Jump to content
Julesimages

What has happened to the motion blur here?

Recommended Posts

Anyone able to explain what has happened to the B's on the bus in this picture please?  I don't understand why they aren't a blurred streak like the rest of the bus? I could understand one B at the end or beginning of a streak but not all those multiple B's!   The exposure was 1/8th second at F4

 

 

DR20BW.jpg

Share this post


Link to post
Share on other sites

Anyone able to explain what has happened to the B's on the bus in this picture please?  I don't understand why they aren't a blurred streak like the rest of the bus? I could understand one B at the end or beginning of a streak but not all those multiple B's!   The exposure was 1/8th second at F4

 

 

DR20BW.jpg

 

 

Because it was a cold night (if it had an R at the end)! ;)

Share this post


Link to post
Share on other sites

That's the LED destination board, probably showing the route number as well.

Characters on an LED display are formed by successive illumination- one LED is lit up at any one time and it's only persistence of vision which makes them appear continuous.

Photograph one with a shutter speed faster that about 1/60 and you will get a partial image.

So he has captured successive scans of the same number during the long exposure.

Edited by spacecadet
  • Upvote 1

Share this post


Link to post
Share on other sites

Ah, that's simple. But first I'd like to explain to you about the Meaning of Life. . . . 

Share this post


Link to post
Share on other sites

That's the LED destination board, probably showing the route number as well.

Characters on an LED display are formed by successive illumination- one LED is lit up at any one time and it's only persistence of vision which makes them appear continuous.

Photograph one with a shutter speed faster that about 1/60 and you will get a partial image.

So he has captured successive scans of the same number during the long exposure.

BBBBBBBBBBBBBBBBRAVO!

Share this post


Link to post
Share on other sites

I think Spacecadet is close. My understanding is that the whole LED panel flashes on and off. The amount of time On is the apparent brightness.

 

Car LED tail lights are doing this now I notice. Medium brightness using a repeating cycle where the On time is about 50%. When the car brakes are applied they go brighter to 100% On time. The cycle frequency is usually just above human eye perception but try this: hold your head still, swing your eyes around quickly in a large circle, and mentally see if you can pick up dots or streaks. Dots will be the blinking LEDs, streaks will be 100% on LEDs or incandescent.

 

Spacecadet might also be right if the case is a "moving" image on the display. The image shows a B, then the image panel goes Off and the B steps one LED to the left, then the image lights, and repeats. The bus and the lighted/blinking sign are speed mismatched enough that each successive sign blink is at a different bus location by enough distance to be able to see the individual blinks.

Share this post


Link to post
Share on other sites

Ah yes!  It must be the LED's.  Other pics I have at the same time show a similar thing happening with destination text etc. whereas the tail lights are blurred.  Thanks everyone for helping solve the mystery!

Share this post


Link to post
Share on other sites

When the next generation of buses come out they'll have LED tail lights too.

Share this post


Link to post
Share on other sites

I counted eleven B's in your pic, so the L.E.D's were blinking at 88 times per second, as your 1/8th second exposure captured the LED blinking 11 times.

 

Parm

Edited by Bhandol
  • Upvote 1

Share this post


Link to post
Share on other sites

All the while the person that took the pick is all of a sudden wondering where this sale is coming from all these zooms  :D

 

( I know. Stats are for registered buyers only) 

  • Upvote 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.