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Pentax Scope VS. Meade Scope

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RPK

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Here's a question for all you digiscopers out there.

I've got a Meade 1000mm 90mm F/11 spotting scope, coated optics (rubber armored) with a 24mm ocular. F/11 isn't too dark but of course I would like to have more light for a fast shutter speed.

I'm looking at the Pentax PF-80ED scope which is 80mm, ED glass, 24mm ocular and from what I hear with a F/10 using. I don't know what the range is on the scope as I do with the Meade (1000mm).

Where does the Pentax fall into the world of focal lenght as the Meade does at 1000mm?

In my inexperience, I would assume that the 90mm scope would be brighter than the 80mm using the same 24mm ocular. Am I on the right path here or does the difference in glass + refractor vs. mirrored scope make a difference?

The biggest question is where and when the Pentax would rise about the Meade 90mm. There's got to be something to the near $1000 price tag for the PF-80ED (ocular included).

Will there be benefits of moving from one to the other OR will they be so sublte that the huge price difference isn't worth it.

Will someone help me out?
 
Hello RPK,

I am looking for either a Meade or Pentax. I just sold (eBay) a 77mm non-ED Kowa and have some funds available. This Kowa just had too much blue fringing. It was a great shooting scope, but as a photography lens it just didn't have it. Start pushing it's 25X with the 995's 4X and the image was intolerable.

That Pentax gets darn good write ups in Precision Shooting Mag. & at

http://www.betterviewdesired.com/ the bird watchers site. Lots of great info here.

If there is only 1 F stop difference, that's pretty darn close. I'm leaning to the Pentax for its ruggedness. Kowa has a new one out that has all the geat features and the 45 degree eyepiece too. That's a great convienence to have. Works great with the 995's and an adapter.

I would like to see a back-to-back' photographic' test between the Pentax and the Meade.

Cheers,
Ron N.
--Click here to see machine work/camera: http://www.pbase.com/packrat
 
I'm confused ...

Will the Pentax gather more light than the 90mm Meade? If they use the same ocular, how will the F/Stops compare. Can I expect better lighting with the Pentax at 80mm or Meade at 90mm?
Ron N. said:
Hello RPK,

I am looking for either a Meade or Pentax. I just sold (eBay) a
77mm non-ED Kowa and have some funds available. This Kowa just had
too much blue fringing. It was a great shooting scope, but as a
photography lens it just didn't have it. Start pushing it's 25X
with the 995's 4X and the image was intolerable.

That Pentax gets darn good write ups in Precision Shooting Mag. & at
http://www.betterviewdesired.com/ the bird watchers site. Lots
of great info here.

If there is only 1 F stop difference, that's pretty darn close.
I'm leaning to the Pentax for its ruggedness. Kowa has a new one
out that has all the geat features and the 45 degree eyepiece too.
That's a great convienence to have. Works great with the 995's
and an adapter.

I would like to see a back-to-back' photographic' test between the
Pentax and the Meade.

Cheers,
Ron N.

--
Click here to see machine work/camera:
http://www.pbase.com/packrat
Click to expand...
 
RPK,

According to some formulas, I have recently found on another web site. The determining factor is the objective lens of the telescopex magnification. By the way the Pentax would be a 800mm FL(10x80)F-ratio x objective lens gives you focal length. Because the 800mm pentax is a shorter lens than the Meade 1000mm, that would explain the slower F ratio on the Meade. I don't know what camera you have, but I have a 995, so I will use that as an example: Effective focal length = power of the telescope x camera focal length. For the Pentax that would be 800/24=33.33= telescope power. 33.33 x 32(focal length of camera at full zoom)=1066mm. You could times this by 4.75 if you want 35mm equivalent. Next formula is

F/ratio = EFL/telescope aperture. So 1066/80= F13.33. If I made the same calculations with the meade at the same Effective focal length as the pentax I would get a F11.85. What I got out of these formulas is the main factors affecting F/ratio is magnification and Objective lens size.

Here is the website were I got this formula and some more. The guys name is Barry Carter.

http://users.htdconnect.com/~chiron/afocal.html
RPK said:
Here's a question for all you digiscopers out there.

I've got a Meade 1000mm 90mm F/11 spotting scope, coated optics
(rubber armored) with a 24mm ocular. F/11 isn't too dark but of
course I would like to have more light for a fast shutter speed.

