17 Jun 2012

Project D800E -secure the shot in low light conditions

This is third post in the series of D800 project. Previous post you can find here and here.
Today I'll move the project a step further, from the general camera configuration settings to the practical shooting situations. I'll start with the low-lighting conditions.

Shooting in the low light conditions is one of the topics that are heavily discussed on Internet in photography communities in context of D800. D800 gives some interesting possibilities to achieve very good results in such situations. For me it is especially important since I take regularly shots of the different events that take place in not so great lighting conditions. If you can control it, you can boost your lighting, but if not - you need how to get the maximum out of your camera having only the ambient light.

So this post is a kind of a theoretical preparation before actual assignment I'll take next week.

When a camera calculates the exposure basically it takes three factors into account: aperture, shutter speed and the ISO sensitivity. Of course one can try to match all three factors manually to achieve the desired result. I will focus rather on the 'semi-automatic' modes that D800 (and BTW many other cameras) offer. Let's start with the most interesting mode to me, i.e. the aperture priority (A). This is the mode I use most of the time. The workflow is quite simple: when one fixes the ISO to an arbitrary value the camera will adjust the shutter speed to ensure the proper exposure. If the shutter speed is too slow, increase the ISO value to let the camera increase the speed. Nice, but as an event photographer I often don't have so much time during the assignment. Meet the Automatic-ISO mode.

Automatic ISO mode

In this mode the camera adjusts the ISO sensitivity in a situations when the two other factors (aperture and shutter speed) don't provide sufficient exposure. Here's how it works in case of D800:
Aperture priority mode:
First the shutter speed is decreased to meet the required exposure. If the shutter speed reaches the limit (more on it in a second) and the exposure is not enough, the ISO is increased (to a predefined limit). If the exposure is still not enough after reaching the limit of the ISO, the shutter speed is lowered further.
Important to note is that here one have two control options: minimal shutter speed at which the ISO starts to increase and the maximum value of the ISO. For the ones who rather prefer the graphs, the diagram below illustrates the whole process:

The two parameters that control the process are marked in red in the diagram.
The auto ISO mode can be set in the Shooting menu, option ISO sensitivity settings.
This menu opens a sub-menu where the Auto ISO sensitivity can be switched on and off and both parameters described earlier (Maximum sensitivity, Minimum shutter speed) can be setup.

The setup sequence is as follows:

1. Enable Auto-ISO:
Menu,,, -> ISO sensitivity settings,,->Auto ISO sensitivity control,,->On, Ok
2. Setup maximum sensitivity:
 -> Maximum sensitivity,->Choose value that suits you, Ok
3. Setup minimum shutter speed:
 -> Minimum shutter speed,->Choose value that suits you, Ok

The minimum shutter speed offer the Auto option. In this option the shutter speed will be set based on the value of the current lens focal length (or 1/30s for non-CPU lenses). So if for example the focal length is set to 50mm, the shutter speed will be set on 1/50 s. While it might be tempting in some situations, I would be cautious here. This rule of thumb may be not so well applicable for the D800 due to its huge sensor resolution and sensitivity to the camera body movement.

Last word about settings: Auto-ISO mode can be easily switched on and off by pressing the ISO button and turning the secondary dial button.

A final question is on how far one can crank up the ISO in case of D800. This of course depends on the scene, lighting conditions, the purpose of the photo, etc. My preliminary experiments show that setting the ISO to 2000 is a safe choice. Just one example. The photo below has been taken at ISO 1800.
Taking the 100% crop of the image reveals some noise grain in the background, but it is acceptable, provided that any noise reduction has been applied to the image. This amount of noise is easily removable in Lightroom.

For the assignment next week I'll start with the minimum shutter speed equal to 1/125s and maximum ISO 2000. We'll see how it works.

As said last time, I have the first version of the D800 cheat sheet ready. Please keep in mind that it is in a very draft status, with lots of empty (or even non-existing) sections. You can see it here.

Next time I'll look more closely at the Dynamic Lighting feature of D800 and the dynamic range of this camera in general.