2438mm Prime focus.

Grandpa Ron

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Twenty years ago I built a simple Newtonian Reflector telescope. Since then light pollution has crept into my dark skies. But tonight the moon was bright and Saturn was near by.

My camera body mounts to the eye piece but he geometry of the scope requires fitting a 2x Barlow lens to achieve focus. So if my math is right, the 48" focal length of the scope mirror, x2 from the Barlow lens gives me a 96 inch effective focal length Prime focus lens. or 2438mm.

Turning it to the moon, I found the image to be larger than my Canon's field of view.
Moon 2x.JPG


Next I moved over to Saturn, a lot smaller and dimmer but still doable. You just have to love those manual setting of a digital camera.
Saturn 1 Prime x2.JPG
 
Impressed you can see Saturn's rings. Nice moon image too.
 
Impressive detail for older equipment.
 
Wow, nice lunar close-up. Saturn looks impressive too. Can we see a photo of your DIY telescope with camera mounted.
 
Nice. Will never forget the first time I saw Saturn in a telescope. I was breathless.
 
Where is what I did.
I had been playing with a hardware store refractor telescope the kids bought grandpa for Christmas. In 2000 I bought a 6" first surface telescope mirror, a diagonal mirror, a lens focusing mount, and some plywood. I then search the web for plans for a Dobson mounted Newtonian telescope.

I built this telescope.

1 Scope 1.jpg


Recently I decided to try digital photos so I bought a camera/telescope adapter, which connects the camera to the eyepiece. it was on ebay for less that $20.00.
2 Camera mount.jpg


As you can see the lens mount had very little adjustment for focus. (less that 2 inches) Telescope are focused at infinity so they only need enough adjustment to allow for lens and a few other attachments.

This is what the adapter looks like on the camera. These are the component parts. Flange with "T" ring camera lens mount, lens tube reducer and 2x lens barrowed from a Barlow.

3 Adapter.jpg 4 Assem.jpg

If the lens holder flange had been about an inch shorter I would not have needed the Barlow lens.

This is a fun project for me but serious astro-photographers would use a CCD detector coupled directly to a monitor. Of course they would not have stared with a home brewed telescope. But that is a tale for another day.

I hope this helps.
 
Impressive! Those results must be very satisfying. I would be proud.
I am struck by the similarities of this and macro. Both are worlds that surround us, but the average person never really sees them or pays much attention to.
 
Twenty years ago I built a simple Newtonian Reflector telescope. Since then light pollution has crept into my dark skies. But tonight the moon was bright and Saturn was near by.

My camera body mounts to the eye piece but he geometry of the scope requires fitting a 2x Barlow lens to achieve focus. So if my math is right, the 48" focal length of the scope mirror, x2 from the Barlow lens gives me a 96 inch effective focal length Prime focus lens. or 2438mm.
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cool
moon by c w, on Flickr
 

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