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Many compact cameras and DSLRs have built-in AF Assist LEDs.

How do I know how long the LED in the camera will last? (That is, how many more beams before the LED requires replacement?)

I notice that the manual does not state how many beams it can take.

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The LED will last forever in this context. LEDs do wear out by loosing brightness over time. But, this will happen over such a long time as to be irrelvant. That LED will still be fine long after the camera is a pointless relic of a bygone era, or a museum piece at best. – Olin Lathrop Mar 1 '13 at 22:26
up vote 11 down vote accepted

"LEDs have a general life expectancy of 50 000 hrs."


Let's say (for simplicity) that the light is on for 3.6 seconds each time, which is 1/1000 of an hour. That would give that the LED should last for about 50 000 000 exposures.

As a comparison, if your batteries lasts for 1000 charge cycles, and last for 100 images per charge, and you use the assist beam every time, you will have bought 500 sets of batteries before you need to replace the LED.

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Put another way, if you took 1712 photos a day for the rest of your life, you would die before your AF assist LED. – AJ Henderson Mar 1 '13 at 14:28
@AJHenderson: Better start right away. Even if I live to a 100, I still need to take 2361 images a day. :) – Guffa Mar 1 '13 at 14:50
It should be noted that LED lifetimes generally describe the period of time at which the LED is producing 50% of the light it produced when new. LED's don't age like incandescent bulbs, where they work the same for a while, and then suddenly die. They generally gradually decay, as the color-conversion phosphor breaks down. – Fake Name Mar 2 '13 at 11:06

LEDs usually have a lifetime on the order of tens of thousands of hours or more. The AF assist beam that your camera uses is probably only activated for a fraction of a second with each exposure. Unless you've got a defective LED, it would be very, very surprising if the AF assist beam ever needed replacement -- it should last far longer than other parts such as the flash, lens zoom motor, battery, shutter release button.

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It'll probably even last longer than the sensor and image processing hardware as well. For that matter it would also probably last longer than the camera's original owner. – AJ Henderson Mar 1 '13 at 14:26

Longer than you or the camera. Approximate LED life is 50,000 hours. Even if it is 10,000 hours, that is still over 300 photos every day for 80 years using the LED for a few seconds at a time per photo. Note that the LED also is only necessary for photos in relatively dark areas which makes that 300 photos a day number even harder to hit.

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Note: I design solar powered LED based lighting products (amongst other things).

Manufacturers can be expected to rate such LEDs to last well in excess of the expected life of the camera.

LED lifetimes for small LEDs are usually less or MUCH less than the lifetimes quoted for power LEDs for a range of reasons.
And manufacturers can choose to drive them hard enough to much reduce lifetimes - in a focus lamp application I would not be surprised if a manufacturer did chhose to significantly over drive the LED above normal ratings. In many contexts an LED lifetime of 1,000 operating hours or even less would be much more common than people realise. But, if you sum the actual operating time of a focus assist LED it will be well under 1000 hours for the most enthusiastic use over decades of use. Even a 100 hour lifetime would be enough for all but the most flash-happy of photographers.

If the assist lamp operates for say 2 seconds then even only 100 hours of use would give you 180,000 operations.
Over 10 years that is 50 focus-lamp-assisted photos every day.
[ 100 hours x 3600 seconds/hr / 2 seconds per use / [10 years x 365 days) = 49.315 = 50 / day.]

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