127mm Mak-Cas or Orion 80ED?

hi all,

I'm looking for a small scope to use on the moon and planets, assuming
cool down isn't a problem, has the refractor got anything to offer over
the Mak-Cass?

cheers
gaz

"Gaz" wrote in message
ups.com...

hi all,

I'm looking for a small scope to use on the moon and planets, assuming
cool down isn't a problem, has the refractor got anything to offer over
the Mak-Cass?

cheers
gaz

No central obstruction(nice for double stars), much wider field view, able
to go lower power, no collimation hassle, no cool down time, smooth images,
more contrast etc...
Julius

Assuming equal optical quality, the 127 mm Mak is equivalent to an 80 mm
refractor for lunar and planetary observing. The refractor would be
better suited for photography and low power/daytime use.


Gaz wrote:
hi all,

I'm looking for a small scope to use on the moon and planets, assuming
cool down isn't a problem, has the refractor got anything to offer over
the Mak-Cass?

cheers
gaz

Tim,

I didn't know that, I'd assumed I'd be losing a bit of resolving power
on the planets if I choose the ED , it was the main reason i was
leaning towards the Mak. Otherwise, as Szaki points out, i could have
a larger FOV, skip collimation etc.

Gaz

In terms of resolving power, the equivalent refractor aperture is
roughly equal to the aperture of the Mak minus the diameter of its
central obstruction. Collimation and cool down are not big issues with
small aperture Maks.

One advantage for the refractor I forgot to mention is less scattered
light because there are no extra reflections involved, This will give
slightly more contrast on planets.


Gaz wrote:

Tim,

I didn't know that, I'd assumed I'd be losing a bit of resolving power
on the planets if I choose the ED , it was the main reason i was
leaning towards the Mak. Otherwise, as Szaki points out, i could have
a larger FOV, skip collimation etc.

Gaz

While I agree with other posters about the optical properties of the refractor,
there are two things that you should also keep in mind. First, the Mak you
mentioned is capable of over 2.5x the magnification of the refractor you
mentioned due to its focal length, not a trivial consideration when it comes to
the Moon and planets, where magnification is as important as clarity of view.
Second, the Mak will have less color dispersion, giving cleaner images than the
refractor - no blue fringes on planet or Moon images.

And I know of three of those Orion Maks, one I own, and they've all performed
better than an equivalent sized Mak and according to one guy I trust, better
than an 8-inch SCT. While a well-made Mak will not outperform a well-made
refractor, the refractor you mentioned is a two element one with a relatively
short focal ratio of f/7.5, and making a good one takes more effort than the
Mak, so you're chances of getting a good Mak is better than the refractor, in my
opinion, given what I've experienced.

--
Sincerely,
--- Dave
----------------------------------------------------------------------
It don't mean a thing
unless it has that certain "je ne sais quoi"
Duke Ellington
----------------------------------------------------------------------

"Gaz" wrote in message
ups.com...

hi all,

I'm looking for a small scope to use on the moon and planets, assuming
cool down isn't a problem, has the refractor got anything to offer over
the Mak-Cass?

cheers
gaz

"David Nakamoto" wrote in message
news:wqQKd.403$zb.85@trnddc07...
While I agree with other posters about the optical properties of the
refractor, there are two things that you should also keep in mind. First,
the Mak you mentioned is capable of over 2.5x the magnification of the
refractor you mentioned due to its focal length,

That's a bull! Orion 80ED should do 250x or more any day, so 2.5x the Mak127
magnificatain, as you suggesting, would put it over 600x. Never
happened!Hahahaha!
I owned 6" Intes-Mak-Cass, much finer and more expensive OTA than the Orion
127 Mak, but it had to have excelent seeing to perform. My 3" f/15 Edscorp
refractor regularly out perfomed the 6" Mak when the seeing was not there.
Mak has a larger central obstruction (37%) than an SCT has, so one has to
deal with large, multable diffrection rings around stars or the moons of
Jupiter.
Person who used to refractor images, would puke.
Julius

Szaki, you're thoughtless in your answers, as simple math will show.

