The Blue Hour: a Quieter, Harder Shot Than Golden Hour

Golden hour gets the marketing budget. Blue hour gets a passing mention. That is backwards. Blue hour is the more technically demanding of the two, it lasts less time at most latitudes, and when it works it makes cities look like nothing else does.

What blue hour actually is

Blue hour is the period when the sun is below the horizon by roughly four to eight degrees. The direct sunlight is gone, but the upper atmosphere is still being lit, and from underneath that scattering looks like a clean, uniform, saturated blue. Wikipedia's page is decent if you want the formal definition.

It happens twice a day: between civil twilight and nautical twilight in the morning, and again in reverse in the evening. The label "hour" is generous — at mid latitudes it usually lasts twenty to forty minutes; at the equator more like ten to fifteen.

Why it is harder than golden hour

Golden hour exposure is easy. Your scene is lit by warm low-angle sunlight, your highlights are obvious, you pick a shutter speed and go. Blue hour is harder for three reasons.

• Dynamic range collapse. Just after sunset, the sky is still much brighter than the foreground, but it drops fast. Within minutes the balance flips and your foreground (especially with city lights) becomes brighter than the sky. The sweet spot where both expose nicely is short.
• White balance trap. Cameras want to push the blue back to neutral. If you let them, the photo will look like an ordinary muddy dusk. Lock daylight white balance to keep the saturation.
• Tripod required. Hand-held is hopeless. You need long shutter times, often two to fifteen seconds depending on aperture and ISO. A solid tripod and a remote release are non-negotiable.

Where blue hour shines

The killer combination is blue sky plus warm artificial light. Office windows, street lamps, neon. The colour temperature contrast between the deep blue sky (around 9000 K) and tungsten lamps (around 3000 K) is what makes the photo pop. A modern city at blue hour with the lamps on is unbeatable.

Skylines are the obvious example. Berlin from Klunkerkranich, Tokyo from the Bunkyo Civic Center observation deck, Hong Kong from the Peak. All of these are different shots at blue hour than at golden hour, and arguably better. The blue lifts everything.

The exposure recipe

Start with these as defaults, then bracket aggressively because blue hour changes fast.

• Aperture: f/8 to f/11 for landscape sharpness, f/4 if you need shorter shutters.
• ISO: base ISO, usually 100.
• Shutter: let it land where it lands. Often 2 to 8 seconds.
• White balance: manual daylight (5500 K). Do not let auto fight you.
• Bracket: at least three exposures. The sky will be over before you can chimp twice.

How to know when blue hour starts where you are

The simple answer is to look at the timeline strip in sunhour. Find the band between civil twilight ending and nautical twilight ending, and that is your evening blue hour. Reverse it for the morning. Be on location and set up at least ten minutes before that band starts. The transition can be faster than you expect, especially closer to the equator.

Why so few people do it well

Because it is uncomfortable. Sunrise blue hour means being on a windy rooftop in the cold half an hour before there is any reason to be. Sunset blue hour means staying after everyone else has packed up and gone for dinner. The light rewards the people who stay an extra twenty minutes. Most do not.

Stay. The blue hour is the underrated shot.