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Hi Warren,
I didn't mention this before, but I paid $7000 for my AP900 used,
in excellant condition and with the newest ROM upgrades. That price
included an AP portable pier, two weights (18# AND 10#), and an extra
mounting base. The extra base is the one that I attached to my fixed
pier, keeping the porta-pier for travel (which I've never actually
done). Anyhow, $7K does seem to be the going price for good used
AP900s with accesories.

Regards,
Gary

--- In C14@y..., "warrenhoss" <warrenhoss@y...> wrote:

Hello all. I plan to use a C14 for CCD imaging, in a portable
fashion (ie. not in an observatory or permanent site). I have 3
choices currently while I wait for a new AP1200GTO:

1. AP 900QMD (circa mid-1990's) - $3500.00
2. AP1200QMD (1994-95, recently serviced by AP) - $4500.00
3. AP 900GTO - $7000.00

Which do you recommend? Will the 900QMD be able to handle a c14

with

CCD equipment? Also, what do you think about an AP 1200 QMD that

is

almost 8 years old? Please let me know ASAP. Any advice would be
greatly appreciated!!

Folks,

I once read a story about someone who woke up the morning after at a star
party and found a puddle of water at the bottom of his SCT tube! I know of
no other scopes who have such a problem to this degree. Perhaps the
manufacturers should put a drain valve at the bottom of the tube. ;-) My
personal strategy is use and location. I try for locations which resist the
formation of dew and avoid leaving my corrector uncovered all night long,
only during actual viewing. I do not leave it pointed up.

I do not think there is anything nicer to look at than a good telescope. I
love to look at them. That is the best part of public parties. However, I
put function ahead of form. I go with what works, and hope and try to make
it aesthetically pleasing too.

The corrector can be easily removed by anyone who has good coordination and
manual skills with delicate and precision work. I always recommend anyone
do the proper research and preparation on anything before hand, but put
simply, one must remove the peripheral screws on the retaining ring, these
thread right into the flange in the front casting--- there is no inside nut
on these. I advise the use of an electronic scribe or pick with a bent tip
to grab one of the screw holes to lift the retaining ring. I place the ota
in an upright position with the two rear handles on wood blocks (the floor
is good for this). Be careful to make sure you don't let a screw drop onto
the corrector. I trust myself to do this, but you must do things at
whatever level you are comfortable with. By taking the secondary out, you
now have a nice handle on lifting out the corrector.

First, after removing the outer ring, there is a mark on the edge, probably
around 3o'clock, which is the number for your optical set. This matches
with the primary. They are a pair. This is your mark. Make a reference
scratch on the casting to line that number up with. You must replace the
corrector in this position. There are cork shims and spacers. They must be
removed and replaced as you find them. They prevent lateral shifting of the
plate. The corrector will probably be stuck to the cork shims of the
backside of the glass (these cushion the pressure from the retaining ring
against the metal flange which holds the corrector. It might take
considerable pull before it lets loose, and when it does it can be sudden
and with no warning. The retaining screws must not be overtightened during
reassembly.

This will get you inside the tube. While I am not endorsing that everyone
reading this go out now and take their SCT apart, it can be done, if you
want to and take the necessary care. I have provided all of the salient
information to do this. However, I must also say that in attempting this,
there are many potential risks, and you are playing with the very life of
your scope. If you screw up or have an accident, you might trash your
optics set. You must be willing to accept this risk and trust your skills
before attempting any of this.

This is why many urge you not to do anything which might cause an issue
inside the scope, like blowing around a bunch of dirt. Dirt by nature finds
itself into the most remote and troublesome places given the time. However,
as an owner of an SCT and other cats, I found that I am much happier with
them knowing I am their master, and not that they are mine! I hate "black
boxes!" ;-)

