How to determine distance of an object in a photo?

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WayneF

Senior Member
People ask now and then, about how to determine the distance of an object in a photo.

There is now a calculator to do this at Calculator to Determine Distance to Object or Subject in an Image

You do have to supply several important details:


  • The real size of the Object, the actual or approximate feet or meters height of it.
  • The lens focal length that the camera image used.
  • The sensor size in the camera, height in both mm and pixels.
  • The size (pixels) of the image of the Object itself.

There are a couple of techniques discussed there about determining some of this for simple cameras that don't tell us much.
 
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WayneF

Senior Member
Maybe architecture or landscape? Sorry, I don't know why, I'm just aware people do ask, and I saw I could provide it. Some of the code (aspect ratio) is common to my Field of View Calculator.
 
Bourbon Neat

Bourbon Neat

Senior Member
That information is generally included in the exif data. How accurate the distance is reported might be questionable but every time I have checked it, it was pretty close to my estimation.
 
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WayneF

Senior Member
Bourbon Neat said:
That information is generally included in the exif data. How accurate the distance is reported might be questionable but every time I have checked it, it was pretty close to my estimation.
Click to expand...

DSLR maybe. But Not in camcorder files. :) And I'm pretty sure not in compacts or smartphones, at least not in the Canons and iPhones I have seen.

And the distance of the object sought might not be at the focused distance.

Prime lenses are fair about reporting distance, and the FX zoom lenses seem a bit better (than the very wide DX zoom lenses), but the very serious inaccuracy of zoom lenses (as it destroys TTL BL direct flash results) is one of my really big peeves.

Non-Nikon brand flashes solve the TTL BL Zoom Problems
Nikon TTL BL flash - D-lens distance data accuracy

I've never heard one other person even mention this very great design error. They do complain about their flash results. :) Yet it is very obvious. And Nikon knows the distance is extremely poor, yet they design their default flash mode around it.

But anyway, if you do want the distance of a object in an image, there is a way if you can determine your details.
 
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