Upgrade Advice Please

A few months ago my wife and I purchased our first scope, an Orion
Starmax 90mm EQ Mak-Cassegrain.

Generally, I like it, and use it often, but I would like something
better.

I like the portability of it. If I had to deal with anything a lot
heavier and bulkier I probably wouldn't use it much.

We've enjoyed looking at the moon, Jupiter, Saturn, and recently,
Mars. Yes, we can see the rings of Saturn and the moons of Jupiter,
but we would like to have a better view; larger and more detail. I
don't expect anything like the Hubble shots I see on the web, but a
larger image in the eyepiece, with more detail visible would be great.

We really like taking it outside when folks come to visit, and show
them some views that they have never seen. We would love to offer them
even more impressive views.

We live on a hilltop in New Hampshire with great view of other hills
and mountains, and we like to use it during the daytime for scenic
viewing. I guess that rules out reflectors.

I've tried higher power eyepieces, but they don't seem to make much
difference.

Where do I go from here??
A larger size Mak?
Dobsonian?
A refractor?

The big question:
How much bigger does the scope need to be to get a noticeable
improvement?
I guess size DOES matter!

I've noticed that the 127mm Maks have exactly twice the light grasp as
the 90mm. Is there a way to state, in measurable terms, how much more
we would be able to see with that scope? For example, how much larger
would Saturn look? How much more detail would we see?

Would the same size (and same power eyepiece) Mak, Dob, and refractor
all offer the same view, or are the substantial differences between
comparably sized models of each type?

If this is much of a consideration, I would really like to attach our
good quality digital camera (Canon G3) to whatever scope we may get.

I've rambled enough, any reasonable suggestions would be greatly
appreciated.

Brian Tilley wrote:

A few months ago my wife and I purchased our first scope, an Orion
Starmax 90mm EQ Mak-Cassegrain.

Generally, I like it, and use it often, but I would like something
better.

I like the portability of it. If I had to deal with anything a lot
heavier and bulkier I probably wouldn't use it much.

We've enjoyed looking at the moon, Jupiter, Saturn, and recently,
Mars. Yes, we can see the rings of Saturn and the moons of Jupiter,
but we would like to have a better view; larger and more detail. I
don't expect anything like the Hubble shots I see on the web, but a
larger image in the eyepiece, with more detail visible would be great.

We really like taking it outside when folks come to visit, and show
them some views that they have never seen. We would love to offer them
even more impressive views.

We live on a hilltop in New Hampshire with great view of other hills
and mountains, and we like to use it during the daytime for scenic
viewing. I guess that rules out reflectors.

I've tried higher power eyepieces, but they don't seem to make much
difference.

Where do I go from here??
A larger size Mak?
Dobsonian?
A refractor?

The big question:
How much bigger does the scope need to be to get a noticeable
improvement?
I guess size DOES matter!

I've noticed that the 127mm Maks have exactly twice the light grasp as
the 90mm. Is there a way to state, in measurable terms, how much more
we would be able to see with that scope? For example, how much larger
would Saturn look? How much more detail would we see?

Would the same size (and same power eyepiece) Mak, Dob, and refractor
all offer the same view, or are the substantial differences between
comparably sized models of each type?

If this is much of a consideration, I would really like to attach our
good quality digital camera (Canon G3) to whatever scope we may get.

I've rambled enough, any reasonable suggestions would be greatly
appreciated.

You'll probably get a lot of advice, and on this newsgroup, it's
mostly good.

The size of the image you see is a function of the magnification
your telescope provides, and this is a function of the objective
focal length and the eyepiece focal length. For the Orion
90mm StarMax, the focal length is 1250mm and the standard
(provided) eyepiece has a focal length of 25mm, this gives a
magnification of 50X.

The usual rule of thumb for magnification provided by a telescope
is that anything above twice the objective aperture in mm is
wasted (because of insufficient light gathering ability and resolution
limits). For your scope, this means that you could (under best
conditions) go as high as 180X (though the Orion catalog says 213X).
A 7mm eyepiece would provide this.

