The farthest object visible with the naked eye.

[esalla]

The speed of light is decreasing as time advances ... these distant galaxies aren't moving away from us, the light they emit is moving faster ... thus only giving the appearance of recession ... when in fact, they are stock still ...

You are joking with Tom Paine, right? That is the sort of argument that a creationist gives to rationalize a young 6,000 year old earth.

That's from an op-ed in SciAm talking about the confrontation part of scientific method ... it's necessity and where lacking hurts the scientific process ... and the author used GR as an example of something nobody is trying to disprove ... and he offer the monstrosity above, noting it didn't have to be good, just competitive ...

Anyway ... it makes for some pretty good amateur-grade crackpotism ...

What scientific process is involved in the universe being a computer program

 

[Wuwei]

Sorry, that was my third scope. My first was a 3" reflector on a ball joint with a wing nut for a lock. Pretty rough. The second was a TASCO 2.4" refractor on GEM. Then the 4.5" TASCO. I've got 13 scopes now, the largest aperture (though not physical size) is a 14-inch folded catadioptric.

Those are beautiful scopes.

I ground the reflective lens from 4 1/4 blanks on my first Newtonian scope. It took 2 weeks to get a four foot focal length because I was tired of grinding the blank. And then another two weeks of fine grind and polishing. I made the tube from a rolled aluminium sheet, the tripod was water pipes connected to a fence post. Two war surplus gizmos with babbit bearings held the cradle and long hose clamps held the tube. It was permanently fixed to 42 degrees (Michigan).

These pictures are (were) my second scope. I bought a 4 inch Bausch & Lomb Tessar lens with a rather large 3 3/4 air gap. It was used for aerial photography in WWII. It cost $40 from Edmond scientific in the 1960's. Today it would probably be a thousand bucks. I threaded an aluminum tube to hold the lenses. (Using a rather big lathe at the physics lab) I still have the scope, but tossed the tripod. It's too heavy for a low cost tripod today. (About 20 pounds).

 

[the other mike]

 

[toobfreak]

Those are beautiful scopes.

Thanks, Wuwei.

I ground the reflective lens from 4 1/4 blanks on my first Newtonian scope. It took 2 weeks to get a four foot focal length because I was tired of grinding the blank. And then another two weeks of fine grind and polishing. I made the tube from a rolled aluminium sheet, the tripod was water pipes connected to a fence post. Two war surplus gizmos with babbit bearings held the cradle and long hose clamps held the tube. It was permanently fixed to 42 degrees (Michigan).

Yep, the plumbing water pipe/gas pipe fittings mounts were a very popular option at one time. A buddy of mine ground his own 6" f/6 on one of those mounts.

These pictures are (were) my second scope. I bought a 4 inch Bausch & Lomb Tessar lens with a rather large 3 3/4 air gap. It was used for aerial photography in WWII. It cost $40 from Edmond scientific in the 1960's. Today it would probably be a thousand bucks. I threaded an aluminum tube to hold the lenses. (Using a rather big lathe at the physics lab) I still have the scope, but tossed the tripod. It's too heavy for a low cost tripod today. (About 20 pounds).

Nice lens! Those large air gaps were used to help suppress certain aberrations as the air itself acted as an additional element. Edmund was a great place for surplus stuff (others have since replaced them) and now today, 'Scientifics' mostly sells gizmos and doodads for education. I have a couple of similar lenses my self, this 5" f/5 doublet that I bought for a friend decades ago that was supposedly originally from an aerial recon camera that has excellent figure and super low secondary colour that when he passed away in 2009, I got back and hope to make into a scope again.

And I also bought about 8 of these ~80mm Fujinon triplet lenses from somewhere back in the 1980s and have made a few into scopes (I have my own machine shop) as sort of super quality industrial finder / guide scopes.

BTW, Wuwei, It doesn't surprise me you should have had your hand in grinding your own optics-- -- I just want to add that while I know we've disagreed on some issues, I generally regard you as the most genuine educated person on this board. To date, of the many times I've put my little math teaser out there of what 'X' equals to those who profess science or math expertise, you are the ONLY one to date to have gotten the answer. And you weren't even the person being asked.

