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

From: Chris Peterson <clp_at_meteoritecentral.com>
Date: Thu Jan 20 10:25:53 2005
Message-ID: <027201c4ff04$4dda4a00$f551040a_at_bellatrix>

Darren-

Your first assumption is the problem. The lens on the Pancam is f/20.
Optical theory says that if this lens is perfect, the smallest size spot it
can produce at the focal plane (the Airy disk) is 32um in diameter. By
sampling at about half that size the sensor will capture all the spatial
information present in the image. And indeed, the Pancam sensor has 16um
pixels. The lens and the sensor are well matched to each other. Adding more
pixels in the same area would not result in pictures of higher resolution,
just the requirement for more bandwidth to send them.

Of course, a higher resolution camera could be made. But that would require
changing the optics as well as the sensor. And in the case of digital
imaging like this, it is really only meaningful to talk about resolution in
an angular sense, not in terms of the number of pixels. When we look at the
image of this Martian meteorite, what we'd all like to see isn't more pixels
as such, but more pixels across the meteorite itself. A lot of the one
million pixels right now are imaging the area surrounding the meteorite. If
the camera had a zoom lens, you could place nearly one million pixels right
on the meteorite. That would be many times the resolution of the original
image, with the same 1MP sensor.

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


----- Original Message -----
From: "Darren Garrison" <cynapse_at_charter.net>
To: <meteorite-list_at_meteoritecentral.com>
Sent: Wednesday, January 19, 2005 11:30 PM
Subject: Re: [meteorite-list] Iron Meteorite on Mars (Color Photo)


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 10:25:42 AM PST