Pimp my finderscope - a flocking post.

[The Thing]

Hi everyone, been reading up on flocking and will get round to doing my LX90 8" SCT when I have received the flocking paper. This experiment has convinced me it will be worthwhile, the finderscope has the same black paint finish internally - read on.

I have been having fun with my Meade 8x50 Finderscope, which I haven't used for years as it makes my neck hurt to twist to use it. So I've sawn off the end   and stuck my modified SPC900NC (SC1/mono) on it. Result - wizzy electronic finderscope.



But I noticed there was a distinct lack of contrast, so I've flocked the finderscope.
I used the black lining material from old CD sleeves that used to come with my Microsoft Developers Network subscription. I left the plastic on one side to make the material stiff.


Here are before and after images. The birdbox is about 15 meters away and it's bright.


And here is the inside of the OTA. In the flocked version you can hardly see the CCD showing a lot less light is being reflected down the OTA.

[Mike]

How did you stop the inside from filling up with dust whilst doing it?

[Carole]

Wow, fancy finderscope.

Carole

[The Thing]

Dust? After sawing off the 2.5cm required to get the webcam to focus I washed the tube with soap and water! The flocking material is made to 'absorb' dust to stop CDs getting scratched, it has a distinct texture. I blew off any visible dust before it went in to the OTA.

One thing that made mounting the webcam possible that I should have included in the main post - I used a Moonfish adapter ring that converts their 30mm 2" EP to a t-thread so you can use cameras afocally (for some reason I have two). It fitted very snuggly in the Meade OTA! I will have to add three self tapping screws to make it fully secure.

Can't wait to try it in the dark. The idea came from an on-line article by a guy who's using one as his guidescope for his C11, there are many similar articles.

[The Thing]

Wow, fancy finderscope.

Yeah, no more neck contortion!

[Mike]

I'm wondering if a direct feed from something like this to a small, lets say 5", LCD screen, attached to a leg of the tripod, would eliminate neck pain for using finderscopes. The camera would need to be either very sensitive or do on-the-fly integration. A very low lux security camera should do the trick.

[The Thing]

New project Mike? It's got to happen, it'll either be you of someone in China. If you wear glasses pressing a lens to an eyepiece is not ideal.

Ideally you would want a small device that could be clamped to an existing finderscope EP to use afocally. You could add a 'red light' feature as well to preserve dark adaptation.

[RobertM]

Mine isn't quite as neat as that as I use plastic drainpipe to hold the SX guider but it does work really well.  The field of view is very large even with a guide camera chip.

I know of people using 50mm guider with up to 1500mm main scopes so I'll be interested to see your results with the LX.

Robert

[The Thing]

I have just received the flocking material. I went for the Edmunds Optics offering as the sheets are big enough for one to do the 8" OTA and they are very quick to deliver.

I hope to have time to install the material before the weekend. I will post before and after comparative shots FYI.

[The Thing]

I have now flocked my 8" LX90 OTA. It's looking good. I cut the material into two pieces that fit between the mirror cell casting and the corrector plate casting which provided nice edges to line the material up on. There is a 1 cm overlap on the joins. I also lined the inside of the secondary holder.

The reflection of the colour of the coated corrector plate is gone in the second image as is the other reflections. The original paint wasn't very light absorbent. Hopefully this will increase image contrast (always a problem with SCTs).

Before:


After:


I flocked my SkyWatcher AT80 while I was at it! I have a complete sheet of material left over.

[Mac]

flocking hell, that looks good.
Was it easy to get the front cell off?

Mac.

[The Thing]

Easy if your careful. I use a plastic tool to prise up the corrector plate while holding onto the secondary holder. I have a stiff paper disk cut out to slip over the draw tube and protect the primary while the corrector is off. You don't need to remove the front cell.

If you've never done it, the corrector plate will be a bit difficult to lift off the cork gasket. Mark the corrector plate first, I have a tippex patch with a pen line to mark the orientation on the corrector plate and on the supporting ring. If you take off the secondary for cleaning the corrector plate (the shield part around the mirror unscrews), mark it and on the corrector plate (there is an area covered by the secondary holder) in the same way. Don't lose the gaskets. The secondary holder moves around in its hole, not a good fit but allows for expansion, try to make sure its centred when you put it back! Mine was very loose the first time I took it apart, made collimation impossible.