Photography - Question About Lens Resolution

First, I know next to nothing about photography - except to make sure my finger isn't blocking the view.

However, I recently read an article from some folks I used to work with about a project they are developing, and a question popped into my head.

Crucial to being able to answer this question is another question that my lack of expertise in the ways of photography, specifically aerial video photography, has left me stumped.


To whit:

How large (right term?) A lens would you need to achieve a 1 meter resolution for a live video feed from an altitude of 125,000 - 150,000FT, airspeed

a reply to: Mantiss2021

How large (right term?) A lens would you need to achieve a 1 meter resolution for a live video feed from an altitude of 125,000 - 150,000FT, airspeed

1 meter? Forget it.

Canon makes a 5200mm mirror lens that will photograph an object at approximately 32 miles. You would need a sizable aircraft to haul it, but even that lens is highly unlikely to resolve 1 meter at that distance.

a reply to: Klassified

Thanks for the info!

I thought a meter would be pushing the envelope, although military grade optics might get somewhat closer to that goal.

Actually, I would suppose a resolution good enough to identify something roughly the size of a battlefield tank would suffice for the purpose. The altitude is to avoid surface to air interference. Current SAM systems, as I understand it, top out at around 125KFT, while the platform in question can station-keep at 140KFT.

a reply to: Mantiss2021

The U-2 large format camera was a 180 inch, f/13.85 lens in a 13x13 housing. It was capable of 2.5 feet from 60,000 feet. They wanted a 240 inch focal length, but couldn't get six more inches to fit it. The LFC was capable of taking 1600 frames per mission, with each frame covering 110 square nautical miles. Syers-2 used on USA-231 (ORS-1) has a 40 cm aperture, with a NIIRS 4 resolution (1.2-2.5 meters) from a 186 mile orbit. Syers-2C is now used on the U-2.

a reply to: Zaphod58
Not bad on that F-Stop. I would have expected it to be a bit higher. That's some quality optics there.

originally posted by: Zaphod58
a reply to: Mantiss2021

The U-2 large format camera was a 180 inch, f/13.85 lens in a 13x13 housing. It was capable of 2.5 feet from 60,000 feet. They wanted a 240 inch focal length, but couldn't get six more inches to fit it. The LFC was capable of taking 1600 frames per mission, with each frame covering 110 square nautical miles. Syers-2 used on USA-231 (ORS-1) has a 40 cm aperture, with a NIIRS 4 resolution (1.2-2.5 meters) from a 186 mile orbit. Syers-2C is now used on the U-2.

So, if I am understanding correctly, the given parameters could be met, with available technology; off-the-shelf, so to speak?


That was kind of what I was concerned about.

I'm afraid some former colleagues have set themselves up to bite off more than they expected, especially given their prior experience as military contractors.

It did not end...profitably.

a reply to: Mantiss2021

Yes and no. The technology exists, but access to it is going to be extremely limited. High end camera technology, such as SYERS will fall under ITAR, and be restricted under DoD rules. You might get close with a COTS camera system, but you won't get access to a high end hyperspectral system like SYERS. A commercial hyperspectral system is going to start somewhere around $30K, so most people aren't going to be buying them.

a reply to: Zaphod58

$30-$100K USD for the cameras alone would still result in a very "cheap" persistent ISR system, using their design.

The problem will be refusing "customers".

That's what happened before.

Zaphod58 is essentially correct here with the exception being that the really state of the art stuff belongs to the National Reconnaissance Office (NRO) and they aren't saying. It's been good enough to tell the Ukrainians though when and where to fire and what to expect to hit. Lately it's been good enough to take out several high value targets who thought they were safe so whatever it is, it's pretty damn good.

I go way back to the days when the NRO was formed and for the better part of 2 decades I knew about their operations and capabilities but retirement took me out of the system so I no longer have a need to know. My best,

a reply to: Mantiss2021

The problem is developing a persistent, survivable platform. Putting a $30K camera on something that's going to be destroyed constantly is going to run you out of money pretty quickly. You're going to need a lot of platforms to keep replacing the ones you lose.

a reply to: airforce47

We worked a contract with the USAF Battlestar back in the late 90's, early 00's.

The contract ended, the funds dried up, but the work continued, apparently.

