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First of all, thank
you for coming.
I will be honest with you, I wouldn't
have been surprised at least
if the room would be empty.
I mean, its security nightmares.
I mean, we're talking about one of the
two major events.
And I'm really, really flattered
by the attention.
So I
see we do have an issue there
cause.
No.
Um, from
that screen number eight,
uh, sorry,
you know how HowStuffWorks don't
don't you?
And of course, I
I'm in the wrong folder, so
you will see me doing some come on line
for, um.
Oh, come on.
Um, two months, three
presentation.
So this is the main part
where I explain to you how you start the
presentation of the command line.
And here we are and
this thing scray,
I think we do have to
solve the problem here.
I do have to
I'm sorry.
Um,
OK.
That's how things work
baboon's to three
presentation.
So, yeah, as you have imagined,
it's about
um making
your own.
Tell us. I will talk.
I will brabo along because
I'm here.
That, that's kind of.
Yeah.
Do you know, um, I'm
sorry, I just screwed up
totally, um,
you know, don't worry about it.
I think you're not right.
Yeah, I don't think so either.
So he told me not to worry about it.
I mean, I don't want
to be to be honest, I don't have
to worry about it because you don't
really screwed up.
It's the last day of Congress.
It's the last talk we had four
days of not much sleep, probably.
Oh, yeah. Tell me more about that.
And we all had so we love tunnels
and when to just look at them
for a few minutes.
So, yeah.
Just appreciate the beauty of
green fonts on black background.
Oh, yes, yeah,
oh, yeah, yeah,
so if you want if you want to pwn
if you want to put my laptop, if you do
it, you're going to die.
Yeah.
And I'm not, I'm not especially the
I'm just, I'm just saying I've
only I've only seen that happen with
Linux machines.
Right.
So
it's not the
same. And you asked
me what I see happening
on his monitor so uh so
maybe we're close.
Um.
Let's set the duration to 45
minutes, shall we?
Yeah, and don't worry about it.
Here we go.
No y yeah.
Huh.
That's cool.
No, I can't.
It's it's,
uh.
Yeah, no, that's not the problem.
The problem is that the other half is on
his laptop monitor.
OK, OK, so now,
now we're going to do it, we're going to
do it this way.
So here, here we are, we
know anything because this
thing sucks
so
that I don't know,
you probably have time.
We are so so.
All right. We've got something here and
we'll have to go.
That's that's that's always the thing,
if you I really I
looked up what should I use
that a lot of once you can buy
and yeah, this one is
open source. And of course, I love open
source, so I
use that and never with the second
monitor because of course, I never
thought about that.
So yes,
it's about amateur telescope.
Me first of all, what
I often hear when I tell someone
I mean, I'm at the
People's Observatory of Munich,
I did also some research in astronomy.
And so I'm
involved and I do
I show people the observatory.
I explain to them how telescopes
work. And when I tell them,
look, you can make a telescope yourself.
Yeah, of course. I mean, it's an optical
precision instrument.
You have to you
have to have expensive
machinery.
You have to
know a lot about optics and
stuff like that.
Um, well, yeah, no,
because you need the expensive machinery
if you are going to do it
with a machine.
So if you're going to go huge,
of course you're going to need a machine
because we are talking about removing
tons of glass here.
But there's a big,
big. But
that sounds wrong.
Um, if
you if you're going to
do it by hand and we're talking about
telescopes roughly in the range
up to a meter meter
diameter, I imagine that that's a huge
telescope. That's a big telescope.
You can do it by hand.
It's a lot of work, but you can
do it with the
mere
attribute of a human being, not
being able to repeat it, to repeat
a motion again and again, the same way,
the exact same way, especially
if you tell the people, look,
embrace the randomness,
you can do it. You can make a telescope
that beats
manufactured telescopes, you can buy
and you can pay
a lot of money for it.
So here, that's that's a short outline.
So if you have more questions,
write me an email,
Twitter, whatever.
Come to me personally, although we don't
have that much time,
we can I can talk to you about
anything you want.
I can tell you where you can get what
you can get the stuff.
And if you are interested, hit me
up and I will I will share
all the knowledge with you because
again, the knowledge I got,
I'm not the best there is.
I happen to live in the same city with
the best with the best guy there is in
Germany. And if he is watching
and I'm sure he's watching, thank you
for showing me that and for making it
possible that
I can make my own telescopes.
I haven't finished a single one yet
because I always rework stuff three or
four times, including those slides.
Yeah. So
why do I need a telescope?
I mean, I can go
out in the dark. Dark is a very important
part of it. Astronomy works better
if you can see the stars
except astronomy.
But we're not talking about here.
We're talking optical astronomy.
Why would I need to I mean, I do have an
eye. I can see the stars.
I can see the Milky Way.
It's an impressive view.
And I know people who
because it was such a nice you, it was
a clear night.
It was lovely.
They went outside, they carried the
telescope. They assembled their
telescope on sight
and thought, well, screw it, I'm going to
lie down on the grass and have a look at
the sky and enjoy it.
That's that's it.
That's about amateur astronomy.
You love to do it.
And.
Well, if that works for you,
go for it.
And if you make a telescope, don't let
anyone tell you,
oh, that doesn't work,
if you know it works or you do it,
it's the most important thing
you can make it like you want.
