It's nice to see a post from someone who just asks for help with identification, rather than the usual large leap to conclusions.. Kudos to you!
Originally posted by burdenofdreams
Anyways, I think that makes this an as yet unidentified flying object. Didn't see any birds that high up in the sky, and my barn swallow was behind
me at that time, swooping into view AFTER I took the photo (also, he was much closer than the speck in the picture). Here's the original photo, plus
a crop, and (everyone loves photoshop filters!)
Umm, no they don't.
like them when used properly, but you have to be very careful when you emphasise by adding false detail. And
I'm afraid glowing edges (and posterising and a whole pile of others) are 'destructive' filters, in other words they remove real detail, and add
false detail. We don't really want either of those - but thanks for trying!
MY QUESTION IS:
Is there any way to tell the distance of the unidentified object to the camera, and therefore the size? Even when you have objects in the foreground,
and at other intervals?
Yes and no. There are some hints (see below) and we can try to apply the black arts of imaging forensics and photogrammetry. Trouble is, unless you
know what you are doing, it is very easy to fool yourself that you can analyse all sorts of things from an image... truth is, there are LOTS of
caveats and traps..
How much can you really tell from a photograph? Nothing?
Let me explain. In your image, we have a few clues, namely the foreground stuff (pole) obviously in focus, and what appears to be a more distant (but
how much?) wire that is out of focus (o-o-f). Then there's the 'thing', also o-o-f. For this particular image, there will be ranges that are too
close to be in focus (eg objects closer than the pole), a range in focus (eg the 'middle ground' where the pole is), and another range out of focus
(beyond middle distance out to infinity). Obviously if the lens was focused at a different distance, the ranges would differ, and the plane of focus
would be located farther or closer. (Also, the size of the aperture determines how MUCH is in focus, ie how 'thick' the plane of focus is, but I
Now, for objects near to the plane of focus (let's say that was ten feet away for the sake of argument), they will gradually get more and more blurry
as you get further away. So an object say 15 feet away will be just a little o-o-f, while one at 100 feet will be more o-o-f. So the amount of
fuzziness gives an indication. The more wide the 'fuzz', the further away.
But wait.. If the object is closer
, say 9 feet, it will also get fuzzy. If it is 3 feet away, more fuzzy again. Now you can probably tell
that these numbers aren't linear - in other words the amount of fuzziness doesn't change in a linear fashion. On some lenses, the appearance of the
fuzziness (it's called 'bokeh') will also change in appearance (shape and texture), so you can also get clues that way.
. How do we know that the out-of-focus-ness is the only issue? Could the object be moving and therefore have motion blur? Well, motion
blur is usually streaky, so probably that isn't a big issue. But what if the object itself has ill-defined edges (eg a tennis ball, a fuzzy insect)?
And as for the wire that we can see, exactly much of its 'blur' is actual blur? - the problem is that the wire is thin, and unless we can actually
determine its real width, we can't really tell how much blur there is, to compare it to the object.
There are more issues, but I think you are getting the picture (pun intended). Yes, if you have enough information, and lots of usefully placed
objects in the image to give lots of clues and things to measure, you may
be able to determine something useful. In this case, we are a bit
short of all that. The 'thing' does appear to be more blurred than the wire, so it is possibly/probably further away, or it could be much nearer to
the camera than the pole... There just aren't enough clues.
In other words... I've been no help at all.
But hopefully this gives you a small taste of the complexity of image forensics. And I'm no expert.. I just get by..
BTW, it' probably not going to help much, but.. camera? lens? I'm being lazy, should have checked exif...
Edited to try make it a bit clearer..
[edit on 29-8-2010 by CHRLZ]