{"id":15797,"date":"2016-06-26T05:46:10","date_gmt":"2016-06-26T09:46:10","guid":{"rendered":"http:\/\/briansolomon.com\/trackingthelight\/?p=15797"},"modified":"2016-06-21T08:59:53","modified_gmt":"2016-06-21T12:59:53","slug":"mbta-at-mansfield-photographing-led-displays","status":"publish","type":"post","link":"http:\/\/briansolomon.com\/trackingthelight\/mbta-at-mansfield-photographing-led-displays\/","title":{"rendered":"MBTA at Mansfield; Photographing LED displays\u2014five images."},"content":{"rendered":"

The MBTA platforms at Mansfield, Massachusetts feature modern information displays.<\/p>\n

As with many modern signs used by\u00a0passenger railways these use light emitting diodes (LEDs).<\/p>\n

You may have noticed that although LED displays seem clear to the eye, in many instances they do not photograph well and appear in your pictures as random spots rather than full letters and words.<\/p>\n

This occurs because many LED systems pulse on and off at a rapid rate. You eye cannot detect this pulsing and so you see a steady light, but when a photograph is made at higher shutter speeds, the exposure may capture an LED during the \u2018off\u2019 portion of the pulse sequence.<\/p>\n

Since the LEDs may not be synchronized with each other, the result sometimes appears as a random collection of spots (each is an individual LED) or if they are synced the pulse may be coupled with a scanning effect that results wide gaps of LEDs in the \u2018off\u2019 portion of the sequence. (Such is the case at Mansfield).<\/p>\n

This unfortunate effect is especially pronounced when the message is scrolling laterally.<\/p>\n

One effective way to\u00a0expose images of LED displays is to set your camera to a slower shutter speed. This will allow the shutter to stay open for a full pulse cycle.<\/p>\n

I\u2019ve found that shutter settings of 1\/60th<\/sup> of a second or less will usually work effectively. (It helps to test this, as display pulse rates vary).<\/p>\n

Below is a sequence of images that I made at various shutter speeds to demonstrate the effectiveness of slower shutter speeds in regards to the LED display. In each situation I\u2019ve used an equivalent shutter speed\/aperture combinations to allow for uniform exposure between images.<\/p>\n

\"Exposed
Exposed at 1\/250th of a second. Notice the black line as the result of high frequency on-off pulse combined with a scan effect.<\/figcaption><\/figure>\n
\"At
At 1\/125th of a second the effect is less pronounced but still annoying. Please note that the bottom part of the message is scrolling from left to right.<\/figcaption><\/figure>\n
\"1\/60th
1\/60th of a second works well in this instance.<\/figcaption><\/figure>\n
\"This
This final view was exposed at 1\/30th of a second during an interval when the scrolling bottom line of the message was not displayed.<\/figcaption><\/figure>\n

In this instance the MBTA train was stationary as it discharged passengers.<\/p>\n

Obviously, using slow shutter speeds with rapidly moving trains will present other problems. No solution is perfect.<\/p>\n

Tr<\/span>acki<\/span>ng<\/span> th<\/span>e Lig<\/span>ht po<\/span>sts<\/span> dai<\/span>ly.<\/span><\/span><\/h3>\n","protected":false},"excerpt":{"rendered":"

The MBTA platforms at Mansfield, Massachusetts feature modern information displays. As with many modern signs used by\u00a0passenger railways these use light emitting diodes (LEDs). You may have noticed that although LED displays seem clear to the eye, in many instances they do not photograph well and appear in your pictures as random spots rather than … Continue reading MBTA at Mansfield; Photographing LED displays\u2014five images.<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":15800,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_s2mail":"yes","jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"footnotes":"","_jetpack_memberships_contains_paid_content":false,"jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[10,48],"tags":[3786,3622,3621,2791,790,3623],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/briansolomon.com\/trackingthelight\/wp-content\/uploads\/2016\/06\/MBTA_1027_Mansfield_DSCF9100.jpg?fit=2449%2C1633","jetpack_shortlink":"https:\/\/wp.me\/p2BVuC-46N","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"http:\/\/briansolomon.com\/trackingthelight\/wp-json\/wp\/v2\/posts\/15797"}],"collection":[{"href":"http:\/\/briansolomon.com\/trackingthelight\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/briansolomon.com\/trackingthelight\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/briansolomon.com\/trackingthelight\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/briansolomon.com\/trackingthelight\/wp-json\/wp\/v2\/comments?post=15797"}],"version-history":[{"count":3,"href":"http:\/\/briansolomon.com\/trackingthelight\/wp-json\/wp\/v2\/posts\/15797\/revisions"}],"predecessor-version":[{"id":15801,"href":"http:\/\/briansolomon.com\/trackingthelight\/wp-json\/wp\/v2\/posts\/15797\/revisions\/15801"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/briansolomon.com\/trackingthelight\/wp-json\/wp\/v2\/media\/15800"}],"wp:attachment":[{"href":"http:\/\/briansolomon.com\/trackingthelight\/wp-json\/wp\/v2\/media?parent=15797"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/briansolomon.com\/trackingthelight\/wp-json\/wp\/v2\/categories?post=15797"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/briansolomon.com\/trackingthelight\/wp-json\/wp\/v2\/tags?post=15797"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}