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How fast is your camera's 30 second shutter speed?

mallman
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p.1 #1 · p.1 #1 · How fast is your camera's 30 second shutter speed?

Or, how long is your camera's 30 second exposure?

If I set my camera's (a Nikon D850) shutter speed to 30 seconds, it records a 32 second exposure. If I set it to 15 seconds, it records a 16 second exposure. Surprised? I had never noticed this. I had never even thought to question this. And yet...

Try it with your own camera. I'm curious to hear others' experience.

I've read from multiple sources that cameras generally lie about their exposure times. Actual camera exposure times differ by an integer power of 2 per stop, and cameras use power of 2 exposure times—not necessarily the times labeled by the camera, either on the LCD or the EXIF data. Your camera's 1/60" exposure time is probably 1/64", and it's 1/125" time is likely 1/128".

(I am ignoring the 1/3 and 1/2 stop increments.)

Anyone have any insight into why camera manufacturers list their cameras' true exposure times? I'm sure this has something to do with tradition, but even in the film days, was a 1/60" shutter speed a 1/60" exposure or was it a 1/64" exposure?

What do you think about reporting? If I post an image with exif metadata claiming my camera's exposure time was 1/60", when I know it was actually 1/64", which is the "correct" time to report?

Hmmm...

Aug 09, 2024 at 03:39 PM

chez
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p.1 #2 · p.1 #2 · How fast is your camera's 30 second shutter speed?

Aug 09, 2024 at 08:46 PM

Imagemaster
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p.1 #3 · p.1 #3 · How fast is your camera's 30 second shutter speed?

I could care less.

Aug 09, 2024 at 09:26 PM

jwpstl
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p.1 #4 · p.1 #4 · How fast is your camera's 30 second shutter speed?

How much less?

Imagemaster wrote:
I could care less.

Aug 09, 2024 at 11:01 PM

Imagemaster
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p.1 #5 · p.1 #5 · How fast is your camera's 30 second shutter speed?

jwpstl wrote:
How much less?

Hard to measure, but a lot less.

Aug 10, 2024 at 02:53 AM

tsdevine
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p.1 #6 · p.1 #6 · How fast is your camera's 30 second shutter speed?

So if you could care a lot less....it kinda implies you care.... Kind of like whether partly cloudy means more sunny and partly sunny means more cloudy....

Imagemaster wrote:
Hard to measure, but a lot less.

Aug 10, 2024 at 06:17 AM

jwpstl
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p.1 #7 · p.1 #7 · How fast is your camera's 30 second shutter speed?

So you care a lot.

Imagemaster wrote:
Hard to measure, but a lot less.

Aug 10, 2024 at 08:58 AM

mcbroomf
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p.1 #8 · p.1 #8 · How fast is your camera's 30 second shutter speed?

https://www.merriam-webster.com/grammar/could-couldnt-care-less

https://www.britannica.com/dictionary/eb/qa/I-COULDN-T-care-less-or-I-COULD-care-less

Clearly though, if the misuse of could vs couldn't doesn't bother you at all does it mean you couldn't care less or you could care less?

Aug 10, 2024 at 10:42 AM

jeffbuzz
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p.1 #9 · p.1 #9 · How fast is your camera's 30 second shutter speed?

mallman wrote:
Or, how long is your camera's 30 second exposure?

If I set my camera's (a Nikon D850) shutter speed to 30 seconds, it records a 32 second exposure. If I set it to 15 seconds, it records a 16 second exposure. Surprised? I had never noticed this. I had never even thought to question this. And yet...

Try it with your own camera. I'm curious to hear others' experience.

I've read from multiple sources that cameras generally lie about their exposure times. Actual camera exposure times differ by an integer power of 2 per stop, and cameras use power of 2 exposure times—not...Show more →

How are you measuring the actual exposure time? SLR's often have mirror lock-up features which delay exposure momentarily after raising the mirror to reduce vibrations. There may also be noise reduction happening which captures a dark frame after exposure. These things may be happening automatically during long exposures even if you did not explicitly set some custom option.

Aug 10, 2024 at 11:43 AM

mallman
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p.1 #10 · p.1 #10 · How fast is your camera's 30 second shutter speed?

jeffbuzz wrote:
How are you measuring the actual exposure time? SLR's often have mirror lock-up features which delay exposure momentarily after raising the mirror to reduce vibrations. There may also be noise reduction happening which captures a dark frame after exposure. These things may be happening automatically during long exposures even if you did not explicitly set some custom option.

I lock up the mirror prior to releasing the shutter. I start my timer when I release the shutter and stop it when I hear the mirror slap down.

Aug 10, 2024 at 12:21 PM

mcbroomf
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p.1 #11 · p.1 #11 · How fast is your camera's 30 second shutter speed?

These methods are OK to get ballpark numbers (as you've discovered) but to get an accurate time you'd need to electronically measure when the 1st curtain starts to open and then the 2nd curtain starts to close.

Aug 10, 2024 at 12:51 PM

chez
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p.1 #12 · p.1 #12 · How fast is your camera's 30 second shutter speed?

mcbroomf wrote:
These methods are OK to get ballpark numbers (as you've discovered) but to get an accurate time you'd need to electronically measure when the 1st curtain starts to open and then the 2nd curtain starts to close.

Yes, there could be a lag after the curtains close to when the mirror is dropped. Also let’s not forget the lag in human reaction time which on average is about 1/4 second.

Aug 10, 2024 at 12:56 PM

Imagemaster
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p.1 #13 · p.1 #13 · How fast is your camera's 30 second shutter speed?

mcbroomf wrote:
Clearly though, if the misuse of could vs couldn't doesn't bother you at all does it mean you couldn't care less or you could care less?

How about I don't care, more or less?

Aug 10, 2024 at 01:03 PM

mallman
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p.1 #14 · p.1 #14 · How fast is your camera's 30 second shutter speed?

chez wrote:
Yes, there could be a lag after the curtains close to when the mirror is dropped. Also let’s not forget the lag in human reaction time which on average is about 1/4 second.

How much of a lag are we talking here? Two seconds is a long time to wait between shutter close and mirror drop. I stand by my observations.

Aug 10, 2024 at 01:10 PM

mcbroomf
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p.1 #15 · p.1 #15 · How fast is your camera's 30 second shutter speed?

No-one's doubting your observation I think, just the accuracy (vs actual exposure time)

Aug 10, 2024 at 01:58 PM

tsdevine
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p.1 #16 · p.1 #16 · How fast is your camera's 30 second shutter speed?

I usually go with “I couldn’t care less.”

Imagemaster wrote:
How about I don't care, more or less?

Aug 10, 2024 at 01:59 PM

chez
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p.1 #17 · p.1 #17 · How fast is your camera's 30 second shutter speed?

mcbroomf wrote:
No-one's doubting your observation I think, just the accuracy (vs actual exposure time)

Then there is the T-stop versus F-stop, the actual F-stop versus what’s labeled on the lens, and the actual focal range from what written on the lens. Anyone think a 100 - 400 is actually exactly those focal lengths.

I think the displayed exposure time has the least affect on your photography.

Aug 10, 2024 at 02:18 PM

SSISteve
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p.1 #18 · p.1 #18 · How fast is your camera's 30 second shutter speed?

Congrats on discovering something that is meaningless in the grand scheme of things and most have no interest in testing even on a super slow day.

Aug 10, 2024 at 11:18 PM


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