Nikon D40: Mechanical/Electronic Shutter

[dcphotography]

At what shutter speed does the D40 stop using the mechanical shutter to control shutter speed and starts turning

the CCD on or off to control shutter speed?

[frank_skomial]

At all speeds. Never stops using mechanical shutter either.

[shuo_zhao]

I think the camera uses a combination of both shutters at shutter speeds faster than 1/90s, because the mechanical shutter can't "open and close" for time intervals shorter than that. Shutter speeds above that are achieved with the mechanical shutter open and close and the CCD turning on and off.

[ShunCheung]

The reason that the D70, D70s, D50 and D40 can have 1/500 sec flash sync (and actually at shutter speeds that are faster) is that they stop using the mechanical shutter at those faster speeds.

[dcphotography]

Shun Cheung: Well yeah I know that :P. But when does the D40 start turning the sensor off and on to control shutter speed? Shuo said 1/90, but I don't know.

[geoffs1]

Shuo Zhao, "I think the camera uses a combination of both shutters at shutter speeds faster than 1/90s, because the mechanical shutter can't "open and close" for time intervals shorter than that."

 

Focal-plane shutters can easily create shutter-speeds well above 1/90s just by starting to close the second curtain before the first one has completely crossed the opening: http://en.wikipedia.org/wiki/Focal_plane_shutter

[richard_driscoll]

I can't remember where I read it, but I think the sequence of events is:

 

1. Shutter is opened.

 

2. When the shutter is fully open the sensor is gated on.

 

3. After exposure time (30 seconds to 1/4000 second) the sensor is gated off.

 

4. Shutter is closed.

[shuo_zhao]

>> "Focal-plane shutters can easily create shutter-speeds well above 1/90s just by starting to close the second curtain before the first one has completely crossed the opening: http://en.wikipedia.org/wiki/Focal_plane_shutter"

 

I know that, and that's the case with many cameras (especially higher end cameras).

 

In the D40's case, Nikon chose to have a mechanical shutter w/ a rather slow top speed to reduce cost, and compensated for the lost capability with the CCD shutter.

[joseph_wisniewski]

Richard is exactly right. That is the D40, D50, D70 action at all shutter speeds.

[geoffs1]

Just out of curiosity, why does Nikon have a mechanical shutter at all in those cameras? Just to protect the sensor/filter assembly?

[geoffs1]

A little searching goes a long way...

(sorry, I should have done that first...)

 

http://www.photo.net/nikon-camera-forum/00CaDT