I guess it depends what you want to use it for & the brightness the surrounding light pollution? At Terrey Hills, I sometimes hold a 10mW green laser against the OTA if I want to see where it's pointing if clouds are getting close or if I'm trying a manual slew to a bright star to focus.
I have seen people with (what seems) more power
I've also noticed not very complementary comments around using lasers at Terrey Hills, as people (including myself) have ended up with lines in their images from others shining lasers in the sky near the object they are capturing. Some think they should be banned if it keeps happening.
Power. A few sites suggest you need >=5mW - but note that specs on cheap lasers are evidently poorly controlled and typical initial powers are higher than the spec but also degrade over time and as they get hot with extended/continuous use. Degradation over life is mainly due lens degradation/soiling. While pretty reliable (from personal experience) - reliability evidently can be a problem. But at $10-15 not a real issue. Lots of places selling this stuff including eBay/Amazon - customs could/can be an issue. Just make sure you get the battery and charger with them.
Some extra notes: I have read (someplace, maybe forums) that you may need proof of membership. I don't think police have to just take your word and are empowered to confiscate the weapon if they are not convinced you are legally allowed to carry it. I carry proof of membership with the astro gear and laser.
I understand importing weapons without a permit is illegal and will be confiscated. I'm guessing a person succeeding in importing is just slipping through the net. I chose to buy from a licensed importer and I needed to show proof of membership before they would sell it (and I paid probably 5 to 10 times the cost but I know I'm all within the law)
Keep in mind that a laser pointer is a hand held battery operated. Outside that, such as say wired in a device as I understand is not covered as a weapon. (Re fact sheet link below and legislation)
I have seen people using wired green lasers and making their own box and mounting on the OTA. I understand this is legal both to import and to use them as it's not covered as a prohibitive weapon legislation - I was thinking of doing the same as I understand it's legal -- Way more powerful lasers (wired and not hand held) for say laser cutting in CNC machines are allowed (note I keep saying "understand" as if to remind a reader that it's just my layman interpretation of the information I've read and not legal advice)
Note 3 months membership from the NSW Police fact sheet: "Who is exempt from the requirement to obtain a permit? A member of an astronomical organisation approved by the Commissioner of Police for use of a laser pointer for activities associated with astronomy. A member means a person who is currently a member and has been a member for 3 months or more,”
And, if you are into 3D printing, you will find a bunch of code on Thingyverse for laser pointer holders
Some extra safety notes: (just because a safety reminder is important for people who are thinking of using a laser pointer) NEVER point it as anyone as they will blind Also not we sometimes get aircraft flying over or too the side of our Terrey Hills site with the occasional helicopter (police??) flying close by. No matter how legal you are, point at an aircraft and you will end up in discussions with the law (and with anyone that sees you doing something so dangerous)
I'm with MaxPower on using a red dot finder, though I have not owned a laser pointer before - I just have had others position theirs somewhere on my scope a couple of occasions for a quick check. I imagine though that because your laser pointer, to be legal, must have a temporary switch, you'll likely nudge the scope each time you use it. Whereas the red dot finder can be left on the whole night. I have mine piggy-backed on my finder scope.
Interest: Astrophotography, Dark Matter Black Holes etc Equipment: Celestron 8" Edge HD
Skywatcher Esprit 120mm APO Triplet Refractor
Skywatcher AZ EQ6 Pro mount
ZWO 1600mm pro cooled camera
EFW 5 Band filter wheel
ZWO ASI290MM mini guide camera
I must admit I really struggled at the beginning without a decent finderscope and when I finally got my Telrad I thought all my problems have been solved. Then my son bought me a good quality RDF and it did improve the whole situation even more. You just have to get into the routine of calibrating it every time though as they tend to have more variability from removing and replacing them than a Telrad. As I've gotten more into astrophotography I find I don't need either as I've taken up SGP which raises it again to another who level as it platesolves. Basically - more money equals less hassle in the field.
Celestron 8" Edge HD Skywatcher Esprit 120mm APO Triplet Refractor Skywatcher AZ EQ6 Pro mount ZWO 1600mm pro cooled camera EFW 5 Band filter wheel OAG through ZWO ASI290MM mini guide camera