EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: BravoV on December 15, 2020, 07:50:02 am
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(https://www.herts.ac.uk/__data/assets/image/0005/316490/Longest-exposure-image.jpg)
... arced trails of the sun, as it rose and fell .. for eight years and one month ...
-> Longest known exposure photograph ever captured using a beer can at the University of Hertfordshire’s Bayfordbury Observatory (https://www.herts.ac.uk/about-us/media-centre/news/2020/longest-known-exposure-photograph-ever-captured-using-a-beer-can)
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I'm impressed that nobody touched or bumped the beer can in that time.
Imagine trying to replicate something like this and even if you put cages and massive signs saying to not touch the can someone would still definitely touch it. :P
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I'm finding the details of that hard to believe. :-\
https://www.nationalgeographic.co.uk/photography/2020/12/longest-known-exposure-taken-by-makeshift-camera-forgotten-inside-uk-telescope (https://www.nationalgeographic.co.uk/photography/2020/12/longest-known-exposure-taken-by-makeshift-camera-forgotten-inside-uk-telescope)
https://petapixel.com/2020/12/11/shot-with-a-beer-can-this-is-likely-the-longest-exposure-photo-ever-captured/ (https://petapixel.com/2020/12/11/shot-with-a-beer-can-this-is-likely-the-longest-exposure-photo-ever-captured/)
https://twitter.com/BayfordburyObs/status/1337007928499466241 (https://twitter.com/BayfordburyObs/status/1337007928499466241)
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I'm finding the details of that hard to believe. :-\
Well, at least you can prove/dis-prove it yourself relative easily and cheap ? :-//
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'Technology' as per se is not needed to grasp the Basics of photography. It's more like basic electrical!!!
Amps volts ohms watts as opposed to aperture stops, time, film/sensor sensitivity and depth of field etc...
The Basics can be demonstrated with an extremely simple 'pin-hole' camera, made for nothing!! (Oh the memories!).
I used to have a commercial/wedding photographic business, (with my own dark-rooms etc) and when my kids were
starting high-school, the school asked me to run some classes for the interested 'Wipper-snappers'. (Young kids, or
'Carpet-Commandos') on photography. I had made up a 10 page document with words & pics for each kid, to accompany
the talks I would give them, including blackboard diagrams/info, and lots of hands-on equipment... About 2 hours into it,
a kid put up his hand and said... "Mr. Sprigg, I don't understand what you are talking about!"... So I reverted to the most
basic of descriptions, and fabricated pin-hole cameras with them. I'd set up a small store room as a dark-room, and blacked
it out. After taking 'shots' outside, we developed them, and made B&W prints in the dark-room. I don't know what they
really understood, but they took home real prints that they had made! Maybe it instilled some to learn more!!... 8)
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Well, at least you can prove/dis-prove it yourself relative easily and cheap ? :-//
I have developed and printed BW photos, and used a pinhole and paper as the film. :)
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Wow that's pretty cool, so how does this work they put the film inside the can and have a small pin hole for the lens, and I assume some tape to add ND filtering?
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So I reverted to the most
basic of descriptions, and fabricated pin-hole cameras with them. I'd set up a small store room as a dark-room, and blacked
it out. After taking 'shots' outside, we developed them, and made B&W prints in the dark-room. I don't know what they
really understood, but they took home real prints that they had made! Maybe it instilled some to learn more!!... 8)
One of my favourite youtube channels, The Royal Institution, features a gentleman called Andrew Szydlo who showed something similar
https://www.youtube.com/watch?v=y033Dwq2tWU (https://www.youtube.com/watch?v=y033Dwq2tWU)
If you're of a mind, I highly recommend the channel and Szydlo's stuff especially.
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No Pinholes here, but i have a collection of vintage cameras and a setup to process and scan C41 and b/w.
This time exposure-went-wrong is from the cutting room floor.
It looks like the T-Model is arriving from Star Trek. I can't understand how the wheel spokes got bent like that.
Taken with an RB67 , a very good slr medium format camera which uses in-lens leaf shutters.
