camera angle-finder for DIY RACI finder mod

[DaveL59]

thought I'd kick off a topic which I'll add to as I progress, tho it could take a while to figure a few bits out. So I was thinking about modding a TAL 6x finder by cutting it back and fitting a diagonal and refitting the eyepiece just for comfort when using the scopes. But I really wasn't that keen on hacking down a nice finder if it was possible to avoid it. An alternative might just be one of these:

managed to land them both for £14-15 each off the bay, one a genuine Pentax unit the other an Ohnar Pentax fit. Notice the different pupil size? I wondered how that'd work and which might be better. I've removed the metal bracket that would normally be there to clip it onto the camera eyepiece, just to prevent any risk of scratching the finder lens and get a closer fit against the finder.

So, off outside and again the Pentax one seems to have a smaller pupil

not as easy to get a pic from the other end but pretty much the same result

yet looking through them into the finder, the Pentax one seems to give a better FoV with less crop. Both give a good image in daylight and vertically correct if still switched L-R. I notice the Ohnar one has a slight rattle - prism loose maybe, might check that later.

An image thru the Pentax one, slightly reduced Fov but not at all bad at first look.

 

And the Ohnar which was harder to not get blackout with tho one-handed ain't the best method. More crop of FoV than the Pentax, apologies, didn't take a shot thru the finder alone to compare.

 

Still, there's possibilities if I can figure a way to mount this onto the TAL finder. I'm thinking some plastic pipe that can clamp to the rear of the TAL finder body and hold the RA adaptor securely with some nylon thumbscrews, perhaps. For sure hanging it direct off the focuser part will just result in focus moving with the weight of the RA part. Would be nice to make an adaptor that the OEM clip could fit onto to make removal and install quick and easy, but might be a step too far given no 3D printer etc  

Also thinking the Ohnar one can be used for the polar scope as a slight loss of FoV may be a lot less of a problem there.

Anyways, will add more if/as I fiddle and have more to add

 

[DaveL59]

will have to try doing a better fixed setup to get a pic via the finder and both adaptors I think so I've a better comparison but for now I think there's possibilities. Quite like the idea of not cranking my neck to silly angles to use the finder on the bigger scopes. That is one of the nice features on the TAL-M, the finder is via the eyepiece so no odd angles needed to use it, just slide the finderscope into the focuser body and look as usual. Plus for some reason I've noticed that these days I get a bit giddy sometimes when twisting my head to look upward so will make things a lot easier on me if I can make this work.