Earth Photography from the ISS

While reading the BBC website (see following link) I noticed a
fascinating detail: They suggested that it was difficult to photograph
the Earth using telephoto lenses on the ISS due to the movement of the
platform. Having tried to follow the ISS with a telescope I can sense
the problem in reverse. Given the interest in Earth surveillance from
space this seemed like the basis for an interesting discussion. Is the
problem one of low orbit and high relative speed of the ISS in
comparison with other photographic/surveillance platforms? Or the
small aperture and low relative shutter speed of hand held cameras?
One would imagine the security services "Hubble-type" platforms have a
very long focal length and very high magnification to achieve their
objectives. These " Inverted Hubbles" must have some orbital velocity
or they would simply fall to earth. Perhaps parallax effects and
relative velocities can be overcome with very high speed (cost no
object) imaging sensors? Is the Earth really such a low light target
for orbital hand held cameras? Or is the problem simply one of the
very large distances involved (from orbit) requires long and "slow"
lenses to show any detail on the ground with hand held cameras?

http://news.bbc.co.uk/2/hi/science/nature/7668965.stm

"Chris.B" wrote:

Or the small aperture and low relative shutter speed of hand held cameras?

I think you've nailed it right there.

One would imagine the security services "Hubble-type" platforms have a
very long focal length and very high magnification to achieve their
objectives. These " Inverted Hubbles" must have some orbital velocity
or they would simply fall to earth. Perhaps parallax effects and
relative velocities can be overcome with very high speed (cost no
object) imaging sensors?

Could well be, but I would think a "push-broom" camera (time-delay integration),
as used on Mars orbiters, would be a better bet.

Chris.B:
While reading the BBC website (see following link) I noticed a
fascinating detail: They suggested that it was difficult to photograph
the Earth using telephoto lenses on the ISS due to the movement of the
platform. Having tried to follow the ISS with a telescope I can sense
the problem in reverse. Given the interest in Earth surveillance from
space this seemed like the basis for an interesting discussion. Is the
problem one of low orbit and high relative speed of the ISS in
comparison with other photographic/surveillance platforms? Or the
small aperture and low relative shutter speed of hand held cameras?
One would imagine the security services "Hubble-type" platforms have a
very long focal length and very high magnification to achieve their
objectives. These " Inverted Hubbles" must have some orbital velocity
or they would simply fall to earth. Perhaps parallax effects and
relative velocities can be overcome with very high speed (cost no
object) imaging sensors? Is the Earth really such a low light target
for orbital hand held cameras? Or is the problem simply one of the
very large distances involved (from orbit) requires long and "slow"
lenses to show any detail on the ground with hand held cameras?

http://news.bbc.co.uk/2/hi/science/nature/7668965.stm

I'm skeptical. I probably can't work out the geometry, but it's not
like being in a low-flying aircraft at, say, Mach 1 and watching the
scenery go by below you; the apparent speed at which the Earth passes
under you from low-Earth orbit is less than that from a fast,
low-flying jet. Actually, anyone who has flown over a land mass in a
commercial airliner on a clear day has observed this. It's easy to
take a sharp photo of the ground from 30,000 feet @ 500 mph, but not so
easy from 300 feet at 200 mph. There are many good photos taken of
Earth from the shuttle with ordinary equipment. It's a bright object
that lends itself to short exposure times. The more detail you want on
the ground, the more focal length you will need, and the slower the
lens will be. I would think that a 300 mm Ÿ2.8 lens of the type favored
by sports photographers might do a decent job. If you need resolution
on the order of a few millimeters then you are going to have to try to
get hold of a photo reconnaissance satellite.

Davoud

--
Don't re-elect the failures of the past eight years.

usenet *at* davidillig dawt com

On Fri, 17 Oct 2008 18:30:38 GMT, Davoud wrote:

I would think that a 300 mm Ÿ2.8 lens of the type favored
by sports photographers might do a decent job. If you need resolution
on the order of a few millimeters then you are going to have to try to
get hold of a photo reconnaissance satellite.

I think a few millimeters is out of bounds for anything up there. But
you can do a back-of-the-envelope calculation for the sort of equipment
somebody is likely to take on the ISS.

A 500mm lens with a typical digital camera has a resolution of about 2.5
meters per pixel at the height of the ISS. I doubt the lens will
actually be good enough to deliver that, but we'll take it anyway. For a
nominal orbital (ground) speed of 450 km/h, or 120 m/s, that means
you'll have one pixel of blur in 1/50 second.

So if you're trying to achieve maximum resolution, especially if you're
using a small telescope (with at least several inches of aperture and
500mm or more of focal length) it does seem likely that active tracking
would be required
_________________________________________________

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

In article , Davoud wrote:

I'm skeptical. I probably can't work out the geometry, but it's not
like being in a low-flying aircraft at, say, Mach 1 and watching the
scenery go by below you; the apparent speed at which the Earth passes
under you from low-Earth orbit is less than that from a fast,
low-flying jet.

Actually, anyone who has flown over a land mass in a
commercial airliner on a clear day has observed this. It's easy to
take a sharp photo of the ground from 30,000 feet @ 500 mph, but not so
easy from 300 feet at 200 mph. There are many good photos taken of
Earth from the shuttle with ordinary equipment. It's a bright object
that lends itself to short exposure times. The more detail you want on
the ground, the more focal length you will need, and the slower the
lens will be.

There are some quite exotic lenses available on the Space Station,
including a 400/2.8 with teleconverter
(http://www.kenrockwell.com/nikon/ima...8/MVC-157E.jpg for a
known-to-be-a-Nikon-400/2.8 and
http://spaceflight.nasa.gov/gallery/...s007e13547.jpg
for the camera in use on the Station, with the rest of their fairly impressive
photographic kit velcroed to the wall)

http://spaceflight.nasa.gov/station/..._letter10.html
writes about photography from ISS.

The interesting article
(http://www.airspacemag.com/space-exp...auts_View.html)
I read was about taking photos of cities *at night*, where you want a
reasonably long exposure, and they concocted a barn-door mount out of
bits and pieces lying around on the Space Station with which they got
some really spectacular shots.

Tom

starting last week a radioamateur Richard Garret is on ISS board and
he is transmiting images in SSTV mode Robot36 for all radioamateurs in
the world on 145.800 mhz also voice FM comunications.
Info details at www.issfanclub.com and www.amsat.org

On 18 okt, 00:02, yo9gjx wrote:
starting last week a radioamateur Richard Garret is on ISS board and
he is transmiting images in SSTV mode Robot36 for all radioamateurs in
the world on 145.800 mhz also voice FM comunications.
Info details atwww.issfanclub.comandwww.amsat.org

It is Garriot. Never played Ultima?

http://en.wikipedia.org/wiki/Richard_Garriott

Thanks for your thoughts and to Thomas Womach in particular for those
excellent links.

The barn door mounting driven by a drill was very clever and displays
the skills of those involved. Rather more sophisticated than my rubber
wheel and cone variable speed drives.

It's odd how cluttered the modules appear in interior shots.

I can just imagine them saying: "You're not coming down again until
you tidy your room!" ;-)