Before you leap to another telescope which may or may not
provide larger images (a larger objective will provide brighter images
and, hence, higher maximum theoretical magnification), I'd
invest in a couple of eyepieces. In your case, I suggest a 18mm
eyepiece and a 2X Barlow (which can be be used with both
the 25mm you already have and the 18mm). This will give
eyepiece effective focal lengths of 25mm, 18mm, 12.5mm (the
25mm used with the Barlow) and 9mm (the 18mm used with
the Barlow, resulting in magnifications of 50X, 70X, 100X,
and 139X, respectively (all rounded).

Orion sells a 17mm Sirius Plossl (close enough to 18mm)
for $39.95 and their 2X Shorty-Plus Barlow for $56.95. I have
both, and they're very good.

The best thing about eyepieces is that when you upgrade
your scope (and you probably will, eventually) the eyepieces
can move to the new scope.


--
Tom Royer
Lead Engineer, Software Test
The MITRE Corporation
202 Burlington Road
Bedford, MA 01730
Voice: (781) 271-8399
FAX: (781) 271-8500


"If you're not free to fail, you're not free." --Gene Burns

Celestron GPS 8 is your answer. Been everywhere with difference scopes and this
is the best all around usefull and great quality I''ve been able to find. If
money is a concern then the 8i.

I think that 6-10" dobs are by far the best bang for the buck but, at least
in these sizes, are not good for imaging. 8" goto scts gives similar
optical performance (when collimated), are great for imaging, but are much
more expensive. Other optical systems (e.g. maks, refractors) require
decent equatorial mounts for imaging, and these are not inexpensive. I
think you need to let people know what your budget is and how badly you want
to do imaging.

Dennis

"Brian Tilley" wrote in message
om...
A few months ago my wife and I purchased our first scope, an Orion
Starmax 90mm EQ Mak-Cassegrain.

Generally, I like it, and use it often, but I would like something
better.

I like the portability of it. If I had to deal with anything a lot
heavier and bulkier I probably wouldn't use it much.

We've enjoyed looking at the moon, Jupiter, Saturn, and recently,
Mars. Yes, we can see the rings of Saturn and the moons of Jupiter,
but we would like to have a better view; larger and more detail. I
don't expect anything like the Hubble shots I see on the web, but a
larger image in the eyepiece, with more detail visible would be great.

We really like taking it outside when folks come to visit, and show
them some views that they have never seen. We would love to offer them
even more impressive views.

We live on a hilltop in New Hampshire with great view of other hills
and mountains, and we like to use it during the daytime for scenic
viewing. I guess that rules out reflectors.

I've tried higher power eyepieces, but they don't seem to make much
difference.

Where do I go from here??
A larger size Mak?
Dobsonian?
A refractor?

The big question:
How much bigger does the scope need to be to get a noticeable
improvement?
I guess size DOES matter!

I've noticed that the 127mm Maks have exactly twice the light grasp as
the 90mm. Is there a way to state, in measurable terms, how much more
we would be able to see with that scope? For example, how much larger
would Saturn look? How much more detail would we see?

Would the same size (and same power eyepiece) Mak, Dob, and refractor
all offer the same view, or are the substantial differences between
comparably sized models of each type?

If this is much of a consideration, I would really like to attach our
good quality digital camera (Canon G3) to whatever scope we may get.

I've rambled enough, any reasonable suggestions would be greatly
appreciated.

Brian Tilley wrote:

We live on a hilltop in New Hampshire with great view of other hills
and mountains, and we like to use it during the daytime for scenic
viewing. I guess that rules out reflectors.

Why? Your Mak is a reflector and seems to work fine for you.

How about an fork mounted 8in or so SCT - reasonably compact and easy to
manage, can be used with a wedge for polar aligned astro use, or alt-az
for terrestrial use. Image is even right side up (but swapped L to R -
which doesn't bother people much; not like upside down terrestrial
images bother people.)

The things are dirt cheap new, and available used for half dirt cheap.

(Brian Tilley) wrote in message . com...
A few months ago my wife and I purchased our first scope, an Orion
Starmax 90mm EQ Mak-Cassegrain.

I like the portability of it. If I had to deal with anything a lot
heavier and bulkier I probably wouldn't use it much.

We live on a hilltop in New Hampshire with great view of other hills
and mountains, and we like to use it during the daytime for scenic
viewing. I guess that rules out reflectors.