The air purge is only a last resort when you find you have serious internal
moisture which cannot be cleared otherwise. The air must be warm and dry,
and the scope must be warm too, not chilled below ambient. The primary
baffle will direct the air 75% of the way to the corrector before exiting
the baffle, and it will tend to go on through and out through the hole where
the secondary normally is. Holding a dew zapper a few inches away from the
rear port should provide a very gentle stream enough for just a slow
exchange of air inside. It might take 30 minutes to dry out the interior.
Any cheesecloth or other filtering agent used to trap dust will extend the
time further. Personally, if I had this problem, and I have not, my first
measure would be to bring the ota inside and let it slowly warm up to
ambient, with the visual back off and rear port open, and the secondary
removed (being careful of the mirror surface), with the scope in a clean,
calm location. This might be all you need to get the interior dried out
overnight. I would then seal it back up, and put some dry dessicant (packs)
in the back of the rear port (maybe tied to a thread hanging out through the
flange) to further remove any moisture. This way, no one can move the tube
unknowingly and send the dessicant further into the tube where it shouldn't
go, and with the interior air sealed in mostly, it would be very unlikely
that you would get further dewing up inside, no matter what the outside
conditions, on your next viewing session.

It wouldn't hurt to look around inside regularly and assess the inside of
your scope for changes in the primary coating, dirt, flaked paint maybe, or
deteriorating tube stiffeners. I've had serious problems in the latter. No
matter what your scope, one should never touch the optical surface unless
absolutely necessary. People who obsess over dirt and clean their lenses or
mirrors regularly are not taking good care of their telescopes but are
harming them with microscopic scratches. Only when a foreign agent
threatens to attract and leave a permanent mark due to chemical reaction
with air-borne compounds do I attempt this. With great care, you might be
able to clean only once every 5 years or much longer.

Wayne E. Gondella
AFA Engineering Company
Pittsburgh, Pennsylvania

Hello all. I plan to use a C14 for CCD imaging, in a portable
fashion (ie. not in an observatory or permanent site). I have 3
choices currently while I wait for a new AP1200GTO:

1. AP 900QMD (circa mid-1990's) - $3500.00
2. AP1200QMD (1994-95, recently serviced by AP) - $4500.00
3. AP 900GTO - $7000.00

Which do you recommend? Will the 900QMD be able to handle a c14 with
CCD equipment? Also, what do you think about an AP 1200 QMD that is
almost 8 years old? Please let me know ASAP. Any advice would be
greatly appreciated!!

Hi Wayne, Paul et al.

Thanks for your response. It seemed to me that moisture inside
is unavoidable but I'd not read of this happening to others, so I
wanted to check before I try to improve the situation. Paul's
comments about Forida humidity and his battle with it reminded me
that things could be worse - much worse. It seems to be a common
human weakness - to feel better when one realizes that there are
those who are even more afflicted.

Wayne recommends an insulated dewshield, and as it happens I have
one, a laminated aluminized mylar, fiber glass batt, vinyl blanket
with velcro attachments. I've not been using it because it's huge,
floppy, and I'd need to really cut it up to fit around my Telrad,
mount, and GuideStar guidescope mounting. However, I suppose I could
put some effort during daylight into it and, with a bit of judicious
velco application to the OTA, make it work OK. I must admit that, to
my shame, I seem to be one who looks at the scope almost as much as
throught the scope - and the insulated cover is ugly! Fortunately,
the is less of an impediment in the dark.

Wayne also observed that the corrector plate can be removed and, if
done carefully, even the collimation might be preserved on replacing
it. I'd not considered doing this before, but will now. It seemd
that I've read comments on the group to the effect that the nuts for
the frount housing are on the inside, complicating its removal. I
must look more closely.

What I think I'll try first is a gentle dry air purge, using a pvc
pipe to insert the air well above the primary and pulling the air
with a small fan trough a filter and over some dry silica-gel. The
suggestion of parking the scope with some dry dessicant in the
eyepiece port is a good one, and I'll try that also. Because of the
low roof in my observatory, I can't park it vertically, but the dryer
doesn't actually have to enter the OTA, a screw on cup at the eyepice
should be OK.

So, I've got a few things to try. I do like the possibility that I
could shut off the Kendricks heater - applying heat at the corrector
can't help the optical performance - but cooking the thing with a
heat gun every half an hour doesn't lead to good images either.