So here are some incentives.
First of all, with the telescope, you can
have a look at galaxies like
that one.
This one is also
from a ground based telescope.
But as you can see, those guys,
well, they do it for a living.
These are the European Southern
Observatory. So you won't see that
in the telescope.
But you can see
a faint blob.
You will see that region here.
If you don't like that, well,
then I have bad news for you.
There are better objects like Albireo
here.
This is a double star
and this is
a star you can see with the naked eye.
But in the telescope, it resolves to two
stars orbiting each other.
You don't see the orbiting, obviously,
and the one is blue, the once red.
So here you can see astronomy.
If you had astronomy in school,
you had astronomy. And at university,
that tells you some stars I read.
Some stars are blue.
Yeah. Wow.
If you see the telescope, then
it's something completely different.
If the more you know, the more this
experience on the eyepiece is
enhanced
and planets.
OK, that's Pluto. Sorry, old habits die
hard planets.
This one is actually what you
would of course not know that
details because there's still an
atmosphere between and those are probably
some thousand pictures
now that's Hubble.
Screw that.
So you can get those
quality pictures similar to pictures with
an amateur telescope.
But you need to take a video.
You cut out parts which are good,
which you like the software
for that, of course. And you end up
stacking like two or three thousand
pictures and then you get good quality.
It will be if you have a look at it
yourself, it will be a bit blurrier,
but you will definitely see the stripes
and the and the big
red spot.
Fun fact. This big red spot
is twice the size of the
earth. So big is
quite a good
name for it, I think.
Yeah.
Let's go back.
So you need light, you need
what the telescope does, it enhances your
sight, your eyesight,
it doesn't make very visible,
you don't see, but it can
make light and regents' visible.
You don't see because it collects light
bundles up the light.
So how do you do that?
Well, there is the classic.
As you saw, a lens
light comes in, focus comes out.
You can't explain that.
Well, actually, we can, but that's
how this thing works.
Everybody who wears glasses, who has used
a binocular or
whatever you do,
that's that's the main principle.
And that's what most people imagine
when they think about a telescope.
Then again, mirrors,
mirrors have one huge advantage.
You have to use only one
surface. So they're cheaper
manufacturing.
You can support them from the back.
They're easier to build.
So nowadays, mirrors are
the way to go.
Doesn't matter how big if you Bill, if
you make a six inch telescope or
a eight meter telescope
like the VLT is or a 40
minute or a 40 meter telescope
like the ELT is going
to be, let's let's see that.
I would love to see that 40 meter
telescope. I mean, that's astronomy
porn. I mean, we're talking hot stuff
here.
So and what that
what this telescope does is basically
you have one main component that's a
Newton, as you can see,
and by the curvature of the
mirror of the main mirror, let's call
it M one here, mirror
one or two.
You can imagine how this is how this
works. Um, you
basically bend
the light in one direction.
You focus in one direction, and then you
have the eyepiece or the camera there or
whatever you want or
your cooking
stove and you cook your pasta if
the mirror is big enough and you have the
sun.
So that's how it works.
The basic concept.
But now, since I mentioned
BASIX, let's go to the basics.
This are some
circles, some colored circles,
what the present is here.
Imagine that being seven millimeters.
That's the eye opening
of a healthy young adult.
At extremely low light conditions.
So that's the maximum your
eye can open up.
And if you go above
30, I have bad news for you.
That's not going to be seven millimeters.
It's going to decrease with age
people of the age
of 60, 70, they're
talking five millimeters.
So you can
see, well,
OK, that's surprisingly
big. If you actually I did that,
I draw it and draw it actually
with millimeters and scale it down
to fit in the slide. And that's big.
Yes, it is surprisingly big, but
it's bigger.
The the circle
next to that is a 50
represents a 50 millimeter
optical, the 50 millimeter aperture.
So this is
the cheap telescope.
You're going to buy your kid for one
hundred euros.
Please don't do that.
The mechanics are crap
most of the time.
So they
end up kids end up being frustrated
and drove and driven away from astronomy
just because of that.
And binoculars are the same diameter.
So you can buy for 100
euros. Really, really this vernaculars
with two times this.
Oh, this aperture.
And have a look at the sky.
It's not expensive hobby.
It's really, really good
what you can see. And people put aside
the big telescopes and use a binoculars.
Every telescope has its own sky.
You see different things, different
magnifications.
And I mean, it's
it's really, really
you can start and you can start small.
That's what I want to say here.
Then we have a 140 millimeter.
That's a typical starter
telescope.
And this here,
this is no moon.
This is a one meter
mirror. It doesn't fit in this light.
So
as you can see,
most of you already know it,
but the surface area grows
exponential.
So you
you increase the diameter by
two. And as you can see here,
the surface goes up by four.
So
in the end.
You collect more and more
light and light is
extremely important here because are
trying to get the last photon out of that
object or
the platform that hits Earth.
Another thing is that
with diameter,
you also increase the resolution.
So here that that's the so-called
baseline, actually,
what to get to the
resolution, you don't need that part.
That part simply collects light.
You could just use this the part
on the left edge and on the right
edge, and you would have that
increased angular resolution.
And in fact, we're doing that.
It's called interferometry astronomy.
