shutter speed

[donut]

so am i right in thinking that the shutter moves at the same speed when a shot is taken at (say) 1000th of a sec as it does when another shot is taken at 125th of a sec ?

 

[arclight]

Not fully sure I know what you mean.
However, a focal plane shutter consists of two blinds.
When the shutter is released the first blind moves followed by the second. The speed selected determines the gap between the two blinds. Therefore a high shutter speed will have a tiny gap between the blinds and a slow speed a much larger gap.
Perhaps some cameras (or even all cameras now) can also vary blind speed.
Hope that is right. It is all from memory when I had film cameras (Fm2).

 

[anwa]

The shutter curtains themselves move at the same speed in pretty much all D-SLRs - I'm not aware of any that can vary the speed the curtains move at though there may be some?

It's the difference in timimg between trigerring the front curtain to open followed by the rear curtain to close that gives you the camera's shutter speed.

 

[arclight]

The shutter curtains themselves move at the same speed in pretty much all D-SLRs - I'm not aware of any that can vary the speed the curtains move at though there may be some?

It's the difference in timimg between trigerring the front curtain to open followed by the rear curtain to close that gives you the camera's shutter speed.

OK - I was just a bit unsure whether shutter technology had changed much since I had a FM2.
I recall my first SLR used horizontal blinds that were made from a rubberised fabric. The FM2 had metal vertical blinds.
If the OP is interested he can open the back of his film camera, select low shutter speed then fire it. The blind movement can then be observed.

 

[HoppyUK]

The blinds always travel at the same speed, though some models are faster than others.

You can tell by the x-sync speed. For example, the Sony entry-level A200 has x-sync up to a max of 1/160sec compared to 1/200sec or 1/250sec for mid-range cameras. Canon 1DMk4 does 1/300sec.

Full frame cameras tend to be a bit slower because they have to travel a longer distance.

 

[arclight]

The blinds always travel at the same speed, though some models are faster than others.

You can tell by the x-sync speed. For example, the Sony entry-level A200 has x-sync up to a max of 1/160sec compared to 1/200sec or 1/250sec for mid-range cameras. Canon 1DMk4 does 1/300sec.

Full frame cameras tend to be a bit slower because they have to travel a longer distance.

Thought you'd have an answer, Richard.
Still not sure whether we have answered the OP's question, though.

 

[donut]

right many thanks to all reply -ees, thats pretty much what i thought . now this leads me to question two ,,,what happens when the shutter speed is something like ( going on my fm's ) half a second or a full second ,,the curtain speed seems much slower , as one would expect being a one second exposure .so does some other system come into play after a certain time ,,15th of a sec ?? 8th of a sec ???

Richard , going on what you say about the sync speed its 250th on the fm2n , so what happens with slower speeds ??

 

[donut]

The shutter curtains themselves move at the same speed in pretty much all D-SLRs - I'm not aware of any that can vary the speed the curtains move at though there may be some?

It's the difference in timimg between trigerring the front curtain to open followed by the rear curtain to close that gives you the camera's shutter speed.

actually the clue might be in this bit ,,,??

 

[HoppyUK]

right many thanks to all reply -ees, thats pretty much what i thought . now this leads me to question two ,,,what happens when the shutter speed is something like ( going on my fm's ) half a second or a full second ,,the curtain speed seems much slower , as one would expect being a one second exposure .so does some other system come into play after a certain time ,,15th of a sec ?? 8th of a sec ???

Richard , going on what you say about the sync speed its 250th on the fm2n , so what happens with slower speeds ??

The speed of the blinds might look slower at longer shutter speeds, but it isn't.

As explained above, the way the shutter creates shorter exposure times is by reducing the delay between the release of the first and second curtains. At the very highest speeds, the gap between the curtains is less than 1mm as they travel down in tandem.

The whole shutter action might take as long as 50-100ms depending on the camera, but the gap between the curtains ensures no single part of the sensor is exposed for longer than the set speed. See this animation http://www.photocourse.com/itext/focalplane/

 

[Scarecrow]

It's also why we have a maximum flash sync speed with our DSLRs. Above the flash sync speed, the second curtain starts to close before the first curtain has completely uncovered the sensor, meaning that if we use a higher speed when using flash, a portion of the image will be dark because part of the sensor was covered when the flash went off.

 

[HoppyUK]

It's also why we have a maximum flash sync speed with our DSLRs. Above the flash sync speed, the second curtain starts to close before the first curtain has completely uncovered the sensor, meaning that if we use a higher speed when using flash, a portion of the image will be dark because part of the sensor was covered when the flash went off.

Another link showing the x-sync speed in action http://www.photocourse.com/itext/sync/

Some good animations on that site.

 

[donut]

thanks all ,,pretty much what i thought ,,but wasnt sure about the slower/longer speeds .

 

[Suvv]

It's also why we have a maximum flash sync speed with our DSLRs. Above the flash sync speed, the second curtain starts to close before the first curtain has completely uncovered the sensor, meaning that if we use a higher speed when using flash, a portion of the image will be dark because part of the sensor was covered when the flash went off.

And with a D40 it is 1/4000 sec
If you do not use a dedicated flash.