Thanks again and Best Regards,
Gary


--- In C14@y..., "W. Gondella" <gondella@s...> wrote:

The fact is that the Kendricks takes a lot of current and battery

power and

causes convective currents at the level needed to heat a C14 as you
indicated. The corrector will be warmer at the edge and colder in

the

center, setting up differential stresses in the glass. Such

heaters are a

last resort when nothing else works. You have all of that to hook

up, wires

and all, and if your battery dies you are sunk. None of this is

needed with

the dewshield I indicated because it covers the entire tube down to

the

finder and out the front by about a foot or more. It is a special,

custom

made shield, fitted to your scope, and of special materials, that

attaches

with velcro and rolls up, and is light. It eliminates the dewing

problem

without all the clutter and power requirements and expense.

Lastly, why

would one want an aluminum dewshield? Not only would it be heavy,

but

aluminum is a great conductor of heat, just the very thing you

DON'T want in

a dewshield. The problem here is the corrector cooling down too

fast! Next

time you dew up, look where the dew is: on all of your aluminum

surfaces

first.

As far as kicking up debris in the tube, I didn't say to stick a

sweeper

hose attachment to the thing! First, the OTA is sealed. Where did

all of

that dirt come from. I've taken many C14s apart and they are always
laboratory clean inside (they are assembled in a clean room). I

said to

apply a gentle heated air, like a dew zapper into the rear port.

Don't stick

it right again the scope, hold it back a couple inches. It will

mostly

blow straight on through and out the front hole with the removed

secondary.

Due to the "venturi" effect, known to anyone with a basic knowlege

of

physics, when the air moves from the constrained area of the baffle

into the

large cavity of the interior of the tube, the speed and pressure of

the air

will dramatically drop. In no way will that "kick up" dirt and

debris in

the tube. It will cause a gentle and slow circulation and

exchange, the

drier air for the moister air. We are not talking blowing a wind

through

the tube. The condensation left in place on the corrector and

secondary

will do far more damage to the optical surfaces than a little dry

air.

What do you think people with newtonians and dobs do with open

trusses out

in the weather? The way you talk, after one night, the optics

would be

done! I doubt even blowing a strong wind through the tube would

cause the

problem you describe. The inside tubes are clean. If any dust is

present,

it will be near the near port where you attach things. Take out the
secondary, and place a gentle vacuum at the rear port if you want

to be

sure. You can also place some cheesecloth over the opening where

the air is

drawn or blown in, if you are unsure. Nearly all the air will go

right out

the hole in the corrector. If you think your insides are THAT

dirty,

everytime you handle the tube and carry it, that dirt will fall and

move

around and end up on the corrector, etc. anyway!

It is a simple matter to remove the corrector and clean and dust the
interior anyway without doing any harm, if you are at all

competent. A

typical newt will see more dirt on its optics in a week than your

C14 will

see in 10 years. But given your typical dirty optics, this dirt

contributes

a small fraction of 1% light loss and scatter to the optic. Taken

together,

it would amount to an area the size of the head of a larger pin.

Look at

the stars, planets or whatever and place a pin in front of the

scope. Can

you see it? Put your finger there? Can you see the effect in the

image?

Try your fist. It will take about that much to seriously alter the
diffraction pattern enough to make a visible effect. That is equal

to a LOT

of dirt!

Think about it.

PS: To they guy looking to choose a C14 over a 12" Meade, if you

are reading

this, buy the C14. It will kill the Meade on the galaxies, and may

have

better images as well. You also get the option of the Fastar

feature. But

don't buy the CM1400. Get a better mount, at least a G11 from

Losmandy, or

an AP 900 from Astro-Physics.

Cheers,

Wayne E. Gondella
AFA Engineering Company
Pittsburgh, Pennsylvania

Date: Fri, 17 May 2002 08:41:57 EDT
From: paulatkinson22@a...
Subject: Re: Question re: Moisture in OTA

Gary,

I found that when I only had one Kendrick heater strip up
front running that the OTA would literally begin to sweat the

farther back

you went towards the EP, like a car left out on a humid night.

Here is

the

solution I found. Remember that the C14 has a huge OTA and is

33" long.

That is a lot of scope. It is very easy to have the air near the

corrector

above ambient, but have the air in the rear of the OTA be below.