It works great with with
radio telescopes.
But they with
optical telescopes, they are right about
bringing it to functionality.
But it's still it's
still a happy road
to go down a bumpy road.
Sorry.
I'm sorry.
I'm I'm totally on coughing
and you know how it is
a big audience.
You get the bright light
in your eyes and you can see the people
down there and that's
how it goes.
So it goes it
goes investigational.
Um, yeah.
So again, the types of telescopes,
how it works
here, the light goes,
it goes in from the front.
And because it's a mirror and it's
reflected, you do have to have that
part here.
The second mirror which goes
up and here you
have a typical
singalongs telescope.
You can see you have color errors
here. But that's not the point.
The point is what I want to make
is here you have two surfaces.
Here you have one one surface
doesn't have to comply with anything.
You can have one surface.
You can make it work.
And at the moment, it works.
It works here.
You have to make two surfaces, work
with each other.
And that that's much, much harder,
because if you make it if you happen to
make it wrong, it can go totally it
can totally go south.
If those two are not
centered properly, the
whole optical
capabilities of the telescope got really,
really bad.
So, yeah,
not the map of making
the telescope actually doing it.
First of all, I will talk about the
optics.
This is the part which is.
Most complicated, most,
I'd say complicated is the wrong word,
less people are familiar with optics than
they are with making words
align and work so that
something works.
So that's the new part
for most of you. I guess I happen
to know that at least one person in the
audience is already
thinking about making a telescope.
So he maybe knows more about that.
But it's not complicated.
It's not hot.
What would you do? What would you make
your own telescope
ask?
Well, basically,
because you
are flexible,
you can make it the way you want.
If you want to make a telescope
that pink, you can make a
telescope that's pink.
If you want to make a telescope, that's
rubbish. You can make a telescope.
That's rubbish.
You can make it however you like.
And you can also include a rocket
launches, which was suggested by
somebody.
But I wouldn't recommend most
other astronomers don't like a rocket
launcher being on your telescope and
destroying the hard work
and the quality.
Again, if you want to make it, you can
make it as good as you want.
You can go through
and plus one iterations and
still add another one.
You don't care, OK, you
can't because at one point you want to
use it actually and make something
with it. But that's where I'm stuck.
I'm making the iterations.
I started writing my mirror from scratch
three times now
so you can adjust that
part if you need the telescope.
That's only going to work for
infrared light because you want to make
an infrared
an infrared transmission path
go for it.
You don't need you don't need to invest
that much time in it.
You just need to polish it
roughly.
And you it works.
You don't you don't have that high
that high specs as you have
in optical with optical light.
The price, of course, although
a small disclaimer here, if you
go if you're going to make a telescope
10 inch big, you want to save
money, don't do it.
You can buy really decent
telescopes nowadays
with up to 16 inch
and you would still
save money.
I'm talking about raw cost, not
not the time invested.
If you calculate that it goes through the
roof, I'm
talking about cash.
Take your hand and put and put on the
counter.
You will save money up to six Netsch,
but make a small
telescope,
one that you would like to use, of
course, to get the experience,
to see how it is, how it works, where the
problems are, and then go
back. If you go really big, where
we go, if you go above
eighteen, twenty, twenty four,
thirty three inches,
40 inches,
you I mean the sky's the limit here.
People are running amateur
telescopes with
one meter diameter.
That's insane.
If a guy arrives at the site
with a trailer
and he tells yeah, that thing is full
with the telescope, with one
single telescope and
you have to climb up a ladder two
and a half meters to get to the
eyepiece.
You know what I'm talking about?
Why I say it's insane.
Crazy, but then
again, we are at the hacker
Congress between between the holidays,
I guess we are crazy, too,
and, of course, availability.
Telescopes above 18 inch.
Light construction light
that you can carry with one person that's
not considered like their.
They're not that abandoned.
There are some small manufacturers
and you order it today,
you will have it at the 30, 33
maybe.
So we're talking to two years, limited
time. And in that time, of course, you
will be able to make your own TELESTAR.
And most importantly, because
you fracking. Can
you.
And I mean, all those outlines
are basically why
should I built my own 3D printer back
back in the day?
I mean, like two years ago, you had no
option. You had to build it yourself.
But nowadays in Germany at least,
you pay five hundred seven hundred euros
and you get a decent one, not the
best one, and still has issues, but
you get a good one.
But many people still do it
their own 3D printers, they
I mean, there's Linux from scratch.
I think I still don't understand, but
maybe that's my my
my lack of understanding that.
But still, people
do things themselves, and that's
always the reason because
I wanted better.
I want it now. I want to
I want it however I
want. And that's so
the shopping list.
So cool.
I want to do that.
And you start and you said, well, I want
to I want to go to the
hardware store and get the stuff.
So what you need is a piece of glass.
A small disclaimer here, you need special
glasses, not always if you make
small telescopes. I know a guy who made
his, uh, his two really
small telescopes, four inch
with standard
window glass, which is
a nightmare if you did.
But it's OK, I guess,
for that size.
And it's cheap.
It's the chip. He paid exactly nothing
for it.
I mean, we're talking four inches.
That's the size.
That's a piece a piece of glass
you get from the from from
the from the junk.
I mean, from the scrap.