I'm looking at the Pentax PF-80ED scope which is 80mm, ED glass,
24mm ocular and from what I hear with a F/10 using. I don't know
what the range is on the scope as I do with the Meade (1000mm).

Where does the Pentax fall into the world of focal lenght as the
Meade does at 1000mm?

In my inexperience, I would assume that the 90mm scope would be
brighter than the 80mm using the same 24mm ocular. Am I on the
right path here or does the difference in glass + refractor vs.
mirrored scope make a difference?

The biggest question is where and when the Pentax would rise about
the Meade 90mm. There's got to be something to the near $1000 price
tag for the PF-80ED (ocular included).

Will there be benefits of moving from one to the other OR will they
be so sublte that the huge price difference isn't worth it.

Will someone help me out?
Click to expand...
 
The Pentax is 800mm if it is F/10. The Meade would ALWAYS be able to gather more light. But, with the same oculars, the Pentax would seem brighter since its field of view is wider. At the same magnification, the Meade would ALWAYS be brighter than the Pentax. (Or an 90mm objective will always gather more light than an 80mm objective.) To be at the same magnification would require the use of different eyepieces. (focal length / ocular length = magnification) or (focal length / magnification = ocular length).

40x on the Meade needs a 25mm eyepiece.
On the Pentax, you need a 20mm eyepiece.

Tony
RPK said:
Here's a question for all you digiscopers out there.

I've got a Meade 1000mm 90mm F/11 spotting scope, coated optics
(rubber armored) with a 24mm ocular. F/11 isn't too dark but of
course I would like to have more light for a fast shutter speed.

I'm looking at the Pentax PF-80ED scope which is 80mm, ED glass,
24mm ocular and from what I hear with a F/10 using. I don't know
what the range is on the scope as I do with the Meade (1000mm).
Click to expand...
 
MR. thank you for the response ... but it leaves the door open for a few more questions.

I do understand that the Pentax is a little bit "faster" at F/11.85 compared to the Meade at F/13.33. That leaves a difference of F/1.48, sure a little bit faster but at the expense of 200mm. Since the Meade 90mm @ 1000mm is 200mm larger than the 800mm Pentax, the slightly larger "zoom" would account for the higher F-Stop of F/1.48. I am on the right track here, aren't I?

So this leaves me back to my original question. The Meade 90mm is a little slower but has an advantage of 200mm additional over the Pentax (as compared with similar eye pieces. Wouldn't the extra 200mm be a benefit at only a small loss of F/1.48?

If I understand things (and I admit I'm a bit fuzzy), the Meade and Pentax should be just about the same minus if you take in consideration the loss of 200mm ?

With this in mind, would the Pentax 80mm provide noticeable optical difference over the Meade 90mm? Are the optics that much better in the Pentax to put the Meade aside? I'm thinking the extra 200mm would be a large benefit to get out there a little further. Seeing the difference in price (Pentax = $1000 / Meade = minus $300), the Meade should compare. Am I missing something here? Being a novice to optics and glass quality, how does the Meade compare? My Meade 90mm looks identical to the Celestron C-90 rubberized scope. From the provided tech facts, they appear to be the same.

I'm just looking to get the best bang for the buck. Bear in mind that I can also put a focal reducer on the Meade 90mm reducing the magnification and F/Stops by 3.6.

Anyone?
MR said:
Here is the website were I got this formula and some more. The guys
name is Barry Carter.

http://users.htdconnect.com/~chiron/afocal.html
RPK said:
Here's a question for all you digiscopers out there.

I've got a Meade 1000mm 90mm F/11 spotting scope, coated optics
(rubber armored) with a 24mm ocular. F/11 isn't too dark but of
course I would like to have more light for a fast shutter speed.

I'm looking at the Pentax PF-80ED scope which is 80mm, ED glass,
24mm ocular and from what I hear with a F/10 using. I don't know
what the range is on the scope as I do with the Meade (1000mm).

Where does the Pentax fall into the world of focal lenght as the
Meade does at 1000mm?

In my inexperience, I would assume that the 90mm scope would be
brighter than the 80mm using the same 24mm ocular. Am I on the
right path here or does the difference in glass + refractor vs.
mirrored scope make a difference?

The biggest question is where and when the Pentax would rise about
the Meade 90mm. There's got to be something to the near $1000 price
tag for the PF-80ED (ocular included).

Will there be benefits of moving from one to the other OR will they
be so sublte that the huge price difference isn't worth it.

Will someone help me out?
Click to expand...
Click to expand...
 