This

means

the scope is battling itself to equalize and if it is humid

enough one

Kendrick strip is not enough especially if the scope is point up

towards

the

Zenith. I put a Kendrick heater strip up front around the

corrector plate

of

the OTA and then I have a second heater strip that I place about

the

middle

to last third of the tube. I found that by running it this way

that it

kept

the entire OTA above ambient and didn't allow certain areas to

cool more

than

others. I also found I did not have to run my heater as hard.

Lastly, If

you can use a dew shield do it. Astrozap (no affiliation) now

makes a

really

nice aluminum dewshield for the 14. I believe they are the only

ones

making

one in aluminum.

Hope this helps.

Paul



One last thing, never, and I mean never blow air into the OTA

through the

rear cell! This will kick up and dust or other debris that may

have

managed

to get inside. If any part of the inside is moist, i.e., the

back of the

corrector that is exactly where is is going to stick. Even if it

is not

moist this dust will end up coating your optics. Avoid this at

ALL cost.

Paul



Step 1: Buy an Insulated Dewshield from Richard Just at
ricvic@d...
Step 2: Put away your Kendricks, it can't keep a 14" glass plate

dry.

Step 3: Allow the tube to breath after humid weather and keep

desicant in

the rear port (scope looking up) when not in use.
Step 4: If in doubt, unscrew the secondary retainer ring, remove

secondary.

Be careful of the mirror surface. Blow warm, dry air in from the

eyepiece

port end. This should dry out the tube prior to use. Also, do

the same

if

it condenses up inside again. The seconday is keyed and can only

be

replaced in the correct orientation. If you are careful, you

won't even

need to recollimate.

Hope this helps,

Wayne E. Gondella
AFA Engineering Company
Pittsburgh, Pennsylvania

The fact is that the Kendricks takes a lot of current and battery power and
causes convective currents at the level needed to heat a C14 as you
indicated. The corrector will be warmer at the edge and colder in the
center, setting up differential stresses in the glass. Such heaters are a
last resort when nothing else works. You have all of that to hook up, wires
and all, and if your battery dies you are sunk. None of this is needed with
the dewshield I indicated because it covers the entire tube down to the
finder and out the front by about a foot or more. It is a special, custom
made shield, fitted to your scope, and of special materials, that attaches
with velcro and rolls up, and is light. It eliminates the dewing problem
without all the clutter and power requirements and expense. Lastly, why
would one want an aluminum dewshield? Not only would it be heavy, but
aluminum is a great conductor of heat, just the very thing you DON'T want in
a dewshield. The problem here is the corrector cooling down too fast! Next
time you dew up, look where the dew is: on all of your aluminum surfaces
first.

As far as kicking up debris in the tube, I didn't say to stick a sweeper
hose attachment to the thing! First, the OTA is sealed. Where did all of
that dirt come from. I've taken many C14s apart and they are always
laboratory clean inside (they are assembled in a clean room). I said to
apply a gentle heated air, like a dew zapper into the rear port. Don't stick
it right again the scope, hold it back a couple inches. It will mostly
blow straight on through and out the front hole with the removed secondary.
Due to the "venturi" effect, known to anyone with a basic knowlege of
physics, when the air moves from the constrained area of the baffle into the
large cavity of the interior of the tube, the speed and pressure of the air
will dramatically drop. In no way will that "kick up" dirt and debris in
the tube. It will cause a gentle and slow circulation and exchange, the
drier air for the moister air. We are not talking blowing a wind through
the tube. The condensation left in place on the corrector and secondary
will do far more damage to the optical surfaces than a little dry air.

What do you think people with newtonians and dobs do with open trusses out
in the weather? The way you talk, after one night, the optics would be
done! I doubt even blowing a strong wind through the tube would cause the
problem you describe. The inside tubes are clean. If any dust is present,
it will be near the near port where you attach things. Take out the
secondary, and place a gentle vacuum at the rear port if you want to be
sure. You can also place some cheesecloth over the opening where the air is
drawn or blown in, if you are unsure. Nearly all the air will go right out
the hole in the corrector. If you think your insides are THAT dirty,
everytime you handle the tube and carry it, that dirt will fall and move
around and end up on the corrector, etc. anyway!