It's like, yeah, you can get
that. Nobody cares about that size of
glass then you need it.
All that tall can be another piece
of glass, can be granite,
can be ceramics, can
be a composite construction
that you take two plates,
two bathroom
tiles, you glue them together,
you put them together with some cement
or some
some clay or whatever you find
and seal
it around. That's important.
But if you want to start it, Google,
Google, Google, Google, or ask me or
you can write me in, I can tell you what
you what you will find your tips
and what you find your materials, because
many, many details are omitted here.
Like 99 percent of the details are
omitted here
and some sand silicon
carbide, actually.
But that's yeah.
We call it you you take the
piece of glass, throw bits of sand in it,
and then you have a telescope.
That's that's how
one guy put it once
when we discussed it.
Other at a astronomy
meeting and polishing
agent. That's most of the
time. That's aluminum, um,
not aluminum oxide.
Really interesting chemistry going on
there. And nobody really knows why.
If somebody in the audience
and that's me asking
somebody for help knows
how how Xerox
it works,
how it polishes glass
come up, you're going to get the matter.
Really, it's I really had a hard
time to research that and pitch
like the black thing pitch, not the tone
one.
So here we have
our that's the mirror.
That's the tool.
Here we I illustrated two pieces of
glass because I was I was lazy,
pure laziness here.
I'm what you do is
you have those two mirrors in between.
There's the sound, there's a piece of
glass, there's the sound, the abrasive.
And here you
you you put pressure
on it. So what happens
in the center of the top part,
you have higher pressure
and on the edge of the bottom part.
You have increased pressure,
so
hands up and I want
you to participate in that, what
will happen with the top
part?
Yes,
you wrote the middle, you're going to get
a hole in the hole in the middle.
Oh, do you remember the slide from back
there where
we had that concave
mirror?
Well, that's what
happens.
You get the curvature.
And if you do that,
cortically.
Enough so you
turned the two parts count
in in opposite directions
randomly, like you make you make.
Actually, I wanted to make a small
demonstration here today,
but guess what?
That's where the demonstration is exactly
at home. But it's absolute, absolute
perfect use.
So you rotated, you move
it along, you make different lines to
make you make you make overall
the cultic movement and you end up
with a sphere.
So what do you do then
is you measure a you
measure how deep you are and, you know,
the shape of the sphere you have.
And
if you get to a point where it is,
what is the shape you want it?
You refine it.
First of all, with silicon, you start
with 60 grand with granule
size of 60.
Oh, by the way, silicon carbide,
you know, everybody knows it.
It's this stuff glued on sandpaper
and you go up to 320,
um, um,
granule size and then you go
Telharmonium.
That's that's a really fun fact.
So I was traveling, I
was traveling around in
Munich taking that the
plane taking the metro and
well as chance will
have it. I forgot my
purse, my my wallet
at home in the wallet.
It was my student, my student
ticket.
So basically I
got check. Of course, when you forget at
home, they check you, they ask
you what's your what's your
ticket? And then you learn, never mind.
So sometimes it
happens that the police isn't as
present. So imagine
a police police officer
or tell me what's in the backpack.
They're actually allowed to do that.
Um, what's in the backpack?
Yeah, some.
I just got my mirror and there is also
some some polishing
engines, silicon
carbide, some aluminum oxide
and whoever knows what
color.
Aluminum oxide is
pure white, and then imagine that being
a powder with the size
of nine micrometers,
that guy started asking questions.
Thank God they had like a rapid test.
And I told them, look, guys, it's you
see, that's I said, that's that's the
that's the 80
granule size of Silicon covid.
That's why it's black silicon.
It has. And I explain and
they believe me, but still
it got complicated.
Yeah.
Sorry, I didn't understand
what.
I really, honestly
don't hear what you're saying.
Is the mike on?
I just said, you can be very
lucky that I didn't ask you for an
biopsy, that you didn't have to try out
a powder and put it into your body
somewhere.
Actually, yes,
there's some research coming up about
what aluminum does to your body.
It basically screws up everything, but
so don't inhale it.
That's a bad idea.
OK,
so then you
you with all the steps,
you go find her.
And finally you refine the surface,
starting with with the 32
micrometer aluminum oxide.
You can already see
if you look at the flat angle
on the mirror, you can see
the you can see it starts reflecting.
That's where you get. Oh, yes, yes, yes.
I'm close to having a mirror.
No, you're not.
Then the work comes in.
This guy here who's putting the polishing
angel on, that's that's the copyright
holder stuff is Kefalas.
That's the guy who's like
the guru in Germany, in my eyes,
my opinion. But he knows a lot
about grinding mirrors and.
Yeah, I know. I know.
And I know he's watching.
So, yeah, I know he's probably going
read right now, but I don't care about
that. So what you need
is cerium oxide and pitch
that black thing.
You know why they call it pitch black.
Well that you see.
And this yellowish
powder, which was also a funny thing,
they wanted to test it.
That too.
You dissolved in water and you
put it on the on the
on the pitch and.
You put really don't put a lot
in it that that here is really, really
just see how thin it is.
You don't put a lot in it, but still
the serum oxide kind of
interacts chemically, chemically with the
glass.
Then again, it bet's a bet
itself in the pitch
and kind of like
like millions and millions
of razors cut the glass
away and polishes, polishes,
polishes it away and
kind of smears it also.
