Sky Watcher Pro Series Mak

I'll be pleased to relieve you of such a burden. Prefer cash...

Sorry, I couldn't resist :-)

Andrea T.

In article .com, wrote:
I'll be pleased to relieve you of such a burden. Prefer cash...

Sorry, I couldn't resist :-)

Nice try :-)

Jim
--
Find me at http://www.ursaMinorBeta.co.uk
JediGeeks http://www.jedigeeks.com
"Ah, gentle dames, it gars me greet, To think how monie councels sweet,
How monie lengthen'd, sage advices, The Husband frae the wife despises!"

"Jim" wrote in message
...
In article . com,
wrote:
NO WAY :-)

Seriously though, how can you expect a 6" to come even only close to a
10" if of the same optical quality.

Probably due to the fact that I've heard (somewhere, not sure where)
that
'slower' telescopes are better for planetary work than 'faster' ones.

Hence the f12 might be better than the f4.8, even though it's smaller.

I take it this is wrong?
Problem of 'levels'.
A 'slower' scope, when dealing with a _refractor_, will display less
chromatic aberration. This was why, before achromats were invented, you
had massively 'long' refractors, using focal ratios like F/40.
A 'slower' scope, for a given eyepiece, will give more magnification
(which may help to get to 'useable' planetary focal ratios).
A 'slower' scope, when dealing with Newtonians, SCTs,and Maksutovs, will
have a smaller secondary obstruction, and should therefore give slightly
better contrast.
A 'slower' scope (in the case of a Newtonian), will be slightly easier to
collimate.
Except for the first effect (you would hate to see the chromatic
abberation, from an uncorrected F/4.8 refractor!...), you are though
dealing with small 'percentage' improvements, rather than massive changes.
This is why you have comparisons between (say), a 5" Maksutov, and a 4"
APO. These differences are only small 'levels'.
The smaller scope, will though almost certainly achieve a large fraction
of it's potential performance, _more often_ than the larger scope. This is
because the larger diameter column of air being 'looked through' by the
larger scope, but when conditions are good, the bigger scope will win.

Best Wishes

In article , Roger Hamlett wrote:

NO WAY :-)

Seriously though, how can you expect a 6" to come even only close to a
10" if of the same optical quality.

Probably due to the fact that I've heard (somewhere, not sure where)
that
'slower' telescopes are better for planetary work than 'faster' ones.

Hence the f12 might be better than the f4.8, even though it's smaller.

I take it this is wrong?
Problem of 'levels'.
A 'slower' scope, when dealing with a _refractor_, will display less
chromatic aberration. This was why, before achromats were invented, you
had massively 'long' refractors, using focal ratios like F/40.
A 'slower' scope, for a given eyepiece, will give more magnification
(which may help to get to 'useable' planetary focal ratios).
A 'slower' scope, when dealing with Newtonians, SCTs,and Maksutovs, will
have a smaller secondary obstruction, and should therefore give slightly
better contrast.
A 'slower' scope (in the case of a Newtonian), will be slightly easier to
collimate.
Except for the first effect (you would hate to see the chromatic
abberation, from an uncorrected F/4.8 refractor!...)

I have two SkyWatcher achros that are in the f5 area - you're right, it's
quite shocking.

, you are though
dealing with small 'percentage' improvements, rather than massive changes.
This is why you have comparisons between (say), a 5" Maksutov, and a 4"
APO. These differences are only small 'levels'.
The smaller scope, will though almost certainly achieve a large fraction
of it's potential performance, _more often_ than the larger scope. This is
because the larger diameter column of air being 'looked through' by the
larger scope, but when conditions are good, the bigger scope will win.

Ah, gotcha. I think it was the contrast I was thinking of but, as usual,
hadn't fully grasped it exactly.

I think I'd still consider the f12 Mak if only to replace my current
'middle' 'scope (a 120mm SkyWatcher f5 achro). Trouble is, I'd have
those notoriously bad Mak cooldown times to think about.

Thanks for the info.

Jim
--
Find me at http://www.ursaMinorBeta.co.uk
JediGeeks http://www.jedigeeks.com
"Ah, gentle dames, it gars me greet, To think how monie councels sweet,
How monie lengthen'd, sage advices, The Husband frae the wife despises!"

In article , Roger Hamlett wrote:
I think I'd still consider the f12 Mak if only to replace my current
'middle' 'scope (a 120mm SkyWatcher f5 achro). Trouble is, I'd have
those notoriously bad Mak cooldown times to think about.

