rcspaceflight
creator of virtual planes
This isn't RC related at all. It's a project that I fully "plan" on actually doing, but right now it's just a plan.
I haven't been using this forum at all lately, but I think it's fitting to post this project on here.
Really I'm half checking that I'm not missing something before I put time and effort into building it. And when I was doing research, I couldn't find any good articles about it.
I want to build a reflecting telescope, and all the articles I've found on how to build one all assume that I'll be buying a primary mirror, and that I'd be basing my measurements off of what's specified for that mirror. Any other article I found trying to figure out what exact shape to make the primary mirror and best distances between the primary and the secondary where far too technical.
I hope to eventually write out an article and posting it onto the Flite Test main page, which hopefully doesn't go against their guidelines as it's not RC or plane related in any way. I want to write the article as easy to follow as possible. I know most people aren't going to be able to actually make one, but it's nice to see people do it.
The large concave mirror in the back of the telescope is called the "primary" mirror, because it's the mirror that's doing all the work of shrinking the image down. The 45(degree) angled small mirror is the "secondary" and is used simply to move the shrunk image into the eye piece.
I'm assuming that the further away the secondary is from the primary, the less distorted the image will be and also the smaller the secondary mirror is, and the less the secondary mirror is blocking the image.
I have no idea as to what the best balance is. How far away is too far, how close is too close, I haven't the faintest. I'd assume the further the two mirrors are away from each other the better, but making a 20' long telescope isn't practical.
I should draw, diagram, this out, but as far as I can figure, the best way to make the shape of the mirror is with a compass. To put one end of the compass right at where I want the focal point, and then use the other end to draw the arc that will be the mirror.
I'd actually want the focal point past the secondary mirror. So I wouldn't be making the focal point at where I'd be placing the secondary. I want the focal point to hit right at the "eye piece", which I'm actually going to be putting a camera. So I'd add the distance of the primary to the secondary with the distance of the secondary to the camera, and make that the distance away from the primary to the focal point. If that makes any sense.
To determine the correct size of the secondary mirror, I'd simply have to draw a line from the ends of the primary mirror to the focal point, then draw in place where I'd be putting the secondary mirror and make sure the mirror is a little bigger than the drawing.
Maybe I'm wrong with all of this. I feel like I'm trying to re-invent the wheel because I couldn't find plain English how to design a Reflecting Telescope.
I'm sure you're wondering on how I plan on making the primary mirror. I'm currently working on building a metal foundry (I'm almost done with it), and I plan on casting a solid piece of aluminum and then polishing it into a mirror finish. It might not give me the sharpest image, but you can get a nice mirror finish with aluminum and this allows me to make a 6" primary, or maybe eventually a 24" primary. Really any size I want.
If you took the time to read this long post, please let me know if you find any flaws with my planning. Maybe I'm missing something. Maybe I'm wrong as to how to come up with the proper shape of the primary.
Any questions, certainly ask. I don't plan on actually building it until this fall.
I haven't been using this forum at all lately, but I think it's fitting to post this project on here.
Really I'm half checking that I'm not missing something before I put time and effort into building it. And when I was doing research, I couldn't find any good articles about it.
I want to build a reflecting telescope, and all the articles I've found on how to build one all assume that I'll be buying a primary mirror, and that I'd be basing my measurements off of what's specified for that mirror. Any other article I found trying to figure out what exact shape to make the primary mirror and best distances between the primary and the secondary where far too technical.
I hope to eventually write out an article and posting it onto the Flite Test main page, which hopefully doesn't go against their guidelines as it's not RC or plane related in any way. I want to write the article as easy to follow as possible. I know most people aren't going to be able to actually make one, but it's nice to see people do it.
The large concave mirror in the back of the telescope is called the "primary" mirror, because it's the mirror that's doing all the work of shrinking the image down. The 45(degree) angled small mirror is the "secondary" and is used simply to move the shrunk image into the eye piece.
I'm assuming that the further away the secondary is from the primary, the less distorted the image will be and also the smaller the secondary mirror is, and the less the secondary mirror is blocking the image.
I have no idea as to what the best balance is. How far away is too far, how close is too close, I haven't the faintest. I'd assume the further the two mirrors are away from each other the better, but making a 20' long telescope isn't practical.
I should draw, diagram, this out, but as far as I can figure, the best way to make the shape of the mirror is with a compass. To put one end of the compass right at where I want the focal point, and then use the other end to draw the arc that will be the mirror.
I'd actually want the focal point past the secondary mirror. So I wouldn't be making the focal point at where I'd be placing the secondary. I want the focal point to hit right at the "eye piece", which I'm actually going to be putting a camera. So I'd add the distance of the primary to the secondary with the distance of the secondary to the camera, and make that the distance away from the primary to the focal point. If that makes any sense.
To determine the correct size of the secondary mirror, I'd simply have to draw a line from the ends of the primary mirror to the focal point, then draw in place where I'd be putting the secondary mirror and make sure the mirror is a little bigger than the drawing.
Maybe I'm wrong with all of this. I feel like I'm trying to re-invent the wheel because I couldn't find plain English how to design a Reflecting Telescope.
I'm sure you're wondering on how I plan on making the primary mirror. I'm currently working on building a metal foundry (I'm almost done with it), and I plan on casting a solid piece of aluminum and then polishing it into a mirror finish. It might not give me the sharpest image, but you can get a nice mirror finish with aluminum and this allows me to make a 6" primary, or maybe eventually a 24" primary. Really any size I want.
If you took the time to read this long post, please let me know if you find any flaws with my planning. Maybe I'm missing something. Maybe I'm wrong as to how to come up with the proper shape of the primary.
Any questions, certainly ask. I don't plan on actually building it until this fall.