Long Exposure Photography Tips by Francis Audet

Francis Audet is renowned for shooting stunning images in natural light. His long exposure photographs of stars, headlight trails and the Milky Way Galaxy are mesmerising to say the least. If you want master the technicalities of long exposure photography, read on his interview with PhotoConcierge.

What settings would you recommend to take images of star trails and headlight trails? 

There is not one single set of settings. It depends on several factors, such as the speed of the movement (relative to our position, a star moves much slower in the sky that a passing car), the brightness of the moving object, and the desired final output, as well as the lens used.

Photo by: Francis Audet

Photo by: Francis Audet

A star trail takes a lot of time. With a wide-angle lens, anything less than 1 minute will do a blurry star, not truly a trail per say. That being said, a 20-minute exposure will gather a lot of noise and light pollution, and it can be quite depressing to realize, 20 minutes later, that your settings were off. As such, for star trails, it is best to do composite images, meaning several images of shorter exposure. Each one individually will not show trailing, but when they are stacked, then the trailing appears. There are some great freewares that offer fantastic star stacking capabilities. Be sure to turn OFF you Noise Compensation setting (cameras, by default, always take a second shot with no light hitting the detector, and subtract this from the real shot to compensate for example for hot pixels). We are seldom aware of this delay since when we shoot at say 1/1000 seconds, a second exposure of that length goes un-notice. On a 10minute shot, the dark shot is also 10minute, making long waiting time, but more importantly well the star does not stop during that minute… so you will have dashed trails when you stack instead of a continuous trail.

Photo by: Francis Audet

Photo by: Francis Audet

Headlights are much brighter and move very fast. The important thing here is to find the balance. Not over-expose the shot, but still have a nice trailing effect. It is very much a trial and error thing, as each occasion is different.

Another important aspect is that any night shot that is close to a city will capture the Sodium Vapor light from city lights, street lamps, etc, and will give a copper-aspect feel to the image. Either in-camera, or in post-processing if the file format is RAW, the white balance for Sodium Vapor needs to be compensated for.

What kind of gear and set up is indispensable for long exposure shots?

There are two pieces of gear absolutely required, and both serve the same purpose: keeping the camera as stable as possible. First is a stable and I mean very stable (especially for hour-long trails) tripod, and the second is a remote trigger, to avoid all physical contact with the camera when you trigger the shot.

Depending on your location and the time of the year, dew can occur during long night expeditions due to the drop in temperature. Cold air contains less humidity than warm air, so the excess humidity will condensate and blur your lens, ruining your shots. The best, and really only way to avoid this, is to find a way to keep your lens warm. Electronic warmers exist, and that is what I use personally.

What are the aspects one needs to keep in mind while scouting locations for photographing stars?

Photo by: Francis Audet

Photo by: Francis Audet

The first and foremost important aspect is light pollution. The darker the sky, the better the image and the star field visibility. Sky clarity is of course paramount… Clouds, or a bright moon, even if far from any city, will ruin sky shots.

Then it is the field of view. A flat horizon will produce a larger starfield than a location with a mountain range.

Finally, any element that is in the field of view of the image that is brighter than the stars themselves will turn out extremely bright on the final shot, since you will likely use long exposure and high ISO to pick up the stars. On the other hand, every object that does not emit light will likely be dark or black on the final shot, so these will create silhouettes on the final capture.

What are the elements involved in photographing the Milky Way galaxy?

Photo by: Francis Audet

Photo by: Francis Audet

The Milky Way is very tricky to capture, as most of it is very dim. One requires high ISO and long exposure, but one also wants a sharp end-result, so exposure needs to be short enough to prevent any star movement. The larger the field of view (smaller focal length, or larger angle lens), the longer the exposure will be before noticing movement. A wide-angle lens can typically shoot between 45 and 60 seconds before star blurring. This is OK to capture bright stars, but limit to capture the dim light of the Milky Way. You really need a camera that performs well in very high ISO, and also need to be at a very dark location. Any light pollution will be picked up by the high ISO and prevent the shot.

The Milky Way is also very seldom a great shot out of the camera. While I am not a fan of extensive post processing, the Milky Way does require a fair amount of it, so do not be disappointed by the In-Camera shot. Be sure to shoot in RAW, be patient, and fine-tune your post-processing skills.

Also, not all seasons provide a nice view of the brightest milky way section. Don’t try to shoot something that is not optimal in the sky.

What filters do you recommend using while shooting long exposure shots?

I do not use any filters, except a good UV Filter to protect the lens from excessive dew possibilities.

What are your tips on composing a good long exposure image?

Most of the photographic rules of composition can apply, depending on the photographer’s inspiration. If doing star trailing, a body on water that will produce reflection of at least the brightest start will add a lot of depth and added value to the shot.

For long exposures, for trailing for instance, be wary of foreground elements that may move during the long exposure. Trees are very nice, but on a windy night, leaves, and branch may move, blurring the image. Human (or animal) silhouette may not stay put forever either.

For headlights, try to have curves, or diagonals. Have the cars enter the image, not exit them, and have a clear view on the fix elements, to put a context to the moving lights (headlight trails on a bridge, or through buildings, on a winding street, are all better than just the lines of the headlights with no context and surroundings).

Can you elaborate on how you shot the following images?

Photo by: Francis Audet

Photo by: Francis Audet

For this shot, instead of having other objects (cars) moving, the camera was moving. The tripod was fixed in the car, on the back seat, and while I was driving in the city, the camera was taking (via remote trigger on my lap) long exposure images. Not being able to see the results as I was driving, the whole time I was triggering shots, I was counting different time lapses, ranging from a few seconds to almost one minute, not knowing what would produce the best results, and because the brightness of the scenery was ever changing. For this, exposure time was set on BULK to allow different exposure times without changing any settings.

Photo by: Francis Audet

Photo by: Francis Audet

This shot was taken exactly as described above for star trails. I knew Northern Lights were active on that evening, so the camera set-up was made to optimize Aurora Borealis images. Since by nature Auroras are always changing shape and brightness, I knew I wanted to take maybe all-night long shots, or at least as long as the auroras were very active. It was only the next day when I looked at all the shots that I tried to see what a star-trail stacking would do. By zooming in on the image we clearly see that the trails are dotted lines, since my noise cancellation was not turned off.

Photo by: Francis Audet

Photo by: Francis Audet

This is a national park, Hopewell Rocks, in Canada. The most complicated part of this shot was having access to the park after closing hours, signing the weavers, etc. But once on location, I just waited for the milky way to be positioned where I was wanting it to be with the rocks as foreground silhouettes. Since there was high humidity, I had a complete lens and camera warming gear to avoid condensation on my lens. Then I applied the Milky Way tips I highlighted earlier.

What is your advice to amateur photographers trying their hand at long exposure photography?

Once you have the appropriate gear, then the same tip applies to any type of photography: read, prepare, practice, be patient, and ask yourselves questions on why and how did that picture not turn out the way you were hoping… Challenge yourself and learn from failed attempts. We all did some, and we all will do some again, amateur or not!

Check out more stunning images by Francis Audet here: http://phtocon.co/3860v2

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