Apo Lens Re-centering tools

I live in Asia and own a 4" TMB triplet. I constantly travelled with
it that's why it suffered many shock from airplane luggage compartment
vibrations, landing shocks, etc. and also direct impact of the case
once. I use a hard luggage case used in travelling. I bought the scope
second hand but when I initially tested it. The airy disc is round
but after all the rough use, it has a slight symptoms similar to
astigmatism as shown in Suiter's star test guide.

To fully understand how to re-center it myself. I need to understand
first how the temperature compensation of the lens cell work. I
think it's the same principle used in the Zeiss triplets? If anyone
knows of a book or illustrated web site that fully describes it, let
me know. If I won't learn how to align it myself. I have to spend
$1000 everytime it gets misaligned and I'd be discouraged to bring
it with me often. So mastering re-centering is the only way for
me to travel and use it constantly worry-free.

If only I get a decentering-resistant AP Traveler, I won't have
problem with it. But my name in the AP notification list is still way
down and prices of it has increased astronomically so I decided not to
wait for the Traveler anymore. Unless someone would sell it second
hand for less than $3000.

opti


t (Ratboy99) wrote in message ...
Useless troll... I suppose he actually decentered his imaginary
TMB lens while mountain biking with it, which was his big troll
last time he got the wild urge to write his stupid posts.

Leela

Remember the old Televue ads that showed a Ranger mounted on a bicycle where
the air pump is usually mounted? I wonder if anyone besides optidud ever did
that.

rat
~( );

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The apo centering tool comes with instructions, dude. Get the tool and the tin
foil (others have already listed the sources for both), and fix your stupid
telescope.



To fully understand how to re-center it myself. I need to understand
first how the temperature compensation of the lens cell work. I
think it's the same principle used in the Zeiss triplets? If anyone
knows of a book or illustrated web site that fully describes it, let
me know. If I won't learn how to align it myself. I have to spend
$1000 everytime it gets misaligned and I'd be discouraged to bring
it with me often. So mastering re-centering is the only way for
me to travel and use it constantly worry-free.


rat
~( );

email: remove 'et' from .com(et) in above email address

t (Ratboy99) wrote in message ...
What intruments
must I need? Such as Ronchi, Laser aligner, Lens distance
spacer, etc.

You need a triplet apo lens centering tool, of course. You'll need either the
air sapced or oil spaced version depending which type of lens set you own. Be
sure to get the one with the laser lens centering chesire collimator already
built in. Much easier to recenter and test if you don't have to keep switching
back and forth. As far as spacers go, I believe most manufacturers of apos use
strips of tin foil for spacing. I've heard that Reynolds foil is the most
consistent for thickness.


rat
~( );

How much approximately is this air spaced triplet laser lens centering
chesire collimator and where can I acquire it? There's a book
mentioned
in Roger's apo article called "The Adjustment and Testing of Telescope
Objectives" written 1983. It's out of print at amazon.com. Anyone got
this book and/or know where to get a copy? Is the TMB lens
compensation
design similar to a generic triplet or doublet and all of them have
just about the same basic design? Before I'd take apart my lenses. I
have to be sure first how all the things work, because I don't want
to make a mistake like cracking the edge of the lens and wasting the
whole scope. I no longer have budget for any apo scope. It would be
my last. I previously owned vixen, tak apos and I prefer apos before
my
viewing preference is color saturation and definition (I'm after
Maximum Color Transfer) and achromats just drive me nuts. Of course if
your target are just stars, achromats would be great and sufficient.

opti







email: remove 'et' from .com(et) in above email address

How much approximately is this air spaced triplet laser lens centering
chesire collimator and where can I acquire it?

Read the #^$*&$ thread!!!!
rat
~( );

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. I no longer have budget for any apo scope. It would be
my last. I previously owned vixen, tak apos and I prefer apos before
my
viewing preference is color saturation and definition (I'm after
Maximum Color Transfer) and achromats just drive me nuts. Of course if
your target are just stars, achromats would be great and sufficient.

On second thought, have you thought about purchasing a Newtonian?
rat
~( );

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V.D.

Say, aren't those the initials that we Americans use as a short name for
Venereal Disease?
rat
~( );

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David wrote in message ...
optidud wrote:

I live in Asia and own a 4" TMB triplet.

What type and what is the serial number ?

