CD / Shutter Speed

Summary

The video explores the evolution of camera shutter mechanisms, from early uncoverers of lenses to leaf shutters to rotary disc shutters in film cameras. It explains how electronic shutters in digital cameras work, enabling adjustable speeds. However, the rolling shutter effect causes distortion. While mechanical shutters avoid this, most cameras use CMOS sensors with inherent rolling shutter. Some companies seem complacent about the artifact. Ultimately, global shutter technology may restore image integrity, if manufacturing improves affordability.

Takeaways

• 😯 Early cameras required long exposure times, limited by media sensitivity
• ⚙️ Mechanical shutters enabled adjustable exposure times
• 🎥 Rotary disc shutters enabled motion pictures by syncing frame rate and exposure
• 📽️ 180 degree shutter angle at 24fps became the cinematic standard
• 🖥️ Electronic shutters in video cameras enabled flexible exposure times
• 🤯 CMOS sensors enabled higher resolution but caused rolling shutter artifacts
• 😵‍💫 Rolling shutter can distort fast movement in unpredictable ways
• 🌀 Mechanical shutters can also exhibit rolling shutter, but it's less noticeable
• 💸 Global shutter sensors are technically possible but more expensive
• 😕 Most people don't notice or care about rolling shutter issues

Q & A

Why were early cameras just boxes that you had to uncover the lens on for a period of time?

Early photographic processes required long exposure times to accumulate enough light to capture an image. Uncovering and covering the lens was a simple way to control the exposure time.

How did the advent of motion pictures impact shutter technology?

Motion pictures required capturing images much faster, at 16 frames per second or more. This was beyond the capability of traditional shutters, so the rotary disc shutter was invented to produce intermittent exposures by spinning a disc with cutouts.

What is the difference between shutter speed and shutter angle?

Shutter speed measures exposure time in fractions of a second, while shutter angle measures exposure as a percentage or proportion relative to the duration of a movie frame at a given frame rate.

How did electronic shutters in video cameras differ from traditional mechanical shutters?

Electronic shutters could be much faster or slower than mechanical ones, with exposure times adjustable down to a fraction of the frame rate. But they still needed a tiny gap to read out the image sensor.

What causes the rolling shutter effect in CMOS sensors?

In CMOS sensors, rows of pixels are read out sequentially. So each row captures the scene at a slightly different point in time, causing distortions of fast movement.

Why don't rotary shutters seem to cause rolling shutter artifacts?

The rotary shutter sits far in front of the unfocused light. So any artifacts get diffused. And with fast spinning shutters, distortions happen faster than our eyes perceive.

What is an electronic first curtain shutter and how does it impact bokeh?

It starts exposure electronically and ends it mechanically. This shifts the bokeh due to the physical difference between the start and end points across the sensor.

What is global shutter and why isn't it more widely adopted?

Global shutter exposes all pixels simultaneously, avoiding rolling shutter. But it's more expensive to manufacture, and most consumers either don't notice or don't care about rolling shutter artifacts.

How can you measure rolling shutter speed?

It's measured in milliseconds - the time it takes the sensor readout to scan from top to bottom. Faster sensors have lower rolling shutter durations.

Will global shutter eventually replace rolling shutter?

As manufacturing techniques improve, global shutter is becoming more affordable. It may eventually be ubiquitous in phones and consumer cameras, eliminating rolling shutter artifacts.