6 ms·

Just to clarify, there’s no concentration of energy involved with the eclipse itself. The concentration involved is no different than setting a leaf on fire wit

Just to clarify, there’s no concentration of energy involved with the eclipse itself. The concentration involved is no different than setting a leaf on fire with a magnifying glass on a regular day. The sun isn’t a garden hose. Putting something in front of it doesn’t make the edges more intense.

Gracana 9y ago
> The concentration involved is no different than setting a leaf on fire with a magnifying glass on a regular day. That's what they're saying. Zooming in on the sun vs the sun happening to be in-frame.
- xsmasher 9y ago
  Are you saying zooming in on the sun makes damage more likely? Wouldn't zooming in spread the sun's energy across more of the sensor? Same energy, larger area = less intensity.
  - grahn 9y ago
    The irradiance is determined by the aperture, which is measured relative to the focal length. So with e.g. f/2 you get the same heating of a given area of the sensor regardless of the focal length (i.e. "zoom"). Put differently, longer lenses typically also have bigger absolute apertures, collecting incident light from a larger cross-section. This compensates for the fact that a given solid angle of incident light is spread over a larger area of the sensor.
resoluteteeth 9y ago
Dingaling is talking about the light being concentrated on certain areas of the sensor. Because the total/average brightness is low, the exposure ends up being much longer then at normal conditions, causing damage to the areas where the light is concentrated. Under normal conditions, the light will be less concentrated on certain spots, so even though there is much more light in total, the camera will choose an appropriate exposure that will prevent damage to the sensor.
- klodolph 9y ago
  You'd have to be incompetent to trust autoexposure during an eclipse.
mikeash 9y ago
There kind of is, because it's darker when the sun is partially covered, so you'll use a larger aperture or longer exposure than you would normally. This is also why it's more dangerous to look at the sun during an eclipse than it is normally: your iris opens wider during an eclipse because it's not as bright.
- nolok 9y ago
  I think you misunderstood his point, which was: there is no more energy coming from the sun at any given point during the eclipse than in a clear day. The sun isn't "sending" more energy on the path that aren't blocked, nor is the energy blocked going around the obstacle and concentrating on the areas still visibles. The reason for the damage is entirely due to the receiver behaving/being differently, be it your eyes or your camera, because they get tricked into thinking it's dark and they act like it, being much more receptive and then overwhelmed.
  - howlgram 9y ago
    "tricked into thinking it's dark" is kind of misleading, because it is in fact darker, but for some reason unknown to me there the energy from the sun harms you as much. I thought the issue with looking at its sun was its brightness, but i guess it isn't?
    - mikeash 9y ago
      The issue is how much light gets focused onto a small area of your retina. When the sun is partially eclipsed, the darkness makes your iris open up to let more light in. That then focuses more light from the visible part of the sun onto the same area of retina.
    - dungle6 9y ago
      No it's not the brightness per se. What you perceive as "brightness" is the intensity of the part of the spectrum that is visible to you. But plenty of the non-visible spectrum has physiological effects, the infrared and UV spectrum. Most of the acute damage from the eclipse and the sun to eyes is not from UV as commonly believed but from the intensity of infrared that your eyes don't detect as "bright" but will cook them right well. This is also why even relativlity low intensity infrared lasers are so dangerous.

Gracana 9y ago

> The concentration involved is no different than setting a leaf on fire with a magnifying glass on a regular day. That's what they're saying. Zooming in on the sun vs the sun happening to be in-frame.

xsmasher 9y ago
Are you saying zooming in on the sun makes damage more likely? Wouldn't zooming in spread the sun's energy across more of the sensor? Same energy, larger area = less intensity.
- grahn 9y ago
  The irradiance is determined by the aperture, which is measured relative to the focal length. So with e.g. f/2 you get the same heating of a given area of the sensor regardless of the focal length (i.e. "zoom"). Put differently, longer lenses typically also have bigger absolute apertures, collecting incident light from a larger cross-section. This compensates for the fact that a given solid angle of incident light is spread over a larger area of the sensor.

resoluteteeth 9y ago

Dingaling is talking about the light being concentrated on certain areas of the sensor. Because the total/average brightness is low, the exposure ends up being much longer then at normal conditions, causing damage to the areas where the light is concentrated. Under normal conditions, the light will be less concentrated on certain spots, so even though there is much more light in total, the camera will choose an appropriate exposure that will prevent damage to the sensor.

klodolph 9y ago
You'd have to be incompetent to trust autoexposure during an eclipse.

mikeash 9y ago

There kind of is, because it's darker when the sun is partially covered, so you'll use a larger aperture or longer exposure than you would normally. This is also why it's more dangerous to look at the sun during an eclipse than it is normally: your iris opens wider during an eclipse because it's not as bright.

nolok 9y ago
I think you misunderstood his point, which was: there is no more energy coming from the sun at any given point during the eclipse than in a clear day. The sun isn't "sending" more energy on the path that aren't blocked, nor is the energy blocked going around the obstacle and concentrating on the areas still visibles. The reason for the damage is entirely due to the receiver behaving/being differently, be it your eyes or your camera, because they get tricked into thinking it's dark and they act like it, being much more receptive and then overwhelmed.
- howlgram 9y ago
  "tricked into thinking it's dark" is kind of misleading, because it is in fact darker, but for some reason unknown to me there the energy from the sun harms you as much. I thought the issue with looking at its sun was its brightness, but i guess it isn't?
  - mikeash 9y ago
    The issue is how much light gets focused onto a small area of your retina. When the sun is partially eclipsed, the darkness makes your iris open up to let more light in. That then focuses more light from the visible part of the sun onto the same area of retina.
  - dungle6 9y ago
    No it's not the brightness per se. What you perceive as "brightness" is the intensity of the part of the spectrum that is visible to you. But plenty of the non-visible spectrum has physiological effects, the infrared and UV spectrum. Most of the acute damage from the eclipse and the sun to eyes is not from UV as commonly believed but from the intensity of infrared that your eyes don't detect as "bright" but will cook them right well. This is also why even relativlity low intensity infrared lasers are so dangerous.