There is something I found
a paper with some Chinese researchers
which.
I dare not I don't know,
I know a lot about that stuff,
but I don't actually believe it,
that there is also some thermal
some thermal process going on, hitting
the glass up and smearing it the way
I honestly have no idea.
Those Chinese guys wrote a paper I don't
believe have more critical credibility
than me and that matter.
So
that you need to test it or the
process is
very precious.
You do something, you see what this
something does, and then you look again
and you see what this something does
again and so on and so on.
First of all, you want to find out how
deep is the mirror?
What is the shape of mosfet?
That's how you do it.
You take a ruler and
measure that distance
fairly easy, isn't it?
No hightech involved here.
The more high tech way,
high tech, whatever,
high tech in terms of the 17th century,
as you take a torch,
you make them real wet.
You take a torch and you look with a
reflection goes, and if you hit the right
spot, you will know that if you hit it,
believe me, you
measure the distance and you have
the right of the radius of the sphere
that this that the surface
is an element of.
Sounds complicated.
It isn't.
It's really basic geometry
because a
spherical mirror will reflect everything
that comes from the center back to the
center.
That's what we use
to make the testing with
IFFCO, with the testing
little for you.
Probably most people know of the
pendulum, but this is also
an ingenious method of
making high precision measurements
on mirrors and reflecting
surfaces in general with
minimum.
Monetary involvement, you
are talking to make it for Cortazar,
we're talking if you if you
really if you are going to go fancy,
really fancy, we're talking 50 euros a
year.
You can make it actually for free.
If you if
you go to scrap yard or something
like that, you it's
really you can make it really cheap and
it's really precise.
It's surprisingly precise.
And then again, Interferometry,
that's like the more techie way
I want Luminita from here I
could make a talk on interferometry alone
or different medical testing of MRIs,
because you have to you have to take into
account so many effects
that I'd simply say that's
nothing for the beginner.
But if you go
there's a lot of a lot of information
on that to read up.
So Google it.
You will be more than happy
with information you got.
Get that. So here
we have a coat tester
on the bottom.
You see the light source
shining onto a mirror, projecting the
light on your on your test
subject.
And here you
have an edge, a knife
edge. That's why it's called also
for cold knife edge testing.
And here what you can see
illuminated is so basically
what's what's the what's the thought
behind this here?
So here we are roughly in the center of
the mirror. We are talking here.
The dimensions of scale are scaled down
in order.
That's a Wikipedia picture
in order for it to be
for you to be able to understand it.
But that that size,
if you if compared to the human eye
that a mirror would be
there, that would be a typical focal
distance for that one.
So we are so
here we are roughly in the center.
So what you
do is, you know,
OK, if I project something from the
center on the mirror, it goes
back to the center on
a single point.
So if I put a knife edge there,
a really, really sharp edge
which blocks or which
is which binary blocks
or allows light to pass through.
I if I had a perfect
sphere, a perfect set up, theoretically,
I would get I
would see that the mirror and all
the test subject illuminated.
And then it goes black as
I move, as I move the edge back
and forth.
Well, reality kicks
in and you
get deviations from
the sphere.
So here, that's more or less
a good thing.
Here you can see you can only see here.
There is there's a you
have kind of something funny
going on here on the edge
here or something.
There is a kind of a mountain
and the center here, smaller mountain,
combined with a with the with a
ruined edge.
I'd say here
you see some shading.
Here you see a pit in the middle.
And again, this, this edge,
this is there's a typical
error beginning to make
nothing you can't.
Correct. But yeah.
So this is what you would see.
And you see here this deviations
from the sphere are
we're talking about maybe
here it's huge.
We're talking about 200 nanometers.
NanoMETERS.
Um, excuse
me.
Um, 20 wavelengths,
sorry, 20 lamda
20, I'm sorry.
Yeah, so this is 20 where Flash
and as a matter what
you would use as wavelength, typically
white light. So you would use that
20 times.
Four hundred nanometers.
That's a deviation here.
We're talking about precise testing.
Um, actually, I don't
know if I do have the picture
where you have that
for Colthurst.
And somebody puts a hand in the
in the in the
in the beam, you can actually
see the thermal,
the thermal turbulences of the hand.
So you can
imagine what the what the
what the resolution here is, it's really,
really good.
And yeah, Interferometer,
this is basically for you to have
something to Google.
Those are fermenters which work
with
which amateurs have built a common path
into fermenters. They are not that
precise, but they have an advantage
in in construction.
So that's basically for you.
If you want to look it up, that's what
you would Google for boffing for
Interferometer Potente diffraction
deferment at the physio, which
is a also pointy fraction different,
but with a special setup.
Again, I could I
could go on.
I didn't exactly lie to you,
but I didn't
tell the whole truth.
This fear does
not.
Provide a perfect image if you have
light coming from the from infinity.
Here we have an illustration.
If you have light coming from from
infinity here, parallel beams.
You, uh, that.
Always helps shaking up batteries.
So here you see that's that's the focal
region that's called spherical
aberration.
You have it always with with
with spherical, with spherical
optical elements.
They kind of have a hard time
focusing like from from infinity
onto one point and correcting
and correcting this fairly
easy.
