Negative ISO in 5d mark 2 ?

<p>Hello<br>

Please can someone tell me what does negative ISO mean ?<br>

Whats the different between shooting at ISO 100 and ISO -100 ?<br>

Thank you very much.</p>

<p>Hi there,<br>

I think something may have been lost in translation in an earlier thread. I think the reference to "negative ISO" was a joke, and that perhaps different cultural backgrounds caused this joke not to be realised. There is no such thing (to my knowledge) as a negative ISO - so I suggest you forget what I think was intended merely as a lighthearted comment.<br>

P.S. No - I was not the one who made this joke - merely trying to help!<br>

Ed</p>

<p>Light bulbs don't give off light, they suck up dark....</p>

<p>ISO 0 (zero) means an infinite amount of light needed to expose.</p>

<p>"Negative ISO" would mean even more than infinite amount of light is required.</p>

<p>(for 30x40 ft. commercial posters, ISO 25 ruled the day YEARS ago)</p>

<p>You can't have a negative ISO. </p>

<p>"You can't have a negative ISO."</p>

<p>Well, yeah, you can, but you'd have to be in a black hole to get it... :-)</p>

<p>ISO in this case denotes the sensitivity of the camera's sensor to light (let's not split hairs about base sensitivity versus signal amplification!). The higher the number, the greater the sensitivity. If ISO were 0, it would be totally insensitive to light. So a negative ISO would suggest that the sensor's sensitivity to light is than zero - i.e. it is even less sensitive than totally insensitive. What could that mean? That it actually destroys light? This is meaningless according to normal physics (since we don't live in a black hole)!<br>

I am sure someone will pick holes in this logic, but for all practical purposes, this is the situation.<br>

I repeat, camera ISO cannot be negative. It was a joke that someone made that happens to have been misunderstood!</p>

<p>haha! :) I went mad searching for it on google! I managed to confuse a top class photographer too! <br>

Thank you very much everyone for explaining it. </p>

<p>A negative ISO would mean that the sensor emits light. So this would be true for the LCD display on the back of the camera. The more negative the brighter the display ... ;-)</p>

<p>:)</p>

<p>Haha, this really got out of hand. My fault. I was referring to dry humor on my part in the earlier post.</p>

<blockquote>

<p>Light bulbs don't give off light, they suck up dark....</p>

</blockquote>

<p>That sounds like a Chuck Norris joke.</p>

<p><em>Chuck Norris doesn't to push-ups. He pushes the Earth DOWN.</em></p>

<p>:-)</p>