» Topic: Canon 5200mm

This topic has 14 replies, 8 voices, and was last updated Dec 12, 2009 at 11:42 pm by Tim Schulz.

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Dec 9, 2009 at 9:20 pm #8245

Brett Colvin
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http://tinyurl.com/yz92c5j

10,400mm w/ a 2x TC.

Dec 9, 2009 at 9:51 pm #69629

David Anderson
Member

You think my casting would be compromised with that in my pack ?

www.dsaphoto.com

A picture is thousand words that takes less than a second while a thousand words is a picture that takes a month.

Dec 9, 2009 at 10:11 pm #69630

John Bennett
Member

The Sigma beast is almost as bad, forget the specs but I want to say 600mm f2.8?? You’d need a forklift almost to use it.

Dec 9, 2009 at 10:12 pm #69631

Brett Colvin
Member

You’ll want to go weight-forward.

Dec 9, 2009 at 10:25 pm #69632

Douglas Barnes
Member

I’d be all over that thing but it’s Canon 😎

Good for waterfowl if there nesting. $hit, you could reach either coast from home with that thing!

Dec 9, 2009 at 11:05 pm #69633

J A Y M O R R
Member

What a let down….it’s not even white! I guess it lacks the “L” factor. Hey look on the bright side, the lens color is just a shade or two off from being correct 😉 Ziiiiiiiing!

Looks like a giant hair stacker!

Dec 9, 2009 at 11:11 pm #69634

Brett Colvin
Member

What a let down….it’s not even white! I guess it lacks the “L” factor.

This is the consumer grade 5200mm.

Dec 9, 2009 at 11:25 pm #69635

Douglas Barnes
Member

What a let down….it’s not even white! I guess it lacks the “L” factor.

This is the consumer grade 5200mm. The pro lens has a faster aperture and adds image stabilization for hand holding.

Plus the good coatings and a hood mount. lol

Dec 10, 2009 at 3:22 am #69636

anonymous
Member

Hmms this tempting- but!!!!

Dec 10, 2009 at 11:22 am #69637

David Anderson
Member

What a let down….it’s not even white! I guess it lacks the “L” factor. Hey look on the bright side, the lens color is just a shade or two off from being correct 😉 Ziiiiiiiing!

That’s a quality sledge considering it came from a Nikon user.. 😀

www.dsaphoto.com

A picture is thousand words that takes less than a second while a thousand words is a picture that takes a month.

Dec 10, 2009 at 12:20 pm #69638

Neal Osborn
Member

You don’t need this lens! Just talk to my neighbor in the satellite business. He contracts with Google Earth and multiple academic/research corporations and unfortunately a certain Asian country known for mega fishing. The algorithms he is working with can “LITERALLY” read the upper right registration sticker from your license plate. Whoa. In the future (sooner than you would believe) the general public will have the ability to query satellite imaging data for a fee.

And that includes photographing big game from space! It’s already being done with insane resolution. 😀

Dec 12, 2009 at 2:35 pm #69639

Tim Schulz
Member

Thinking about reading a registration sticker from space . . .

A satellite in low-earth orbit is typically more than 200 km from the earth’s surface. (Space station is about 300 km and the Hubble is about 550 km, I believe.) The shortest wavelength for visible light is about 400 nm. Reading those tiny stickers probably requires about a tenth of a centimeter resolution. So, the telescope’s lens would need to be about 80 meters (nearly a football field) in diameter to overcome the limits imposed by diffraction. If we relax the resolution to about a centimeter (might be able to read the big numbers on the plate), then the telescope’s lens would need to be about 8 meters in diameter (about 26 feet).

It’s early in the morning, so I might have messed up some of the math here, but these would be impressive pieces of glass and mirrors. It seems like that kind of resolution would call for a sensor on a plane or drone that was just a few kilometers from the ground.

Dec 12, 2009 at 3:18 pm #69640

Neal Osborn
Member

That is a good point Tim and one I posed myself.

Dec 12, 2009 at 10:05 pm #69641

John Bennett
Member

And that is why they are affectionately known as rocket scientist and not the people who design, manufactor, or assemble the rockets. It’s the people that engineer the “mathematics” that drive the rockets.

Dec 12, 2009 at 11:42 pm #69642

Tim Schulz
Member

For fun, here is an example of the sort of images that these satellites could collect. It is from these that the image processing wizards would need to work their magic.

Here is my license plate:

Now, let’s turn the Hubble Space Telescope toward Earth and take a picture of this. The Hubble is orbiting at 550 km and has a primary mirror that is 2.4 m in diameter. Here is what it would see:

Hard to imagine much luck with processing, so let’s bring the Hubble down to 225 km. This is a very low orbit, and this is what we would get:

Still tough. Let’s get crazy and bring that bird down to about 100 km. Now we would see this:

Processing could probably help with this, but I’d still be skeptical about getting at the sticker in the upper right.

Just for fun, let’s see what happens at 10 km, which is about the cruising altitude for a commercial jet:

Now we’re talking. Of course, the ‘lens’ on this camera is about 8 ft in diameter, so you couldn’t take this picture from any of the plane’s windows.

This gives you some idea of the challenges that the signal processing experts face when trying to recover lost resolution from satellite photos.

Cheers,
Tim
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