Not that it was really a hard problem, just that so many here blow their hole claiming far more than they really know that sometimes you just have to call their bluff. You've been the ONLY person here to show that you actually DO have real background in solid math / science and I respect that. All the rest (including one idiot from Russia who used to come here to put down the USA) all ran like scalded cats when asked.

If you don't mind, I'm going to share your pictures and little story with my little astronomy forum friends to show them the stuff you did.

 

[Wuwei]

Not that it was really a hard problem, just that so many here blow their hole claiming far more than they really know that sometimes you just have to call their bluff. You've been the ONLY person here to show that you actually DO have real background in solid math / science and I respect that. All the rest (including one idiot from Russia who used to come here to put down the USA) all ran like scalded cats when asked.

If you don't mind, I'm going to share your pictures and little story with my little astronomy forum friends to show them the stuff you did.

Thank you for the accolades. Sure, you are welcome to use the pictures. I told all the neighborhood kids to stand away so I could take a picture of the scope and solar eclipse. I had to put a rather large eye piece at the focal point to magnify the eclipse, and hoped it wouldn't be fried by the sun.

I thought my long four foot FL Newtonian scope would be able to see Andromeda clearly, but the magnification was too high and it was only a barely perceptible mist.

Back in those days there was a different type of inventiveness from kids. They did things and built things from scratch. While in high school in the 1950's I also dabbled with transistors when the price came down to $5 for a Raytheon CK722. You could buy electronic components from local stores (Radio Shack!). I made a radio and a hearing aid for my aunt. Today's kids replaced that with the Raspberry Pi and apps etc.

.

 

[ReinyDays]

And you can achieve the millionths of a millimeter precision thickness and curvature needed for a precision lens.
Yea kid if you say so

Hell no ... we're good to 1/4 wavelength ... 50 nanometers is close enough ... in a garage ... I had a friend set up a rough grinding machine in the spare bedroom of his apartment for up to 18" mirrors ... a few days figuring and off to the aluminizers ...

Flats are a little more difficult, but still kitchen counter science ...

Foucault knife-edge test - Wikipedia

en.wikipedia.org

 

[esalla]

And you can achieve the millionths of a millimeter precision thickness and curvature needed for a precision lens.
Yea kid if you say so

Hell no ... we're good to 1/4 wavelength ... 50 nanometers is close enough ... in a garage ... I had a friend set up a rough grinding machine in the spare bedroom of his apartment for up to 18" mirrors ... a few days figuring and off to the aluminizers ...

Flats are a little more difficult, but still kitchen counter science ...

Foucault knife-edge test - Wikipedia

en.wikipedia.org

What you will learn as you age is not to reinvent the wheel. There is no way to create precision optics from raw materials at home.

I could invent a camera and lenses but would it rival the Nikon's that I have had photos published with

Camera and lenses
CPU, intel

You go ahead and build your own

 

[ReinyDays]

What you will learn as you age is not to reinvent the wheel. There is no way to create precision optics from raw materials at home.
I could invent a camera and lenses but would it rival the Nikon's that I have had photos published with
Camera and lenses
CPU, intel
You go ahead and build your own

10 seconds on Google brought this up:

"Build your own telescope part 1: The mirror"

"Another surprising advantage is that hand made optics (if guidelines are followed) tend to have a higher surface quality than the mirrors polished by industrial machines."

The operative word here is "mirror" ... which is something different from a "lens" ... try to avoid this confusion if you please ...

Sadly, my ATM books have gone missing after all these decades ... I'd like to remember that there where chapters on grinding out eye pieces, if they did it was more trouble than it's worth ... today's modern coating technology is so out of this world that buying eye pieces is the best way to go ...

My mirrors weren't even worth silvering ... they called me the coma-kid ... turned edges were my specialty ...

 

[Wuwei]

And you can achieve the millionths of a millimeter precision thickness and curvature needed for a precision lens.
Yea kid if you say so

Hell no ... we're good to 1/4 wavelength ... 50 nanometers is close enough ... in a garage ... I had a friend set up a rough grinding machine in the spare bedroom of his apartment for up to 18" mirrors ... a few days figuring and off to the aluminizers ...

Flats are a little more difficult, but still kitchen counter science ...

Foucault knife-edge test - Wikipedia

en.wikipedia.org

Right. With hand grinding I would to do it for a half hour to set a good rhythm and then rest a while. A 1/4 wave spherical mirror can be achieved. A machine can go all day.