Where do I go from here??
A larger size Mak?
Dobsonian?
A refractor?

The big question:
How much bigger does the scope need to be to get a noticeable
improvement?
I guess size DOES matter!

I've noticed that the 127mm Maks have exactly twice the light grasp as
the 90mm. Is there a way to state, in measurable terms, how much more
we would be able to see with that scope? For example, how much larger
would Saturn look? How much more detail would we see?

Would the same size (and same power eyepiece) Mak, Dob, and refractor
all offer the same view, or are the substantial differences between
comparably sized models of each type?

If this is much of a consideration, I would really like to attach our
good quality digital camera (Canon G3) to whatever scope we may get.

Well, you have quite a decision to make here. The first thing I will
note is that it will be ahrd to find a single scope that has all of
the things you are looking for here (portability, aperture, daytime
use, and photography). I would recommend that you consider getting 2
scopes. Scope 1 will be for daytime use and quick looks. The one you
have now is a good candidate for that (just keep it).

Scope 2 will be a larger scope for nightime only use. If you are
really interested in the photography aspect, something like a C9.25
Schmidt-cassegrain might be a good choice (or something similar, C8,
Meade 8" LX200 or LX90, etc.). These scopes have mounts that are
adequate for at least moon and planet astrophotos right away, and can
be used for deep sky photos with a little effort. They are still
reasonably portable, and they have enough aperture to be a big step up
from the 90mm you currently have.

If you are only interested in photographing the moon and planets (but
not deep sky), you can do this with a digital camera and a dobsonian
(even undriven). An equatorial platform will make this a bit easier,
but is not absolutely required. The advantages of a dob are that they
are more portable and quicker to set up than an SCT on an equatorial
mount, and you can get more aperture for the same money.

Resolution goes up linearly with aperture, so doubling the aperture
will double the amount of detail visible. Light gathering goes up by
the square, so doubling the aperture makes things 4 times as bright at
the same magnification. For planetary resolution, an 8-10" scope will
often show as much detail as possible (limited by the atmosphere), but
larger scopes will show more if the seeing is very good (or in moments
of good seeing). For deepsky, larger is ALWAYS better, since
light-gathering is the critical component. Again, this assumes the
same quality optics in all cases.

As to your questions about types of scopes, there have been many flame
wars here before on reflector vs. refractor vs. catadioptric, but the
basic breakdown is:

For the same aperture, refractor gives best images, followed by
reflector, followed by catadioptric (assuming all have good quality
optics).

For the same money, you can get a much bigger reflector, followed by a
catadioptric, distantly followed by a refractor (by far the most
expensive).

For the same transport size, you can a bigger Catadioptric, followed
by reflector, followed by refractor. Note that his is somewhat
dependent on the model of reflector, some dobs break down into quite a
compact package....

For daytime use, refractors and catadioptrics have easily available
erecting prisms, reflectors do not.

So you have to decide what the most important criteria are to you. For
myself, I have both a short tube refractor and an ETX (90mm Mak) for
daytime spotting use and quick evening looks, and a large dobsonian
for more serious night observation. This combination works well for
me. I am not very interested in photography, though. You might be
better off with an SCT in the 8-10" range (also, the C5 is supposed be
quite nice if the 8" is too expensive, although not as big a step up),
since you want to try photography.

Hope this helps, and hasn't just made it more confusing! ;-)

Jarad

Hi Brian,
Lots of great advice here as usual but one thing I would do is to try to
look through as many different scopes as possible before you make your
decision. Everyone has different tastes. Some like all types of scope, some
prefer particular types. Now I'm not trying to start anything, just my
opinion here, but I use to think I preferred the views in a good quality MAK
until I looked through a good quality refractor. I still like my MAK but I
love my TAK :-)

What I'm trying to say is find a astronomy club or a star party in you area
and get a look through as many scopes as you can. Once you do, you'll have a
better idea of what direction to go.

Brian A

"Brian Tilley" wrote in message
om...
A few months ago my wife and I purchased our first scope, an Orion
Starmax 90mm EQ Mak-Cassegrain.

Generally, I like it, and use it often, but I would like something
better.

I like the portability of it. If I had to deal with anything a lot
heavier and bulkier I probably wouldn't use it much.