It is a simple matter to remove the corrector and clean and dust the
interior anyway without doing any harm, if you are at all competent. A
typical newt will see more dirt on its optics in a week than your C14 will
see in 10 years. But given your typical dirty optics, this dirt contributes
a small fraction of 1% light loss and scatter to the optic. Taken together,
it would amount to an area the size of the head of a larger pin. Look at
the stars, planets or whatever and place a pin in front of the scope. Can
you see it? Put your finger there? Can you see the effect in the image?
Try your fist. It will take about that much to seriously alter the
diffraction pattern enough to make a visible effect. That is equal to a LOT
of dirt!

Think about it.

PS: To they guy looking to choose a C14 over a 12" Meade, if you are reading
this, buy the C14. It will kill the Meade on the galaxies, and may have
better images as well. You also get the option of the Fastar feature. But
don't buy the CM1400. Get a better mount, at least a G11 from Losmandy, or
an AP 900 from Astro-Physics.

Cheers,

Wayne E. Gondella
AFA Engineering Company
Pittsburgh, Pennsylvania

Date: Fri, 17 May 2002 08:41:57 EDT
From: paulatkinson22@...
Subject: Re: Question re: Moisture in OTA

Gary,

I found that when I only had one Kendrick heater strip up
front running that the OTA would literally begin to sweat the farther back
you went towards the EP, like a car left out on a humid night. Here is

the

solution I found. Remember that the C14 has a huge OTA and is 33" long.
That is a lot of scope. It is very easy to have the air near the

corrector

above ambient, but have the air in the rear of the OTA be below. This

means

the scope is battling itself to equalize and if it is humid enough one
Kendrick strip is not enough especially if the scope is point up towards

the

Zenith. I put a Kendrick heater strip up front around the corrector plate

of

the OTA and then I have a second heater strip that I place about the

middle

to last third of the tube. I found that by running it this way that it

kept

the entire OTA above ambient and didn't allow certain areas to cool more

than

others. I also found I did not have to run my heater as hard. Lastly, If
you can use a dew shield do it. Astrozap (no affiliation) now makes a

really

nice aluminum dewshield for the 14. I believe they are the only ones

making

one in aluminum.

Hope this helps.

Paul



One last thing, never, and I mean never blow air into the OTA through the
rear cell! This will kick up and dust or other debris that may have

managed

to get inside. If any part of the inside is moist, i.e., the back of the
corrector that is exactly where is is going to stick. Even if it is not
moist this dust will end up coating your optics. Avoid this at ALL cost.

Paul



Step 1: Buy an Insulated Dewshield from Richard Just at
ricvic@...
Step 2: Put away your Kendricks, it can't keep a 14" glass plate dry.
Step 3: Allow the tube to breath after humid weather and keep desicant in
the rear port (scope looking up) when not in use.
Step 4: If in doubt, unscrew the secondary retainer ring, remove

secondary.

Be careful of the mirror surface. Blow warm, dry air in from the eyepiece
port end. This should dry out the tube prior to use. Also, do the same

if

it condenses up inside again. The seconday is keyed and can only be
replaced in the correct orientation. If you are careful, you won't even
need to recollimate.

Hope this helps,

Wayne E. Gondella
AFA Engineering Company
Pittsburgh, Pennsylvania

Gary,

Your problems are inherent. The corrector cools faster than the surrounding
air and condenses moisture on the glass.

Step 1: Buy an Insulated Dewshield from Richard Just at
ricvic@...
Step 2: Put away your Kendricks, it can't keep a 14" glass plate dry.
Step 3: Allow the tube to breath after humid weather and keep desicant in
the rear port (scope looking up) when not in use.
Step 4: If in doubt, unscrew the secondary retainer ring, remove secondary.
Be careful of the mirror surface. Blow warm, dry air in from the eyepiece
port end. This should dry out the tube prior to use. Also, do the same if
it condenses up inside again. The seconday is keyed and can only be
replaced in the correct orientation. If you are careful, you won't even
need to recollimate.

Hope this helps,

Wayne E. Gondella
AFA Engineering Company
Pittsburgh, Pennsylvania

Please reply with price/condition/accesories

? paulatkinson22@... wrote:

One last thing, never, and I mean never blow air into the OTA through the rear cell! ?This will kick up and dust or other debris that may have managed to get inside. ?If any part of the inside is moist, i.e., the back of the corrector that is exactly where is is going to stick. ?Even if it is not moist this dust will end up coating your optics. ?Avoid this at ALL cost.

