Revived project - Finderscope for my C11

[bojan]

Some time ago I was playing with idea to use old 60mm binocular objective for finder scope ( I don't remember where it came from, it was a long time ago)... Realization of this project was tricky because I didn't want to abuse (too much) my friend with machining...
So - today, I had some free time and decided to finish this.
I prepared:
- the lens in its tube
- 48mm OD Holman drain pipe from Bunnings and associated caps
- 3D printed rings (I did them 3 years ago, just in case...)

After 1 hour of planning and machining the finder scope is pretty much functional.

I still need to make the bracket which will fit onto C11, that will require a search through my junk in the shed...

[Tinderboxsky]

I like it. I am also a keen fan of re-purposing items.

[Saturnine]

Also like your work there, great to see people still DIY. I have made several finder scopes from old binocular objectives and the eyepieces, just glue in some crosshairs and an 90 deg correct image diagonal.

[bojan]

Well, we are armatures, right ;) ? and DIY is only part of this wonderful hobby. It is a pity it was not encouraged more.. maybe this is one of the reasons why prices for astro-equipment is so inflated...

Attached bellow is how the attachment to C11 finderscope base will look like.

[mswhin63]

Very nice project. I have a busted bino's and am still considering repairing them but has been a tricky endeavour. This has inspired me to consider it for another project.

Possibly right about the inflated price.

[bojan]

Rings are on...

[h0ughy]

Great project and the results are a quality product by the looks.

[Tinderboxsky]

Yes, a great looking outcome. I like the way you have added a “serial number” for it.

[bojan]

:lol:
This is temporary,I will spray it (white outside, black inside) later

[bojan]

Functional on C11... (~12x). I found a better fitting for eyepiece (from Russian binos)

Still to do:
- 3D print lens cover

- insert cross hairs (from optical fiber)
- attach RDF

[bojan]

RDF mounted (on aluminium flat bar 20x3mm, Aluminium Trade Centre)

[bojan]

Placing cross hairs..

Optical fiber is glued (one side only) with UV-curable glue ($5 on ebay).
Very delicate operation, with help of stereo microscope.

[Sunfish]

Great work. Very delicate.
What lenses did you use.?
I wonder if an old 135mm screw mount would work.

[bojan]

Ray, I am sure any old(er) telephoto it will be OK for this purpose (even for guiding).. however probably it will be heavier than this single Ø60mm/230mm doublet. (The Plössl eyepiece came from old russian binos).

[bojan]

In use tonight...

[LostInSp_ce]

Nice work all round but especially with the crosshairs. Don't forget to print a logo on the cap. It isn't official until it's branded. :)

[Sunfish]

Impressive Bojan. Much better than the celestron version if it was anything like mine. And double cross hairs.

Do you think this one will work as a guider?

The tubular part is just a few thick t2 adapters screwed together to get the focal plane distance of the old t2 screw mount lense.

[bojan]

Ray, most likely it will, I read people successfully used even 50mm lens.
As to my cross hairs.. it is single fiber. It only looks like double because of refraction of light (fiber acts as cylindrical lens).
However.. now you gave me a bug in my ear.. I will try to do double cross soon, I have enough fiber for couple of them.

[Sunfish]

Hi Bojan,

Thanks. The 135 lense works and as an auto guide scope. Focusing a little beyond infinity but maybe that helps.

Would be interesting to try and add your crosshairs.

[bojan]

When trying to observe the planets during daytime (and close to the Sun) it occurred to me it would be good to have lens lid at hand all the time, to prevent the damage inside (until now I didn't bother to cover the finder lens..).
So I designed and printed it.. It may need some refinement in the future (like spring loaded stop to prevent it falling back and covering the finder during aiming at objects), but most likely it will be OK as is.