My RX80-L Refractor

Wanna make a scope? Or better still, grind a mirror yourself. Or, you have some good tips in making a really useful accessory? This is the place to show what your hands can do...
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harlequin2902
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My RX80-L Refractor

Post by harlequin2902 »

Here are some shots of my self assembled RX80-L Refractor :D

It's an 80mm f/8.75 Achromat with a 2" R&P focuser.

The OTA is made out of a PVC tube, but I spray painted it (including the blue coloured dew shield that came with the lens cell) in Ivory to make it look a little nicer. And while posting these pics, I just realized that I should have taken some 'before' shots of everything too.....will remember to do that for the next project (127mm f/10 !)

Image

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:lol: :lol: :lol:

It's really fun to put your own scope together !

Will be testing it outdoors when I receive the tube rings I've ordered for it.
Samuel Ng
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VinSnr
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Re: My RX80-L Refractor

Post by VinSnr »

harlequin2902 wrote:Here are some shots of my self assembled RX80-L Refractor :D

It's an 80mm f/8.75 Achromat with a 2" R&P focuser.

The OTA is made out of a PVC tube, but I spray painted it (including the blue coloured dew shield that came with the lens cell) in Ivory to make it look a little nicer. And while posting these pics, I just realized that I should have taken some 'before' shots of everything too.....will remember to do that for the next project (127mm f/10 !)

Image

Image

Image
:lol: :lol: :lol:

It's really fun to put your own scope together !

Will be testing it outdoors when I receive the tube rings I've ordered for it.
Very cool. Nice to know someone is putting a refractor together. Before you know it, you could be selling some of these.....
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ChaosKnight
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Post by ChaosKnight »

Nice telescope! But why PVC for the tube? PVC is a polymer, it flexes easily, especially if the diameter is small and the lens/focuser are heavy. Any optical advantage from diffraction limited, achromatic lenses will be gone.
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zong
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Post by zong »

Hi, although I don't have experience at all in scope assembly and making, I may be able to answer on behalf of samuel. :)

PVC is the easiest to get for the casing for a telescope (right?). So it is actually a great inexpensive way to make the scope tube. Also, not all polymers flex easily, they can be made to take great weight. The lenses are light enough to fit in I suppose. And it is a (relatively) short tube, which means it takes far more weight to bend than a long tube. You can try on your PVC pipes at home, it actually takes quite a lot of weight, far more than that of the lenses, to bend it by just a little bit!

I don't really understand what you mean by limited optical advantage, achromatic lenses only try to solve CA, and it's more of the property of the lens and its coating than the pipe that characterises what optics standard is gotten.

I've seen the scope (real life), it's done really nicely! And it isn't heavy at all, not weight that might bend the pipe by even less than 1 mm.
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harlequin2902
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Post by harlequin2902 »

Nice telescope! But why PVC for the tube? PVC is a polymer, it flexes easily, especially if the diameter is small and the lens/focuser are heavy. Any optical advantage from diffraction limited, achromatic lenses will be gone.
The choice for PVC was, as Zong Yao had said - convenience, especially this is also my very first telescope project, and a rather low cost one too. I just wanted to try out what it would be like to put the lens cell at one end, the focuser through the other and see how it will work. I didn't even bother to blacken the interior for this one.

Maybe for my next project : likely a 127mm achro (or even an 80mm ED if my supplier still has those ED objectives), I will be looking at a proper aluminium tube for it's body.
Samuel Ng
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ChaosKnight
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Post by ChaosKnight »

zong wrote:
I don't really understand what you mean by limited optical advantage, achromatic lenses only try to solve CA, and it's more of the property of the lens and its coating than the pipe that characterises what optics standard is gotten.

I've seen the scope (real life), it's done really nicely! And it isn't heavy at all, not weight that might bend the pipe by even less than 1 mm.
That's the problem. I've seen achromat lenses (for electronics) that can focus light where the error at the wavefront is 1/18 wave. Or for less expensive, optical lenses, 1/4 wave. If your tube flexes by even a tiny little bit, most likely your optics will already be out of alignment.
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ChaosKnight
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Post by ChaosKnight »

Samuel, if you're doing your next telescope, can i help?? i would like the experience, and i got a little experience in machining.
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kayheem
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Post by kayheem »

ChaosKnight wrote:Samuel, if you're doing your next telescope, can i help?? i would like the experience, and i got a little experience in machining.
Sam, you may remember our experience with the ED lens. It would be good to machine a tube to realize the lens' full potential. Is the lens cell collimatable?

Kay Heem
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harlequin2902
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Post by harlequin2902 »

Sam, you may remember our experience with the ED lens. It would be good to machine a tube to realize the lens' full potential. Is the lens cell collimatable?

Kay Heem
The lens cell is not collimatable, but a new 2" diagonal from Antares is.
I wonder if that will help ?
Samuel Ng
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harlequin2902
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Post by harlequin2902 »

Samuel, if you're doing your next telescope, can i help?? i would like the experience, and i got a little experience in machining.
Hm, maybe for the 3rd one.

I would still like to be personally involved in everything for the 2nd :)
Samuel Ng
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