Simple mount for laser pointer as a finder

[PeterAnderson]

The problem with SCT's is that it is difficult to sight along the tube and the finder eyepiece is often difficult to easily access. The idea I had is so simple that many others are probably doing this already and I have just re-invented the wheel (as it were).

I know what I want to look at and don't like using 'go-to' unless I have to. (Too slow) I suppose that comes from being an oldie...

With the C14 on an equatorial mount, I installed two of the standard 50 mm finders, one on either side at the 'top' of the tube, so one is generally in a moderately convenient position. With the CPC11, being altazimuth, I installed a 9X50 right angle finder (great for high in the sky) and tweaked it so the back end could easily rotate 90 degrees in the event of something near the horizon. - A couple of adhesive rubber pads act as a stopper so the prism unit just unscrews 90 degrees. (Otherwise I would have to get on a step to use the finder to line it up for low objects.)

What spurred me to think of this new method was that my new C9.25 ('portable' instrument) was lower than the C14 and C11. Since I don't bend like I used to, to enable me to squint up a finder would be a major effort. . It works very well. (see image) Pointing by the laser is accurate to well under a degree and I have always found it within the low power (X59) field. Once the object is in the low power field, just centre the image in the low power eyepiece using the hand controls. The laser is also great for sweeping across the sky to the vicinity of the object and then using the 'proper' finder (if you wish) to do the final job.
In Queensland anyway, astronomers are allowed to use lasers.

[MichaelSW]

Yes Peter, if you are a member of an Approved Organisation as per QPOL website:-

Approved Organisations

Pursuant to section 67 (5) of the Weapons Act 1990 details of recognised astronomical organisations are published as follows:

Astronomical Association of Queensland (AAQ)
Astronomy Connect Inc.
South East Queensland Astronomical Society
Townsville Astronomy Group Inc.​

Of course, other organisations might have done all the paperwork, been Approved by QPOL, but the website isn't updated as yet.

https://www.police.qld.gov.au/programs/weaponsLicensing/crgwc/arao.htm

[PeterAnderson]

Yes Michael, you are right. I should have been more precise with my 'throw away' line at the end and explained it further. Thanks setting this out.

Being an oldie my membership in astro societies dates back to the late 50's (1950's, not 1850's though sometimes it feels like it.) Yes, I am a member of the Astronomical Association of Queensland and have been involved in the astro society world for many years.

[RB]

Good one Peter, I love my laser too, so handy and it looks cool.

:)

[Meru]

Hi Peter, nice one! I have the same issue with my pointer (I just hold it against the tube and 'wing' it - really should try doing something better). I was going to say that if you wanted a proper holder, I 3D printed one earlier this year (link (http://www.iceinspace.com.au/forum/showthread.php?t=134985&page=2), post #23). I'm considering making one which slots into the finderscope holder or via magnets to the OTA. If you're interested let me know, would be something useful for all members that use pointers

[Allan_L]

Hi Peter, I know your pain from bending over for finder scopes.
I agree the laser is a good solution for you ...
but not so much if you are sharing the observing field with long exposure astrophotographers. (or so They tell me :( )

[PeterAnderson]

Hi Allan,
Very good advice about not using a laser in company when other people are imaging. I have not been guilty of this myself but have witnessed anguished howls from astrophotographers when this was done, swiftly followed by shouts... However I operate my scopes well away from the crowd - Here are a couple of images by a friend (Terry Cuttle) from an errant hot air balloon. They show my twin section roll off roof observatory on a ridge top back of Mt Coot-tha in Brisbane. One of my main problems is...you guessed it - trees and this is the reason I got the 9.25 inch so I could go to various spots outside the observatory (within our land) where I could get a good view of particular events/objects. The observatory is great east&west, which is my main area of interest but north is pretty poor - and some other angles can be a problem.

Thanks for the offer about 3D printing a holder,Meru, but this simple clip is amazing and easy to use with an instrument mounted on one of these rails. It holds the laser securely without movement. I have added a little padding adjustment to the rail and also discovered another easy adjustment because the laser alignment does not perfectly coincide with its tube. - Just rotate the laser a bit.

I posted this because the solution was so remarkably simple. Usually when you devise a simple solution, you have overlooked something, but this one looks okay, and so I thought I would share it.

Another point I would make is that these mounting rails might be used to attach other accessories, especially if you wanted to leave the telescope tube alone. Okay it would affect the fore/aft balance but it wouldn't reguire as much counterweighting as mounting it atop the telescope further away from the fulcrum. There are a whole lot of factors at play here and I don't want to do more than just flag it.

Peter.