A reminder for some memebers as to what the F stop is all about.

Started Jan 26, 2014 | Discussions thread
Messier Object
Messier Object Veteran Member • Posts: 8,418
Re: To all who continue to accuse me of all kinds of photographic sins...

windsprite wrote:

gsergei wrote:

Or why the light meter doesn't care.

Hello, again.

Let me repeat my point:

Given the same light source conditions and ISO setting the illumination, measured in lumens, received by any size of sensor is equal across all formats (no Ifs , no buts) , when cameras are set to the same A , S, ISO values. So, in practical terms this means, that the illumination received by my tiny c7070 at 125/5.6 and ISO 100 is exactly the same as on the so called FF sensor camera set to the same values. This will result in the same picture brightness/darkness , subject to DR and noise differences.

Please, do not feed me things like "amount of light", "sensor area", "light power" , "bigger lens opening" etc. and try to operate , using known physical terms and concepts.

Here is the final word.

Sorry, but you do not get to decide what the "final word" is.

Please, do me a favor:

get hold of ANY light meter (be it a 40 year old analogue one, or a modern Sekonic) and look at it carefully and then tell me , where do you see "Canon FF" or "Olympus c2020" or Fujifilm X100s ??? And then prove me wrong.

One might say the same of a ruler. Why, then, is it acceptable to say 300mm on FT is equivalent to 600mm on FF?


And one might also ask why it is that  nation states, universities and mega-dollar consortia build huge telescopes with enormous imaging sensors.  
Each of the two Keck telescopes is FL=17,500mm f/1.75 . . .they know that the huge 10 metre aperture captures more photons.


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