Pushing the image

As someone who really got into landscape astrophotography from doing time lapse sequences, one thing that has been a constant challenge is getting just the right amount of light on the foreground subject in a short exposure to capture sufficient detail. Too much light and you risk blowing the highlights or having a foreground subject that dominates the composition and looks out of place, not enough light and detail recovery can look muddy and over sharpened. Luckily time lapse sequences are somewhat forgiving here as a single image is only displayed for a fraction of a second. What if you want to take some of these frames and edit them for still photography though? Can you push the image of these single short exposures to a satisfactory level for print?

Well, the short answer is no. At least not something I would feel comfortable charging people money for. There really are no shortcuts here, even when using modern cameras with advanced sensors, photons are what ultimately render the image on your camera’s sensor. To render a better, cleaner images, simply capture more photons. For untracked landscape astrophotography, and especially time lapse sequences being taken on a slider or rotator, the parameters here are pretty much set in what you can do here. Fastest lens you can get with your exposure value set to the highest allowed by the NPF rule.

I was lucky enough to get out for two shoots recently before the world went lockdown crazy. One night was a new moon, even with my eyes adjusted to the dark I could not see my hand in front of my face. The other was a few days after, however this was in a town with two street lights about 70+ metres away which resulted in my foreground target being way over illuminated for the composition. The following images are examples of what I was able to produce with these single exposures coming from my Sony A7S.

Image taken with a Sony A7S and Samyang 24mm f/1.4 set wide open, 13 second exposure at ISO 4000 .

I actually kinda like this shot straight from the camera, however foreground detail is completely lacking. The RAW file processed in RawTherappee 5.8 and Affinity Photo I was able to extract the following.

RAW file from above photo processed in RawTherappee and Affinity Photo.

Pretty remarkable the detail that was present in the foreground here, the A7S remains a real monster of low light scenarios. What happens though when the issue is reversed and the foreground is over illuminated?

Image taken with a Sony A7S and Samyang 24mm f/1.4 set wide open, 20 second exposure at ISO 4000

Here I had the A7S settings as far as I could take them without star trails in an effort to capture more milky way detail which was looking quite washed out by the refracted light of the town. These church ruins certainly look way over illuminated to give this composition balance between the foreground and the sky. Bringing the RAW file into RawTherappee 5.8 and Affinity Photo again, I was able to extract the following, though it took significantly more time.

RAW file from above photo processed in RawTherappee and Affinity Photo.

Detail looks shoddy on a full resolution copy, however on a downsized copy the balance between foreground and sky looks a lot more natural and balanced.

Looping back to the original premise of this exercise though: Can a single image from a time lapse sequence be edited to level to be suitable for print. For the most part I’d have to say no, especially if your foreground subject is quite close as the fine detail just won’t be there. I asked this question of myself as I am starting to look to produce more compositions that can stand on their own for print or online media. Capturing time lapse (especially with constant lighting) and stills require quite different approaches, I will need to give it some thought as to how I manage my nights out if I am am to be happy with the results of both.

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