The real tricky part is turning the sphere into a parabola. That has to be done at the final rough grind, just before polishing. The problem is that the glass at that stage is a poor reflector and you have to wet it, and be careful that the wetting is uniform so you can accurately do the Foucault knife test.

.

 

[esalla]

And you can achieve the millionths of a millimeter precision thickness and curvature needed for a precision lens.
Yea kid if you say so

Hell no ... we're good to 1/4 wavelength ... 50 nanometers is close enough ... in a garage ... I had a friend set up a rough grinding machine in the spare bedroom of his apartment for up to 18" mirrors ... a few days figuring and off to the aluminizers ...

Flats are a little more difficult, but still kitchen counter science ...

Foucault knife-edge test - Wikipedia

en.wikipedia.org

Right. With hand grinding I would to do it for a half hour to set a good rhythm and then rest a while. A 1/4 wave spherical mirror can be achieved. A machine can go all day.

The real tricky part is turning the sphere into a parabola. That has to be done at the final rough grind, just before polishing. The problem is that the glass at that stage is a poor reflector and you have to wet it, and be careful that the wetting is uniform so you can accurately do the Foucault knife test.

.

I buy my lenses from nikon

They are the finest in the world

http://assets.hardwarezone.com/img/2014/11/factoryTour-2.jpg

 

[toobfreak]

I told all the neighborhood kids to stand away so I could take a picture of the scope and solar eclipse. I had to put a rather large eye piece at the focal point to magnify the eclipse, and hoped it wouldn't be fried by the sun.

Yes, I noted the nice partial eclipse! You're generally OK if you can use a simple eyepiece like a Huygens for projection, any cemented elements is a no no.

I thought my long four foot FL Newtonian scope would be able to see Andromeda clearly, but the magnification was too high and it was only a barely perceptible mist.

Andromeda is that rare object that really benefits from a large 5-7mm exit pupil, which for most scopes is in the 15-30X power range, though I did see a super view of the dust lane once at higher power through an Orion 6" f/6 russian mak-newt (maksutov-newtonian).

You could buy electronic components from local stores (Radio Shack!).

I remember Radio Shack very well. We also had Olson's and Lafayette as well. In their day, the Shack were a smorgasbord of parts for the hobbyist. Then later they abandoned that. I probably have most publications they ever released. Here is a picture of some of their mini books I have.

Back in those days there was a different type of inventiveness from kids. They did things and built things from scratch. While in high school in the 1950's I also dabbled with transistors when the price came down to $5 for a Raytheon CK722. I made a radio and a hearing aid for my aunt. Today's kids replaced that with the Raspberry Pi and apps etc.

Damn, I had to look that one up! Very cool. It was literally the first commercial transistor for sale on the street. Towards its end, prices on them dropped down to a $1 a piece. They were giving them away. Interesting that they doped it with germanium and not the more common arsenic, but then, it was a p-doped transistor (hole as current carrier). I actually collect old stuff like that and looked on eBay to see if I could buy a CK722. You should have hung onto a few, the going rate for them is now between $50 to $80 PER TRANSISTOR depending on the colour of the case!

I think I'll pass, but I do have a fair collection of old things ranging from original unused nixie tubes (I actually still have a working H-P frequency counter using nixie tubes) to this old thing: a table top D'Arsonval ammeter where you connected to the terminal you needed for the scale you intend to use. It is made out of baklite I think and is in good working condition.

What is interesting is that it was made by Weston Electric, the forerunner of Western Electric and was actually used at Bell Labs. For all I know, it was used in the development of the transistor. If you look at it very close, you'll see it's patent is the year '94. That is not 1994 but 1894! Right around the time that Bell was first widely commercializing his new telephone and Weston was evolving into the Western Electric Engineering Department which eventually became Bell Labs. The needle is so fine that it is hard to see even in this close up.

I should fire it up some day just to test it next to my Fluke bench meter to see how accurate it still is.

 

[toobfreak]

And you can achieve the millionths of a millimeter precision thickness and curvature needed for a precision lens.
Yea kid if you say so

Hell no ... we're good to 1/4 wavelength ... 50 nanometers is close enough ... in a garage ... I had a friend set up a rough grinding machine in the spare bedroom of his apartment for up to 18" mirrors ... a few days figuring and off to the aluminizers ...
Flats are a little more difficult, but still kitchen counter science ...