Paul

To unsubscribe from this group, send an email to:
C14-unsubscribe@...



Your use of Yahoo! Groups is subject to the .

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- Your Yahoo! Music Experience

Sorry to bother you all

I am the President of Star Astronomy Club, my name is Ismael Cuellar.? The problem that I have right now is that we just got a $7000.00 donation to spent.? But that is'nt my problem ! ( LOL) is that half of the club members want to buy the Meade 12' LX 200, and the other half wants to buy the CM 1400 GT Celestron.? I have no idea which of this two telescopes have better optics, or which one gives better celestal views.? We as a club want to buy something that is really worthy.? Can you all help ME PLEASE ON THIS!!!! Also our club members ask how good Galaxies look through the CM 1400, can you see the spirals of the Galaxies.? Thank you for your time, GOD Bless you all !!!

PS please check out our Website ( )

? paulatkinson22@... wrote:

One last thing, never, and I mean never blow air into the OTA through the rear cell! ?This will kick up and dust or other debris that may have managed to get inside. ?If any part of the inside is moist, i.e., the back of the corrector that is exactly where is is going to stick. ?Even if it is not moist this dust will end up coating your optics. ?Avoid this at ALL cost.

Paul

To unsubscribe from this group, send an email to:
C14-unsubscribe@...



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Do You Yahoo!?
- Your Yahoo! Music Experience

Hi all,

This past Tuesday evening I was doing some ccd imaging when I noticed
that a raw image seemed out of focus. I was unable to sharpen the
focus much, so I finally looked at the corrector on my C14. It was
badly "dew'ed" around the secondary mirror, only about 2" around the
edge remained clear. The dew'ed area was dense enough to be almost
opaque. I had a Kendricks heater running at 100% so I was a bit
surprised. I used a hairdryer to clear it up and was again surprised
to see that after 30 seconds or so it had not even started to clear.
Using a flashlight and my fingernail, I found the condensation was
inside of the corrector plate. It took several minutes of heat to
clear this up, at which time the scope needed to equilibrate to
ambient again.

The local weather in central Ohio has been very wet, over 85%RH, with
occasional dry periods when the humidity will drop to near 30%RH.
That night was unseasonably cool, about 35F.

My questions are: is this a common problem and, what should I do
about it? The OTA must "breath" of course, daily temperature swings
of 40F are not uncommon here. The observatory is ventalated so the
temperature inside probably does not exceed 10F over the outside
temp - therefore the scope changes through about 50F between day and
night. I can rig an air filter, fan, and dessicant chamber to blow
dry air in through the eyepiece port, but it seems it will just get
wet in there again. I bought the OTA from California and it is in
fine condition. There appear to be stiffeners inside which, if this
continues, I think might start to oxidize. Further, when the moisture
drys it leaves marks from the dust that adhered to it.

Thanks for your interest.

Regards,
Gary

Yes, here in Pittsburgh, we give our scopes a good flocking every night. I
prefer a rubber hose, myself, but if the views are particularly bad, I can
switch to a leather belt (at least until the paint begins to come off). The
scope has got to know who is boss! :-)

I'm sorry. . . seriously, I put flocking paper on any surface which might
receive/return unwanted or scattered light, so that at the eyepiece (as much
as was humanly possible) only light from the image made it there. I wanted
to know what was possible in an SCT. It was my experiment. It took a
month. Generally, this reduced the level of the background illumination and
aided contrast. I cannot recommend that anyone try to fully duplicate my
process, or even attempt to line the inside of the tube unless you are very
confident in your skills.

Wayne E. Gondella
AFA Engineering Company
Pittsburgh, Pennsylvania

Date: Mon, 13 May 2002 21:29:55 EDT
From: paulatkinson22@...
Subject: Re: Digest Number 110

Wayne,

Again, you have lost me a little. You flocked your scope (no pun here)?

Are

you saying you lined the inside of the scope? How did this make a
"signifcant" difference? I am all about making my scope preform to the
utmost. Any other enhancement tips would be appreciated.

