Blur Busters Forums

Who you gonna call? The Blur Busters! For Everything Better Than 60Hz™ Skip to content

Motion blur in old photography - long exposures 19th century

All Unidentified Forum Objects go in this area! Any fun alien talk goes in this U.F.O. Abduction Lounge, even topics other than monitors or computers.

Motion blur in old photography - long exposures 19th century

Postby Chief Blur Buster » 12 Dec 2014, 19:33

There was once upon a time that photography shutter times were so slow, they had never captured portraits or humans in pictures. The first photograph, 1826, was of a stationary scene. It was not until 1838, when humans were accidentally captured and observed on photograph:

Image
This is a busy street with lots of carriages and pedestrians!
But where are they? They are invisible because of motion blur!

See the person at the shoeshine, standing still:
Image

The rest of the photograph doesn't show anything because all the pedestrian traffic & horse carts are so motionblurred because camera exposure (persistence) was a full 7 minutes! At this level, blurring becomes so faint and prolonged that moving objects are rendered imperceptible. The photo film is so insensitive to momentary changes.

It apparently took many months (after this photograph) before people figured it out, that people had to stay still in order to be photographed! In this early photography era, people such as Sameul Morse (inventor of morse code) apparently thought it was very strange/amazing that moving objects were rendered invisible in photography.

As exposures shortened to less than a minute, you finally saw faint motion blur in moving objects. And exposures became shorter, there was less motion blur, and you finally could eliminate motion blur with ultrafast shutters or ultrafast flash photography. But when image persistence is several minutes, most moving objects becomes invisible to the human eye!

As a thought experiment, to understand this better, you take a camera photograph of a human walking at average speed:
Motion blur for 0.001s shutter -- clear photograph
Motion blur for 0.1s shutter -- slightly blurry
Motion blur for 1s shutter -- super blurry
Motion blur for 5s shutter -- very blurry and ghostly motion. Clear background shows through.
Motion blur for 15s shutter -- faint ghostly smear that's mostly see-through to background.
Motion blur for 1min shutter -- super faint smudge smear, almost no evidence of motion. Background perfect looking.
Motion blur for 5min+ shutter -- smudge is so imperceptible it completely disappears from human eye.
Motion rendered invisible by motion blur!
Head of Blur Busters - BlurBusters.com | TestUFO.com | Follow @BlurBusters on Twitter!
To support Blur Busters: Official List of Best Gaming Monitors | G-SYNC | FreeSync | Ultrawide
User avatar
Chief Blur Buster
Site Admin
 
Posts: 3760
Joined: 05 Dec 2013, 15:44

Re: Motion blur in old photography - long exposures in 1800s

Postby blargg » 12 Dec 2014, 21:54

Oh nice, this sets up a continuum between that image above of the eerily empty city, and a monitor with strobing. As the strobe gets longer, things get blurry (more faint at the edges). As persistence lengthens, the blurry edge consumes the object and thus the whole object gets more faint. Keep increasing persistence and objects effectively get smeared over the whole of their movement path (including when they're "off-screen"), and thus so faint that they are invisible. This is the sample-and-hold continuum that all non-strobed displays are inherently part way along, and why they cannot solve it without directly addressing the holding of the image.
blargg
 
Posts: 66
Joined: 20 Sep 2014, 03:59

Re: Motion blur in old photography - long exposures in 1800s

Postby Chief Blur Buster » 15 Dec 2014, 22:08

Yep, it's a continuum.
As strobe length lengthens to full frame, you've got a full frame's worth of persistence.
And when you're not strobing, more persistence (e.g. persistence longer than a refresh cycle) is accomplished by slowing the LCD pixels further (33ms, 100ms, etc) and you've got even more blur. Until things ghost/smears so much.

Display persistence is like a camera shutter.
X milliseconds of display persistence produces the same amount of motion blur as X milliseconds of camera shutter. The distance the image has moved over the time period of persistence/shutter -- so 16.7ms of persistence (blur on display) creates the same amount of sample-and-hold motion blur as a 16.7ms camera shutter (blur in picture), for a moving object moving at the same relative speed (e.g. 1mm of motion blur per 60mm/second motion, since 16.7ms is about 1/60sec).
Head of Blur Busters - BlurBusters.com | TestUFO.com | Follow @BlurBusters on Twitter!
To support Blur Busters: Official List of Best Gaming Monitors | G-SYNC | FreeSync | Ultrawide
User avatar
Chief Blur Buster
Site Admin
 
Posts: 3760
Joined: 05 Dec 2013, 15:44

Re: Motion blur in old photography - long exposures in 1800s

Postby spacediver » 15 Dec 2014, 23:06

just an fyi, this thread got me thinking about something. Discussion over here: viewtopic.php?f=7&t=1674
spacediver
 
Posts: 482
Joined: 18 Dec 2013, 23:51


Return to Offtopic Lounge

Who is online

Users browsing this forum: No registered users and 2 guests