How to Shoot a Transition Timelapse

Bulb Ramping ( Transition Timelapse)

Some say the “holy grail” of time-lapse photography that captures the transition from day-to-night or night -to-day.  It is a skill that requires the photographer to deal with the subtle or dramatic changes in light between sunset and/or sunrise.  Controlling the right exposure from the start to the finish of the time-lapse.  After this, the final sequence is edited into a smooth transition.

This process can be done in a number of ways.  One is to manually monitor the exposure of the time-lapse. For example, set the shutter speed between the shots to control the right exposure throughout the sequence. 

Automatic bulb ramping devices, such as Michron from Alpine labs www.alpinelaboratories.com  and Miops  www.miops.com  Control the exposure from start to finish. There require time to set up for the best results.and involve a good amount of trial and error before shooting your sequence.

The other easier way is to cheat a little and Cross –dissolve two time-lapses shot from identical positions. One shoot in the day and the other at night. The two time-lapse sequences are then subtlety blended together.

In my setup, I decided to shoot manually and at home, out of my office window, for ease. This helped with this fairly advanced method as it can take a few attempts to get the right result.

The day before I shoot the timelapse, I took an exposure reading of the scene at the desired start time of 20.50 HH ( ISO 400 1000/2.8 ) and at the end 22.20 HH(ISO 400, 4sec /2.8). Between 20.50 and 21.50 the sunset to night time/ Starlight, this was when the majority of change in exposure happened. You can either calculate the set times to change each exposure or do it by eye, using the cameras inbuilt exposure meter.

As the rate the light changes is exponential and not linear, an exact change depends on latitude and time of year. The light can fall somewhere between twice or three times as fast.  I shot with 15-second intervals using a remote shutter trigger and kept a close eye on the exposure as the light levels changed and adjusted accordingly.

This technique is not called the Holy grail for anything! it’s sometimes difficult and challenging, but very rewarding when you get it right.