Edit: "leaf shutters" replace my error "focal plane" as pointed out by Sal and Helius below
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Taken with an RB67 , a very good slr medium format camera which uses in-lens focal plane shutters.
It uses in-lens leaf shutters.
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No fooling, the focal plane cannot be in the lens!
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No Pinholes here, but i have a collection of vintage cameras and a setup to process and scan C41 and b/w.
This time exposure-went-wrong is from the cutting room floor.
It looks like the T-Model is arriving from Star Trek. I can't understand how the wheel spokes got bent like that.
Taken with an RB67 , a very good slr medium format camera which uses in-lens focal plane shutters.
I suspect the bent spokes are the result of a shutter sweeping across the film creating an effect somewhat similar to rolling shutter, albeit at a very different frequency.
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Excuse me on the shutter error. I will edit.
Yes, the Mamiya RB67 used in-lens leaf shutters as noted. I have 3 RB67 lenses here
I also have two Graflex here, and one is a Speed Graphic with the focal plane shutter.
I have various lenses for the Graphlex, including Pentax 6x7 lenses with no shutters, which use the focal plane shutter.
i have used both the Graflex and Mamiya at Greenfield Village where the photo was taken.
Edit photos of the old cameras added, incuding the home-brew metal camera I built in 2012
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[...] I can't understand how the wheel spokes got bent like that. [...]
The wheels rotated a little while the shutter was open, making the spokes bent on the film.
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"The wheels rotated a little while the shutter was open, making the spokes bent on the film."
Yes if it was a rolling down shutter the left and right spokes would be quite different from each other.
I like the last pic of a coin, I'll try it one day at > 1/200 sec.
https://www.diyphotography.net/this-video-helps-you-understand-the-rolling-shutter-effect (https://www.diyphotography.net/this-video-helps-you-understand-the-rolling-shutter-effect)
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But that T-Model photo was on the RB67 with a leaf shutter which is concentric.
I might have photo-diode traces of the penumbra and open-time somewhere of that or a similar RB67 lens.
I will try to find tomorrow and put up here if so.
The camera was hand held.
I do not understand the trajectory that the spokes make.
Anyway, sorry to have hijacked the good pin-hole thread.
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If it was a focal-plane shutter effect, the whole wheels including the rims would be bent, as seen in Henri Lartigue's 1912 shot of the Grand Prix (https://www.francetvinfo.fr/culture/arts-expos/lartigue-luxe-vitesse-et-volupte_175763.html). This amazing picture also shows distortion of the crowd in the background, because the photographer panned his camera to track the car during the exposure (but slower than the car itself).
That effect happens as the position of the wheel in the picture changes during the exposure, enough to be recorded at a different position by the shutter opening as it scans from bottom to top. (The effect only works if the shutter curtains move vertically, so that the wheel and shutter motion are perpendicular to each other.)
In your picture, the shutter moves concentrically, but that is also perpendicular to the direction the spokes move, which is rotatory. So the bending effect looks different, but is caused by the same phenomenon.
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Hi Helius,
I agree that the falling slit focal plane shutter ( Like the Speed Graphic above) exposes the bottom of the image first (upside down on film),
and takes time to get to the top, which causes the "race car" distortion of the car leaning forward.
In the concentric leaf shutter, if considering the optic (ray tracing) the mode is quite different.
The shutter opens as the smallest pinhole.
The light at that time exposes the whole film plane, as Bravo's example in post one shows.
As the leaf shutter continues to open to the aperture setting ( I would have used F11) ,
the light intensity increases over the whole film frame, then reverses as it closes.
So there are no shutter "slit effects" where the timing of the exposure varies over the film plane.
Exposure all happens simultaneously with a leaf shutter.
The spoke outer ends near the ground are almost stationary, while the spoke ends at the top are moving at 2 X the car speed.
That effect is observable on the T-model.
But I can't understand why the spokes moving vertically, in front of , and behind the axle, are both tilted downward.
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There could be an effect of incident light (or lack of light, e.g. a cloud or a tree or a building) getting reflected differently in the spokes as they rotate?