Anthony, thank you for the response.

So it has been established that the Meade 90mm will be brighter than the Pentax 80mm using the same eye piece. Now the bigger question, will the Pentax provide better / superior imaging due to the difference in scope design (mirror vs. refractor) and glass quality?

At $900+, what does the Pentax 80mm have over the Meade 90mm? There has to be something I'm missing here. If they are comparable, why the price difference.

I've been told that the Pentax being a refractor type (excuse me if wrong) will deliver better imaing over the Meades mirrored design. Is there truth there.

Pentax scopes are decently priced with the 20-60x ocular. I'm in need of advice of if there would be benefits of moving from the Meade 90mm to the Pentax 80mm spotting scope. From what I understand, they are pretty much the same and I can expect similar results.
Anthony Medici said:
40x on the Meade needs a 25mm eyepiece.
On the Pentax, you need a 20mm eyepiece.

Tony
RPK said:
Here's a question for all you digiscopers out there.

I've got a Meade 1000mm 90mm F/11 spotting scope, coated optics
(rubber armored) with a 24mm ocular. F/11 isn't too dark but of
course I would like to have more light for a fast shutter speed.

I'm looking at the Pentax PF-80ED scope which is 80mm, ED glass,
24mm ocular and from what I hear with a F/10 using. I don't know
what the range is on the scope as I do with the Meade (1000mm).
Click to expand...
Click to expand...
 
RPK said:
Anthony, thank you for the response.

So it has been established that the Meade 90mm will be brighter
than the Pentax 80mm using the same eye piece. Now the bigger
question, will the Pentax provide better / superior imaging due to
the difference in scope design (mirror vs. refractor) and glass
quality?

At $900+, what does the Pentax 80mm have over the Meade 90mm? There
has to be something I'm missing here. If they are comparable, why
the price difference.

I've been told that the Pentax being a refractor type (excuse me if
wrong) will deliver better imaing over the Meades mirrored design.
Is there truth there.
Click to expand...
Remember, you're comparing a "good" refractor with a realitivly "cheap" compound scope. That is where the difference will be.
RPK said:
Pentax scopes are decently priced with the 20-60x ocular. I'm in
need of advice of if there would be benefits of moving from the
Meade 90mm to the Pentax 80mm spotting scope. From what I
understand, they are pretty much the same and I can expect similar
results.
Click to expand...
As far as angle of view goes, yes they would be similar. If you want maximum detail, the Pentax should be the clear favorite. The Pentax should have more contrast, be less prone to flare, resolve more detail, and it won't give you funny looking specualr highlights like the compound scope will. It's up to you to decide if that's worth the $$$.

Isaac
 
I'm not sure where you are going here but there are a lot of other choices other than the two you have listed.

One you have listed is a spotting scope with 1 or 2 specialized eye pieces. (the Pentax) One you have listed is a telescope that can use any 1.25" eyepiece. (The Meade)

You should research some alternatives. Any number or size of scope can be found through Orion, who specializes in astronomical and bird watching equipment. They can be found at http://www.telescope.com and list a number of spotting scopes, which use specialized eyepieces, are sealed and are light to carry around. They also have a number of 'short tube' refractor telescopes, in various objective sizes that can be purchased with or without a tripod for well under the two scopes you have been researching. These are also quite light and small although larger than the specialty scopes but have very low F ratios. Or, if you want a catadioptric, they have a number of these, again in various objective sizes and strengths. These tend to be smaller than the refractors but of much higher F ratio, like the Meade.

This will give you some choices. You will find several that have a very low F ratio, or you can chose a higher power, higher f ratio scope. I am sure you can find something that meets your needs and your budget here.

Tony
 
Luckily, the Pentax spotting scope uses standard 1.25 ocular eye pieces. This is the advantage (my opinion) of choosing the Pentax. It seems to be a quality scope without a proprietary eye piece.

My point was to get to the quality of the optics. As I said, I am a novice and don't have a good understanding of one scope type over another.
Anthony Medici said:
I'm not sure where you are going here but there are a lot of other
choices other than the two you have listed.