D

Funny. Anyway. I took a picture of my 4" f/8 TMB with
you Leela & your name on a piece of paper (see

http://www.angelfire.com/pro/tmb/tmbcase.JPG

....so you'd know it's not an imaginary TMB that
is decentered. It's taken with a cheap video cam and
captured in a computer software in my office.
In the picture, the scope is inside the hard case with
the Finder and extension tube (unfortunately I don't
have fitted padding that's why the scope can move or
rattle inside). About the serial no., the person where I
bought it from second hand (he wants to upgrade to 5"
size) doesn't want it identified because Markus may
no longer sell him stuff if he found out I take it apart
and examine it (or perhaps even reverse engineering it )

In the picture below, the dew shield is retracted
showing the lens and lens cell. The mount is a
Custom D Alt-Azimuth mount.

http://www.angelfire.com/pro/tmb/tmbcustomd.JPG

opti

In the Takahashi old FC series especially the smaller size, the
lens and the lens cell wall have a few spaces so when you jingle
the scope, you can hear the lens rattling inside the lens cell.

You know its funny but when I bought my Tak they told me that it was possible
for the lens to get out of place in its cell and if it did it might be
necessary to give the tube a rap to get the cell back where it belongs. At
first I thought they were kidding, but I actually think it may be true. I've
never had to smack my Tak yet though.
rat
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"Markus Ludes" wrote in message news:5e7dfb32970dc89b0f318972f37b94df.30545@mygat e.mailgate.org...


So, switch to TAK's FS-102 or TV-102 doublets and you will be
able to re-center the lenses quite easily. The same with BORG.


V.D.

Valery,

maybe a single lens chromat with a super chromacorr would be the best
for biking and traveling ?
or hey a new idea, a apo-coma-corrector from you , that would be a nice
new toy to own

Markus

Really, why not? :-)

As for Chromacor. Singlet + Chromacor will be more sensitive to
decentering, than doublet.
So, the doublet is the best for easiest collimation - all is clear.
One need to move only one element and this will solve the problem in
any case. Not so with an air-spaced triplet regardless of manufacturer
name. Princip.

V.D.

(ValeryD) wrote in message . com...
The best instruments a

1. good high pwer eyepiece
2. screw driver (or allen wrench screw)
3. Not very distant star-like source (30-50n away).

See which lenses can be moved (which ones have their centering scres.
The best to not tweak the inner lens made of very fragile ED glass.

You always need to move the lens in the direction of the coma
(or) and lateral color.

Without experience this is purely trial-error process. However if
you are patient enough, you will reach the success earlier or later.

Good luck.

V.D.

Hmm... I wonder what I'd do with an allen wrench screw.
The lens cell has no push-pull flange. To adjust the middle
element. I have to remove the outermost lens first. Looking
at the front of the lens cell. I can see two separate 4 inches
ring that holds the first lens. So you mean I have to remove
the two 4" rings and remove the first lens to adjust the second?

Now after I remove the first outermost lens. How the
hell can you collimate for 2 lens only with the 3rd one
taken out of the lens cell. I suppose the 3 is needed to
make up a complete image.

Also I'm worried I may disturb the spacers, temperature
compensator, etc..

Rayboy mentioned of a Triplet chesire collimator. I
presume he is kidding. You only use a chesire collimator
in a reflector to align the primary with the secondary.
Isn't it. However, there may be an exotic technology
where you can put one device outside the lens of a
refractor, the other at the eyepiece, and the latter will
determine the optical axis of the telescope and give the
distance of the deviation of the center or the decentering.
Ever heard of one?

Markus may know how to fix it all but for business
purposes, keep it to himself (and it's understandable).
But the costs of sending it to me would be immense.
If the lens cell costs $1500. My country tax me for
whatever import regardless if it is sent for repair or not
(they remove the distinction because many people used
to trick customs about repaired items when it is brand new).
Minimum tax is 50% so I need to pay at least $750 and
at most $1000 for high tech intruments.. Now
I have to pay Markus $600 for recentering. So the
cost is now let say $1350. And the shipping back and
forth would cost another $300 or $600 with insurance.
So total I have to spend is $1950 just to have my lens
cell recentered (and I can buy a brand new FS-102
with it). And what if months or a year later, it gets
decentered, then I have to spend another $2000
(I may as well just get the Wizards' Traveler with it).
So only sensible option left is to align it myself (and
learn all the technique with patience and determination).
Therefore those who have done this. Pls. do share
tips so disaster can be prevented such as cracking the
lens edge and ruining the entire scope. Thanks.

Opti