ISO 400 / f/5.6 / 30 SECONDS - TAKEN AT 5:17 P.M.
Did you know "the blue hour" comes from the French expression l'heure bleue, no wonder I'm falling in love with it. It refers to the period of twilight when there is neither full daylight nor complete darkness. A "blue hour" happens twice each day - once in the morning and once in the evening, and is a brief period of time (not an hour) when the quality of ambient light for photography is superb.
Without going in to too much detail, I should mention that there are three widely accepted subcategories of twilight and the NOAA (National Oceanic and Atmospheric Administration) defines them as follows:
- Civil Twilight: the time at which the sun is 6 degrees below the horizon. At this time, there is enough light for objects to be clearly distinguishable and that outdoor activities can commence (dawn) or end (dusk) without artificial illumination. Civil twilight is the definition of twilight most widely used by the general public.
- Nautical Twilight: the time when the center of the sun is 12 degrees below the horizon, and only general or vague outlines of objects are visible. During the evening this is when it becomes too difficult to perceive the horizon, and in the morning this is the point when the horizon becomes distinguishable. This term goes back to the days when sailing ships navigated by using the stars.
- Astronomical Twilight: the time at which the sun is 18 degrees below the horizon. It is that point in time at which the sun starts lightening the sky. Prior to this time during the morning, the sky is completely dark. During the evening, this is the point where the sky completely turns dark.
The "blue hour" straddles the end of civil twilight and most of nautical twilight. To us lay-people, it's after sunset and usually when we would pack up our gear and go home, but we shouldn't for the best is yet to come.
I'm learning so much in this Night Photography eClass I'm taking with Kent Weakley. First I've learned that the "blue hour":
- does exist
- is incredibly beautiful
- can't necessarily be seen by the naked eye, and
- happens "come rain or shine".
To get the best results shooting at this hour, you have to have a tripod, and a remote control or timer on your camera because your exposures can be very long. Some of mine went a full half minute, and many wanted to be even longer, and I could never have stayed still handheld for that long.
It's also a big help to have an app or two to help you pinpoint exactly when l'heure bleue will be. I've been using an app called "Daylight" for the last couple of years which shows exactly when the three twilights are on a twenty-four hour clock. (An added benefit is that it also shows the phase of the moon.) Kent introduced me to another app called The Photographer's Ephemeris (TPE) which is available for free for a computer and for a charge for handheld devices. Ephemeris, according to my very good friend Merriam-Webster, is "a tabular statement of the assigned places of a celestial body for regular intervals" which means it shows you where the sun and moon are or will be. Both are helpful tools if you want to capture l'heure bleue.
These are my first attempts at Blue Hour photography? What do you think?
ISO 200 / f/10 / 15 SECONDS - TAKEN AT 4:54 P.M.
ISO 100 / f/18 / 30 SECONDS - TAKEN AT 6:24 A.M.
ISO 100 / f/20 / 3 SECONDS - TAKEN AT 6:36 A.M.
You'll rightly note that the evening and morning shots were taken quite late. I'll get out much earlier the next time.