You just make it take your sphere.
This is a bit exaggerated,
but you take a sphere and make
a little.
A dimple in the middle
and you end up with a parabola and a
parabola focuses all the light on one
point coming from infinity.
Again, this is really,
really exaggerated.
Car lights use
that inverse path, you have
the the light bulb here
and you get a parallel path that
parabolic antennas, guess
where they got the name from.
So testing that
is kind of big a
challenge because you don't
test the whole mirror as a whole and you
only know how to test spheres.
So what we do is we make
we cover up some areas there.
It's called a it's called a,
uh, it's
called a mask.
You have black paper and you cut
holes in it.
So what you do is you approximate
that parabola with a lot
and lots and lots of
depending on how many you want for a
small mirror, three regions for a
big one, you would use up to eight, up to
10, 12.
I've seen one with 14.
That's just insane.
So you approximate the
mirror with zones.
You assume that you
have a steady
you have a steady curve.
You don't you don't make funny stuff
between the between the regions.
So what you do is you measure a lot of
spheres. And if the relations of the
first to each other is correct,
everything works fine.
There's also software where you can
calculate what the relation has to be,
which fits everything and stuff like
that. You can do that in an Excel sheet
or LibreOffice
calc sheet or whatever you
you want. You can do that.
There's a lot of software and if you
search for four core interferometry, you
will stumble upon those those,
uh, those
piece of software.
Most of it runs and runs on
Windows. But why works just
fine.
So
this is the grinding part,
making the mirror for
a eight inch, 200 millimeters,
eight inch or 200 millimeter a
mirror we would
calculate, if you are good,
90 hours of grinding,
polishing and everything included and
testing if you
are average.
We are talking rather about one hundred
and thirty to one hundred and fifty
hours.
The biggest part
is building the telescope, first
of all, you have to decide
what do I want?
Do I want a telescope which I want to
perfectly possible with an eight inch to
take it with you on the airplane luggage?
I don't know if the TSA likes it because
they know, but
that's I know people who take their
telescope on the plane as hand
luggage.
Maybe you want to what?
I had the problem.
I needed public transport.
I didn't have a car directly,
so I needed to carry that telescope
with me on public transport.
So I bought one
blame on me. But yeah, I bought a small
telescope, have that in my backpack,
have a tripod in my hand and
the eyepiece,
the eyepieces on the other hand.
And I just can go ahead,
people can take me with with them
in the car or whatever.
So it's not hard for them.
It's not easy for them, for
them to say no and just say, OK,
I don't want to I
don't have a room or whatever.
It's I it was really,
really compact.
And people are even going for a hike
with their telescope.
So we are talking about really,
really light, lightweight and compact
compact stuff.
Yeah, but
if you want to observe from your
backyard, there's no
there's no need there's no point
in investing all the time.
And the money and the complicated
constructions and the many failures
or whatever, you just build a
telescope that works and you don't care
how heavy it is.
You would you put a
a plastic sock on it
and it's protected from rain and
everything. It's just there.
If you want to take pictures with it,
there are different demands.
So you have to decide,
what do I want here?
What do I want to build?
So let's start
with what are the main
factors I mentioned transportability.
Handling the
best telescope is of no use if you can't
use it.
That's a tautology anyway,
and.
You wanted to be rigid, you don't
want to invest tons
of hours and your optics
and make everything
perfect and then everything
being sloppy and shaking
around, because
that's the main reason.
Do you remember those cheap telescopes I
told you about?
Don't buy too cheap
telescopes for kids because
they have sloppy mechanics
and they are no fun to use.
And if it's no fun to use, you won't use
it. And if you don't and if you want to
use it, then don't start in the first
place.
So that's those are really
important factors.
And especially the transportability is
is, I think, also your
budget.
If you have no budget and if you have no
car, there's no point
in making a one meter telescope.
We are talking about five thousand euros
only for the mirror.
And if you
if you are not careful and
that guy in the stream watching right
now, he knows what I'm
talking about.
He made an effort.
You can have a you maybe you ruined
four hundred euros worth of glass.
He was nearly done.
It was nearly done. He was doing his
final test.
Had he still had his mirror
on the bench
and his kids were in the house.
He was eager to finish it,
one of the kids opened the door.
I went, went through the house,
kicked the mirror off
of the stand, and you had
three really, really
well polished chaat.
And
that hurts another guy.
The stuff has gotten those pictures from.
Thanks for that.
By the way,
in order to avoid that,
he put his foot under
the mirror to catch it.
He had a broken foot.
The mirror was once OK.
He said it was worth it.
Imagine, imagine.
So. Yes, we are.
Be careful with it.
And.
Calculate a
failure shouldn't ruin your budget
planning for the next holiday.
So basically,
one thing you have also to decide is how
do I want to mount here?
This is an out of azimuth Mt.
shortened up days.
So you see, it's easy
up and down, left, right.
You have to access perpendicular
to the perpendicular to gravity.
Perfectly fine. Engineering, no
challenge.
Here we have a German mount.
The reason you would do that is you want
to take pictures so
the Earth's axis is tilted.
And what they do here is you
have one axis parallel to the other,
the Earth's axis, and you
counteract the movement of the earth
of the stars relative to the earth, of
course, and you just
move your telescope along.
