Calculating Long Exposure Times Film Light Meter

Calculating long exposure times for film photography is crucial for capturing low-light scenes and creating motion blur effects. This guide will walk you through using our interactive calculator and understanding the math behind it.

1. Select your film speed (ISO) from the first dropdown.
2. Select your aperture from the second dropdown.
3. Select your initial shutter speed from the third dropdown.
4. Click the “Calculate” button to see your results and chart.

The formula for calculating exposure is:

Exposure = (Aperture * Shutter Speed) / Film Speed

Our calculator uses this formula to determine the correct shutter speed for a given aperture and film speed.

Real-World Examples

Let’s look at three examples:

1. Low Light Scene: ISO 1600, f/2.8, 15s
2. Motion Blur: ISO 400, f/8, 1s
3. Night Sky: ISO 100, f/11, 30s

Data & Statistics

Film Speed	Recommended Aperture	Recommended Shutter Speed
ISO 100	f/8	1/125s
ISO 200	f/5.6	1/250s
ISO 400	f/4	1/500s

Scene	Recommended Film Speed	Recommended Aperture	Recommended Shutter Speed
Low Light	ISO 1600	f/2.8	1/60s
Motion Blur	ISO 400	f/8	1s
Night Sky	ISO 100	f/11	30s

Expert Tips

• Use a tripod for long exposure times to avoid camera shake.
• Consider using a remote shutter release or the camera’s self-timer to minimize vibrations.
• Experiment with different exposure times to achieve the desired effect.

Interactive FAQ

What is the reciprocal rule?

The reciprocal rule states that the product of the aperture and shutter speed should be equal to the film speed. This is a simplified way to understand the exposure triangle.

How do I account for reciprocity failure?

Reciprocity failure occurs when the exposure time is too long or too short, causing the film to respond differently to light. You can use reciprocity failure tables to adjust your exposure accordingly.

For more information, check out these authoritative sources:

• Ken Rockwell’s Exposure Guide
• Cambridge in Colour’s Exposure Tutorial