# Determining resolution of aerial pictures - Photography

We're trying to figure out what type of resolution you would likely get with a camera flying about 10,000 above the ground, with a 6" lens using large format film. That all I know, but would appreciate any general guidelines or guesses. Thanks in advance....

1. ## Determining resolution of aerial pictures

We're trying to figure out what type of resolution you would likely get
with a camera flying about 10,000 above the ground, with a 6" lens using
large format film. That all I know, but would appreciate any general
guidelines or guesses.

Thanks in advance.

c0@earthlink.net Guest

2. ## Re: Determining resolution of aerial pictures

This sounds like a trick question.

"Film resolution" has nothing to do with altitude.
"Resolving power" -- how small an object on the ground can you identify
clearly may be the question you're asking. I have a family member who does
aerial photography for a living so may be able to answer this question.

<net> wrote in message
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Larry Guest

3. ## Re: Determining resolution of aerial pictures

<net> wrote in message
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The resolution would be the same at 10,000 ft as it would a 1ft

sQuick..

sQuick Guest

4. ## Re: Determining resolution of aerial pictures

sQuick wrote:

>
>
> The resolution would be the same at 10,000 ft as it would a 1ft
>
> sQuick..[/ref]

What could you likely see from 10,000 feet, a dime?

c0@earthlink.net Guest

5. ## Re: Determining resolution of aerial pictures

<net> wrote in message
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That's got nothing to do with "resolution", but "image amplification".

If you see aim a lens with similar optical characteristics to the human eye
at a dime-size object from 10,000 feet away, you'd be lucky to see a glint
the size of a grain of sand. But, magnify that view, and it'll be abit
larger.

It's not your resolution, but your zoom/magnification that matters. Of
course, if your resolution is distorted or otherwise substandard to begin
with, all the lens in the world isn't going to help.

Start with a good camera, and build upon that with a good lens.

Chris Guest

6. ## Re: Determining resolution of aerial pictures

<net> wrote in message
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There are two limits here: the film and the lens.

Film resolution tops out about 4000 dpi. Multiplying
this by the size of the exposed film gives you a
total resolution. Divide this into the size of your
ground footprint, it will give you the smallest
possible resolvable item on the ground.

That number will then be restricted by the sharpness
of the lens and by how much you can zoom in (obviously,
the smaller your ground footprint, the higher the
effective resolution).

Hugh Guest

7. ## Re: Determining resolution of aerial pictures

There are three big factors in determining the ground resolution of a lens:
magnification, lens resolution, and film resolution. Magnification is
determined by the focal length and the altitude (5*10^-5 in this case).
Lens resolution depends on lens design and f-stop. Most aerial camera
lenses resolve near their defraction limits for reasonable apertures. For
f/8 that would be about 185 lines per mm. Figure 150 lines per mm. Film
resolution depends on the contrast of the object, the design of the film,
and the processing. Representative figures are 125 lines per mm for 1000:1
contrast and 50 lines per mm for 1.6:1 contrast. The resolutions of the film
and the lens must be combined to get a net resolution. Using the reciprical
of the sum of the reciprocals method, this gives 68 lines per mm for high
contrast 37.5 line per mm for low contrast. Applying the magnification, you
will resolve about 300 mm (1 foot) on the ground for high contrast items,
533 mm (21 inches) for low contrast items. Notice there are a lot of
assumptions in these calculations: f stop, quality of the lens, quality of
the film, perfection of the other conditions.

<net> wrote in message
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Norman Guest

8. ## Re: Determining resolution of aerial pictures

Not sure if it might help, but do a search for USAPhotoMaps, you can
download a program, look at the zoom feature, I believe the resolution
of their aerial photos is something like 1 meter/ pixel

net wrote:

Marty Guest

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