So you just
have to worry about one axis
being properly.
That's a huge advantage.
Trust me on that, you have one even.
There are clockwork like.
This clockwork old
Russian clockwork mount's,
which worked marvelously.
They are great, the only problem is
once you wanted them up
again, police.
So you are on to number if you have your
club. Oh, it's a great night tomorrow
I'm flying. I don't care.
I want to take pictures.
So you wind it up.
You're winding up a bit too much because
you want to do one bit further than you
think you will need.
And then on the next day,
somebody checks the bags,
the luggage.
And here's a
coming from back
at
explaining.
Oh, actually, you see what
shape this thing has
won over a certain amount.
She's she's a really great person,
great humor.
And she was
on top of a mountain and
she was setting up her telescope, was
observing.
And nearby
there is a military area.
One of the residents saw
somebody putting a
silhouette that looked like that
on top of a mountain.
So
there is a German, there is a
if somebody if you observe
you want to do you want everything to
stay dark? Because adaptions
in darkness is something that breaks
really easily and needs about half an
hour to rebuild. So you avoid
light. And there is the term
vice zao which means
white light. Pigou
so the.
She was there on the telescope, somebody
they sneaked up on on her.
We're talking we're talking
about special ops,
spec ops, sneaking
up to her, liking the whole
area, and
she just saying fell
and then looking up and
seeing guns pointed at her
and people screaming, go away
from the rocket launcher.
So you see, astronomy is
a really, really peaceful
hobby.
But yet again,
those are some that doesn't happen
all the time. So I don't want to scare
you off here, but I just want to to
listen to those of you up.
So that's
how you would build an alt azmath.
That's a an example.
So here you have your main mirror.
You have to Rud's here you have
your your
secondary mirror, your focus.
The focus is something you can build it
yourself, and especially nowadays
with three nowadays with 3D
printers, you can easily print one
for yourself, but you need high
precision. And honestly, they don't cost
a lot. If you get a really, really fancy
one, you're paying three hundred
euros.
But we are talking about really, really
fancy stuff.
OK, if you got really big then it goes
really, really expensive
actually. How much time do.
Five minutes.
Holy crap.
I mean I was told
OK, I have five minutes.
I'm sorry for that.
So what you can
make a trust that's called the Dobson.
So here is a full tube, Dobson
and that's like kind of the stuff you can
buy.
This one is really, really heavy.
We're talking about they make you can
separate the pieces here and
and carry them around because you can't
cover that in the hole.
I think it's a 14 inch and
yeah, that's
that's a full full one.
Then it stops.
This one is a 32 inch Dobson.
Thirty two, yes.
So basically what I'm telling you here,
that's this one here, the
finder is also
a Newtonian telescope.
It's just four and a half inches,
but that's the finder.
This mirror here, the
mirror has that size, so we're talking
about a really decent one and you can
see really nice things with it.
Oh, no, I stand corrected.
28 inch, sorry.
And again, I trust
that that's the classical design with
eight rods, by the way.
And here this one is meant for
photography.
So this one has to be really,
really, really, really sturdy.
You don't want your your camera, which is
which can be quite heavy here in the
front to move relative
to your main mirror.
That's really, really bad karma.
You don't want to do that.
Your picture is going to bring your half
an hour luminosity
picture is going to be crap.
So really, you wanted to
be as strong as possible.
So that's why it's made like that
with a huge diameter in the middle and
smaller thin outside, because
it's also mainly supported in the middle.
So here you have a three
three wrought design, a two
design.
This one is really, really, really
compact.
You can the roads are
separated. You see this here?
Those are our base
strengths.
This thing as setup
and you can play music with it.
Not good one, but you could play music
and this and here
you have really the buffer in
front of these.
So this one is a compromise
going totally for transportability.
You lose light if you do that
because you have the strings going in the
in the optical path.
You have this huge thing here.
So you want to have it really light
you losing light, but you want it to
carry it with you.
And I know and I happen to know that
stuff has made a
with this with his motorcycle
with that.
And so, yeah,
everything possible.
So the top part called I
have to speed up a bit.
So if you don't understand something,
please forgive me on that.
So the the top part
has two main components which you want to
support thoroughly here.
The the secondary mirror.
That's the shiny thing that gets what
and the focus.
And that's that's one of the fancy ones
that costs, that costs two
hundred euros.
And you want that hat
to be as loud as possible because you are
away from the center of mass
and you want it to be stable.
You see engineering problems
coming up.
Everybody does.
And solving this problem seems
impossible. But it's really,
really well, they're really,
really good solutions.
So here you see trusses here
on the on
the supports and yeah.
Here another solution
on that.
And yeah.
So you can solve it.
People have actually made
had made second secondary
mirror supports with guitar strings.
So everything's possible here.
Two minutes over
two minutes.
It's.
Maybe I'm speeding
up here. Sorry, I sorry.
And here you have the mirror box, which
is basically quite
easy.
You have this structure here which
supports the mirror here.
That would be silicone pads if it's done
and everything movable, easily movable,
that everything can be canela in such
a way that there is no, no, no
to work on the main mirror.
You don't want that.
You really don't want that.
It ruins your image for no particular
reason. So you don't want to do
that.
