!

Would you be disappointed in your weenie 22" if I brought a 40" dob to one
of your star parties? How about a 6.5 meter model? Bigger may be better for
seeing more stars in a cluster and more structure in a nebula or galaxy,
but.. how ridiculously big do you want to get?

Bigger may be better for
seeing more stars in a cluster and more structure in a nebula or galaxy,
but.. how ridiculously big do you want to get?

You know, this thread is ridiculous. What people who bash certain kinds of
telescopes don't understand is that the scope that gets used is the one that
people keep. If it's a refractor or reflector, who cares? Some people like
motorcycles, others like trucks. Depends on your personal need. No one is
right or wrong here.

Mark
The Catman
^..^

www.geocities.com/mark_rosengarten
Owner/Coordinator of the Neko Ultraportable Solar Observatory
Fun WITH The Sun for Everyone!

"Rich Lauzon" wrote in message m...
[...]
SCTs. So bottom line to me, if there is any scope design that doesn't make
sense to me particularly for visual observing it is the SCT.

That's an odd comment.

For visual astro viewing, an SCT on a tracking Alt/AZ fork mount is the most
comfortable and easiest to use for long viewing sessions:

1. eyepiece position doesn't vary all that much from horizon to zenith so one
can remain comfortably seated

2. no problems with meridian flip that plague many EQ mounts

3. no outstretched counterweights to whack body parts of passersby

4. SCTs are available with apertures easily permitting viewing faint fuzzies

5. really great for star parties

"Rich Lauzon" wrote in message m...
From my observations the most prevalent scope amongst serious amateurs is
the 8" and 10" SCT. I have a homemade 10" Dob which has been a great scopes
for many years. About two years ago I built a 90mm achro. refractor and find
I am using it more and more. Just a few days ago I ordered one of these 80mm
ED's from Orion to replace it and can't wait to get it. I think the buyers
of the SCT's are disappointed with these instruments and in someway regret
their purchasing decisions or at least long for another instrument with
complimenting features. The more observing I do the more I enjoy low power,
wide field views and I don't think I'm alone. Recently when set beside club
members with their SCT's there is always excitement about looking through my
refractor even though it is not a premium Apo. The high contrast and wide
field make the views more pleasing. At the recent Lunar eclipse I was a late
arrival but once my refractor was set up the others starting packing up
their gear and took turns watching through the refractor. Obviously this
was a perfect opportunity for a decent refractor to shine but there have
been other similar experiences. I've also heard the comments from those
looking through my Dob. that they can't believe how much better the images
are and how easy to that scope is to use compared to their fork mounted
SCTs. So bottom line to me, if there is any scope design that doesn't make
sense to me particularly for visual observing it is the SCT.

This must depend on other factors. The folks I generally observe with
in Northern Califnrnia mostly have dobsonians in the 18" to 30" range.
There are a couple of SCTs and a couple of refractors used as
secondary telescopes. There are a couple of dobs under 18". OTOH, we
have observing spots with relatively good skies - if the weather
cooperates, mag 6-6.5 skies are the norm. Plus, most of the year, we
have observing locations with altitude - at least 5,000 feet. I'm now
wondering if this has something to do with the prevalence of large-ish
dobs in our group.

Clear skies,
Shneor Sherman