Fast lenses, and High ISO

Started 3 months ago | Discussions thread
EinsteinsGhost
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Re: "the light"?
In reply to Great Bustard, 3 months ago

Great Bustard wrote:

EinsteinsGhost wrote:

Great Bustard wrote:

Albert Silver wrote:

tko wrote:

Remember that F4.0 is considered kind of slow on FF, but is equal to F2.0 on M43rds, which is considered "fast."

That's not entirely accurate. You are describing the depth of field equivalence, from one sensor to the next, not the light. f/2 on a m43rds may have the depth of field of f/4 on a full-frame, but the light will still be f/2.

What do you mean by "the light will still be f/2"? For a given scene luminance, shutter speed, and lens transmission, the density of light (exposure) projected on the sensor will be the same regardless of format, but not the total amount of light projected on the sensor.

Total light does not matter for correct exposure. It does not change the time value for which an exposure is made for a specific aperture value.

A competent mFT photographer with an EM10 + 12-40 / 2.8 shoots a scene at 25mm f/5.6 1/100 ISO 400. What settings would result

in the "correct exposure" if they had instead been using FF with a 6D + 24-70 / 2.8 VC?

For same exposure, any competent photographer would use f/5.6, 1/100 and ISO 400 on ANY format. This, of course assumes same shooting conditions, transmissive properties of the lens, and metering used in respective cameras.

So, in what way does the density of light falling on the sensor matter more than the total amount of light falling on the sensor?

The answer to the "correct exposure" question should make it easier to answer the question immediately above.

Only if you knew what "correct exposure" is. Can you quantify and describe it?

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