Apo Lens Re-centering tools
optidud
in color correction has more potential for decentering. I think I'll
keep my triplet and re center the lens myself. The reason I can't
send my TMB triplet to the manufacturer is because I have to
spend huge on shipment (back and forth half a world away),
recentering charges (which runs into hundreds of dollars), and
when it'd be reshipped to me, I have to pay 50% taxes in my
country so I'd be spending more than $1000 total (and not
to mention the possibility of it getting decentered again in
its trip back to me as shipment workers sometimes just toss package
up the air).
That said. I'm willing to spend $500 on buying tools that can
enable me to recenter the TMB triplet myself (It fell to the
ground from 1 meter above when I put the luggage case in a
big rock at an angle). So where do I begin. What intruments
must I need? Such as Ronchi, Laser aligner, Lens distance
spacer, etc. Who among you have recentered a lens on your
own? I presume the lens cell has a spacer guide so I don't
need to know what is the distance between the lenses.
Recentering the elements with a common axis would be
enough.
Because I travel a lot with the triplet put in the airline
compartment. There would be many more days when it
would get decentered from unusually big shock. So I want
to learn to recenter it myself. If anyone can recommend a book
on fixing apo lenses and recenter. I'd greatly appreciate it too.
Thanks.
opti
Erick
> Learning that doublet apo with steeper curves that matches triplet
> in color correction has more potential for decentering. I think I'll
> keep my triplet and re center the lens myself. The reason I can't
> send my TMB triplet to the manufacturer is because I have to
> spend huge on shipment (back and forth half a world away),
> recentering charges (which runs into hundreds of dollars), and
> when it'd be reshipped to me, I have to pay 50% taxes in my
> country so I'd be spending more than $1000 total (and not
> to mention the possibility of it getting decentered again in
> its trip back to me as shipment workers sometimes just toss package
> up the air).
Where are you coming from?
If you are living in Europe, send it to Markus - Germany.
If you are living in the USA, ask Thomas back!
You should never have to pay again for import!
In any other cases, ask a local TMB dealer. Don't do it yourself!
Erick
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ValeryD
The best instruments are:
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.
Ratboy99
>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
~( );>
email: remove 'et' from .com(et) in above email address
Chris1011
Where can one buy tin foil? I thought all you could get now is aluminum.
Roland Christen
David
put <tin foil> in the search box
they have even platinum foil, that would go well with the AP scopes ;-)
David
Jon Isaacs
>put <tin foil> in the search box
>they have even platinum foil, that would go well with the AP scopes ;-)
>
>David
Try ESPI (Electronic Space Materials International) I have purchased quite a
bit of stuff from them (including Platinium sheet.) Good service, friendly and
they have a huge selection.
As far as Tin goes, they have tin foil in thicknesses ranging from 0.001" to
0.009" in grades from 4N to 6N (99.99% to 99.9999)
They also have Thulium, Terbium, Tellurium, Samarium, Praseodymium and just
about any thing else one can thing of....
jon
Bob May
cell is going to be fun if there are adjustments for that. I'll note that
all of the lenses should not have any wedge in them so there should be no
problems in that regard. All that I've seen for lenses is that they allow
for tilt on the cell assy. just like a Newt. primary mirror so that the
optical axis of the cell is pointed at the center of the focuser.
--
Bob May
Losing weight is easy! If you ever want to lose weight, eat and drink less.
Works evevery time it is tried!
Leela
Go away.. do not feed OptiDud.
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
Ratboy99
>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.
rande...@rogers.com
Any plutonium or U-235/8?
-Rich
Can we be sure that terrorism and WMD will join together?
If we are wrong, we will have destroyed a threat that, at
its least is responsible for inhuman carnage and suffering.
That is something I am confident history will forgive.
But if our critics are wrong and we do not act, then we will
have hesitated in face of this menace, when we should
have given leadership. That is something history will not forgive.