We're talking about an f/7.5 system in the 80ED, which you would have known if
you took the time to visit the Orion website, and thought anything about giving
correct answers instead of "showing off", and doing research before writing
anything down. This means the focal length is 600mm. Since "focal length of
telescope" / "magnification" = "focal length eyepiece", 600 / 250 = 2.4 mm.
Even if such an eyepiece exists, it also means you're pushing 80x per inch
aperture in a two element 80 mm telescope, only possible with the best optics
(which the Orion is not), long telescope focal ratios, and under absolutely
steady nights.

And your comparison is not correct either. You're comparing a 3-inch f/15
refractor to a 3-inch f/7.5 refractor (the Orion ED). No matter what you do,
you cannot achieve as much magnification through the same eyepieces from the
latter as through the former. As anyone who knows optics knows, figuring and
testing long focal ratio systems is easier than short focal ratio systems
(steepness of curves as well as tighter requirements on the figure of the curves
for the short focal ratio systems are two reasons). I have no doubt that a
3-inch f/15 refractor, if properly made would outperform a similarly sized Mak
(127 mm aperture and f/12 focal ratio) but we're not comparing such a Mak to an
f/15 instrument, but a much shorter focal ratio instrument. Color dispersion is
greater in such systems and affects performance, while the Mak is more immune to
such effects.
--
Sincerely,
--- Dave
----------------------------------------------------------------------
It don't mean a thing
unless it has that certain "je ne sais quoi"
Duke Ellington
----------------------------------------------------------------------

"Szaki" wrote in message
...

"David Nakamoto" wrote in message
news:wqQKd.403$zb.85@trnddc07...
While I agree with other posters about the optical properties of the
refractor, there are two things that you should also keep in mind. First,
the Mak you mentioned is capable of over 2.5x the magnification of the
refractor you mentioned due to its focal length,

That's a bull! Orion 80ED should do 250x or more any day, so 2.5x the Mak127
magnificatain, as you suggesting, would put it over 600x. Never
happened!Hahahaha!
I owned 6" Intes-Mak-Cass, much finer and more expensive OTA than the Orion
127 Mak, but it had to have excelent seeing to perform. My 3" f/15 Edscorp
refractor regularly out perfomed the 6" Mak when the seeing was not there.
Mak has a larger central obstruction (37%) than an SCT has, so one has to
deal with large, multable diffrection rings around stars or the moons of
Jupiter.
Person who used to refractor images, would puke.
Julius

I'm a user not a builder of telescopes. Good quality APO refractor, one can
push over 100x per inch on a good seeing night, compound telescopes like the
Mak, lucky if you can do 50X.
I'm getting tired of arguing with Newt,Mak, SCT guys about this, cause I
know they put down refractors for the price/aperture.. What I'm telling you
is from experience, not from theory.
I owned all those scopes, but I don't give up my refractor. After owning
many telescopes, I settled to C102F APO refractor (most used), 4" Mak(
MTO-11CA 10/1000 Telephoto Lens) for portability and a Ultima C-11 OTA for
DSO's. They all fit on my EQ mount or the GiroII for alt/az movement.
All these telescopes are very portable and easy to store, I know the pros
and cons of these scopes also.
My 4" Mak don't even come close to my TV Pronto I use to own. I heard good
things about the Orion80ED.
One has to use barlows for short focus length refractors, to get higher
magnification, that's all. I hate to use a Mak for terrestrially, long focus
length, narrow field. Yak!!!!
JS




"David Nakamoto" wrote in message
news:i6UKd.1078$UB6.973@trnddc01...
Szaki, you're thoughtless in your answers, as simple math will show.

