Tips for photographing constellations

Living in a Bortle Four, a.k.a. a pretty dark place, constellations can be difficult to render. The star pattern is very discernible to the eye. Yet the camera captures so many more stars the pattern gets lost. In even Lower score Bortle One areas, it’s even worse. For the unfamiliar, Bortle One shows the most stars with no light pollution. Bortle Nine, forgeddaboutit! Fear not, there is an alternative. Here is one I found.

Capture

When making the image make sure that the stars are point sources with no trailing. You may have heard of the “500 Rule” to accomplish that. Old news, my friend. Modern camera sensors have gotten so strong in capturing light this no longer works for spot stars.

There’s a phone app called PhotoPills that gives you tons on information about the night sky and all things celestial. Sun, moon, Milky Way tracks and position at any time of the year in any place. The Spot Stars feature gives you the latitude to give you spots stars that are super sharp or just acceptably sharp. What is the difference? If you are only making an image that is to be viewed online or printing small images there’s room to play. If you print larger any streaking will be magnified.

Photo of the same sky as the header image above with no filters. Notice how difficult it is to ‘read’ the constellation Orion against the star field.

The problem

There is a strange phenomenon viewing constellations in dark sky areas. The constellation is quite visible to the naked eye. When you make a longer exposure the stars in the distance, even though they are smaller, make it difficult to find the star of the show. There are a couple of workarounds.

Another example of the full Orion constellation with no filter and slightly different camera settings. Below see the constellation and result from softening the image.

Orion with a diagram showing the constellation over soft focus filter image.

Final Orion image made with Tiffen soft focus number three warm filter. Color adjusted in post production in Adobe Photoshop.

A fix

While capturing the constellation Orion I ran into this problem. After some research I found a way to make the constellation stand out during capture. Adding a soft focus filter makes the brighter foreground stars stand out and the smaller less bright stars recede. In this case, I used a Tiffen warming soft focus filter. I adjusted the warm color in post to slightly cooler for a more natural look. While I didn’t try it as yet, I’ll bet you can add a nylon stocking stretched tight over the lens for a similar effect.

Yours in Creative Photography,

Bob

• Posted on October 21, 2024