So here again,
the the altitude wheel's attached
to the box and the rods
here and you basically
and all that goes on the rocker box,
which is basically Teflon
grinding on top of Ebonie Star.
Ebonie is top counter
cover, a kitchen counter,
kitchen counter.
So, yeah, it's easily
accessible. They don't produce any more
alternatives, but yeah.
So that's how you would do everything.
I want to thank those guys statis
Martin Carcillo and the
People Subsecretary and.
I want this to I want to dedicate
this talk to John Dobson, without
whom this Dobson design
would not have been possible.
He died earlier this year, in
January last year, this year,
last year.
So he died earlier this
year. And,
yeah, was a huge loss definitely
for the community.
And that guy was the one that
made democratic,
democratized astronomy
for everybody, the sidewalk astronomy
and yeah, some software.
Just Google it up, open source
everything.
Do download it, modify to
improve it and
some links where.
Yeah, cloudy nights.
That's that's an English forum.
Everything is organized with forums and
um, in the sector
I would have a national media
are sites
that are German.
So everything happens in German
and. Yeah I
would. Can we arrange five
minutes for a Q&A?
I think that's possible and thank
you.
So yeah.
So if anyone has
questions, just come to one of the four
microphones and we'll just, you
know, just go ahead with microphone
three.
Hi.
I was curious.
Hello.
I was curious whether amateur
astronomers using these systems have ever
done things like calculate redshift
and whether they actually look into the
more sort of scientific side or whether
it's purely observing.
There is some science done,
but it's mainly
variable stars and,
um, asteroids and
and planetoids stuff like that,
because the problem with you
could possibly calculate or
measure redshifts.
But the matter with that is you need time
for redshift calculation, you need high
resolution
spectrometers.
And those are expensive
and they are expensive for a reason.
So they're really, really hard to make.
So, yeah, to to calculate
redshift, it's kind of a hard thing.
And you can only
spectrometers need a lot of light.
So you can only do that on bright objects
and all the bright objects have already
been measured, thus
the hell measured out of them.
So you can
do that, but you can't contribute
in science with that main contribution
of amateurs.
Again, as I told you,
small planetoids
and variable stars.
But there's also one site called
Galaxy Zoo dot com
where you have pictures
of galaxies and you can
sit there on your PC
works great. If you have to wait on some
somebody, you can
say, OK, that's a spiral Galaxy Tab and
so on. So you can help classify
galaxies back that.
So you're welcome.
Yes, please know my number, too.
Hello. Yes.
If you're using purely class for the
mirror without the shiny surface.
Yes. Isn't that a bit lost
of light?
Yes. Yes, yes it is.
You have to you have to cover it up.
I completely forgot that.
My token. I forgot that completely.
Thank you for pointing that out.
You have to send it somewhere.
You need a vacuum chamber to illuminate
it and to put also
a cover material
on top.
Um,
come on.
Silicon oxide so that you have
to have that sealed, but you can do it.
Also at home there's a chemical reaction
which drops out
element to the mentor
soda and you can cover that
in silver, but it produces hydrogen
and hydrogen is kind of
an explosive matter.
So you want to be careful with that
magic.
Number three, I just wanted
to mention you mentioned Dobson at the
end, so I just wanted to mention
something is a funny thing to stop since
he started astronomy because he was
converting to Hinduism.
And the funny thing is Hinduism has very
oh, no, Christian Christian
kids. Listen.
Yeah, it's a funny business.
Seven twenty years old.
The problem with Hindus is
they have to accept different problems
they have in universities,
billions and billions of years old.
And so one of the reasons he tried
this one was to get people full and
steady state universe model.
And so I think it's
something to show.
Is that the.
Tolerant to religious people, they may
be idiots quite often, but when
it comes to get a nice outback
fire, I happen to have seen
an interview where he said that
the Big Bang, the Big Bang
Theory thing is incomplete.
And we're not talking to show here.
Yeah, that's bogus.
He said that.
True, but.
He he made a huge contribution,
just wanted to say, because he had
a problem with it, because
we are we're running tight on schedule,
maybe.
Thank you for sharing that with us.
I have a question.
And you said you cannot use
regular glass or what kind of glass, I
suppose, to buy. You want to use glass
that has a that doesn't
expand as much with with thermal
differences because you want it to
you want to mirror to cool down smoothly
so you don't have bumps and ridges
building up just because the glass is
expanding or cooling down
because you have to imagine
you are carrying the telescope from a 20
degree Celsius perfect environment
to if you are not lucky
to a minus 10 degree
turn, minus degree environment,
understanding the environment.
And even with that special glass,
you need to wait some time
until the mirror has cooled down.
Enough that you can observe.
It's it's really
that that's the whole thing.
And if you make small telescopes,
you can use thin sheets of glass,
normal, normal floating
glass for for windows
and then again, thin sheets cool down
easily and you have no problem
at all.
So that's the only reason.
What is what is called the glass use.
It's called Becae seven.
It's called a Pyrex.
There are many it's
basically most of the time it's floating
glass so that
many trademarks on it.
But if you the way I would buy
glass where that is set up, a guy who
sells glass for
for those for those purposes,
there are many and it's not really it's
not that expensive.
OK, so I think that was
what was it with the questions.
Looks like it. Yeah.
Think again.