Planning a Twilight Shot
- By: Luis Argerich
The photo above shows a conjunction between a 3% crescen moon, Venus and Mercury seen from a rural area of Argentina. Sometimes you are lucky to get such a nice view and be there with your camera but many other times shots like this one require some planning. In this small article I will discuss some useful tools to plan your twilight shots.
The first tool I use is Stellarium (from www.steallarium.org) this application can show the sky at any time from any location in the world, you can select the location from a list or just entering latitude and longitude so it also works for remote locations. In stellarium you can scan the sky from sunset until the night begins looking for interesting things in the sky. The moon and bright planets like Venus, Jupiter and Mercury present the best photo opportunities. Once you find a view that you like the next step is to plan which lenses you need to take the photos you want.
I wanted a wide view of the conjunction so I adjusted the zoom tool in stellarium until I was seeing something like what I wanted for the shot. I took note of the field of view that Stellarium was reporting, in this case 19 degrees.
I also wanted a closeup view of the conjunction, zooming in I took note of the field of view needed for the shot: 5 degrees.
Then I used an online tool from Howard Edin (http://www.howardedin.com/articles/fov.html) to calculate the field of view of lenses for my camera to decide which focal lengths were needed for the shots I wanted.
For the wide angle shot I needed a lens with 19 degrees in horizontal field of view, that’s a 105mm focal length for my camera. For the closeup shot I needed a 5 degree field of view about 300mm focal length for my camera. So I took a 70-200 lens with a 1.4x extender knowing that it will be suitable for the shots I was planning.
The wide angle shot.
And the closeup shot.
The last step in planning is to select a location for the shot. For that you can use a great application known as “The photographer’s ephemeris” from Stephen Trainor. (http://photoephemeris.com/)
TPE can be used to display the direction of sunrise, sunset, moonrise and moonset from any location. It also provides information about sunrise and sunset times, moonrise and moonset times as well as twilight. This conjunction was visible after sunset so I looked for a rural area with a clear horizon in the direction of sunset.
Then after the planning was done you just have to be there at the right time with the equipment you selected. If things went well you will see exactly what you expect to see at the right time.
This set of tools is really nice to plan shots including the moon, conjunctions, sunrises and sunsets and unless you are very lucky they will help you save plenty of time.