I dropped out before things, supposedly, went pear shaped.

Looking down like this, Your limit will be set by the distortion caused by the air between the lens and the target.

a reply to: Zaphod58

Two options there.

The platform under final development can fly itself out of theater, either by radio control, or by GPS-guided autonomous control. Altitude control is also possible, with final recovery via self-deployed parachute.

This method has been tested and has proved reliable.

The second method would involve the sensor suite detaching from the carrier frame and descending via winged glide vehicle. Preliminary studies of this method were conducted in the late 90's as part of a precursor program.

So all the important "expensive" bits can be recovered.

We had very little money when we started (and not much more even after the Air Force came on-board), so we had to get very creative about our equipment recovery procedures.

originally posted by: Mantiss2021
a reply to: airforce47

We worked a contract with the USAF Battlestar back in the late 90's, early 00's.

The contract ended, the funds dried up, but the work continued, apparently.

I dropped out before things, supposedly, went pear shaped.

That should be "Battle-Lab".

Curse Auto Correct!

originally posted by: Mantiss2021
Actually, I would suppose a resolution good enough to identify something roughly the size of a battlefield tank would suffice for the purpose.

The minimum resolution should be at least half of the smallest object you want to identify, so a 1 metre resolution would be good enough for something at least 2 metres long/wide.

Smaller objects will appear with only one pixel, so they cannot really be identified.

a reply to: Mantiss2021

That’s assuming you’re not being shot at though. A double digit SAM would knock an air vehicle out far too quickly to release a payload. It would work for a low threat environment like Afghanistan, but somewhere like Ukraine, you’d need something more survivable.

a reply to: Zaphod58

Barring ASAT systems, realistically, don't SAM systems top out at around 125KFT (less than 25 miles altitude)?

And even then, a SAM would need a hard lock on the target, acquired either by IR, RF, or visual. IR would be difficult at such range if the propulsion system was all electric (we successfully tested high altitude propellers above 90KFT, based on a modified NASA design) and the system powered up only when used to station-keep or enter/exit target area. The vehicle structure itself is over 90% carbon fiber, including the prop(s), and that structure is itself, minimal, meaning there is very little for radar to target.

And, given the operating altitude, you'd actually have to be looking specifically for the thing to have even a chance of seeing it, provided your optics were powerful enough.

Basic flight control avionics have been field tested, at least in prototype.

The ISR suite could, conceivably left to the end users to integrate.

a reply to: Mantiss2021

And building something that flies that high is even more expensive, and insanely difficult. The absolute record for horizontal flight by an air breathing aircraft is 85, 068 feet, when an SR-71 (61-7958) reached that altitude while being monitored by FAI. Aircraft have reached higher, but were high modified to be as light as possible, and couldn't sustain that altitude. The X-15 air launched rocket plane reached as high as 325,000 feet, but adjusting for inflation, each aircraft cost $317M.

As for SAM systems, the SM-3 used by the Aegis BMD program can shoot down aircraft, and missiles at extremely high altitudes. A number of BMD systems are capable of hitting missiles or aircraft with the same missile. Extremely high altitude flight has almost never been the cure for missile systems. They thought the U-2 was not capable of being shot down because of the altitude it flew at, until Gary Powers was shot down over the Soviet Union. The S400 48N6 family of missiles can reach 200,000 feet.

a reply to: Zaphod58

Have already flown an electric vehicle at 95,000FT.

Granted, not an air breathing (not a breathing at all) vehicle, but, if by "flown" we mean relying upon its own power to transit from point A to point B, then, mission accomplished.


Really, it is not the altitude that runs up the tab, it's the means chosen to reach that altitude that gets expensive.


Everyone always focuses on speed. Speed costs. And yes, speed can save lives. But speed isn't always necessary to the task at hand, and speed isn't always an advantage.

a reply to: Mantiss2021

Current electric aircraft don't have the loiter time to be an effective ISR platform. The longest ranged electric aircraft are somewhere around 800 miles total range. If you want any kind of loiter time, you're looking at staying over targets that are close to where the front lines are. If you want high altitude, you're going to need a revolution in batter technology to allow for much longer range, and loiter time. You aren't going to get a 24+ hour loiter time like you will with current UAVs with current battery technology.