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Subject: [M]: 10 lb Weight in Mak OTA?
From: Ed Stewart
Reply To: mapug@shore.net
Date: Fri Jul 25 14:04:06 1997

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A friend forwarded this interesting note from sci.astro about there being a
10lb. weight in the Mak's OTA (except for those purchased as just an OTA).
Was any one else in Mapug aware of this?

> From: Wil Milan <wmilan@airdigital.com>
> Newsgroups: sci.astro.amateur
> .... I negotiated a lower price
> with the dealer and was going to keep it, but then I found that the ~10
> lbs of weights Meade puts inside the 7" Mak (yes, Meade puts 10 lbs of
> pig iron in the back of the 7" Mak tube; that's so it'll balance on
> their existing fork mount, but it makes for a !@#% heavy OTA) would
> *not* come out. The dealer who sold it to me thought the weights should
> be easy enough to take out, but in fact the weight is either pressed or
> glued in and apparently won't come out without destroying the whole
> case. So, back goes the Mak; it's too heavy (~23 lbs) for the mount on
> which I was going to use it.
> ... I also need
> to throw a brickbat about the 7" Meade Mak: Putting the pig-iron weight
> in the back of the tube is a !@#% lousy idea, Meade. Dumb, dumb, dumb.
> It not only makes the scope needlessly heavy (making a 7" OTA almost as
> heavy as a C11), but all that extra metal inside must greatly lengthen
> the cool-down time of the scope. Even with the tiny built-in fan it
> takes a long time for this scope to stabilize. The extra weight also
> needlessly taxes mounts and drives, again for no good reason. At the
> very least they could have made the weight disk removable rather than
> taking the cheapest solution and making it non-removable. The one
> positive note is that if one buys the 7" Mak from the factory as an OTA
> only (i.e., not part of an LX50 or LX200) it comes *without* the weight.
> But that is of no use to those who would dearly love to remove the !@#%
> pig-iron weights from tubes we already have.

--
Ed Stewart, Austin, TX <stargzer@austin.cc.tx.us>
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
<http://www.austin.cc.tx.us/astro-ES/AstroDesigns/index.htm>
Mapug (Meade Adv. Products Users Group) Topical Archive site.
Accessory designs and information for the Meade LX200 and Dobsonian telescopes.
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>From the desk of: Tom Robichaux tie-line 678-5977
I.E. - PC Co.- Austin ECAT
Bld 005/2C-010 Mail 1750
SUBJECT:

Interesting post from the Usenet. Were you aware of the internal
counter-weight? :




From: Wil Milan <wmilan@airdigital.com>
Newsgroups: sci.astro.amateur
Subject: Surprises from an LX10 (8" SCT) and a 7" Maksutov
Date: 25 Jul 1997 11:40:01 -0700
Message-ID: <33D8F369.7612@airdigital.com>
Reply-To: wmilan@airdigital.com

In the last few days I've learned a few things about a couple of popular
telescopes, so I thought I'd pass on:

Yesterday I purchased an LX10, Meade's low-end econo-model 8"
Schmidt-Cassegrain. I don't exactly *need* another telescope :) , but
I've been wanting a scope that I can use for quickie everyday observing,
something bigger than the Genesis but smaller than the C11. (The former
is fun but doesn't do well on dimmer objects, the C11 is a bear to drag
out for quick observing.) What I've been thinking of getting is a 6" -
7" Maksutov.

And in fact I did buy a 7" Meade Mak OTA from a used-scope dealer. But
that deal was jinxed: First the scope arrived damaged by UPS (finder and
bracket were broken - the third telescope UPS has broken in the last
year). Then the condition of the scope was not what I thought: it had
been touted as "like new," but when I examined it I found that there
were cleaning marks and thin scratches on the corrector and even the
back side of the corrector needed cleaning. I negotiated a lower price
with the dealer and was going to keep it, but then I found that the ~10
lbs of weights Meade puts inside the 7" Mak (yes, Meade puts 10 lbs of
pig iron in the back of the 7" Mak tube; that's so it'll balance on
their existing fork mount, but it makes for a !@#% heavy OTA) would
*not* come out. The dealer who sold it to me thought the weights should
be easy enough to take out, but in fact the weight is either pressed or
glued in and apparently won't come out without destroying the whole
case. So, back goes the Mak; it's too heavy (~23 lbs) for the mount on
which I was going to use it. Too bad, because the optics were good --
not perfect, but good.

I was then thinking about one of the popular Russian 6" Maks, but while
I was picking one up at a local astronomy shop I noticed that for less
money I could buy a Meade 8" SCT, the economy LX10 model. This is not
only the OTA but also the fork mount, drive, RA corrector, and wedge (no
tripod, but I've got scope tripods). Hmmm, I wondered, wouldn't this be
a better deal -- an 8" SCT vs a 6" Mak? But would it be as good
optically? And how much more would the 8" weigh vs. the 6" Mak?
(*Anything* would be lighter than the 7" Mak and its pig-iron ballast.)

To shorten the story, I bought the LX10 and took it home. As soon as I
got home I took the OTA off the forks and found the OTA by itself is
very light -- only 11 lbs, only about 1 lb more than the 6" Mak, about
the same as my Genesis and less than half the weight of the 7" Mak. I
was going to use just the OTA on my existing AP400 mount and sell off
the mount, but what the heck, I decided to try it with its own mount
just to see what it's like. So I put the tube back on the forks, put the
tube, forks, and drive base on my Celestron Ultima-11 wedge, and went
out for a look.

