Wednesday, May 20, 2009

Photographing stage events (Low Light shooting)

Photographing stage events brings a lot of challenges for the photographer. You are trying to get the best picture with low light from a considerable distance. Shooting in low light forces you to open up your aperture or reduce your shutter speed or crank up your ISO in your fight against elements such as noise, blur, DoF and exposure. Shooting from a distance means, you need a long lens which will add more fuel to the fire. Here I am going to cover how you should prepare and what equipment will help to get good result.

Lens:
Even though I am a prime lens freak, for stage events I would recommend a zoom lens. Remember that you will need to shoot the picture as it happens, the performer is not going to pause for you, there is no replay and they could be moving all over the stage. So using multiple prime lenses and switching between shots might not suite well.

A lens with a 70-200mm is a good range for shooting stage programs if you have access to area about 30-50 feet from the stage. The further you are going to be from the stage, you will need longer lens.

Wider the aperture (faster the lens) the better. Select a lens that has wide aperture (low FStop) available at a highest zoom value. Some zoom lenses have a constant aperture at the different zoom levels. Some has variable apertures at different zoom levels - at max zoom, the aperture might be narrower (higher FStop) than at the min zoom (wide angle).

Having capability to correct blurs caused due to camera/hand movement is a great advantage. Different manufacturers call it with different names - VR, IS, VC, etc. Some implement this within the lens, others with in the camera.

Camera Settings:
Shooting Mode:
As much as possible I love to control every situation (my wife hates it), so I shoot with my camera in manual mode in most cases. However, for a stage program, I prefer and recommend one of the camera priority modes - "Aperture Priority" or "Shutter Priority". Like I said earlier, the performer is not going to stop & pose for you to shoot, so you have to reduce the number of variables you need to adjust. In the priority mode, you get to select one value and the camera selects a value for the other based on information from the light meter. In Aperture priority, you select aperture value and camera selects shutter speed. In shutter priority it's vice verse.

In aperture priority mode select the widest aperture (lowest FStop number) at the highest zoom if you have a zoom lens with variable apertures at different zoom values. If you have a constant aperture lens, an aperture value of 5.6 (or +/- 1 stop) is what I recommend. Smaller the aperture (larger the FStop number) the larger the DoF will be. Key point here is at the best ISO settings on your camera, the shutter speed should not drop below a point causing blurs due to camera movement.

In shutter priority mode select a shutter speed that will not cause a blur due to camera movement. Remember your hands can get tired holding your equipment (zoom lenses tend to be heavy) through the program.

ISO:
This is the measure of the image-sensor sensitivity to light. When using film, your options are to get a higher sensitive film, thus less exposure time, which means smaller aperture and/or faster shutter speed. Today in the digital era, the film has been replaced with an electronic image-sensor, and the sensitivity can be adjusted by the photographer. Like the film, if you increase the sensitivity of the image-sensor, you can capture pictures at low lighting.
Choose an ISO setting, that yields to the least amount of noise in the picture, for the size you plan on printing and using the images. This depends on the camera's technology and you probably can get to what is the best ISO from reference documentation (printed or online). However, if you can experiment and find the ideal ISO setting, there is noting better to make you feel more confident.

White Balance (WB):
WB is the adjustment to ensure the image-sensor understands the neutral colors - White, Grey & Black. This is how I understood WB - my theory may be incorrect and I might change it as I understand & learn more about it.

  • The fact is neutral colors will look different when we look at them under different light sources (sunlight, incandescent, fluorescent, etc). Unlike an image-sensor in our camera today, our eyes can adapt automatically based on ambient light and reproduces the correct colors for our brain to process the image.

  • As color is measured in Kelvin temperature, each light source will produce a temperature range. WB is a configurable value to tell the camera's image-sensor what temperature range to expect when reading the neutral colors.

