more pixels are better!

Started Dec 14, 2008 | Discussions thread
bobn2
bobn2 Forum Pro • Posts: 70,344
Re: Are those figures for "print" or "screen"? (nt)

Les Olson wrote:

Iforgetwhat8was4 wrote:

The OP is really more interested in whether a 6Mp compact will be a
better all around performer than a 12Mp compact, or if this is just
an artifact of other design choices made that reviewers don't like.
In particular, what are the theoretical and practical limits in IQ if
you downsize to 6Mp?

The only downside of fewer MPs is that you cannot print as big at
high resolution. 6MP allows you to make a 10 x 8 print at 270 dpi,
and for ordinary purposes (a print framed behind glass and displayed
in living room light and viewed from a meter or two) 270 dpi is
plenty. So it is uncontroversially true that a 6MP compact will not
be a worse performer than an otherwise identical 12MP compact
unless you want to make very large prints. On the other hand,
there is no such thing as otherwise identical 6MP and 12MP compacts,
and if a 6MP compact had a less good lens that a 12MP compact it's
images might be visibly worse, despite the advantages of bigger
pixels. The excellent advice to pay no attention to MPs cuts both
ways!

The major downside of lower MP is lower image contrast at frequencies approaching the output Nyquist. This is because the final downsampled MTF of a sensor/OLPF which is effectively oversampling the final image is much more benign than one designed to cut off precisely (or, because of practical considerations, imprecisely) at the output nyquist referred back to the sensor (or 'printed native' in popular parlance).

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Bob

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