One you have listed is a spotting scope with 1 or 2 specialized eye
pieces. (the Pentax) One you have listed is a telescope that can
use any 1.25" eyepiece. (The Meade)

You should research some alternatives. Any number or size of scope
can be found through Orion, who specializes in astronomical and
bird watching equipment. They can be found at
http://www.telescope.com and list a number of spotting scopes,
which use specialized eyepieces, are sealed and are light to carry
around. They also have a number of 'short tube' refractor
telescopes, in various objective sizes that can be purchased with
or without a tripod for well under the two scopes you have been
researching. These are also quite light and small although larger
than the specialty scopes but have very low F ratios. Or, if you
want a catadioptric, they have a number of these, again in various
objective sizes and strengths. These tend to be smaller than the
refractors but of much higher F ratio, like the Meade.

This will give you some choices. You will find several that have a
very low F ratio, or you can chose a higher power, higher f ratio
scope. I am sure you can find something that meets your needs and
your budget here.

Tony
Click to expand...
 
RPK said:
Here's another question. I've heard that the Orion scopes are
pretty good. They have a Short tube 90mm refractor scope for under
$250.

Comparing the Orion to the Pentax, would they compare? Being the
same design type, would the Pentax still fair better than the
Orion? Are there better optics (glass) and workmanship from one to
the other?

http://www.telescope.com/cgi-bin/OrionTel.storefront/3c3b4e1801cf6f16271cc0a80a0b063e/Product/View/A024

The only downside is the 500mm focal length.
Click to expand...
through all of this, remember, you get what you pay for. i am familiar with orion, they have good stuff and they have bad stuff. their good stuff costs a lot more than their bad stuff. to answer your question, no, the $250.00 refractor will not be as good as the $1000.00 pentax. --c.johnson
 
RPK said:
MR. thank you for the response ... but it leaves the door open for
a few more questions.

I do understand that the Pentax is a little bit "faster" at F/11.85
compared to the Meade at F/13.33. That leaves a difference of
F/1.48, sure a little bit faster but at the expense of 200mm. Since
the Meade 90mm @ 1000mm is 200mm larger than the 800mm Pentax, the
slightly larger "zoom" would account for the higher F-Stop of
F/1.48. I am on the right track here, aren't I?
Click to expand...
Yes your on right track, Looking back at my previous post it would be the Pentax with the F13.33 to the Meades F11.85. Sorry for the mistake.
RPK said:
So this leaves me back to my original question. The Meade 90mm is a
little slower but has an advantage of 200mm additional over the
Pentax (as compared with similar eye pieces. Wouldn't the extra
200mm be a benefit at only a small loss of F/1.48?
Click to expand...
The Meade is actually faster at eqaul effective focal lengths. Depending on what you would be shooting would determine how much you would need that faster f/ratio.
RPK said:
If I understand things (and I admit I'm a bit fuzzy), the Meade and
Pentax should be just about the same minus if you take in
consideration the loss of 200mm ?
Click to expand...
I believe the Pentax is a high quality refractor(APO) telescope. And the Meade is a Matsukov-Cassegrain. With the same objective lens size, Refractors especially a (APO), are considered the sharpest telescopes. Would it be a lot better, I don't know.
RPK said:
With this in mind, would the Pentax 80mm provide noticeable optical
difference over the Meade 90mm? Are the optics that much better in
the Pentax to put the Meade aside? I'm thinking the extra 200mm
would be a large benefit to get out there a little further. Seeing
the difference in price (Pentax = $1000 / Meade = minus $300), the
Meade should compare. Am I missing something here? Being a novice
to optics and glass quality, how does the Meade compare? My Meade
90mm looks identical to the Celestron C-90 rubberized scope. From
the provided tech facts, they appear to be the same.
Click to expand...
Probably can't answer this question. I would need to have tried the Pentax.
RPK said:
I'm just looking to get the best bang for the buck. Bear in mind
that I can also put a focal reducer on the Meade 90mm reducing the
magnification and F/Stops by 3.6.

Anyone?
MR said:
Here is the website were I got this formula and some more. The guys
name is Barry Carter.

http://users.htdconnect.com/~chiron/afocal.html
RPK said:
Here's a question for all you digiscopers out there.

I've got a Meade 1000mm 90mm F/11 spotting scope, coated optics
(rubber armored) with a 24mm ocular. F/11 isn't too dark but of
course I would like to have more light for a fast shutter speed.

I'm looking at the Pentax PF-80ED scope which is 80mm, ED glass,
24mm ocular and from what I hear with a F/10 using. I don't know
what the range is on the scope as I do with the Meade (1000mm).

Where does the Pentax fall into the world of focal lenght as the
Meade does at 1000mm?

