
From: Victor Golubic <Peetkin.nul> Date: Fri, 27 Feb 2004 18:54:14 EST Fwd Date: Sat, 28 Feb 2004 08:53:22 0500 Subject: Re: WhittleseaBeveridge Photo  Golubic >From: Tom DeMary <t.demary.nul> >To: UFO UpDates  Toronto <ufoupdates.nul> >Date: Fri, 27 Feb 2004 00:30:23 0600 >Subject: Re: WhittleseaBeveridge Photo >>From: Victor Golubic <Peetkin.nul> >>To: UFO UpDates  Toronto <ufoupdates.nul> >>Date: Wed, 25 Feb 2004 15:59:00 EST >>Subject: Re: WhittleseaBeveridge Photo  Golubic ><snip> >>Given the statement that the camera operates optically from, >>what I assume is 1.0X through 3.0X optically with a zoom >>equivalent focal length on a 35 millimeter camera of 39117 mm, >>the actual focal length as stated, is instead, 6 to 18 mm for >>the DC240. >>Therefore, with the given information, one can assume that the >>CCD measures approximately 6 millimeters diagonally (assumed, >>but could be purely horizontal), with an aspect ratio (width to >>height) of 2.6/3.4 (as measured from various pages both >>featuring and stating these width to height values). ><snip> >Victor, >Your math is sound, and a 6 mm diagonal is a reasonable >assumption, but you are in effect assuming the FOV, since it is >determined by sensor size and focal length of the lens. The >sensor size could be from 4 to 9mm, which makes a big difference >in the angle of the Field of View, if the focal length was 10mm, >as given in the EXIF data. >>For wide angle settings, I've sent questions to various testing >>resource outfits and await a response. Other than that, testing >>the camera and interviewing the witness, as Brad has stated, is >>the only logical course of action. >The camera, as far as I can tell, has no wide angle setting  it >has a zoom lens (39  117mm as stated above). 39mm is not very >wide. The camera does have an optional accessory lens, which >fits over its zoom, to give a wide angle 35mm equivalent of >24mm, as Brad Sparks mentioned in material I snipped out. >I thought that the 35mm equivalency was straightforward, until >I saw this is a link that explains three different ways that >camera makers can specify it: >http://www.panoramafactory.com/equiv35/equiv35.html >These proliferating lowend digital cameras are all about ease >and convenience, with very little useful documentation >about their photographic specifics. >Tom DeMary Thanks for updating my assumptions...with some input and the other info on the posssible 24 mm focal attachment (Brad). I was simply giving the standard setup. Yes, the manufacturers don't give you everything you want within their specs and it becomes frustrating to say the least! If everyone will go to this web page you'll see that my calculation is very close, except that my assumption of the diagonal aperture of 6 mm is instead 6.44 horizontal . . . which was the other explicitly stated alternative. http://www.imagingresource.com/PRODS/DC240/240PICS.HTM Once your there, page down to the data on the macro shot of the dollar bill, it gives all the distance and width info from which you'll see that my assumption is quite close for 3.0x (others too). If it was 10 mm, then you just need to plug it in...I was only giving three reasonable points at 1, 2, and 3x. There you will read this, "With its zoom lens run out to the telephoto end of its range (3.0X), and the camera set for "macro" focusing, the DC240 does a very respectable job of closeup photography. The minimum focusing distance of 9.6 (9.5) inches (0.25 m) results in a reasonably "tight" minimum viewable area of 2.6x3.4 inches (65 x 87 mm)." Calculating from this: 2 * Arctan ((3.4/2)/9.5) = 20.3 degrees, one arrives at a value very close to what I provided for my 3.0X estimate of 18.9. However, this is the true horizontal dimension (confirmed here), Therefore, my assumption of the diagonally "film" aperture for the CCD being 6 mm is instead 6.44 mm horizontal. We now have a little wider FOV from what I had estimated previously: 1X magnification  2 * Arctan((6.44/2)/6) = 56.4 Degrees. ...therefore, horizontally the FOV is 56.4 Degrees ...vertically the FOV is 43.2 Degrees, and diagonally ...it is, 2* Arctan((7.33/2)/6) = 62.8 Degrees 2X magnification  2 * Arctan((6.44/2)/12) = 30.0 Degrees ...therefore, horizontally the FOV is 30.0 Degrees ...and vertically the FOV is 22.9 Degrees, and diagonally ...it is, 2* Arctan((7.33/2)/12) = 34.0 Degrees 3X magnification  2 * Arctan((6.44/2)/18) = 20.3 Degrees. ...therefore, horizontally the FOV is 20.3 Degrees ...and vertically the FOV is 15.5 Degrees, and diagonally ...it is, 2* Arctan((7.33/2)/18) = 23.0 Degrees Therefore, at 10 mm, which I hadn't been aware of until someone had emailed me off the line (this is still an estimate of the zoom setting from what I gather), we get... 2 * Arctan((6.44/2)/10) = 35.7 Degrees....therefore, horizontally the FOV is 35.7 Degrees...and vertically the FOV is 27.3 Degrees, and diagonally...it is, 2* Arctan((7.33/2)/10) = 40.3 And, by direct input, the magnification is 1.67 X for that setting. And, yes, the CCD imging area could be smaller or larger to accommodate different lenses at different focal lengths. This would change everything above by a factor of 35/24 (6.44 becomes 9.4, just plug it in and recalculate). Perhaps there's a panoramic setting too? I think we have it fairly close now for the 24 mm style attachment (if present). At 9.4 and a 10 mm focal length (1.67X), we get: 2 * Arctan((9.4/2)/10) = 50.3 Degrees....therefore, horizontally the FOV is 50.3 Degrees...and vertically the FOV is 38.5 Degrees, diagonally...it is, 2* Arctan((10.7/2)/10) = 56.3 Degrees. The web page I provided should help with many other camera manufacturers as well. Victor Golubic
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