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Old 10-20-2013, 12:58 PM #17
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Default Re: eye safety question

No. It doesn't matter if you have a huge objective lens or a smaller one. They're all doing the same thing: taking a field of view, and concentrating that light on a smaller area.

That's what magnification does.

It will always increase the power density with respect to what is being viewed (and therefore brightness) because -- fundamentally -- you're concentrating the same amount of light on a smaller amount of area. It doesn't matter if you're using a microscope, a telescope, or anything in between. It doesn't matter how large your objective lens is. They all work on the same principle.

The lens' aperture only determines how much light can be gathered. However, any magnification that is performed will always concentrate the power density (the figure of merit when it comes to safety) and therefore increasing the brightness. Unless your aperture is occluding parts of the light source you'll never be reducing the total power that your magnification system will receive.


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Old 10-20-2013, 11:54 PM #18
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Default Re: eye safety question

Okay, I found it. Google this phrase in quotes:

"the higher the magnification the dimmer the image"

I got 793 hits in web search, five in Google books. That's only for this exact wording. Not bad for 8 consecutive words in quotation marks.
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Old 10-21-2013, 08:15 AM #19
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Default Re: eye safety question

Quote:
Originally Posted by Bionic-Badger View Post
No. It doesn't matter if you have a huge objective lens or a smaller one. They're all doing the same thing: taking a field of view, and concentrating that light on a smaller area.

That's what magnification does.

It will always increase the power density with respect to what is being viewed (and therefore brightness) because -- fundamentally -- you're concentrating the same amount of light on a smaller amount of area. It doesn't matter if you're using a microscope, a telescope, or anything in between. It doesn't matter how large your objective lens is. They all work on the same principle.

The lens' aperture only determines how much light can be gathered. However, any magnification that is performed will always concentrate the power density (the figure of merit when it comes to safety) and therefore increasing the brightness. Unless your aperture is occluding parts of the light source you'll never be reducing the total power that your magnification system will receive.
you are wrong .
you can do a simple experiment - take a regular light bulb . look at it from close distance , then take a bino , and look at the same light bulb from a distance that shows the bulb at the same size .
does the brightness looks the same?
no.
without bino , the bulb will be much brighter.

this is due to lens aperture .
if you have a bino with very fast aperture lens , then yes , it can increase the brightness. but on most binos and telescopes the aperture is low.
as far as I know , only photography ad cinema lens come with wide apertures .
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Old 10-21-2013, 03:37 PM #20
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Default Re: eye safety question

SSS

You are the one who is WRONG. In collecting laser light, aperture size matters, period.

Let me ask you a simple question:

A upcollimated laser beam is sent across a lake as part of a laser show.
The beam is 1 meter in diameter. A person on a tower across the lake is in a point to be exposed to the beam. Which collects and delivers more energy to the retina, a 7 mm pupil or a 50 mm aperture of a pair of 7x50 binoculars ?

If the 50 mm aperture collects less energy, I'd really like to know that how energy magically disappears??? I could make a lot of money with developing optical stealth if that were the case. But stealth would no longer be needed, because in your world, antennas would stop working. Ants would no longer have fear of being burned by kids with magnifiers.

You, and whomever wrote the poorly defined binocular article, are confusing basics of ETENDUE and REFLECTION LOSS with CONSERVATION OF ENERGY.

The mere definition of a telesecope is to collect more energy.

HINT, 8 times more energy enters the eye with the 50 mm collection device then with the bare eye.

Otherwise why does FDA and OSHA require me to calculate laser safety with a 50 mm collector when exposed personnel are wearing glasses?

I've been at this a long time. I'm going to give you a few days to show me some math proving me wrong. I doubt you'll find it. Then I will do math showing I'm right.

I do this for a living. If I'm wrong, people get hurt.

Your about to learn that textbooks are not infallible.

Steve ILDA CERTIFIED LSO. CORPORATE ON SITE LSO FOR MY EMPLOYER.

Last edited by LSRFAQ; 10-21-2013 at 04:02 PM.
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Old 10-21-2013, 08:25 PM #21
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Default Re: eye safety question

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Originally Posted by sss View Post
you are wrong .
you can do a simple experiment - take a regular light bulb . look at it from close distance
Now...one thing that's makes me skeptical...

Who would look "at a close distance" to a Light Bulb? *Just Saying*
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Old 10-22-2013, 04:23 AM #22
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Default Re: eye safety question

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Originally Posted by LSRFAQ View Post
SSS

You are the one who is WRONG. In collecting laser light, aperture size matters, period.
lol
did you read the last paragraph of my last post?
this is exactly what i said . the aperture size controls the BRIGHTNESS , and magnification does not control brightness .
so for most binos , the aperture is narrow , no matter the magnification power ,so they DECREASE brightness due to narrow aperture .

of course , as i said earlier , if you have large aperture bino , then yes , you can increase the brightness , but those are uncommon .
most binos and telescopes use narrow aperture , around f/8 for telescopes with high magnification power .
some photo lenses use very wide aperture , like f/1.2 - f/2 and they increase brightness .
with high magnification optical device , like a telescope , its very hard to manufacture wide aperture , so most of the time they decrease brightness .
maybe the huge observatory telescopes have wide aperture , i dont know .


here is a good video comparing brightness with different aperture binos.
note that the magnification power stays the same .

Understanding Binoculars: Aperture - YouTube
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Old 10-22-2013, 12:09 PM #23
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Default Re: eye safety question

Quote:
Originally Posted by sss View Post
lol
did you read the last paragraph of my last post?
this is exactly what i said . the aperture size controls the BRIGHTNESS , and magnification does not control brightness .
so for most binos , the aperture is narrow , no matter the magnification power ,so they DECREASE brightness due to narrow aperture .

of course , as i said earlier , if you have large aperture bino , then yes , you can increase the brightness , but those are uncommon .
most binos and telescopes use narrow aperture , around f/8 for telescopes with high magnification power .
some photo lenses use very wide aperture , like f/1.2 - f/2 and they increase brightness .
with high magnification optical device , like a telescope , its very hard to manufacture wide aperture , so most of the time they decrease brightness .
maybe the huge observatory telescopes have wide aperture , i dont know .


here is a good video comparing brightness with different aperture binos.
note that the magnification power stays the same .

Understanding Binoculars: Aperture - YouTube
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Old 10-23-2013, 11:56 AM #24
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Default Re: eye safety question

I'm on the road for a week. When I get home this weekend
I'll shoot the pictures proving my point.

Steve
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Old 11-01-2013, 02:37 AM #25
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Default Re: eye safety question

Lets be realistic about this. Binoculars incease the amount of light captured by the eye. A typical set rated '10X50' would increase your exposure tenfold for any beam less than 5 cm radius.

Looking at a laser spot using such binoculars can be perfectly safe. The problem arises when the spot is not stationairy, and the source may airm the laser directly at you (perhaps by accident).

If that happens the binoculars would increase your exposure a hunderdfold (it goes with the square of XnY rating, X being the factor squared).

So sure, it is okay to look at the dot produced by your own laser through binoculars, as long as you can ensure that that laser dot is in a fixed position. If you are looking at a laser dot produced by someone else, never observe it with binoculars, unless it is someone you are working with that can guarantee that the laser will never be aimer directly at you.
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