What you will learn as you age is not to reinvent the wheel. There is no way to create precision optics from raw materials at home.

Dude, do you have some compulsion for talking out your ass making a TOTAL idiot of yourself because you need the attention that badly? People have been known to grind their own optics to well beyond the diffraction limit. Alvin Clark made his optics totally empirically and made some of the finest refractors in all the world, including the 36" Lick (which I've looked through), and the Yerkes 40". Get a grip on yourself.

Here is one of his smaller, personally owned telescopes.

 

[toobfreak]

"Another surprising advantage is that hand made optics (if guidelines are followed) tend to have a higher surface quality than the mirrors polished by industrial machines."
The operative word here is "mirror" ... which is something different from a "lens" ... try to avoid this confusion if you please ...
Sadly, my ATM books have gone missing after all these decades ... I'd like to remember that there where chapters on grinding out eye pieces, if they did it was more trouble than it's worth ... today's modern coating technology is so out of this world that buying eye pieces is the best way to go ...

1. Modern automated machine optical grinding is capable of producing optics to the highest level, though the final spot figuring is still often done by hand. But without a doubt, in its day, the best optics were made by the very patient and fastidious optician.
2. Actually, lenses can be easier to make than a first surface mirror! All of the wavefront depends on that one surface of a mirror, whereas with a standard doublet, the wavefront is a combination of the R1-4 allowing any given surface to be made to 1/4 the required final accuracy.
3. I have whole bookshelves full of just about any ATM book you might ever want, from Edmund's 'All About Telescopes' to ATM Vol. 1-3 and many others to the graduate level. These books are disappearing now.

 

[Wuwei]

I remember Radio Shack very well. We also had Olson's and Lafayette as well. In their day, the Shack were a smorgasbord of parts for the hobbyist. Then later they abandoned that. I probably have most publications they ever released. Here is a picture of some of their mini books I have.

That brings back memories. I did use Lafayette, but not Olson's.

Damn, I had to look that one up! Very cool. It was literally the first commercial transistor for sale on the street. Towards its end, prices on them dropped down to a $1 a piece. They were giving them away. Interesting that they doped it with germanium and not the more common arsenic, but then, it was a p-doped transistor (hole as current carrier). I actually collect old stuff like that and looked on eBay to see if I could buy a CK722. You should have hung onto a few, the going rate for them is now between $50 to $80 PER TRANSISTOR depending on the colour of the case!

You are right. I should have hung on to them. The one I had did not have the rounded corners as your picture shows. You could actually see saw marks on the top of the transistor. They were not shiny. I had about three of them.

I think I'll pass, but I do have a fair collection of old things ranging from original unused nixie tubes (I actually still have a working H-P frequency counter using nixie tubes) to this old thing: a table top D'Arsonval ammeter where you connected to the terminal you needed for the scale you intend to use. It is made out of baklite I think and is in good working condition.

Wow. I used a meter like that at Chrysler Introl Div. I was with a consulting group that built a prototype of the first automotive electronic instrument panel in the mid 1970's. We used the worlds first CMOS computer board with an RCA 1802.
They didn't have an operating system so I wrote the application in hex assembly language. I'm not kidding. There was not too much in the instruction set and it was well organized. I used a teletype with punched paper tape for program storage and instruction input. The system was installed in a test car driven by an executive. His wife didn't like the neon color of the 100 tiny rectangles of the linear meter (according to rumors) so it was abandon.

I was one of the first to buy an 8 bit South West Technical products computer kit with a Motorola 6800. I also programmed that with a teletype/paper tape.

They had an assembly language, but no high level language, so I wrote a threaded interpretive code for it. I can't believe the energy I had back then.
.

 

[ReinyDays]

"Another surprising advantage is that hand made optics (if guidelines are followed) tend to have a higher surface quality than the mirrors polished by industrial machines."

