Fireworks photography (Fireworks) long exposure: B door black card occlusion method and overexposure prevention

1. The exposure triangle rule of long exposure for fireworks: aperture determines thickness, time determines quantity

The core principles for understanding the physical properties of fireworks: The light intensity of the fireworks itself is a fixed luminous body determined by the chemical composition of gunpowder combustion. The shutter speed cannot change the brightness and darkness of a single light track, but can only determine the length and overlap of the light track:

1. Aperture setting (f/8 ~ f/13):

• An aperture that is too small (such as f/16~f/22) will cause the light track to be as thin as a hairspring and produce diffraction blur;
• If the aperture is too large (such as f/2.8f/4), the center highlight will be severely overflowed and the color will become white and distorted when several fireworks overlap. f/8f/11 is the best aperture for recording rich colors and sharp lines.

2. ISO Lock Native Low Sensitivity (ISO 100 or 64): Ensures the night sky is pure black and noise-free, while providing the maximum highlight dynamic range to avoid color channel saturation.
3. Shutter speed control (2s ~ 8s basic): It usually takes 3~5 seconds for a single firework to go from liftoff to complete explosion. If the shutter speed is shorter than 2 seconds, the bouquet will be incomplete; if the shutter speed is longer than 8 seconds, if there is no obstruction, excessive smoke will be superimposed, causing the picture to be gray.

2. Actual combat skills of the Black Card Technique at Door B

In a fireworks show, the most shocking picture is often the simultaneous blooming of large fireworks in the sky and potted flowers in the lower sky. But live fireworks are dispersed in batches. How to collect multiple groups of beautiful fireworks in one photo without overexposing the background?

• Tool Preparation: A piece of cardboard (black card) with matte flocking or matte pure black surface, shutter cable (with door B lock function).
• Practical steps:

1. Set the shutter to Bulb, press the shutter release cable to lock and start exposure.
2. When the first firework takes off and blooms, the black card leaves the front group of the camera and records the complete blooming process (about 3 seconds).
3. After the fireworks fade, immediately cover the front of the lens with a black card (keep a distance of about 1~2cm, and do not touch the lens to cause the body to shake). At this time, the camera is still exposed, but the sensor does not receive light.
4. Wait for the next wave of beautiful fireworks of different heights or colors to take off and burst. Remove the black card and continue recording for 2~3 seconds, and then block it again.
5. Repeat 2 to 3 times and then release the shutter release cable to end the exposure.

• Effect: The night sky is clean and dark, the landscape and landmarks are moderately exposed, and there are several perfect fireworks blooming neatly in the sky, completely avoiding ambient light pollution and drifting smoke during the intervals between fireworks.

3. Forward planning of focusing and viewfinder positions

• Turn off autofocus and lock manual focus (MF): When shooting in the air at night, autofocus will inevitably be affected. In the evening when it is not completely dark, aim the focus at the distant landmark building near the launch point, or focus at infinity during the day and then adjust it slightly back a little, and fix the focus ring with tape.
• Wind direction and location selection (a matter of life and death):
• Do not choose the downwind outlet: 3 minutes after the fireworks are set off, the downwind direction will be completely shrouded in thick white sulfur smoke, and all photos will become a "fire scene".
• Must be in an upwind or side draft: The wind will quickly blow away the remaining smoke, revealing a clear dark night sky and clear light trails.
• The golden first five minutes rule: The air is the most transparent and pure during the first 3~5 fireworks of a large-scale fireworks show, which is the golden time for blockbuster movies. As time goes by, the particles in the air increase, so black cards need to be used more rigorously.

4. Consideration of composition combined with urban landmark environment

Simply photographing fireworks in the sky will quickly lead to aesthetic fatigue. Excellent fireworks works must include regional identification:

1. Reflection on the water surface: For fireworks shows by rivers, bays or lakes, use low angles to incorporate the water surface. Long-exposure reflections on the water surface will double the color brilliance.
2. Depth of front and rear scenes: Incorporate dark silhouettes of bridges, skyscraper skylines, or crowds of spectators to establish spatial scale contrast.
3. Multiple slice stacks in post-production (Layer Blend - Lighten): Under the premise that the tripod position is completely fixed, take a single exposure to take a perfectly exposed negative of the background building, and then continuously capture multiple single shots of fireworks. In the later stage, set the layer blending mode to "Lighten" in Photoshop to freely combine the most perfect visual feast.

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