[LRflex] Re: [LRflex] Re: [LRflex] Focal-plane shutter distortion of aëroplane propellers
- From: David Simms <simmszee@xxxxxxxx>
- To: leicareflex@xxxxxxxxxxxxx
- Date: Wed, 3 Feb 2010 16:08:36 -0800 (PST)
I could imagine the blade tip being exposed first and, as the slit moved,
likely from l-to-r, the blade would have moved. So, as the rest of the blade
gets exposed, it rotated further until the root would have made a considerable
angle compared to its original position at the beginning of the exposure (of
the blade).
How many rpm do chopper blades turn ? 1,000rpm ?
Interesting. The distortion of the building, in the other shot, is equally
interesting.
Dave
________________________________
From: Charlie Falke <chfalke@xxxxxxx>
To: leicareflex@xxxxxxxxxxxxx
Sent: Wed, February 3, 2010 2:51:52 PM
Subject: [LRflex] Re: [LRflex] Focal-plane shutter distortion of aëroplane
propellers
On 2/3/2010 5:20 PM, Jeffrey L. T. Gluck wrote:
> Apropos of this discussion, I recall seeing interesting pictures of
> focal-plane shutter distortion of aëroplane propellers. If anyone has a
> link, please post it. I saw it several years ago but lost the link. I'm
> sure most here are familiar with that.
> Jeff Gluck
>
Jeff,
Here are two. The first is from Wiki, and shows severe
distortion of helicopter main and tail rotor blades, including
the blades' shadows not corresponding to where the blades are.
This was taken with a DSLR, according to the text.
http://images4.wikia.nocookie.net/chdk/images/4/46/Focalplane_shutter_distortions.jpg
The next one I almost sent after the discussion on FP distortion
during panning. This was almost certainly shot with a Speed Graphic,
in any case the shutter moves from the top of the camera to the
bottom during the exposure, which means from the bottom of the
image to the top. The bottom of the hangar is exposed first, and
as the camera is panned to the left, the hangar moves to the right,
but only a thin slice is exposed at a time. The airplane looks
pretty good, the photographer did a good job panning.
There are two propellers on an XB-42, turning in opposite
directions, the front propeller turns in the normal (for the US)
direction of right handed, that is clockwise from the rear.
The rear propeller turns the other way. The blades are not
tapered at all, all the appearance of sweep is due to the shutter.
http://www.nationalmuseum.af.mil/shared/media/photodb/photos/060912-F-1234S-006.jpg
If you do a close up with a Speed Graphic using the body shutter, you can
get a blade curved all the way around and back the other side of the rotor
hub.
--
Charlie Falke _____ /\
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"One test result is worth | |/ `o
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