-Tony Blair
rande...@rogers.com
wrote:
>How do you know that the lens needs adjusting? Centering the lenses in the
>cell is going to be fun if there are adjustments for that. I'll note that
>all of the lenses should not have any wedge in them so there should be no
>problems in that regard.
That is funny.
Howie Glatter
> Where can one buy tin foil? I thought all you could get now is aluminum.
It can be scavenged from tin cans. Recycling centers are good places to check.
You can also scrape the TiN coating off of some drills and milling cutters.
H.
optidud
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
ratb...@aol.comet (Ratboy99) wrote in message news:<20030723185334...@mb-m17.aol.com>...
Ratboy99
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
>$1000 everytime it gets misaligned and I'd be discouraged to bring
>it with me often. So mastering re-centering is the only way for
>me to travel and use it constantly worry-free.
>
rat
optidud
How much approximately is this air spaced triplet laser lens centering
chesire collimator and where can I acquire it? There's a book
mentioned
in Roger's apo article called "The Adjustment and Testing of Telescope
Objectives" written 1983. It's out of print at amazon.com. Anyone got
this book and/or know where to get a copy? Is the TMB lens
compensation
design similar to a generic triplet or doublet and all of them have
just about the same basic design? Before I'd take apart my lenses. I
have to be sure first how all the things work, because I don't want
to make a mistake like cracking the edge of the lens and wasting the
whole scope. I no longer have budget for any apo scope. It would be
my last. I previously owned vixen, tak apos and I prefer apos before
my
viewing preference is color saturation and definition (I'm after
Maximum Color Transfer) and achromats just drive me nuts. Of course if
your target are just stars, achromats would be great and sufficient.
opti
Ratboy99
>chesire collimator and where can I acquire it?
Read the #^$*&$ thread!!!!
rat
~( );>
Ratboy99
>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
~( );>
ValeryD
>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.
> opti
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.
David
optidud wrote:
> I live in Asia and own a 4" TMB triplet.
What type and what is the serial number ?
D
Markus Ludes
>
> 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
--
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG
Ratboy99
Say, aren't those the initials that we Americans use as a short name for
Venereal Disease?
optidud
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
optidud
Funny. Anyway. I took a picture of my 4" f/8 TMB with
optidud
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.
It was explained to me that it's done this way so that when
the lens cell expand (does the lens expand too). It wouldn't burst
the lens. This means there is some inherent coma in the scope.
Now in the triplet apo designed by Zeiss, TMB, etc. The Design
is such that as the lens and lens cell expand (or just 1 of them
I don't know) there is some form of holder that can compensate
for the expanding lens cell. I can't quite imagine how it all work
mechanically or how the lens is hold by this compensation ring.
Is this temperature compensated design the reason why triplet can
get decentered easily. What if they design it like the old FC with
distances between the lens and lens cell. The tradeoff may be
more inherent coma but at least it won't get decentered. However,
they may prefer the temperature compensation design for more image
sharpness. I guess this latter design have similar mechanical workings
like how they make push-pull collimation screws in the objective
lens. So it's not a top secret stuff that must be guarded, right.
Hope someone can draw an illustration in paper how it's all put
together or point to other references. Thanks.
opti
"Markus Ludes" <apm_tel...@web.de> wrote in message news:<5e7dfb32970dc89b0f3...@mygate.mailgate.org>...
Ratboy99
>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.
optidud
I wonder if it's only the old Tak FC series that does the rattling
thing or the FS has it too... maybe the FS series have temperature
compensated cell in place already? or maybe the shallower curve
of the lens don't require one? How about Televue... I should have
researched first about decentering resistance before getting an apo
scope as my requirement is rough use and constant travel (now
I know why the AP 4" is called a Traveler... because it is
decentering resistant). I got rid of my Vixen flourite and FC
because at high magnification, they are kinda dim owing to their
total lack of coating in the flourite... however, i didn't know
they are more decentering resistant than the TMB).
opti
opti
ValeryD
> >
> >
> > 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.
optidud
> The best instruments are:
>
> 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