Thanks for the info.
This sort of scope, can make a great little planetary scope (with the
cooldown caveats), with the size making them nice to mount/handle (the
downside of the larger scope..).

In general, what advantages does a slow 'scope have over a fast one?
Apart from easier collimation and higher mag for a given e/p?

Jim
--
Find me at http://www.ursaMinorBeta.co.uk
JediGeeks http://www.jedigeeks.com
"Ah, gentle dames, it gars me greet, To think how monie councels sweet,
How monie lengthen'd, sage advices, The Husband frae the wife despises!"

"Jim" wrote in message
...
In article , Roger Hamlett
wrote:

NO WAY :-)

Seriously though, how can you expect a 6" to come even only close to
a
10" if of the same optical quality.

Probably due to the fact that I've heard (somewhere, not sure where)
that
'slower' telescopes are better for planetary work than 'faster' ones.

Hence the f12 might be better than the f4.8, even though it's smaller.

I take it this is wrong?
Problem of 'levels'.
A 'slower' scope, when dealing with a _refractor_, will display less
chromatic aberration. This was why, before achromats were invented, you
had massively 'long' refractors, using focal ratios like F/40.
A 'slower' scope, for a given eyepiece, will give more magnification
(which may help to get to 'useable' planetary focal ratios).
A 'slower' scope, when dealing with Newtonians, SCTs,and Maksutovs,
will
have a smaller secondary obstruction, and should therefore give
slightly
better contrast.
A 'slower' scope (in the case of a Newtonian), will be slightly easier
to
collimate.
Except for the first effect (you would hate to see the chromatic
abberation, from an uncorrected F/4.8 refractor!...)

I have two SkyWatcher achros that are in the f5 area - you're right,
it's
quite shocking.
Remember that these are already achromats, so have quite a lot of
correction!...

, you are though
dealing with small 'percentage' improvements, rather than massive
changes.
This is why you have comparisons between (say), a 5" Maksutov, and a 4"
APO. These differences are only small 'levels'.
The smaller scope, will though almost certainly achieve a large
fraction
of it's potential performance, _more often_ than the larger scope. This
is
because the larger diameter column of air being 'looked through' by the
larger scope, but when conditions are good, the bigger scope will win.

Ah, gotcha. I think it was the contrast I was thinking of but, as usual,
hadn't fully grasped it exactly.

I think I'd still consider the f12 Mak if only to replace my current
'middle' 'scope (a 120mm SkyWatcher f5 achro). Trouble is, I'd have
those notoriously bad Mak cooldown times to think about.

Thanks for the info.
This sort of scope, can make a great little planetary scope (with the
cooldown caveats), with the size making them nice to mount/handle (the
downside of the larger scope..).
Have fun.

Best Wishes

In article , Jim wrote:
In article , Roger Hamlett wrote:
I think I'd still consider the f12 Mak if only to replace my current
'middle' 'scope (a 120mm SkyWatcher f5 achro). Trouble is, I'd have
those notoriously bad Mak cooldown times to think about.

Thanks for the info.
This sort of scope, can make a great little planetary scope (with the
cooldown caveats), with the size making them nice to mount/handle (the
downside of the larger scope..).

In general, what advantages does a slow 'scope have over a fast one?
Apart from easier collimation and higher mag for a given e/p?

I'm thinking of reflectors here, BTW, not refractors...sorry, should
have mentioned that to begin with.

Jim
--
Find me at http://www.ursaMinorBeta.co.uk
JediGeeks http://www.jedigeeks.com
"Ah, gentle dames, it gars me greet, To think how monie councels sweet,
How monie lengthen'd, sage advices, The Husband frae the wife despises!"

Jim wrote:
In general, what advantages does a slow 'scope have over a fast one?

Easier to get the figure of the optics within acceptable limits.

More forgiving on eyepieces generally.

(Assuming same aperture) the slower scope will need a longer fl eyepiece
for the same mag, therefore better eye relief and eyepiece aberrations
easier to control (eyepiece lenses less highly curved).

Best,
Stephen

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None. I use routinely fast (f/5.5) scopes for high magnification
planetary work. Another planetary visual observer I know of is using a
f/5.1 apo refractor with good results.

Andrea T.

wrote:

None. I use routinely fast (f/5.5) scopes for high magnification
planetary work. Another planetary visual observer I know of is using a
f/5.1 apo refractor with good results.

Right-o. Thanks.

Jim
--
Find me at http://www.ursaminorbeta.co.uk AIM/iChatAV: JCAndrew2

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