Possible or mad?

[swlloyd3]

Ok so I had this thought, an idea for a telescope, a way to get more aperture for cheaper!

I think that it wont work as it seems to simple..... BUT I thought I would show my idea all the same....

Basically its two reflector telescopes joined together... The light is reflected from both into an eyepiece in order to gain the light from two telescopes instead of one...

Both telescopes eyepiece holes should be facing each other and in-between the two there is an extension piece that has two mirrors. One facing each telescope hole and further reflects the light at an angle into one eyepiece.

Problems I guess might be some form of double image?

Collimation would probably also be very difficult?

First attachment shows the basic idea.... but the actual extension piece that holds the two mirrors should be rotated 45 degrees away from the scopes... The second attachment shows how it would sit when viewing.

Anyway just wanted peoples opinions!

whether this design is flawed or otherwise!

Ste.

[brantuk]

Very possible - not mad at all - have a gander at this

http://stargazerslounge.com/diy-astronomer/104439-diy-16-binoscope.html

[barkis]

Your idea isn't new I'm afraid Ste.

Binocular scopes have been in use for many years now.

I've never looked through such an instrument, but I would like to very much. I can imagine a very pleasant experience.

Nothing to stop you making your own mind you.

Ron.

[swlloyd3]

That is awesome!!!!!!

although is there a reason for two eyepieces? and does that not just give equal amount of light to each eye and thus not double aperture or does it?

Would one eyepiece work?

[pete_l]

It's not really a binocular telescope, as there's only one eyepiece. If I've interpreted the diagram correctly, the light from both objectives is merged into a single image to be seen by a single eyeball.

That sounds a lot like interferometry to me

If so, then there will be interference patterns created if the light from each optical tube travels different distances to the eyepiece. If you could hold the whole thing VERY rigid, so there was no movement between the tubes and they were both kept at the same temperature so you didn't get any differential expansion then you might have a chance. However, the tolerance for movement is very small: smaller than a wavelength of light, so I don't think it would be practical for an amateur to do - especially if you want to put it on an astronomical mount.

[brantuk]

I've never looked through one either but I do use binoviewers with my Sct and it gives a wonderful 3D effect to the view cos the brain registers depth. I'd guess you might get a very sharp and contrasty view with a single ep - but it is only a guess

[swlloyd3]

@pete_l

Ok so two eyepieces are better then!

Does this actually increase the amount of light gathered though?

Ste.

[brantuk]

It's subjective really - depends what you like. Some people don't get on with binocular viewing but I love it. Before investing money in the project you need to confirm you can a. do it successfully and b. enjoy it.

I'd suggest trying a pair of binoviewers initially. For the single ep effect try an Ethos - I imagine that would be similar to what you're trying. Maybe someone at your local club can help - or visit a star party - bound to be everything you need there

[pete_l]

@pete_l

Ok so two eyepieces are better then!

Does this actually increase the amount of light gathered though?

Ste.

Yes, it doubles the amount of light. But that light isn't coherent, so it doesn't "add" together to make images twice as bright.

You can certainly use two eyepieces - one for each tube. You then have 2 telescopes sharing a single mount - as others have said a large pair of binoculars, which should give a very nice view.

[Cornelius Varley]

JMI binocular telescope

Peter

[FraserClarke]

The way you've drawn it wouldn't work, as you end up having an angle between the two images and hence a double image. However as people have pointed out, you just feed each telescope into it's own eyepiece and have a massive binocular -- very popular in some circles -- never tried one myself. You also have the slight advantage here that your eye/brain can do *some* of the image processing to compensate for mislaignments, and therefore slightly ease your tolerances on co-aligning the telescopes. There was a nice example of a binocular telescope on this forum a few months ago [edit, found the link; http://stargazerslounge.com/diy-astronomer/104439-diy-16-binoscope.html#post1437499] .

If you want to use multiple mirrors to feed a single focal plane (eyepiece), you need to be a bit more advanced. The mirrors all have to have the same optical axis, which means a normal parabolic mirror won't work. You either need to go to off-axis paraboloids (pricey) or spheres (need a clever optical design to make it work). You also have much tighter tolerances on alignment of the mirrors. You would get the gain in light gathering power you suggest, but the spatial resolution you'll get would just be equivilent to one of the individual mirrors (unless you control the mirror positions to ~100nm -- which you don't even want to think about!! ).

So your idea certainly isn't mad. In practice it has some problems to overcome, and it's almost certainly not a way of getting more aperture for less money

[swlloyd3]

Oh well looks like I will just have to save the pennies for an orion 50" monster

Ste.