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Originally posted by Duckear:

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Originally posted by jorge:

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Originally posted by stomper:
sorry to beat a dead horse but I think what he may be asking is which scopes appear brighter in low light. and yes ALL scopes "gather" light. They do so via their aperature. If you build a radar and use it to make pictures you do so via methods of Synthetic Aperature Radar. that's where the velocity of the plane is used as the aperature to make more radiation available for capture. The more radiation the higher quality your image is. this is how israli f16's will fly in Israeli air space and paint pictures of the neighboring countries and then use the SAR to relay coordinates to the onboard jdam in order to deliver the payload to the front door. we put the same design into the UAE's block 70 f'16's that we sent them but those were fixed aperature radar which was a whole new beast. I could get into the f22 stealth raptor radar but that one is really complicated and not up for discussion. If you simplify all this down to a scope the aperature of a scope is its objective diameter. the larger the diameter the more light that gets in. the more light that gets in the brighter your image appears. Saeed is right in that you can't amplify light without night optics but the larger your objective diameter the more light you are able to use which allows you to see better in low light scenes. So if you plan on magnifying the picture you need a lens diameter exponentially increasing with your power magnification. basically the picture in swaros appear brighter because you are able to see at 100 yards with the clarity you can see with your own eyes at 10 yards. Most optics cant focus light well enough to have useful zoom powers due to poor lens structures. So your definition of "light gathering" is what is at question here. However for an optics guy the whole ball game is built around "light gathering" the real trick is to be able to operate at the 3db point which is where your optics are able to pull useful information out of complete noise. Some scientists are getting quite good at this.

WRONG. To "gather" is to actively execute a function and a scope doesn't go out and "gather" light you for example "gather" flowers. Scopes ALLOW (passively) the transmission of light first through their objective lenses, through the tube, ocular lens through your pupil, optic nerve, brain etc. No gathering involved, just transmission.

Quick, call Zeiss!!!!!

http://www.zeiss.com/de/bino/g...9/Index/?ReadForm&71

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Geometric light gathering power
Geometric light gathering power is a measure of the image brightness provided. It is calculated as the "square of the exit pupil". For instance, a 10x40 binocular has a geometric light gathering power of 16 - the minimum figure for sufficient image brightness in twilight - and a 8x56 binocular a figure of 49. A comparison: An 8x30 binocular has a geometric light gathering power of 14.1 and thus is less suitable for viewing in twilight.
Note: The geometric light gathering power is only one parameter among many, it does not say anything about the image quality which is a determining factor in image brightness!