4/3 has no focal length advantage-correct him if he is wrong

Started Nov 15, 2008 | Discussions thread
Lobalobo Senior Member • Posts: 2,445
Re: higher sensor resolution (pixel density) gives focal length advantage

BJL wrote:

clevechan wrote:

A friend using Nikon FF told me recently that the E520 system I am using has no focal length advantage ...

Your E-510 has a clear focal length advantage over his 12MP 35mmFF
camera due to higher sensor resolution (lines per mm), which comes
from the higher pixel density so often disparaged by the likes of
Phil Askey.

If you photograph a scene filling your 10MP frame with the desired
subject matter and your friend then photographs it using the same
focal length, the desired image will fill only 1/4 of the area of his
35mmFF sensor, so after cropping to the same scene, he has only 3MP:
substantially less image detail.

And if he claims that the 3MP crop has enough resolution, the E-510
can get a 3MP cropped image with an even shorter focal length. The
bottom line is that for equally detailed images of the same subject,
a 12MP 35mmFF sensor needs almost twice the focal length as a 10MP
4/3 sensor.

To overcome the focal length disadvantage, a 35mmFF sensor would need
about four times the pixel count as 4/3: 40MP sensors to match 10MP
4/3 sensors, or about 50MP to match the new 12MP sensors of the E-30
and Panasonic G1. There has been no trend in this direction: instead
35mmFF has held fairly steady for over six years at only about twice
the maximum pixel count of 4/3, needing at least 1.4 times the focal
length for equal resolution of the same subject even after cropping
to equal pixel count.

-- hide signature --

What focal length disadvantage? Holding pixel count and image constant, larger focal length and larger sensor produces a better image (better dynamic range and color) than a smaller sensor and smaller focal length. (This is why Phil Askey disparages pixel density as I understand.) The only disadvantage of the full-frame sensor is cost and bulk.

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