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#11
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Focal Plane Shutters
On Sun, 27 Aug 2006 08:28:08 -0700, "Frank ess"
wrote: JohnR66 wrote: wrote in message ups.com... snip Another common attribute of focal plane shutters is the creation of a "leaning into motion" when the shutter slit traveled vertically. Early pictures of racing cars were good examples. This became almost an icon of speed, and even comic strip illustrators drew fast moving objects tilted. Wheels went from round to ovals tilted in direction of motion. This effect was magnified by the slow speed of the film in those days. In daylight photograhy with a vertically moving focal plane, the distortion is still there but is so small as to be unnoticable with today's films. The effect was pronounced because of the relative slow speed of the traveling slit. Modern multi bladed focal plane shutters are relatively fast with some syncing with flash units at 1/250th or more of a second (full open). John I figured the vertical-slot shutter in my film SLR of the early 80s should be able to show that leaning-wheel phenomenon, if oriented portrait style at slow shutter speeds. Spent a nice roll of Kodachrome 25 without demonstrating the effect. If I could find the slides, maybe my eye would work better on a scanned example, and I could see something. Otherwise, a disappointing attempt. The old Houghton Butcher Ensign reflex camera I owned during the 1940s had the xposure controlled by both the slit being adjustable, and the spring tension on the shutter release also being adjustable. Attained an astonishing 1/250th second! |
#12
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Focal Plane Shutters
See the Olympus E10/20 - Mechanical aperture but electronic shutter.
Sequence - "Shutter" open, 1/2 press to lock distance and aperture, Full press to CLOSE "Shutter" and process image and flush imager, "Shutter open to max aperture (or preset). Gary Eickmeier asked: But the real question is, does digital permit the possibility of electronic shutters that work entirely differently from either type of mechanical shutter? Don't some amateur cameras work by exposing electronically? Grabbing the data over a reduced period of time? Does that cause shutter lag, in order to flush the sensor before letting it fill back up again for the exposure? Any camera engineers out there? |
#13
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Focal Plane Shutters
EO wrote: See the Olympus E10/20 - Mechanical aperture but electronic shutter. Sequence - "Shutter" open, 1/2 press to lock distance and aperture, Full press to CLOSE "Shutter" and process image and flush imager, "Shutter open to max aperture (or preset). OK I have an E20, and I thought it was purely a leaf shutter situation. It only goes up to 1/640th of a second, and it flash syncs at any speed. Let's see... it has the possibility of live preview, and the viewfinder image comes thru a prism ahead of the imager... that means it has to be wide open during viewing, then when you press the shutter it has to close down to shooting aperture and expose the imager. I suppose it could be either closing down completely before exposure, or just closing to shooting aperture and exposing electronically. All I know for certain is that there is very little shutter lag, and the shutter is silent. Gary Eickmeier |
#14
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Focal Plane Shutters
On Sun, 27 Aug 2006 20:56:32 -0400, Bill wrote:
The Nikon D50 has a mechanical shutter that only reaches 1/90 then the electronic "shutter" of the CCD takes over for higher speeds. The Nikon D70 has a mechanical shutter that only reaches 1/250 then the CCD takes over. The Nikon D80 has a fully mechanical shutter that reaches up to 1/4000. Flash sync is 1/500 for the D50 and D70, and 1/200 for the D80. But the D50/D70 models cheat by using the CCD "shutter" to get this high, which can introduce some nasty image artifacts. High speed flash sync is possible on all models up to their rated top speeds 1/4000 or 1/8000 using compatible flash units. Thanks for that information. |
#15
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Focal Plane Shutters
EO wrote:
Gary - It closes and then calculates the exposure (electronic). Remember the only time the viewfinder is blanked is immediately after you full press the shutter and then it immediately opens up again. Note that at slow shutter speeds (1/2 sec or longer) the finder is blanked longer - shorter speeds you don't notice it. Ed Gary Eickmeier wrote: I suppose it could be either closing down completely before exposure, or just closing to shooting aperture and exposing electronically. |
#16
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Focal Plane Shutters
Gary - It closes and then calculates the exposure (electronic).
Remember the only time the viewfinder is blanked is immediately after you full press the shutter and then it immediately opens up again. Note that at slow shutter speeds (1/2 sec or longer) the finder is blanked longer - shorter speeds you don't notice it. Ed Gary Eickmeier wrote: I suppose it could be either closing down completely before exposure, or just closing to shooting aperture and exposing electronically. |
#17
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Focal Plane Shutters
On Mon, 28 Aug 2006 14:25:22 -0800, EO wrote:
Gary - It closes and then calculates the exposure (electronic). Remember the only time the viewfinder is blanked is immediately after you full press the shutter and then it immediately opens up again. Note that at slow shutter speeds (1/2 sec or longer) the finder is blanked longer - shorter speeds you don't notice it. Ed Gary Eickmeier wrote: I suppose it could be either closing down completely before exposure, or just closing to shooting aperture and exposing electronically. I don't suppose many people remember the slr before the introduction of the instant return mirror, that was one of the reasons I bought a Miranda D when it became available (around 1960 IIRC). After slrs that stayed blank after exposure it was an enormous advance that doesn't sound very good when just written down but was a revolution in use. -- Neil Delete l to reply |
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