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Hi Dave and others,
At risk of flogging a dead horse, I=92ll take up cudgels with Dave=92s call=
that "35=B0 from image horizontal when measured [see below]... means almos=
t nothing". In the BBC interview, this UK guy has a big rig camera and app=
ears to be an experienced photographer. Anyone like this who has to take a=
snap decision for a quick bird photo is going to try to hold the rig horiz=
ontal, and my guess is that anyone competent could hold it level to within =
=B12=B0 of horizontal, even me. Photographers may wish to comment.
How about 'when measured=92? I imported a JPEG copy of the woodpecker-weas=
el image into the very useful image analysis program ImageJ*, and with the =
angle-measurer tool measured the shadow angle from the vertical at 47.17=B0=
(=B1 1.5% coefficient of variation, n=3D7); my eyeball guess had been 50=
=B0, and the very low CV% means that the wing shadow, clear and almost line=
ar, made it possible to make very reliable repeat measurements. The sun=92=
s implied elevation then is (90 minus this), or 42.83=B0, not 35=B0.
I thought it would take at least a degree in Astronomy (not me) and a load =
of work to estimate where the sun actually was on the day in question in th=
at part of UK, but this turns out to be relatively easy.
For the calculation you first need the coordinates of the site from one of =
the several latitude-longitude calculators available on the web, for instan=
ce:
www.latlong.net/<http://www.latlong.net/>
The result is latitude 51.562254, longitude 0.218605, for Hornchurch, E. Lo=
ndon, UK.
Several sun height calculators are also available, for instance:
keisan.casio.com/exec/system/1224682277<http://keisan.casio.com/exec/system=
/1224682277>
Besides the latitude and longitude, the date needs to be specified, which i=
s the Monday the day before the BBC post, therefore 1 March 2015; zero refe=
rence, 0 GMT; then the time (not yet daylight saving time) which is only gi=
ven in the BBC post as 'afternoon=92. My guess for this would be ~3PM, bu=
t maybe it could have been as early as 2PM.
The results returned by the calculator for sun elevation (altitude measured=
from earth horizontal) using these 1 March 2015 values for Hornchurch are
2PM: 26.47=B0
3PM: 20.78=B0
4PM: 13.47=B0
The maximum height of the sun on that day occurs near 12:30PM, but is still=
only 30.74=B0
Conclusion: The measured estimate of the sun=92s elevation from the JPEG (=
42.83=B0), is therefore too high by 16.4=B0 at 2PM, and 22.4=B0 at 3PM, to =
have been taken on 1 March 2015. I don=92t believe that an experienced pho=
tographer would be holding his camera at anywhere near either of these angl=
es to make the situation right. And if that were true, the loaded woodpeck=
er would actually be heading upwards by 22=B0 (3PM), probably close to stal=
l angle. In fact according to the report, the woodpecker was heading towar=
ds a crash landing, therefore downwards.
Another way to look at it using the Keisan calculator is to ask on what fir=
st date/time the sun elevation would equal close to the value measured from=
the image, 42.83=B0. The answer is several weeks later than 1 March, on 23=
May 2015 (if 3PM) and on 19 April (if photo was taken at 2PM).
This seems like pretty good evidence that this photo could not have been sh=
ot on or even close to 1 March 2015. If the =91Monday=92 in question were=
even earlier in the year, the sun would be lower and the angle fit would b=
e even worse. Among other salient points, Randy=92s is particularly persu=
asive, about the relative weight of the weasel with solid bones versus the =
woodpecker=92s hollow bones implying that the bird could not fly carrying s=
uch a large load.
The only powerful point of view that needs to be considered is that of the =
weasel itself, as relayed in Dave=92s original post, which in case you miss=
ed it was:
>> But as, is often the case, the passenger felt he was taken.
http://newsthump.com/2015/03/03/weasel-shocked-by-hidden-charges-after-chea=
p-woodpecker-flight/
DW<<
Steve (Hfx)
*Google to ImageJ, select the site and download the version for your operat=
ing system. It is a very useful, powerful but easy to use program, develop=
ed and maintained to the present with US govt funds and so is available for=
free. Highly recommended.
--------------------------------------------------
On Mar 4, 2015, at 11:31 AM, David & Alison Webster <dwebster@glinx.com<mai=
lto:dwebster@glinx.com>> wrote:
Hi Steve & All,
I think there is no reason to suppose it not to be genuine.
The angle of shadow cast by the wing, more like 35o from the image horizo=
ntal when measured, means almost nothing because this angle would be depend=
ent upon the angle of the camera relative to true horizontal. One would exp=
ect a loaded bird to fly with maximum angle of attack so as to avoid an uns=
cheduled pancake landing.
The foreleg, being small, against the bird, perhaps somewhat buried in sh=
ort feathers, with an edge of sparse fur to cast the shadow, the shadow tra=
ce possibly dimmed by light reflected from the neck and just barely at a gr=
eater angle from the image horizontal than the wing shadow would be expecte=
d to cast faint or no detectable shadow. Even the shadow distal to the foot=
is very faint.
This is in addition to the complaint registered by the passenger which ad=
ds authenticity. Why would a non-existent passenger complain about being tr=
eated unfairily ?.
Time will tell.
Yt, Dave Webster, Kentville
----- Original Message ----- From: "Stephen Shaw" <srshaw@Dal.Ca<mailto:s=
rshaw@Dal.Ca>>
To: <naturens@chebucto.ns.ca<mailto:naturens@chebucto.ns.ca>>
Sent: Wednesday, March 04, 2015 1:57 AM
Subject: Re: [NatureNS] BBC Article - Weasel photographed riding on a woodp=
ecker's back
Hi Keith,
I could only find one other shot, a low power pan with poor focus which the=
refore doesn=92t resolve anything. Do you have a URL for other shots?
If you look at the prominent bright area on the side of the bird=92s throat=
which abruptly turns into a dark shadow on the breast just forward of the =
wing, this must have been shot in bright sunlight (in mid afternoon in Febr=
uary, apparently). From the angle of the shadow (caused by occlusion by th=
e bend of the extended wing), sunlight would have to have been falling from=
the right, top, about 50 degrees off vertical, and roughly in the plane of=
the photo. I=92m not sure, but am surprised that the