ViewFinder mounted on my LX200 Piggy Back Platform with webcam and SLR Photolens.
Note: on the picture the LX200 piggy back rail was mounted on my Astro-3 mount: yes, I like to be able to use my equipment in multiple configurations.

Webcams are nice, but have one huge disadvantage: they lack a ViewFinder.
This is no problem at all when using the Webcam for its originally intended purpose, but when removing the original lens and replacing it with an SLR Photolens and use it for astrophotography you soon badly miss the ViewFinder.
Here is what I did.

My SLR Photolenses are mounted on a LX200 Piggy Back Platform on top of my LX200 10" f/10 telescope
Between the Piggy Back Platform and my scope I have my Witty slow motion adjuster
Aligning the SLR Photolens with my main scope is tough and takes up a lot of time, because I have to aim the SLR Photolens by a guessed aim at a bright star (I want the same one my main scope is already looking at) and then look at the preview screen on my laptop with the hope that the bright star is also there.
With short(er) focal length SLR Photolenses - which have a rather wide field of view - I usually can see the bright star, but with longer focal lengths this is hard and when the bright star is not showing on the preview screen I have to gamble in which direction to adjust: I am working in the blind.

But no more: I found a nice and cheap solution. Yep, I bought a toy scope !

I visited a temporary shop - we call them ' flying shops' - which for a short term use the space of vacated shop room (usually because the shop that used to be there has moved and the new regular shop is not yet there).
In that temporary shop I spotted an 'astronomic ground telescope'; costs Euro 17 only.
It came with a reasonable tripod, a diagonal, several eye pieces and even a Barlow .

I got intrigued and asked if I could unpack it and have a closer look.
No problem.

The optics of the OTA did not look too bad, but I was surprised by the quality of the small 'cigar-like' finder on a bracket: it even has cross hairs!
The OTA has found another owner, but I kept the finder (and for a good reason !!)

ViewFinder on piggy-back platform
The camera is clamped by the U-shaped aluminium bar, in which I drilled 2 extra holes and mounted 2 bolts to attach the ViewFinder.
Done !
When setting up I align webcam and ViewFinder by aiming at a bright source [not necessarily a star], after which I align the combo with the main scope, similar to aligning the finder of your scope with the main OTA (whereby my Witty is a great help).
Note: on the pictures the LX200 piggy back rail was mounted on my Astro-3 mount: yes, I like to be able to use my equipment in multiple configurations.