  • In your camera, you select the type of light source for your WB and camera adjusts for the color temperature as it digitized the image. The image-sensor will then reproduce the colors as close as seen by our eyes.
When using film, you had the option of using customized film that is balanced for the light source. Normally a Daylight balanced film was used that worked well with sunlight and flash. Other options where tungsten film, this was balanced to reproduce the color best under tungsten light source. If we used the other way you would end us with a cooler (more blue) or warmer (more red) picture.
The fun about digital is you can adjust this in post processing. So if you know what is the light source in the stage you are going to shoot, you can set it to that, else go with auto and fine tune during post processing.

Aperture & Shutter speed:
Depending on your creativity, you can play with aperture and shutter speed to produce different results. Keep in mind, higher ISO values will open up more room to play with a range of aperture and shutter speed. On the other hand watch our for image noise.

Note:

  • Wider aperture means faster shutter speeds and the less Dof .

  • Slower shutter speed means narrow aperture and more prone to shakes and vibrations.
So you will need to strike a balance between ISO, aperture & shutter to get to the appropriate result. Here it's difficult to recommend an aperture and shutter speed because it will depend on what result you are looking for, lens and ISO. However if you use a F-Stop of 5.6 you can get a picture with average DoF, higher F-Stops will improve DoF. On the other hand, if you use a Shutter Speed of 1/100 or faster you can avoid most shakes & vibrations to increase sharpness.
Exposure Setting:
Using spot-metering can help with exposure to start with. Many stages have black background screens and your camera's light meter end up reading the black area as dark area if you use matrix or center weighted metering and fool you with incorrect exposure. Even though center weighted meeting will reduce the variance in exposure, I highly recommend spot metering.

Once you have practiced and have a few hundred stage event pictures under your belt, you probably should switch to manual exposure mode. During the event, calibrate your aperture and shutter speed based to a value - spot reading based on an object in the stage (a person's face/arm, chair, table, etc) and use that setting through out the event to shoot pictures.

Post Processing:
Let me confess, I am a newbie at this. My knowledge and experience of post-processing is below average and do not consider myself good enough to preach what you need to do. So it's up to you to figure out what you want to do. You will need to read up about the software and figure out how to work on each of these parameters. Also many software provide various features and you have to figure out how to play in that playground. There are many online articles and tutorials to help you understand how to draft a work flow and do certain functionality. I use Nikon CaptureNX2 and GIMP for my image processing. Often use Picasa when I feel lazy, mainly to make small & simple adjustments.

The most common post processing adjustments I ended up doing to my stage pictures were the WB, EV, Composition (CROP) & Sharpness.

Experiment and Practice:
Do your experiment to learn about the limitations of your equipment. Shoot pictures in a room with similar lighting and try to be at an approximate distance from the subject as you will for the program.

Set your camera to aperture priority mode, use an aperture value of 5.6 or +/- 1 stop. If your lens has a variable aperture, that is aperture changes as the zoom varies, use the lowest aperture available at the highest zoom value. Enable "High-Noise Reduction" and set the ISO to the highest value to start with.

Shoot 3-4 test pictures at different Zoom settings (say for example 200mm, 150mm, 100mm, 70mm). Once you have done this reduce the ISO by 100/200 and repeat the test. I would suggest get as many test pictures between ISO1000 and the highest available ISO in your camera.

Once you have all your pictures, compare them in your PC (full screen mode). You are looking for noise (or grain) and camera shake (blurred images) in the test pics. Pick one picture for each zoom setting, that you feel is sharp, well exposed and least grains - look in the EXIF data and take note of the zoom setting (focal length), ISO settings and the aperture you used.

If you are shooting hand held, I recommend selecting pictures taken at around 1/100 sec shutter speed. Anything lower could cause a blur, but again it depends.

I shot a stage event using a D700 and the Nikon 70-200mm F/2.8G VR. Two features that turned out as an advantage for me was high ISO and VR capabilities, which helped a lot. Here are some pictures from the event.




























Glossary:
ISO - International Standards Organization

IS - Image Stabilization
VR - Vibration Reduction
VC - Vibration Control
DoF - Depth of Field
FStop - Fractional Stop (also called as F Number or F Ratio)
WB - White Balance
EXIF - Exchangeable Image File Format