First of all I found that it took the OTA more than an hour to come up
to ambient temperature. I say come *up* to temperature because I live in
Phoenix and the temperature outside (mid-90s F) at 10pm was about 20
degrees warmer than inside. Still, it warmed up faster than the 7" Mak
had the night before, probably because the 8" SCT doesn't have the
thermal mass of the !@#% pig iron inside the 7" Mak.

While the optics were warming up I played with the drive and mount.
Turns out it's a surprisingly decent drive and mount; for the price I'd
expected something barely useable. But in fact I found them quite good;
the 5.75" worm drive is steady and accurate and the forks are rigid
enough that focusing even at 400x did not wobble it much. I do wonder,
however, how much of that steadiness has to do with the ultra-beefy
wedge and tripod to which the drive base was bolted: the Ultima-11
tripod is far beefier than the standard LX10 tripod, and the wedge I was
using is a custom wedge and frame made from solid 1"-thick aircraft
aluminum slabs. Perhaps with the standard (and much lighter) LX10 wedge
and tripod it would not be so vibration resistant.

Once the tube currents had died away I set about comparing the LX10's
optical performance against the 7" Mak I'd tested the night before. The
seeing was not good enough to do a critical star test, but high-power
star images looked to have a couple of diffraction rings and -- hard to
tell in the conditions -- perhaps the hint of a third. Not as good as
the 7" f/15 Mak, but one would expect that from the larger central
obstruction of the f/10 SCT. Collimation of the 8" was dead-on out of
the box, which surprised me.

I found that the 8" would split Epsilon Lyrae just as easily as the 7"
Mak, with the stars a bit less point-like (could have been the
difference in seeing from one night to the next) but both pairs showing
a line of black space between the two stars. The Ring Nebula (M57)
showed just as high a contrast in the 8" as in the 7" Mak and I could
make out the same amount of detail, while the Dumbell Nebula (M27) was
visibly brighter and showed a bit more structure with the 8". M13 showed
strings of individual stars all the way across (as one would expect)
with overall contrast about the same as on the 7" Mak. Once Jupiter was
high enough in the sky at 220x and 400x I could clearly discern the
relative sizes of the satellites (interesting set of conjunctions last
night). But to my surprise the 8" clearly outperformed the 7" Mak in
planetary detail: I could make out more bands and lines more clearly
with the 8", and the edge irregularities in the major bands were more
clearly discerned in the 8". This despite seeing which was so-so at
best. (A 105-degree day -- the norm in Phoenix this time of year --
makes for lousy seeing all night.)

Later when the moon came up I found that contrast on lunar features
seemed a hair less with the 8", but again that could have been due to
conditions and the fact that I was observing the moon lower in the sky
with the 8" than I had with the 7" Mak. Finally, just before turning in
I took a look at Saturn, which had just come up, and found that in clear
moments of seeing Cassini's Division was clearly discerned, but that is
no surprise. Saturn was too low in the sky to try any more critical
observation, so I called it a night.

Overall I was surprised by several things I found about the LX10:

- I was surprised that all around its optical performance matched or
exceeded that of the 7" Mak. With 1" more aperture perhaps one should
expect that, but based on scuttlebutt and Meade's marketing literature I
would have expected the 7" Mak to be optically superior. That's
particularly true because the 7" Mak has a smaller central obstruction,
but apparently the larger aperture of the 8" must more than make up for
that.

- I was surprised that the LX10's optics are quite good overall, in fact
very good indeed. I'd heard all the horror stories of lousy quality
control, but this one, at least, is very good. A friend who sells scopes
of all brands tells me that of late (last 2 years or so) Meade's SCTs
have been consistently very good. I'm sure some lemons still get out,
but based on my one experience I'd have to say they're also turning out
some very good scopes.

- I was surprised that the drive and mount are as good as they are. It's
not as sophisticated as an Ultima or Losmandy mount, but very useable
indeed, in my opinion much better than the German equatorials Meade puts
on their Newtonians.

- Trying to optimize the LX10's planetary performance, I tried
substituting a Tele Vue 1.25" mirror diagonal for the prism diagonal
which came with the LX10. To my surprise the Meade prism diagonal was
*better* than the Tele Vue mirror diagonal. Not a lot better, but enough
to be detectable in the star images. This was a shock; I was *sure*
images would be better through the Tele Vue diagonal (which has always
seemed OK in other scopes).

- Remembering the last SCT I owned and others I've used, I expected a
fair amount of mirror shift when focusing. To my surprise I found very
little, and in fact it's barely perceptible at 220x. The 7" Mak was even
better in that respect: I could not detect any confirmable mirror shift
at all. Apparently Meade has improved its focusers in the years since I
last owned a Meade SCT.

Having said all those wonderful things about Meade's 8" SCT, I also need
to throw a brickbat about the 7" Meade Mak: Putting the pig-iron weight
in the back of the tube is a !@#% lousy idea, Meade. Dumb, dumb, dumb.
It not only makes the scope needlessly heavy (making a 7" OTA almost as
heavy as a C11), but all that extra metal inside must greatly lengthen
the cool-down time of the scope. Even with the tiny built-in fan it
takes a long time for this scope to stabilize. The extra weight also
needlessly taxes mounts and drives, again for no good reason. At the
very least they could have made the weight disk removable rather than
taking the cheapest solution and making it non-removable. The one
positive note is that if one buys the 7" Mak from the factory as an OTA
only (i.e., not part of an LX50 or LX200) it comes *without* the weight.
But that is of no use to those who would dearly love to remove the !@#%
pig-iron weights from tubes we already have.

Now I need more eyepieces, of course, but that's another problem... :)

Wil Milan

Tom .........................................................


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