Laser Finder - minimum power?

[kmk]

Hello. I am in Queensland. I would like to add a laser finder to my telescope.

What is the minimum power I would need for rural skies?

Is 1mW enough?

In red or only green?

What do you need for an urban sky?

Thank you.

[bojan]

The laser finder is good, but VERY inconsiderate tool.
Just imagine, your friend in the same area is imaging while you are playing with this "toy".. possibly destroying their whole evening effort without being aware if it.

Yes, green laser, 1mW is enough to achieve all of this above.. and it could be illegal (in VIC it is treated as a weapon, and requires registration and license)

You should consider red dot finder instead.
http://www.ebay.com.au/sch/i.html?_o...inder&_sacat=0

They work OK (similar to laser - no magnification), and the mark is visible only to user.

[N1 (Mirko)]

Yep get an RDF. I've never understood what a laser can do better than a red dot finder when it comes to finding things by yourself.

If you must use a laser (e.g. because you want your friends to find your target at the same time), just use a bog standard hand held green laser & shine it through the eyepiece or optical finder. It will show the exact direction your telescope is pointing.

[kmk]

Hello.

Originally Posted by bojan

The laser finder is good, but VERY inconsiderate tool.
Just imagine, your friend in the same area is imaging while you are playing with this "toy".. possibly destroying their whole evening effort without being aware if it.

You don't explain how far away from me it would be a problem - how far is 'the same area'?
I live in a rural area and gaze by myself in my paddock. If I were ever with other people with telescopes or cameras, I would ask if they were imaging - I am not stupid. If it were only a few people, they could probably even tell me when they are in between shots.

Originally Posted by bojan

Yes, green laser, 1mW is enough to achieve all of this above.. and it could be illegal (in VIC it is treated as a weapon, and requires registration and license)

As I posted above; I am in Queensland. And I have already researched the current legality nationwide. You are incorrect. - It is lasers greater than 1mW. And it is New South Wales that issues permits, (however members of a recognised astronomical society are exempt). In Queensland you can have greater than 1mW if you have a reasonable excuse - such as astronomy.

Originally Posted by bojan

You should consider red dot finder instead.
http://www.ebay.com.au/sch/i.html?_o...inder&_sacat=0
They work OK (similar to laser - no magnification), and the mark is visible only to user.

Originally Posted by N1

Yep get an RDF. I've never understood what a laser can do better than a red dot finder when it comes to finding things by yourself.

Thank you for the suggestion. Is using a rdf similar to a finderscope? - They look like you must look through the lens and therefore be often craning your back and neck? That's one of the main reasons I am sick of my finderscope.

Originally Posted by N1

If you must use a laser (e.g. because you want your friends to find your target at the same time), just use a bog standard hand held green laser & shine it through the eyepiece or optical finder. It will show the exact direction your telescope is pointing.

How do I hold and shine a laser through either of those while adjusting my alt azimuth mount across two planes?

[N1 (Mirko)]

Hi,

I think both replies you got earlier were based on the information you had provided, not the fact that anyone may think that you are "stupid".
Anyway to the forum.

1mW may or may not be enough for your purposes, depending on how clear the air is above your paddock. It's a bit low compared to what we use in outreach. The wattage will also determine how far away from you the laser might be a problem to others. If your property is big enough, and no other stargazers nearby then it's probably a non issue. Change your site (your questions suggest you are considering at least 2 sites), and things may change there. At the low power end, the beam may be less obvious in light polluted skies. But others on here may be able to elaborate.

Re holding it to the eyepiece, many AltAz mounts and all dob mounts allow the scope to be moved by the tube or guide handle, using one hand and moving in both planes at the same time - yours isn't among them it appears. I assumed it was. My mistake, see first paragraph in this post. So the suggested method may not work for you...

Yes, RDFs work similarly to finderscopes but allow a bit more freedom as to eye placement as they don't magnify and don't have an optical tube (in the traditional sense) to peer through. Worth a try perhaps, as might be a finder whose eyepiece angle is 90° from what you use now. That could make a big difference.

[doppler (Rick)]

A word of caution, do not try and import a laser greater than 1mw as they are a customs restricted import, and you will not get a laser but instead a nasty letter warning you not to attempt this again. In Qld you can (legally) own a laser up to 20mw, if you are a member of a recognised astronomy club, and if you want to import one you will have to fill out a lot of paper work and wait a couple of months to get approved by police and customs. If you have a QLD firearms licence you can have a laser (sight) up to 10mw.

It is perfectly legal to import the parts to assemble your own laser, as long as they don't come in the same package.

Even a high powered laser becomes invisible when viewed side on after only a short distance. The beams intensity is directed straight forward for many kilometers but as it is only about 1mm wide it is not bright side on. Green is the only one to get you will need to get at least a 250mw red laser before you will see a beam at all.

[The_bluester (Paul)]

An RDF or similar is generally easier to use than a finderscope, I am just about to get one for my scope as sick of craning my neck. They are generally more convenient as you do not have the eye relief problem that comes with a finderscope. You can be back away from them a bit and eye position is not so critical.

[barx1963 (Malcolm)]

I used to use a 10Mw laser and worked OK but now only use red dot finders. Main reason is that most star parties don't allow lasers so having to switch to a RDF was a pain so best to just use one and get used to it. Other reason is that the lasers really hate cold!! Once temp drops below 10 degrees C they start to play up and become more trouble than they are worth.

Really the only advantage is you don't have to crane your neck with them, but it is really not that much of a benefit to outweigh the disadvantages.

Malcolm