Part 2: Shooting in the darkness of the night « Ingo Meckmann Photography

HDR Tutorial - Part 2: Shooting in the darkness of the night

OK, so part 1 was about High-noon light and I’m shifting now to the other extreme: Shooting in the darkness of the night. I also talk about how to calculate the proper +30 seconds exposure and discuss long exposure noise reduction.

Shooting at night has one big advantage over other lighting situations – you have a looooot of time and the light conditions are generally very stable once you get past astronomical twilight.
Just to make things clear, I am not covering twilight in this tutorial – which is my favorite time of the day to photograph – this is about total darkness without having the moon as a light source. I totally rely on artificial, but available light – no strobes or speedlites.

What you need:

Hardware:

A Camera supporting Bulb mode
A cable release, timer remote control or a wireless remote
A sturdy Tripod
A Mac – ok any computer, but you really should have a Mac.

Software:

any kind of HDR tonemapping software – preferable Photomatix Pro by hdrsoft.com or HDR Efex Pro by Nik Software

Optional:

Adobe Lightroom 3
Adobe Photoshop CS5

The Assignment:

My idea was to shoot the pool area of our Vacation Home in Naples, FL – it’s not ours, unfortunately, just rented for 2 weeks over the Xmas holidays – but not during daytime or twilight but in the middle of the night. Naples is a big enough city to provide enough light pollution to not just end up with a sky looking like a black hole. In addition to that, the pool lights illuminated the netting that covers the pool area and I switched-on a tiny light in the house to get some shadow patterns of the blinds on the otherwise boring floor. I also wanted to see some star trails so I decided on a very low ISO setting that I usually avoid for night shots to keep the exposure times low. My aperture of choice for that composition was f/10 because I guessed that my favorite “landscape” exposure of f/16 would require too much time but f/10 still gives me enough depth of field to get everything in focus.

How to guess calculate the proper exposure at night

This step is optional and it gets very technical now – but don’t run away yet – it’s fun!

My approach of ~~guessing~~ calculating the exposure at night is to start with a very high ISO test-shot – ISO 12800 – using a fairly wide aperture to get a very quick exposure. I set my camera to Aperture priority and chose f/4 at ISO 12800 to get a shutter speed of 0.6 seconds.

High ISO sample f/4 / ISO 12800 / 0.6sec

High ISO test shot

Based on that test exposure, I calculated my 0EV using a f/10 aperture and low ISO of 100:

There are 7 f-stops between ISO 128000 and 100
-> 12800->6400->3200->1600->800->400->200->100
There are 2 2/3 f-stops between f/4 and f/10:
f/# 1.0 1.1 1.2 1.4 1.6 1.8 2 2.2 2.5 2.8 3.2 3.5 4 4.5 5.0 5.6 6.3 7.1 8 9 10 11 13 14 16 18 20 22

That gives me 9 2/3 f-stops to be added to the shutter speed of 0.6 which brings me to ~5 minutes for the 0EV exposure – adding 2 additional stops gives you 20 minutes for the 2EV.

Let’s get started for real – enough math for now

I didn’t do those calculations in the field – it was way too late for that – but rather guessed and decided to start with a 30 seconds exposure and go from there by adding one f-stop for every additional exposure until I got my desired result. I ended up with 6 exposures between 30 seconds and 16 minutes.

30 seconds

1 minute

2 minutes

4 minutes

8 minutes

16 minutes

Distraction alert:
One thing to know about those long exposures is the implication of noise and and I’m not talking about the well-known high ISO noise. I’m talking about the long-exposure noise that is much easier to fix in camera than later in post.
I was planning to link to an explanation on what long-exposure noise reduction is useful for and how it works but I failed to find something useful on the web. Therefore, I’m going to add my own explanation here:

Long Exposure Noise-reduction

This explanation is based on my own experience with long-exposures which may differ from others. Keep in mind that not all cameras have that function available but most recent DSLR’s including the entry-level ones should have it.
Long exposure noise is different from the high ISO noise and has nothing to do with your ISO settings. If you are doing long exposures, the camera sensor heats up and this is what causes that noise. I made the experience that it starts to get visible in exposures over 2 minutes. If you enable that feature – which might be hidden in the menus of your camera – the camera will create a second, same length exposure without switching the mirror so no light is hitting the sensor. The noise data produced by the heating sensor is recorded by the second exposure and will be subtracted from the first exposure – this works for both JPG and RAW files. The noise reduction is significant and superior to to post-processing noise-reduction. The big disadvantage of course is that it doubles the time you need for each picture.

Photomatix

I’m not going into as much detail as in Part 1 of the Tutorial and rather concentrate on specifics for that kind of picture style.
I brought the 6 exposures into Photomatix and did my “magic” – you see the exact settings in the screenshot below.

One thing to mention is the unusual high “Black Point” setting that I purposely used to darken the shadows. Most HDR tools available today tend to brighten the shadows too much – this could be problematic, especially for night shots where you do not have details in the very darkest shadow areas and all you get is noise.

My longest exposure was not giving me details in all the shadow areas but I was ok with that plus I didn’t want to do another exposure of 30 minutes plus 30 minutes of noise-reduction just get some uninteresting shadow details. You see the little spike on the left of the histogram. It’s the dark area behind the shark that lacks details – nothing to worry about.

As usual the Photomatix result is rather flat and boring and lacks excitement.

Photoshopping-in some excitement

I wasn’t doing extensive work in Photoshop for this picture – I just used the darkest and brightest exposures to perform some dodge and burning on the HDR picture. Therefore I used those 3 exposures and imported them as layers into Photoshop.

One part of the picture I wanted to concentrate-on is the blue shark on the right side that needed some teeth whitening.

I used the brightest exposure as background layer with the HDR on-top, then added a white layer-mask to paint the eyes and teeth with black to literally burn a whole through it. Merging the layers afterwards

I also didn’t like the very bright water in the pool and jacuzzi so I used the darkest exposure to burn that part of the picture.

Back to Lightroom

This is what the picture looked like after leaving Photoshop:

Pre Lightroom adjustments

Below you can see how you can make a picture pop with just a few slider settings in Lightroom – check the left column where all the edits are visible. The major adjustments I’ve done are the graduated filter to add some contrast to the sky, the clarify and sharpening settings and the black clippings.

The “Black Clippings” feature is one of the most used feature for me in Lightroom. I use it on most of my RAW files and especially HDR images that come out of Photomatix to increase the contrast without clipping the highlights.

You can see in the final picture below that those few adjustments made in Lightroom changed the picture dramatically. I also included the graduated filter settings (right column on top) and the placement of that filter in the screenshot.