Cheating the 'holy grail' of time-lapse: How to shoot dynamic day-night sequences without bulb ramping
The holy grail of time-lapse - capturing the transition from day-to-night or night-to-day - is so called because of the skill required in dealing with the large change in light that occurs at sunrise and sunset.
The most common method for capturing the transition is bulb ramping, where you slowly step up (or down, depending on whether you're shooting sunrise or sunset) the exposure and later edit the sequence into a smooth exposure transition.
Necessity is the mother of invention and as photographers have worked to capture holy grail transitions they have invented a number of great tools.
On the shoot, you can use the bulb-ramping feature built into some intervalometers (such as Promote Control, Timelapse+, Little Bramper and Ramper Pro) to incrementally change the exposure over a set time period automatically.
In post-production you can use the fantastically helpful Holy Grail Workflow in LR Timelapse* and Adobe Lightroom's 'Match Exposure' to turn your exposure changes into smooth transitions.
How to cheat the holy grail
There is a lesser-known cousin of the day-night transition and that is the day-night cross-dissolve.
A day-night cross-dissolve shows the same place at, you guessed it, both day and night, and it can be made to look so much like a transition that it's hard to pick the difference.
It also requires less fiddling with exposure during the shoot and less editing in post-production (at least with regard to exposure changes - you'll still need to pretty-up the photos and edit the cross-dissolve!).
How to achieve the day-night cross-dissolve
The day-night cross-dissolve is essentially a hybrid of standard time-lapse and the time-study method made popular by nature documentaries (taking video footage from exactly the same position at regular intervals and then slowly cross-dissolving between them).
It is the same as the time-lapse technique used in this great video by Jamie Scott of the changing seasons in Central Park, NY (which we've previously featured here).
To achieve these cross-dissolve shots for a day-night sequence, you need to shoot a standard time-lapse during the day and then another from exactly the same place during the night.
This means you only need two exposure settings - one for day and one for night - and you don't need to change exposure mid-sequence.
It also means that you don't have to smooth out multiple exposure changes in post-production.
Instead, you compile the two sequences on their own and then create a long cross-dissolve transition between them.
Voila! You've created a day-night 'transition' without having to ramp and edit exposure changes.
When to use day-night cross-dissolve
On the one hand, a day-night cross-dissolve is (/may be!) easier to shoot and edit than a bulb-ramping transition.
The flip side is that you have to stay in the same place longer to shoot two sequences several hours apart, instead of just one.
As with all things, it's horses for courses; so, how do you decide which is more suitable?
As well as working out how much time you want to stay in the one place and how confident you are with your editing skills, the decision on which method to choose will be influenced by exactly what you're trying to capture.
Are you trying to capture the actual light transition or are you trying to show the difference between a scene at night and at day?
If you want to capture the sun rising or setting over the prairie, i.e you want to capture the transition between day and night, then there is no way to cheat the holy grail - bulb-ramping is the way to go.
But, if you want to show the difference between day and night at a bustling street market that lights up like a rainbow at night (like the merry-go-round in Marc Donahue's video above), then a cross-dissolve may suit better.
Adding dynamic motion to the cross-dissolve
You will have noticed in Marc Donahue's video that his day-night cross-dissolves are dynamic (i.e moving).
Marc has not just taken two time-lapses from the same position, but two time-lapses from the same position and with exactly the same movement. What enables Marc to do this is the fantastic TB3 three-axis control system from eMotimo.
One of the outstanding features of the TB3 is that motion sequences are fully repeatable.
With the simple click of a button (on the TB3's cool Wii-style controller), the TB3 will perform the same shoot-move-shoot (or smooth movement if shooting video) motion sequence time and time again.
With the click of another button, you can also perform the same movement in reverse.
This repeatability allows for some very cool cross-dissolving of moving footage in all sorts of scenarios, such as featured in eMotimo's Thanksgiving greeting.
And, as Marc has shown, it allows for some fantastic day-night dynamic time-lapse.
Other holy grail techniques?
Bulb ramping and cross-dissolve are not the only techniques for shooting day-night sequences.
Dynamic Perception (whose sliders incidentally integrate really well with the eMotimo TB3) have listed a range of techniques for capturing the holy grail, including fully auto (aka the "newbie" approach) and exposure bracketing.
There is also a wealth of holy grail information on Gunther Wegner's LRTimelapse site and a great how-to by Preston Kanak, complete with 50 minutes of video tutorial.
Do you know of any other techniques for shooting day-night sequences?
Or is there a particular technique you're keen to try?
Let us know if you've stumbled across a new way to tackle the holy grail!