Too many megapixels? Six is enough for an 8x10.

Started Apr 26, 2009 | Discussions thread
ejmartin Veteran Member • Posts: 6,274
Re: Nikon have some good examples

strawman_John wrote:

bobn2 wrote:

The D3 has been optimised for high ISO in three ways:
i) the sensor is unusually efficient in converting photons to
electrons. This is probably due to effective 100% microlenses.

It might also be due to the fact that with a larger surface area it
collects more photo's as well. Is that unusual, no it s a result of
the simple fact that bigger pixel area leads to a greater ability to
capture photons, its not difficult to grasp unless you have an
ilogical ability to not recognise the advantages of greater pixel
area.

The Panasonic LX3 records .106 electrons per raw level per square micron (e- µ^2 per raw level) at ISO 400 with 2µ pixels.

The Nikon D3 records .115 e- µ^2 per raw level at ISO 400 with 8.46µ pixels.

When properly looked at as densities of electrons per unit area rather than per pixel, a given patch of sensor of a given size records about the same number of photons (or photo-electrons) independent of the pixel size. That is because the photon sensitivity is a property of the semiconductor materials used, and doesn't care how the photosensitive surface is partitioned into pixel-sized bins. One 8.46µ pixel or 18 2µ pixels, it's the same area and the same number of photons collected, to a very good approximation.

As for well capacity,

The Panasonic LX3 saturation count at base ISO 80 is 2250 e- µ^2
The Nikon D3 saturation count at base ISO 200 is 920 e-
µ^2

Thus the D3 actually saturates at lower illumination than a rather good P&S. I think this supports Bob's contention that the D3 is optimized for high ISO.

(Note: the Nikon data are due to measurements on RAW data taken and analyzed by Peter Facey; the LX3 data is my own analysis of RAW images taken by others according to my specifications)

I'm done replying to your posts in this thread. I think your forum name says it all.

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