We've enjoyed looking at the moon, Jupiter, Saturn, and recently,
Mars. Yes, we can see the rings of Saturn and the moons of Jupiter,
but we would like to have a better view; larger and more detail. I
don't expect anything like the Hubble shots I see on the web, but a
larger image in the eyepiece, with more detail visible would be great.

We really like taking it outside when folks come to visit, and show
them some views that they have never seen. We would love to offer them
even more impressive views.

We live on a hilltop in New Hampshire with great view of other hills
and mountains, and we like to use it during the daytime for scenic
viewing. I guess that rules out reflectors.

I've tried higher power eyepieces, but they don't seem to make much
difference.

Where do I go from here??
A larger size Mak?
Dobsonian?
A refractor?

The big question:
How much bigger does the scope need to be to get a noticeable
improvement?
I guess size DOES matter!

I've noticed that the 127mm Maks have exactly twice the light grasp as
the 90mm. Is there a way to state, in measurable terms, how much more
we would be able to see with that scope? For example, how much larger
would Saturn look? How much more detail would we see?

Would the same size (and same power eyepiece) Mak, Dob, and refractor
all offer the same view, or are the substantial differences between
comparably sized models of each type?

If this is much of a consideration, I would really like to attach our
good quality digital camera (Canon G3) to whatever scope we may get.

I've rambled enough, any reasonable suggestions would be greatly
appreciated.

"Brian Tilley" wrote in message
om...
A few months ago my wife and I purchased our first scope, an Orion
-----snippage----

The big question:
How much bigger does the scope need to be to get a noticeable
improvement?
I guess size DOES matter!

You have to decide if you're a visual observer, or an instrumented observer.

If you're a celestial, visual observer, and you live on a hilltop, and you
want to hear your in-law's dentures hit the patio when they look through
your eyepiece, then the answer is a large dobsonian. Get a large enough
dobsonian, and the sheer shock of what they'll see through the eyepiece may
kill them, in which case you may stand to inherit some money.

If you're a celestial, instrumented observer, an 8" SCT is a good start.
Come Christmas, your wife can get you a nice Starlight Xpress camera and a
Viao laptop. If you get a GOTO/GPS 8" SCT, then you have the ability to take
near-Palomar-quality astrophotos while knowing absolutely nothing about what
you're photographing. It's an age of miracles and wonders, isn't it?

You expressed in interest in planetary detail...
Eric Ng, of Hong Kong, has a 10" newtonian telescope with which he is able
to photograph planetary detail of....not Jupiter, but *Io* (pronounced
EYE-oh). That's one of Jupiter's moons. Dark at the poles, yellow in the
middle, his photos show. All with a 10" mirror from light
polluted-to-beat-the-band Hong Kong.
You've doubtless seen Jupiter's moons through your scope, so you can imagine
the improvement.

So you go from 127mm to 8" and you'll notice a big difference. But if you
go from say, 127mm to 10" newtonian, you get crazy big difference. 10" to
16", crazy big difference. 10" to 18 or 20", massively crazy big
difference. Then you have to go to 30" to get a crazy big differrence,
imho. 24" is big, but not crazy big. After 30", all of your friends and
relatives begin to die off from the shock of looking through your eyepiece.
I know there is a 72" mirror blank that sometimes appears on Astromart.com
and at other times, it appears in Sky and Telescope in the little classified
section. I think this guy is dangerous. Possibly a terrorist.

Personally, I have an 8" SCT, and an 18" dob. My in-laws are dead.

Warmest regards,

Etok



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"Etok" wrote in message ...


If you're a celestial, visual observer, and you live on a hilltop, and you
want to hear your in-law's dentures hit the patio when they look through
your eyepiece, then the answer is a large dobsonian. Get a large enough
dobsonian, and the sheer shock of what they'll see through the eyepiece may
kill them, in which case you may stand to inherit some money.


If you only knew how accurate that last part really is!!

Thanks to all for the information and advice.

I've found the web site for the local astronomy club, and plan to
attend a star party or two before I make a decision.

Looks like I have to see for myself what the different scopes have to
offer, and decide what it would take to get one that I consider to be
substantially better than what I have.

Thanks again.