1. Modern automated machine optical grinding is capable of producing optics to the highest level, though the final spot figuring is still often done by hand. But without a doubt, in its day, the best optics were made by the very patient and fastidious optician.
2. Actually, lenses can be easier to make than a first surface mirror! All of the wavefront depends on that one surface of a mirror, whereas with a standard doublet, the wavefront is a combination of the R1-4 allowing any given surface to be made to 1/4 the required final accuracy.
3. I have whole bookshelves full of just about any ATM book you might ever want, from Edmund's 'All About Telescopes' to ATM Vol. 1-3 and many others to the graduate level. These books are disappearing now.

I thought your #1 above was the case these days ... this was back in the 1970's ... I moved to Western Oregon and optical telescopes are kinda useless here ... rains every day all day long ...

ATM Vol. 1-3 is what I thought I had ... I may still have them stuck away someplace safe ... they've been stolen from me a few times, I guess they're that good ...

William Herschel is famous for discovering Uranus ... he built his own telescopes before the Faucault tester was developed ... [scratches nose] ... kinda of amazing I think ... did he guessed at the figure, a quick silver job and test it in situ? ... God that must have been tedious work ...

 

[the other mike]

How do you melt and shape the glass

Jesus you must be a bright 8 year old or a shrink out to prove your ignorance

I've already reported you for trolling on this thread.
Now I'm asking for a thread ban.

 

[toobfreak]

You are right. I should have hung on to them. The one I had did not have the rounded corners as your picture shows. You could actually see saw marks on the top of the transistor. They were not shiny. I had about three of them.

What you describe sounds like the earlier plastic case. They later went to metal case. One of those could be worth over $100.

They didn't have an operating system so I wrote the application in hex assembly language. I'm not kidding. There was not too much in the instruction set and it was well organized. I used a teletype with punched paper tape for program storage and instruction input. The system was installed in a test car driven by an executive. His wife didn't like the neon color of the 100 tiny rectangles of the linear meter (according to rumors) so it was abandon.

Dude! You gotta be up there in years! Damn. I never got past FORTRAN and that was considered a fix so people DIDN'T have to program by assemly language! But I was lucky to have an instructor who actually worked on the ENIAC. He was a real cool dude.

I was one of the first to buy an 8 bit South West Technical products computer kit with a Motorola 6800. I also programmed that with a teletype/paper tape.
View attachment 335172

They had an assembly language, but no high level language, so I wrote a threaded interpretive code for it. I can't believe the energy I had back then.

That computer drew some serious power. I'll leave you with these two interesting images.

The first is a 5 MB HDD from 1956:

This second picture was a model of Rand Corporation's vision for the home computer in the year 2004, but it relied on technology not yet invented but which they were sure we would have by then. The only problem they saw was the average home affording one. If only they could see today.

 

[toobfreak]

I thought your #1 above was the case these days ... this was back in the 1970's ... I moved to Western Oregon and optical telescopes are kinda useless here ... rains every day all day long ...

Yeah, back in the 70's, you built a mirror grinder out of a washing machine to hog out the basic curve, then fine figured it by hand.

 

[Meister]

Please stay on topic going forward, one poster removed.

You have a good thread, and I cleaned it up the best I could.

 

[Meister]

And you can achieve the millionths of a millimeter precision thickness and curvature needed for a precision lens.
Yea kid if you say so

Hell no ... we're good to 1/4 wavelength ... 50 nanometers is close enough ... in a garage ... I had a friend set up a rough grinding machine in the spare bedroom of his apartment for up to 18" mirrors ... a few days figuring and off to the aluminizers ...
Flats are a little more difficult, but still kitchen counter science ...

What you will learn as you age is not to reinvent the wheel. There is no way to create precision optics from raw materials at home.

Dude, do you have some compulsion for talking out your ass making a TOTAL idiot of yourself because you need the attention that badly? People have been known to grind their own optics to well beyond the diffraction limit. Alvin Clark made his optics totally empirically and made some of the finest refractors in all the world, including the 36" Lick (which I've looked through), and the Yerkes 40". Get a grip on yourself.

Here is one of his smaller, personally owned telescopes.


View attachment 335162

Wow! That is so cool...certainly old school.
Years ago I bought a Celestron Nexstar 8. My first scope. Joined an Astronomy club in Orange County Ca.
That was such a blast being able to go deep in space, but had to travel to get to some relatively dark skies.

I moved to northern Id. and I have dark skies in my back yard. What a hoot that is.
My favs are the Nebula's in the fall and winter.