In my inexperience, I would assume that the 90mm scope would be
brighter than the 80mm using the same 24mm ocular. Am I on the
right path here or does the difference in glass + refractor vs.
mirrored scope make a difference?

The biggest question is where and when the Pentax would rise about
the Meade 90mm. There's got to be something to the near $1000 price
tag for the PF-80ED (ocular included).

Will there be benefits of moving from one to the other OR will they
be so sublte that the huge price difference isn't worth it.

Will someone help me out?
Click to expand...
Click to expand...
Click to expand...
 
The Orion 90mm short tube lens, is a Achromatic, so is prone to chromatic aberrations
charles d. johnson said:
RPK said:
Here's another question. I've heard that the Orion scopes are
pretty good. They have a Short tube 90mm refractor scope for under
$250.

Comparing the Orion to the Pentax, would they compare? Being the
same design type, would the Pentax still fair better than the
Orion? Are there better optics (glass) and workmanship from one to
the other?

http://www.telescope.com/cgi-bin/OrionTel.storefront/3c3b4e1801cf6f16271cc0a80a0b063e/Product/View/A024

The only downside is the 500mm focal length.
Click to expand...
through all of this, remember, you get what you pay for. i am
familiar with orion, they have good stuff and they have bad stuff.
their good stuff costs a lot more than their bad stuff. to answer
your question, no, the $250.00 refractor will not be as good as the
$1000.00 pentax.
--
c.johnson
Click to expand...
 
Or the upside is the 500mm focal length. Having only a 500mm focal length means it has a F ratio of F5.6. Lots of light gathering ability and enough power to make for good digiscoping.

To digiscope, you need to be able to find the subject through the scope and then hold it still enough to take a picture. It is always easier to take a picture if you can use a faster shutter speed.

I saw mentioned that the Orion 90mm short tube is not apochromatic. True, but you have never tried this type of setup so $250 is not very much to see if you camera, tripod and skill level are up to digiscoping. I wouldn't want to get vinnetting after paying out $1000+ for a scope that you only want to use for digiscoping.

Of course, without budgetary constraints, I could suggest a Questar field scope. Best telescope in the world at the 90mm size. Or maybe the Orion VX102-ED, which is a apochormatic refractor having 665mm FL and a 102mm objective. Focal ratio F/6.5. A bargan at only $1600.

Me personally, I have a 400mm, 500mm and 1250mm scope and I use the two little ones most often because they are the easiest to carry around.

Tony
RPK said:
http://www.telescope.com/cgi-bin/OrionTel.storefront/3c3b4e1801cf6f16271cc0a80a0b063e/Product/View/A024

The only downside is the 500mm focal length.
Click to expand...
 
If anything, I'm more confused now than ever, sorry.

Since I already have the 90mm Meade I need to get the adaptor and see what I get. The image clarity (to the eye) appears very good, I cannot see any issues.

My intent was to get an opinion if the Pentax 80mm refractor would give me a measurable difference over my existing Meade 90mm mirror.

From what I have gathered, the Meade 90mm will be a bit darker BUT has a 200mm longer reach at an expense of about 1.5 F stops. That's not too bad.

There are quite a few others here with Meades and Celestrons that have good luck and quality images. The other concern is not limiting myself to a lense system that has the specifics for one camera only. I love my CP 995 but in a year I'll have a new one and I don't want to go through this all over again.
Anthony Medici said:
To digiscope, you need to be able to find the subject through the
scope and then hold it still enough to take a picture. It is always
easier to take a picture if you can use a faster shutter speed.

I saw mentioned that the Orion 90mm short tube is not apochromatic.
True, but you have never tried this type of setup so $250 is not
very much to see if you camera, tripod and skill level are up to
digiscoping. I wouldn't want to get vinnetting after paying out
$1000+ for a scope that you only want to use for digiscoping.

Of course, without budgetary constraints, I could suggest a Questar
field scope. Best telescope in the world at the 90mm size. Or maybe
the Orion VX102-ED, which is a apochormatic refractor having 665mm
FL and a 102mm objective. Focal ratio F/6.5. A bargan at only $1600.

Me personally, I have a 400mm, 500mm and 1250mm scope and I use the
two little ones most often because they are the easiest to carry
around.

Tony
RPK said:
http://www.telescope.com/cgi-bin/OrionTel.storefront/3c3b4e1801cf6f16271cc0a80a0b063e/Product/View/A024

The only downside is the 500mm focal length.
Click to expand...
Click to expand...
 
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