Just had a thought...
I have a right angle viewer (Olympus) and think with a suitable adaptor (3D printed??) it could easily be fitted to the eyepiece end of the polar scope to get around lying in the grass and trying to twiddle the adjustment knobs at the same time.
If the weather ever gives me the opportunity I'll try it out.
What are your thoughts????
Amusing you should mention this. Two thoughts come to mind.
My first thought is to shift the focal plane out far enough to put a star diagonal on the back of the polar scope then insert eyepiece as usual. Which entails shortening the polarscope tube. The reticle will have to be flipped or a roof prism diagonal used.
The other thought I had is why shove it up the polar axis, anyway. I can’t see any reason why it can’t be on a bracket that sits on top of the scope while you align it, then remove later. This would put it in a much more accessible place as well. I’m sure it would be possible to make a dingbat that fits the hole in the dec axis, and fits onto the tail of the polar axis and carries the polar scope on top.
If you follow this line of thought there’s no reason why it couldn’t be on the main scope provided you have a way of reliably setting the scope to -90 declination and there’s no cone error.
If you are into plastic 3D printing there’s another alternative.
1. Since the polarscope is small, remove it from the usual position completely
2. Fit a star diagonal in front of the objective folding the view by 90 degrees.
3. Make a dingbat that plugs into the hole on the dec axis and mounts the scope so that the star diagonal is facing the pole, with the polarscope sticking out sideways from the top of the dec axis which should be pretty convenient to view. As above have to flip the reticle.
Location: '34 South' Young Hilltops LGA, Australia
Posts: 1,481
I think Ken is referring to the type that you clip to the camera viewfinders, these have zoom magnification and are designed to look through another eyepiece. They are not just a mirror.
Provided you can mount it, it should work. They are a 1-3x telescope designed to look through another optical device. Try it during the day by just holding it. Anyone who wants one can also buy them on eBay for about $60.
Wavytones idea would also work fine. For best results you need an adjustable mount for the finder that can be locked off tight and immovable and something like two flat milled plates one attached to the mount, one to the finder, with 3 dowel pins as precise locators to precisely relocate the finder each time.
Joe yes I know - I had a Pentax one once, zoom of 1...2.5X and it fitted on the back of an old SLR I had. But from memory there was a lot of light lost - the image was pretty dim which suggests the placement of it with respect to the exit pupil of whatever is in front of it (ie the polariscope) is critical.
They're still around on eBay if you want to try one.
Yes, this gadget may be very useful.
However, $90 is a lot of money for something that is not used so often.
It has to be a low-magnification (very short focal length) telescope, with mirror - I think I have some suitable parts (I made one RA-viewer, for focussing some time ago but I don't use it any more - live view made it obsolete), and 3-D printed enclosure for small diagonal shouldn't be a problem to design.
Webcam is probably OK as an idea, but it may prove to be not sensitive enough (if not modified for long exposures). And I personally hate to many wires around...
I have done it a year ago. Get a piece of PVC plumbing tube fitting over the polar scope eyepiece and some double sided tape at Mitre10 or another hardware store. Total cost : a few $$.
My angle finder (Seagull from Ebay) has some extra camera eyepiece adapters provided of which I glued one to the PVC socket.
As for Seagull... take care, the FOV may prove to be an issue... Polar finder eyepiece is quite wide, while cameras viewfinders are generally more narrow.
BTW...
There is another possible approach to this.
The eyepiece of the polar finder could be removed (reticle stays where it was, of course), and the low-power microscope or just low power eyepiece (with 90° mirror or prism) could be used instead.
As for Seagull... take care, the FOV may prove to be an issue... Polar finder eyepiece is quite wide, while cameras viewfinders are generally more narrow.
Well, with the Vixen SP it works fine as I get the NP star Alpha UMi (40' off pole) in the field, and in the south it is even easier: I put BQ Oct in the center of the field because it is only 10' off pole. Sigma is too far, I use the 'trapezium' which contains Sigma (easily visible to the naked eye) to look up the +6.9 BQ.
Just found a plastic 35mm film cassette fits exactly over the end of the SW polar scope eyepiece.......
Cut about 15mm off the open end to give an even neater tight fit.
Last edited by Merlin66; 02-11-2017 at 11:56 AM.
Reason: typo
We used to sell the right angle illuminated polar finderscopes but they were eye-wateringly expensive to get even for us. (That, and I hate polarscopes. Or polar alignment. Or the fact that we don't have a "Southlaris".)
I've got a 3D printer so I will definitely try some of the things.