We're talking about an f/7.5 system in the 80ED, which you would have
known if you took the time to visit the Orion website, and thought
anything about giving correct answers instead of "showing off", and doing
research before writing anything down. This means the focal length is
600mm. Since "focal length of telescope" / "magnification" = "focal
length eyepiece", 600 / 250 = 2.4 mm. Even if such an eyepiece exists, it
also means you're pushing 80x per inch aperture in a two element 80 mm
telescope, only possible with the best optics (which the Orion is not),
long telescope focal ratios, and under absolutely steady nights.

And your comparison is not correct either. You're comparing a 3-inch f/15
refractor to a 3-inch f/7.5 refractor (the Orion ED). No matter what you
do, you cannot achieve as much magnification through the same eyepieces
from the latter as through the former. As anyone who knows optics knows,
figuring and testing long focal ratio systems is easier than short focal
ratio systems (steepness of curves as well as tighter requirements on the
figure of the curves for the short focal ratio systems are two reasons).
I have no doubt that a 3-inch f/15 refractor, if properly made would
outperform a similarly sized Mak (127 mm aperture and f/12 focal ratio)
but we're not comparing such a Mak to an f/15 instrument, but a much
shorter focal ratio instrument. Color dispersion is greater in such
systems and affects performance, while the Mak is more immune to such
effects.
--
Sincerely,
--- Dave
----------------------------------------------------------------------
It don't mean a thing
unless it has that certain "je ne sais quoi"
Duke Ellington
----------------------------------------------------------------------

"Szaki" wrote in message
...

"David Nakamoto" wrote in message
news:wqQKd.403$zb.85@trnddc07...
While I agree with other posters about the optical properties of the
refractor, there are two things that you should also keep in mind.
First, the Mak you mentioned is capable of over 2.5x the magnification
of the refractor you mentioned due to its focal length,

That's a bull! Orion 80ED should do 250x or more any day, so 2.5x the
Mak127 magnificatain, as you suggesting, would put it over 600x. Never
happened!Hahahaha!
I owned 6" Intes-Mak-Cass, much finer and more expensive OTA than the
Orion 127 Mak, but it had to have excelent seeing to perform. My 3" f/15
Edscorp refractor regularly out perfomed the 6" Mak when the seeing was
not there.
Mak has a larger central obstruction (37%) than an SCT has, so one has
to deal with large, multable diffrection rings around stars or the moons
of Jupiter.
Person who used to refractor images, would puke.
Julius

"Szaki" wrote in message
news
I'm a user not a builder of telescopes. Good quality APO refractor, one can
push over 100x per inch on a good seeing night, compound telescopes like the
Mak, lucky if you can do 50X.
I'm getting tired of arguing with Newt,Mak, SCT guys about this, cause I know
they put down refractors for the price/aperture.. What I'm telling you is from
experience, not from theory.

Same here. Obviously you're not reading my message carefully enough. I pointed
out legitimate and KNOWN deficiencies in relatively short focal ratio
inexpensive two-element refractors, while acknowledging the benefits that others
have pointed out.

And what you call theory is the collective wisdom of many decades of visual
amateur astronomer experience from a lot of people on this newsgroup. You
obviously have a strong and I must say skewed bias toward refractors, without
taking into account the differences in performance brought about by such things
as focal ratio, two vs. three-element design, et al.

And I own a short focal ratio refractor, so I know something from personal
experience, if you're going to tout that out as your badge of authority. And
one thing I would not do, which you do, is to think that a refractor is a
refractor is a refractor. Focal ratio and objective design DOES MATTER, but I
doubt you understand this, given your responses to my messages.

Whatever experience you think you have, it's clear to me you need a lot more
before you can make cogent and fact-backed statements. That, and read the
messages your responding to more carefully.



I owned all those scopes, but I don't give up my refractor. After owning many
telescopes, I settled to C102F APO refractor (most used), 4" Mak( MTO-11CA
10/1000 Telephoto Lens) for portability and a Ultima C-11 OTA for DSO's. They
all fit on my EQ mount or the GiroII for alt/az movement.
All these telescopes are very portable and easy to store, I know the pros and
cons of these scopes also.
My 4" Mak don't even come close to my TV Pronto I use to own. I heard good
things about the Orion80ED.

