[meteorite-list] Iron Meteorite on Mars (Color Photo)

From: Darren Garrison <cynapse_at_meteoritecentral.com>
Date: Thu Jan 20 01:28:54 2005
Message-ID: <rgjuu09oajhuc5kqvrpcicg21n3buj38i8_at_4ax.com>

On Wed, 19 Jan 2005 23:08:45 -0700, "Chris Peterson" <clp_at_alumni.caltech.edu> wrote:

>Hi Darren-
>
>Replacing the Pancam sensor with, say, a 5MP array wouldn't yield better
>resolution. If the physical size of the sensor were larger, you would have a
>greater field of view. But even if the sensor had smaller pixels, the
>resolution wouldn't increase because the simple, three element f/20 lens of
>the camera has a spot size of 32um, twice the current pixel size. So packing
>in more pixels would just be empty resolution- there would be no real
>increase in the amount of information available. A blown up image from this
>5MP image would look the same as the image from the 1MP sensor after you
>resized it to 5MP.
>
>In this case, what we'd really like would be the ability of the Pancam to
>switch in a longer focal length lens. Maybe the next mission!
>

I must be misunderstanding something fundamentally here, then. My assumptions are:

1.) the optics are precise enough to focus enough photons on the CCD to provide a sharp image to the
CCD cells at the higher pixel density

2.) the CCD cells are able to capture enough photons at the higher pixel density/smaller pixel size
to record a meaningful signal.

Given those two assumptions (and neglecting for a moment that it may not fit the real-world
situation) how can putting a 5 million pixel CCD of the same size as the 1 million pixel CCD in the
place of the 1 million pixel CCD NOT collect five times as many points of information for the same
image focused on it? Not talking about changing the focal length of the optics, just having a CCD
that can sample the same focused optical image in much smaller segments. Are you saying that this
would NOT give a better resolution, given the established meaning of "image resolution" as applies
to digital camera image output?

If so, I don't understand how.
Received on Thu 20 Jan 2005 01:30:56 AM PST


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