Hi ughh users,
I was wondering out of curiosity, what length in mm do satellite cameras in space use (for example photos you would see on google maps). Also, if anybody else knows the answer to this, what mm lens do military drones have equipped (ex. US military predator drones).
I looked on quora for an answer but it isn’t photography oriented. Thanks everyone!
Hubble focal length is 56 m.
LarryFitz wrote:
Hubble focal length is 56 m.
That's a figure you don't hear very often.
sb
Loc: Florida's East Coast
LarryFitz wrote:
Hubble focal length is 56 m.
Wonder if you could hand-hold that baby......
I'm a geospatial scientist and a technical advisor for some space imaging programs. Focal lengths are typically less than a few meters. What really drives things are the density of CCD's (charged couple devices) on the sensor and the aperture. For example, the aperture on Digital Globe's Worldview 4 is an amazing 1.1 meters. The lens (telescope) is definitely some fine glass, but it's all about packing in sensors and the speed of acquisition and data transmission.
For reference, the aerial imaging camera I have has a max focal length of 210mm. That gets me 5cm pixels flying at 6,000' art a speed of about 300mph.
I believe you are referring to the focal length of the lens in mm; having said that, not knowing the format or the size of the sensor (in some cases the film plate) of the camera, the length in mm is almost of very little use. An 80 mm lens on a medium format camera, i.e. Hasselblad, will be considered a normal lens while on a DX or FX camera it would be accepted as a medium telephoto or portrait lens. The combination of these two numbers would provide a more significant value, better known as the field-of-view (FOV). How many square miles does a Google camera cover during a normal sweep?...
sb wrote:
Wonder if you could hand-hold that baby......
Not holding at all. The hubble stays hold itself.
I do believe the OP is referring to the earthbound-facing cameras - Hubble points the other way of course.
That said, no doubt the "effective foal length" (or really, angle of view) of the Keyhole satellites are still kept somewhat secretive. Years back the declassified documents about them indicated they could resolve down to 4" from an altitude of 200+ miles, as I recall. And that's what the declassified documents stated! Nowadays, with active image correction technology to correct for atmospheric distortions it's no doubt better than that.
DirtFarmer
Loc: Escaped from the NYC area, back to MA
While there are a lot of satellite cameras looking down at us, I suspect that what you will see on Google maps or Google earth are predominantly aerial photos, not satellite photos. Aerial photography is done on a regular basis by a lot of organizations for all sorts of purposes. Utilities do it to keep track of what's going on around their power lines, pipelines, etc. States do it to track development for planning purposes, collect environmental information for planning and emergency purposes, probably even for traffic monitoring. The USDA does it to track crops and environmental effects. Aerial photographs can be taken for specific purposes at any time desired, while satellite cameras are limited by their orbital parameters.
LarryFitz wrote:
Hubble focal length is 56 m.
Does it have a Hoya or B+W multi-coated polarizer on it?
If you want to reply, then
register here. Registration is free and your account is created instantly, so you can post right away.