newbie question: 8mw vs. 5mw green lasers

http://cgi.ebay.com/ASTRONOMY-GREEN-LASER-POINTER-PEN-8mw-532nm-BRIGHT-BEAM_W0QQitemZ330052235287QQihZ014QQcategoryZ94882QQtcZphotoQQcmdZViewItem

As there is a significant magnitude difference between the numbers 8 and 5, i'd assume that 8mw green lasers are significantly stronger than their 5mw relatives. or is this a misconception?

have any of you had any experience with this?
because there's quite a few green lasers being sold as 8mw on ebay now and i was debating between choosing this over a 5mw one.

thanks in advance!

"Winners don't use eBay lasers."
(Insert 3 credits to play!)

Stay away from eBay lasers. They're usually low quality, low power, or lack an IR filter, which is dangerous.

Try Arnold Beland's www.atlasnova.com (CPF handle abeland) for great bang for the buck, or look into CPFer FNinjaP90's PGL sales thread, or try www.wickedlasers.com or www.dragonlasers.com.

My first few posts at CPF were also "should I buy this laser." Welcome to CPF!

thanks for the heads up!

how does the 8mw power rating realistically compare up to a 5mw though?

Lets say this:


I bought 1 just to see how it worked. It was DOA. When I opened it up, it was a hunk of crap - VERY low quality compared to leadlight, etc.

I'd say STAY AWAY (when it was working, it was TEM-shifting on me, and it was about 3mw)

If both lasers were operating at there rated output (5mW and 8mW), you would likely not be able to tell the two apart honestly. Aprox 4 times the power will give you about twice the aparent brightness though this usually doesn't seem to follow this until about 20mW or so. Either way you would need somewhere around 15mW to really notice any difference, even a 10mW will seem only a tad brighter then a 5mW.

If you haven't used a green laser before, you'll most likely be really disappointed by anything under 10mw. Your naked eye won't be able to really tell the difference between 5mw and 8mw.

thanks for the warnings. i guess this is sort of a gamble then, hmm.

i recall reading a thread here where someone said that 5mw was good enough for star-pointing on a dark night. hell, i'm often impressed by the glow of some red laser pointer pens on fresh batteries. i'm sure most of you think this is like medieval and ignorant of me, but i've never seen a greenie in my life so really don't have any idea of what to expect really, other than something brighter than red lasers.

I too have heard that 5mw is the best, as anything higher will just be too bright to really enjoy the stars. Please note that the green lasers only appear brighter in comparison to a similar output red laser because of the way our eyes sense light. Feel free to correct me if I am wrong but I think the optimum frequency for cones is like 500nm and for rods is around 560nm, I might have the numbers backwards. Anyways, because these frequencies are a lot closer to green than red, the green laser appears brighter.

either i lucked out, or you laserheads are way too critical of green lasers. i don't know what standards you guys are measuring up to, but they must be pretty damn high up there.

i've just recieved my 8mW secret weapon in the mail today. was initailally disapointed by two recharchable AAA batteries, but the alkalinees did the trick. Extremely well.

this thing is like a Blaster gun, beaming it onto the white walls of my room lights the whole room up. and under darkness outside, it works perfectly as a star-pointer for others standing nearby. the beam is visable in darkness, especially against a darkned night sky. i wouldn't want it to be too visable, so this is just perfect for what i had in mind. and a feature i like about it is the initial burst. everytime i trigger it the first 1/4 second is a slightly brighter flash, lights up the place a bit brighter..

anyways, i became aware of the issue of these cheapies lacking infra-red filters. and this thing is bright enough that it's unpleasant to look at it when beamed on a white surface. so i'm guessing the infra-red might be hazard.


so until i can find a way to put an infrared filter on this thing, i'm going to treat this thing like a firearm (don't use indoors).

waterwings said:

so until i can find a way to put an infrared filter on this thing, i'm going to treat this thing like a firearm (don't use indoors).

Click to expand...

Even with an IR filter you should treat it as a firearm. Well, maybe use it more than one but respect it like one also. :candle:

funny thing is, what motivated me to get this was the fun some friends and i have had climibing onto rooftops with red laser pointers.

when the new Nintendo video game system recently came out in november, and you had people literally camping out at night for their relaese we discovered how much confusion and fun a laser dot could create....

i'll be responsible though. this is a secret weapon, this is high technology i'd rather not have others know i possess! imagine how respected you'd be if you took one of these green lasers back before 1500. you'd be a wizard.

waterwings said:

imagine how respected you'd be if you took one of these green lasers back before 1500. you'd be a wizard.

Click to expand...

they would think your a witch and burn you at the stake

its best not to use them in a active public area especially around people you dont know.

Some number of years ago, I "lasered" the Westlake Mall Christmas tree lighting ceremony and the Bon Marche Star lighting ceremony in Seattle with a green laser after both failed to light when their switches were thrown, and the green spot buzzing around near the treetop and on the star were clearly visible on the nightly news later that evening.
Thankfully, they did not trace the green laser back to me.

I would like to remind everyone!, (yes, that means you too Craig... :tsk: ) of one of the rules of the laser forum:

"The discussion and/or promotion of any illegal activities in this forum will not be allowed. Moderating of this will be done on the side of caution and not necessarily by law. Members who repeatedly violate these rules risk permanent removal from the forums."

Translation? Just because you got away with it doesn't mean it's ok to discuss it. This might be taken as a suggestion to others who may not be as mature or "smart" as you that it's ok to do it if you can get away with it.

The rules of this forum are "stickied" at the top of the thread index. Please refresh your memories of them everyone!

TigerhawkT3 said:

"Winners don't use eBay lasers."
(Insert 3 credits to play!)

Stay away from eBay lasers. They're usually low quality, low power, or lack an IR filter, which is dangerous.

Try Arnold Beland's www.atlasnova.com (CPF handle abeland) for great bang for the buck, or look into CPFer FNinjaP90's PGL sales thread, or try www.wickedlasers.com or www.dragonlasers.com.

My first few posts at CPF were also "should I buy this laser." Welcome to CPF!

Click to expand...

For experimental purposes I purchased a cheapo eBay laser pointer. In this case, I wasn't so concerned about getting a useful item. Here's what I found.


Item # Item Title Qty. Price Subtotal
190040780297 Super Bright Green Laser Pointer 5mw 532nm - Silver 1 US $11.03 US $11.03


Subtotal: US $11.03
Shipping and handling via Standard Int'l Flat Rate Shipping: US $16.99
Shipping insurance (optional): US $1.50
Seller discounts (-) or charges (+):
US $0.00
Total: US $29.52


As you can see, shipping is rather high, but oh well - I think many eBay sellers do that, since the Final Value Fee doesn't include the shipping cost in the calculation.

I was expecting bad things, but the laser arrived promptly and put out more than 5mw of 532nm energy. There were a few shortcomings, such as bad plating on the end, the beam coming on weakly at first, then coming on strongly after a bit, no batteries, no case, and a lack of IR filter, but for 30 bucks what do you really want? Over half the energy emitted by this laser is IR energy (I used an IR passing filter to determine this) so maybe this isn't exactly the best laser from a safety point of view. On eBay, you can get what you paid for, but usually not much more.

It's better for people not experienced with purchasing lasers to go to some of the reputable sellers here rather than trying to get a deal off eBay. The cheap lasers really aren't so much of a bargain - it's better to spend a few extra bucks and get something you'll be happy with.