Forums
New posts
Search forums
What's new
New posts
New media
New media comments
New profile posts
Latest activity
Media
New media
New comments
Search media
Members
Current visitors
New profile posts
Search profile posts
Log in
Register
What's new
Search
Search
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Forums
Lenses
General Lenses
The Impact of VR on IQ at Faster Shutter Speeds
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="WayneF" data-source="post: 429364" data-attributes="member: 12496"><p>I think it may be hopeless. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /></p><p></p><p>but for a focal plane shutter and a 1/4000 second shutter speed, there is a narrow open slit (between the opening front curtain, and the closing rear curtain - see the previous links, Wikipedia is good), that exposes a narrow moving slit on the sensor for 1/4000 second duration (under the narrow slit). 1/4000 second probably can stop any reasonable motion. It is 1/4000 second.</p><p></p><p>However, the total curtain travel time is more like 1/200 (or some are 1/300) second... as the slit moves down the frame.</p><p></p><p>That means as the slit moves down the frame (exposing), that the early 1/4000 second exposure at the top of the frame (inverted to be seen at the bottom) occurs a few milliseconds before the 1/4000 second at the bottom (inverted to top). That can distort the moving subject - for example, the classic oval racing car wheels. The wheel moves sideways while the curtain slit moves down. Top and bottom of wheel are both exposed for 1/4000 second, but at different points in time (different points in curtain travel - which is also different points in time of wheel travel).</p><p></p><p>The curtains always move at the same speed, but the timing when the second closing curtain starts varies. 1/4000 second is a very narrow slit, and 1/1000 second is a 4x wider slit (allowing 4x longer exposure). At about 1/200 second (much wider slit - but the duration corresponding to shutter travel time - the front fully opens, and THEN the rear starts shutting), the total frame height is open for an instant, allowing instantaneous flash to expose the total frame (called maximum flash sync speed). This is still a slit moving across the frame, a slit width equal to the frame width, shutter speed equal to the curtain travel time. For longer exposures, the full frame remains fully open longer, maybe seconds (a very wide slit)</p><p></p><p>shutter speed (duration) = slit width / curtain velocity</p><p></p><p>1/200 second is 5 milliseconds curtain travel time. 3 milliseconds is possible in top end models. FWIW, the D300 and D800 curtains travel different directions, some models move down, some move up.</p><p> </p><p>This is the fundamental basics of focal plane shutters.</p></blockquote><p></p>
[QUOTE="WayneF, post: 429364, member: 12496"] I think it may be hopeless. :) but for a focal plane shutter and a 1/4000 second shutter speed, there is a narrow open slit (between the opening front curtain, and the closing rear curtain - see the previous links, Wikipedia is good), that exposes a narrow moving slit on the sensor for 1/4000 second duration (under the narrow slit). 1/4000 second probably can stop any reasonable motion. It is 1/4000 second. However, the total curtain travel time is more like 1/200 (or some are 1/300) second... as the slit moves down the frame. That means as the slit moves down the frame (exposing), that the early 1/4000 second exposure at the top of the frame (inverted to be seen at the bottom) occurs a few milliseconds before the 1/4000 second at the bottom (inverted to top). That can distort the moving subject - for example, the classic oval racing car wheels. The wheel moves sideways while the curtain slit moves down. Top and bottom of wheel are both exposed for 1/4000 second, but at different points in time (different points in curtain travel - which is also different points in time of wheel travel). The curtains always move at the same speed, but the timing when the second closing curtain starts varies. 1/4000 second is a very narrow slit, and 1/1000 second is a 4x wider slit (allowing 4x longer exposure). At about 1/200 second (much wider slit - but the duration corresponding to shutter travel time - the front fully opens, and THEN the rear starts shutting), the total frame height is open for an instant, allowing instantaneous flash to expose the total frame (called maximum flash sync speed). This is still a slit moving across the frame, a slit width equal to the frame width, shutter speed equal to the curtain travel time. For longer exposures, the full frame remains fully open longer, maybe seconds (a very wide slit) shutter speed (duration) = slit width / curtain velocity 1/200 second is 5 milliseconds curtain travel time. 3 milliseconds is possible in top end models. FWIW, the D300 and D800 curtains travel different directions, some models move down, some move up. This is the fundamental basics of focal plane shutters. [/QUOTE]
Verification
Post reply
Forums
Lenses
General Lenses
The Impact of VR on IQ at Faster Shutter Speeds
Top
