Shutter speed-actual time: This is a question about how shutter speed is actually measured. Shutter speed is the amount of time the shutter is open during the exposure. Is this time...

papakatz45 Loc: South Florida-West Palm Beach

This is a question about how shutter speed is actually measured. Shutter speed is the amount of time the shutter is open during the exposure. Is this time measured from the when the shutter first starts to open until it is completly closed or is it just the time the shutter is fully open excluding the time from start to full and from full to close?

MT Shooter Loc: Montana

The camera shutter is a two part system. The first shutter starts to move across the sensor and expose it to the light. Then the second "curtain" of the shutter starts to close. On fast shutter speeds the second curtain is already closing before the first curtain has completely moved across the sensor. The exposure time is calculated by the exact amount of time any one particular pixel has been exposed to the light, not necessarily the entire sensor surface. All pixels of the sensor will be exposed exactly the same amount of time. On long exposures, the first curtain reaches full open and the sensor is fully exposed for the duration before the second curtain closes. The shutter moves extremely fast, this is what allows those 1/8000 sec shutter speeds to be accurate.

Ched49 Loc: Pittsburgh, Pa.

That's a very good question.

Ched49 Loc: Pittsburgh, Pa.

MT Shooter wrote:

The camera shutter is a two part system. The first... (show quote)

And a very good answer! So if the shutter speed is set at, say, 1/25 of a second, that doesn't necessarily mean the whole sensor was exposed at 1/25 of a second.

tainkc Loc: Kansas City

cjkorb wrote:

That's a very good question.

And a very good answer.

GoofyNewfie Loc: Kansas City

Even if the shutter is set to 1/8000th/sec, it still takes most cameras 1/200 or so to fully expose the image. That's why there is a maximum sync "speed" and that's how long it takes for the shutter curtains to travel from one side to the other.
At longer settings there is a delay between the first curtain opening and the second one closing. At shorter settings, the second curtain starts before the first gets all the way across. The shorter the setting, the narrower the slit.
That's why, if you use a flash above the sync setting, you get only part of the picture exposed by the flash. The shutter gets in the way.

http://digital-photography-school.com/photography-1016-shutter

"Slower" settings: http://vimeo.com/11216272
"Faster" shutter setting: http://jon-rista.deviantart.com/art/Fast-Shutter-Speed-Animation-148885927

Nikonian72 Loc: Chico CA

Unfortunately, the term shutter "speed" has been incorrectly used for decades. The speed of the leading shutter and the trailing shutter are constant. What varies is the timing between curtains, which alters the time duration that the sensor sees the scene between curtains.

"Shutter duration" is a more accurate term to describe shutter speed.

tainkc Loc: Kansas City

GoofyNewfie wrote:

Even if the shutter is set to 1/8000th/sec, it sti... (show quote)

I wonder how that works on SLT's like on Sony's?

mdorn Loc: Portland, OR

GoofyNewfie wrote:

Even if the shutter is set to 1/8000th/sec, it sti... (show quote)

Love that animated GIF in your above link!

jerryc41 Loc: Catskill Mts of NY

Nikonian72 wrote:

Unfortunately, the term shutter "speed" has been incorrectly used for decades. The speed of the leading shutter and the trailing shutter are constant. What varies is the timing between curtains, which alters the time duration that the sensor sees the scene between curtains.

"Shutter duration" is a more accurate term to describe shutter speed.

Would "fast" and "slow" ever have been appropriate? Like in the early 1900's?

TLCarney Loc: Englewood, Florida

Yes Jerry, pre-focal-plane shutters. But then action photography was a bit easier, the dinosaures didn't move so fast.

Pablo8 Loc: Nottingham UK.

papakatz45 wrote:

This is a question about how shutter speed is actually measured. Shutter speed is the amount of time the shutter is open during the exposure. Is this time measured from the when the shutter first starts to open until it is completly closed or is it just the time the shutter is fully open excluding the time from start to full and from full to close?

Consider this, then... A leaf shutter (as opposed to a focal-plane shutter) I hope you know the difference. With the aperture set at full-bore for instance f/1.4..OK are you keeping up? The shutter blades open from their closed position, and exposure begins to take place. But the aperture through which the light is coming, is changing from a tiny hole (f/32...f/22..f/16 ) etc., to the full opening area of the diaphragm blades..f/1.4 and the shutter blades close down again through the ever diminishing size hole. So...some of the exposure has been made through an aperture other than your selected f/1.4....Fact?...or Fiction?

NoSocks Loc: quonochontaug, rhode island

Pablo8 wrote:

quote=papakatz45 This is a question about how shu... (show quote)

Please forgive my ignorance, but on what type camera is a "leaf shutter" found?

wilsondl2 Loc: Lincoln, Nebraska

Just to add a little. There are leaf shutters too that were in most film cameras that did not have interchangeable lenses. I would think point and shoot still use leave shutters. They opened from the middle and then closed from the rim so the center got a little more exposure. The Speed Graphics had a curtain that had five (i think) slits that were different sizes and the curtain could be set at different speeds. It had a chart on the side that gave the shutter speed for different combinations of curtain speed and slit size to give you your shutter speed. If you look at old time pictures of race cars the look like they are leaning because the car moved while the slit was being pulled over the film and the exposure was made on different parts of the film at different times. Just Trivia - Dave

NoSocks Loc: quonochontaug, rhode island

wilsondl2 wrote:

Just to add a little. There are leaf shutters too... (show quote)

Might be trivia, but it's interesting trivia.