So have I, but the fact remains that those reports I've gotten from observers
who I know to have lots of experience evaluating telescopes of various designs
and makes have said it was good for a two-element short focal length refractor,
meaning it will perform within the expectations of such a telescope, and NOT
like a longer focal ratio one, or a three-element one, or an expensive one, et
al.


One has to use barlows for short focus length refractors, to get higher
magnification, that's all. I hate to use a Mak for terrestrially, long focus
length, narrow field. Yak!!!!

But the Mak will deliver 2.4 times the magnification for the same eyepiece, so
it is also capable of delivering higher magnification, important for planetary
viewing. And in any case, I don't think that, given what I've heard and seen of
the Orion 80ED at star parties, that you can push it much past 30x per inch of
aperture, so your objection that this is the "limit" on the Mak (something I
also disagree on, from collective experience) is moot.

And the original poster asked specifically for planets and the Moon. Why drag
terrestrial viewing when it was not specified? In this case, the Mak is an
instrument he should consider, given that for a given eyepiece it will deliver
more magnification, less color dispersion, and potentially sharper views, if the
contrast isn't too bad.

--
Sincerely,
--- Dave
----------------------------------------------------------------------
It don't mean a thing
unless it has that certain "je ne sais quoi"
Duke Ellington
----------------------------------------------------------------------


"David Nakamoto" wrote in message
news:i6UKd.1078$UB6.973@trnddc01...
Szaki, you're thoughtless in your answers, as simple math will show.

We're talking about an f/7.5 system in the 80ED, which you would have known
if you took the time to visit the Orion website, and thought anything about
giving correct answers instead of "showing off", and doing research before
writing anything down. This means the focal length is 600mm. Since "focal
length of telescope" / "magnification" = "focal length eyepiece", 600 / 250 =
2.4 mm. Even if such an eyepiece exists, it also means you're pushing 80x per
inch aperture in a two element 80 mm telescope, only possible with the best
optics (which the Orion is not), long telescope focal ratios, and under
absolutely steady nights.

And your comparison is not correct either. You're comparing a 3-inch f/15
refractor to a 3-inch f/7.5 refractor (the Orion ED). No matter what you do,
you cannot achieve as much magnification through the same eyepieces from the
latter as through the former. As anyone who knows optics knows, figuring and
testing long focal ratio systems is easier than short focal ratio systems
(steepness of curves as well as tighter requirements on the figure of the
curves for the short focal ratio systems are two reasons). I have no doubt
that a 3-inch f/15 refractor, if properly made would outperform a similarly
sized Mak (127 mm aperture and f/12 focal ratio) but we're not comparing such
a Mak to an f/15 instrument, but a much shorter focal ratio instrument.
Color dispersion is greater in such systems and affects performance, while
the Mak is more immune to such effects.
--
Sincerely,
--- Dave
----------------------------------------------------------------------
It don't mean a thing
unless it has that certain "je ne sais quoi"
Duke Ellington
----------------------------------------------------------------------

"Szaki" wrote in message
...

"David Nakamoto" wrote in message
news:wqQKd.403$zb.85@trnddc07...
While I agree with other posters about the optical properties of the
refractor, there are two things that you should also keep in mind. First,
the Mak you mentioned is capable of over 2.5x the magnification of the
refractor you mentioned due to its focal length,

That's a bull! Orion 80ED should do 250x or more any day, so 2.5x the Mak127
magnificatain, as you suggesting, would put it over 600x. Never
happened!Hahahaha!
I owned 6" Intes-Mak-Cass, much finer and more expensive OTA than the Orion
127 Mak, but it had to have excelent seeing to perform. My 3" f/15 Edscorp
refractor regularly out perfomed the 6" Mak when the seeing was not there.
Mak has a larger central obstruction (37%) than an SCT has, so one has to
deal with large, multable diffrection rings around stars or the moons of
Jupiter.
Person who used to refractor images, would puke.
Julius