Here are some shots of my self assembled RX80-L Refractor
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 !)
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.
My RX80-L Refractor
- harlequin2902
- Posts: 744
- Joined: Tue Sep 30, 2003 11:04 am
- Location: Singapore, Sengkang
My RX80-L Refractor
Samuel Ng
Re: My RX80-L Refractor
Very cool. Nice to know someone is putting a refractor together. Before you know it, you could be selling some of these.....harlequin2902 wrote:Here are some shots of my self assembled RX80-L Refractor
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 !)
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.
-
- Posts: 293
- Joined: Sun Oct 05, 2003 6:54 pm
- zong
- Administrator
- Posts: 621
- Joined: Thu Oct 02, 2003 9:41 pm
- Favourite scope: 1x7 binoculars (my eyes)
- Location: Toa Payoh
- Contact:
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.
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.
- harlequin2902
- Posts: 744
- Joined: Tue Sep 30, 2003 11:04 am
- Location: Singapore, Sengkang
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.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.
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
-
- Posts: 293
- Joined: Sun Oct 05, 2003 6:54 pm
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.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.
-
- Posts: 293
- Joined: Sun Oct 05, 2003 6:54 pm
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?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.
Kay Heem
- harlequin2902
- Posts: 744
- Joined: Tue Sep 30, 2003 11:04 am
- Location: Singapore, Sengkang
- harlequin2902
- Posts: 744
- Joined: Tue Sep 30, 2003 11:04 am
- Location: Singapore, Sengkang