Paul

Glad to hear about Chiefland, Paul! Many people don't realize the
exponential curve of light gathering and the eyes non-linear reponse to it.
One person calculated that the step up from naked eye to a Questar 3.5, the
same proportional step again would require something like a 55 inch scope!
As a good test, take a typical non-initiate from the public, who has little
experience in looking through a telescope. Have them look at M57, or some
other deep-sky object in a 12-14 inch and a 20-24 inch and ask them to
comment. We are straining to see the smallest differences (because they are
important to us) and we magnify the smallest gain in our minds (and often
pay huge sums for that gain).

I happen to be playing with my mirror lock screws today, and I observed that
there is no gap between the mirror focus yoke and the rear housing. In
mine, the lock screw threads are about as long as the casting is thick, and
just clear the casting before engaging the mirror yoke. However, it feels
like one continuous thread, but in fact there is a minute point where it can
spin free of the casting to engage the threads in the mirror yoke (this is a
3 sided aluminum yoke which has three "arms", 2 for the lock screws, 1 or
the focus mechanism). As a test, I tried a regular screw, and it threaded
until it hit the yoke, so these threads are not tapped in one operation as I
had thought (which really makes sense), but one should retain the original
lock screws and use them always during transport and mounting, as they are
made just for this application.

By the way, I employed some extreme measures back in March flocking my C14
to the max (9 surfaces), and am very pleased with the results. There is
undoubtedly a significant improvement. I also redid my entire focus
assymbly and all moving parts with that teflon lube and this has made my
focus silky smooth even during critical focus, eliminated all traces of
backlash and all but the tiniest vestiges of mirror shift, detectable only
at high (300X) powers. The scope is now 125% over what Celestron supplies
from the factory.

Wayne E. Gondella
AFA Engineering Company
Pittsburgh, Pennsylvania

Date: Mon, 13 May 2002 08:52:32 EDT
From: paulatkinson22@...
Subject: Re: Digest Number 110 - Ed and Wayne?

Ed and Wayne,

I have a new (Feb. 2002) C14 with Fastar. My mirror simply moves to the

back

of the cell and I screw the retaining bolt in to the mirror cell and make
finger tight. I do not notice any problems or feel any pull. Also, the
screws fit perfectly. Am I missing something to your conversation?

By the way, just got back from the Star Party in Chiefland, Florida. Wow.
Great viewing. Even with some very thin, high cirrus clouds I got the

bridge

on M51. Many people, including a gentleman with a 20 inch Starmaster

could

not believe the images. I was comparing with a Tak Mewlon 300 Cass and I
thought mine was better. Of course 2" of ap also help but I didn't pay

12k

for my scope either.

Paul Atkinson


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Your use of Yahoo! Groups is subject to

Wayne, It seems that "C" made a design change between our scopes. I'm
not sure exactly when mine was made - purchased used - it is a Faster
series but probably an early one. With the mirror holder all the way back it
lacks 3/8 in of reaching the cell. That's why I have those special machined
screws with cut away threads - yours sound like regular machine screws. When
I tighten down the screws they apply a bending load to the baffel tube as
they draw down the mirror holder- not exactly good design. Maybe that is why
they made a change.
I have been out the last 3 nights trying to learn CCD imaging. No dew in
Phoenix but it is untill midnight before the dots from my Hartman mask stop
swimming around from heat. I have a lot more respect for people presenting
their imaging work now- even the "mediocre" stuff. My next step is f2.1 with
the fastar assembly. I have been disappointed with the miniscule image scale
at f11 - not very practicle for deep sky - as nothing seems to fit. Ed
Joganic (grew up in Lawrenceville)

After waiting and waiting we got our new Paramount ME for a C-14 (1980's model).
To get the best pointing I want to get rid of the mirror flop (it's adding a 30 arc second error to our Tpoint model).
I just have some cap screws pluging up the holes and can't find the original locking screws. The back of the tube will have a filter wheel, TCF-s focuser and ST9.
After I set the focus with the CCD, is locking the mirror as simple as getting a screw long enough to thread into the mirror cell? Any special method to this?
Craig