Shutter lag

In photography, shutter lag is the delay between triggering the shutter and when the photograph is actually recorded. This is a common problem in the photography of fast-moving objects or people in motion. The term narrowly refers only to shutter effects, but more broadly refers to all lag between when the shutter button is pressed and when the photo is taken, including metering and focus lag.

Film cameras

In film cameras, the delay is caused by the mechanism inside the camera that opens the shutter, exposing the film. Because the process is mechanical, however, and relatively brief, shutter lag in film cameras is often only noticeable (and of any concern) to professionals. SLRs have slightly longer shutter lag than rangefinders, because of the need to lift the mirror. Point and shoot film cameras often have significant shutter lag.

Digital cameras

Shutter lag is much more of a problem with digital cameras. Here, the delay results from the charging of the charge-coupled device (CCD) image sensor and relatively slow transmission of its capture data to the circuitry of the camera for processing and storage.

The lag that early CCD sensors suffered from was significantly reduced by the invention of the pinned photodiode (PPD).[1] It was invented by Nobukazu Teranishi, Hiromitsu Shiraki and Yasuo Ishihara at NEC in 1980.[1][2] It was a photodetector structure with low lag, as a result of low noise, high quantum efficiency and low dark current.[1] In 1987, the PPD began to be incorporated into most CCD devices, becoming a fixture in consumer electronic video cameras and then digital still cameras. The PPD has since been used in most CCD sensors and then CMOS sensors.[1]

Recent improvements in technology, such as the speed, bandwidth and power consumption of processor chips and memory, as well as CCD technology and then CMOS sensors, have made shutter lag less of a problem. As of 2007, the greatest advancements have been limited mostly to professional, "prosumer," and high-end consumer-grade digital cameras. Inexpensive (most "point-and-shoot") digital cameras, however, have even reduced the average shutter lag to half seconds, and higher-end "point-and-shoot" cameras have reduced this down to a quarter second or less.

AE & AF lag

However, what many people consider shutter lag is in fact the time the camera takes to meter (set the exposure) and auto-focus, which is lag of a different cause but similar effect.

These causes of lag can be eliminated by pre-setting the exposure and focus, by either manually setting the exposure and focus, or by pre-exposing and pre-focusing. Pre-exposing and pre-focusing mean "using automatic exposure and autofocus, then fixing the settings so they do not change"; this can often be done by holding the shutter release halfway down, or by using a separate "AE / AF lock" button (useful if taking multiple photographs that are not in a burst), and means the subsequent photographs will be taken faster. These techniques can be combined – one can manually set the exposure and then use AF lock or conversely.

Examples of various shutter lag times

Camera	Type	Shutter Lag [ms]
Samsung Nx-Mini	DSLR	350
Nikon Coolpix L3	Digital Point and Shoot	1800
Nikon Coolpix S550	Digital Point and Shoot	590
Panasonic DMC Lumix FS20	Digital Point and Shoot	480
Canon PowerShot A590 IS	Digital Point and Shoot	350
Sony Cyber-shot DSC-W80	Advanced digital Point and Shoot	150
Pentax MZ-50	Amateur 35mm film SLR	120
Konica Minolta Maxxum 7D	Advanced amateur APS-C digital SLR with built-in image stabilization	117[3]
Sony NEX-5	Amateur APS-C digital compact camera	115[4]
Minolta Maxxum 9	Professional 35mm film SLR	90[5]
Leica M8	Professional digital rangefinder	80
Leica M9	Professional 35mm digital rangefinder	80
Sony Alpha DSLR-A850	Professional 35mm digital SLR with built-in image stabilization	74[6]
Sony Alpha DSLR-A900	Professional 35mm digital SLR with built-in image stabilization	72[7]
Minolta XD-7	Amateur 35mm film SLR	60
Nikon D300s	Advanced amateur APS-C digital SLR	53
Sony Alpha SLT-A77	Advanced amateur APS-C digital SLR-alike with built-in image stabilization and electronic 1st curtain	53[8]
Canon EOS-1D Mark IV	Professional APS-H digital SLR	49
Nikon D3s	Professional 35mm digital SLR	43
Nikon D3x	Professional 35mm digital SLR	40
Canon EOS-1D Mark II	Professional APS-H digital SLR	40
Minolta XE-1	Amateur 35mm film SLR	38
Nikon F6	Professional 35mm film SLR	37
Nikon D2H/D2Hs	Professional APS-C digital SLR	37[9]
Canon EOS-1D X	Professional 35mm digital SLR	36[10]
Sony Alpha NEX-5N	Amateur APS-C digital compact camera with electronic 1st curtain	22[11]
Contax RTS33	Professional 35mm film SLR	22
Leica M3	Professional 35mm film rangefinder	16
Leica M7	Professional 35mm film rangefinder	12
Canon EOS RT	Advanced amateur 35mm film SLR	8
Canon EOS-1N RS	Professional 35mm film SLR	6

References

1. Fossum, Eric R.; Hondongwa, D. B. (2014). "A Review of the Pinned Photodiode for CCD and CMOS Image Sensors". IEEE Journal of the Electron Devices Society. 2 (3): 33–43. doi:10.1109/JEDS.2014.2306412.
2. U.S. Patent 4,484,210: Solid-state imaging device having a reduced image lag
3. Imaging-Resource Preview Konica Minolta Dynax/Maxxum/Alpha 7D
4. Imaging-Resource Preview Sony Alpha NEX-5
5. Josef Scheibel, Robert Scheibel: Foto-Guide Minolta Dynax 9. vfv Verlag für Foto, Film und Video, Gilching 1999, ISBN 3-88955-116-5 (176 pages, , retrieved at 8 January 2011).
6. Imaging-Resource Preview Sony Alpha DSLR-A850 (Firmware 1)
7. Imaging-Resource Preview Sony Alpha DSLR-A900 (Firmware 1)
8. Imaging-Resource Preview Sony Alpha SLT-A77V
9. "Nikon D2hs Press Release". 2005-02-16. Retrieved 2014-06-04.
10. "Canon Professional Network - The EOS-1D X explained: inside Canon's flagship DSLR". Retrieved 2015-06-04.
11. Imaging-Resource Preview Sony Alpha NEX-5N

External links

• Shutter lag comparison chart for digital P&S
• Imaging Resource camera reviews often with measured shutter lag times
• NY Times article on shutter lag
• Photographer's Article on Shutter Lag
• What is Zero Shutter Delay (ZSD) on your mobile camera