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#11
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Dpreview does away with formal resolution tests in their reviews
On Wed, 02 May 2012 21:52:47 +1200, Eric Stevens
wrote: On Wed, 02 May 2012 01:02:35 -0400, John A. wrote: On Wed, 02 May 2012 13:29:03 +1200, Eric Stevens wrote: On Tue, 01 May 2012 15:51:17 -0400, Alan Browne wrote: On 2012-04-30 22:55 , Eric Stevens wrote: On Mon, 30 Apr 2012 19:13:56 -0400, Alan Browne wrote: On 2012-04-30 11:58 , RichA wrote: http://www.dpreview.com/reviews/olympusem5/ Very nice stabilization system (pitch, roll, yaw, y, z). I suspect only the X and Y rotational axiis matter much. Translation (y,z) are a lot of it (same as the Sony system). The weakness of that is pitch and roll is also present. Yaw is a lesser concern. When you depress the shutter you can easily roll the camera a little. Along the lens axis, if not well balanced, is the other concern (pitch). Pitch movement of the lens axis is the same as roll around the X axis. My point is that roll only matters if it deflects (as distinct from rotates) the lens axis. The lever effect of a long lens axis (to the subject) makes such movements critical. So if the camera is spinning about the lens axis so as to turn, say, ten degrees during the exposure, that will make no difference to the shot so long as said axis itself doesn't move? I was considering only the movements likely to be encountered in normal use. I'm not quite sure how you could obtain 10 degrees rotation during any exposure sufficiently short for any stabilisation system to have any effect. In fact, I don't think any stabilisation system could cope with 10 degrees of rotation. 1/10 degree, then. That will give you about a pixel-width of rotational motion blur per ~573 pixels (1800/pi) out from the center of rotation. (So at about 1150 pixels from the center you get about 2 pixels of motion blur, and so on.) Hmmm... Presumably lateral (x & y) stabilization would take care some portion of that if the center of rotation is way off-center, say at your tripod mount or monopod foot. So I imagine that would that reduce the task of rotational stabilization to being centered mid-sensor. |
#12
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Dpreview does away with formal resolution tests in their reviews
On 2012-05-01 21:29 , Eric Stevens wrote:
On Tue, 01 May 2012 15:51:17 -0400, Alan Browne wrote: On 2012-04-30 22:55 , Eric Stevens wrote: On Mon, 30 Apr 2012 19:13:56 -0400, Alan Browne wrote: On 2012-04-30 11:58 , RichA wrote: http://www.dpreview.com/reviews/olympusem5/ Very nice stabilization system (pitch, roll, yaw, y, z). I suspect only the X and Y rotational axiis matter much. Translation (y,z) are a lot of it (same as the Sony system). The weakness of that is pitch and roll is also present. Yaw is a lesser concern. When you depress the shutter you can easily roll the camera a little. Along the lens axis, if not well balanced, is the other concern (pitch). Pitch movement of the lens axis is the same as roll around the X axis. Not that it matters much, but to my (aviation based) reckoning : x is along lens axis, y is right and z is down. So pitch is about the y axis, roll about the x axis and yaw around the z axis. Thence the the translation axes are along: y (right left) and z (down up) and x (out in) - but not existent in the Oly sensor system for good reason. My point is that roll only matters if it deflects (as distinct from rotates) the lens axis. The lever effect of a long lens axis (to the subject) makes such movements critical. In the case where the camera pitches down, the ability to translate in z (move the sensor) is as important as tilting the sensor in pitch. But at the same time, the camera is likely to roll to the right and back (shutter depress) and the ability to roll the sensor about the lens axis is also important.. Unlike the Sony system (y and z only) the Oly system adds 3 more corrections. That is what I was referring to as advantageous. -- "A person with a new idea is a crank until the idea succeeds." -Samuel Clemens. |
#13
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Dpreview does away with formal resolution tests in their reviews
On 2012-05-02 05:52 , Eric Stevens wrote:
I was considering only the movements likely to be encountered in normal use. I'm not quite sure how you could obtain 10 degrees rotation during any exposure sufficiently short for any stabilisation system to have any effect. In fact, I don't think any stabilisation system could cope with 10 degrees of rotation. In the limited space inside a camera, the compensation is probably no more than a degree (maybe more, probably less) in any axis. There are commercial and military stabilization systems for various cameras and sensors that cope with much more. They are larger and often extremely expensive. -- "A person with a new idea is a crank until the idea succeeds." -Samuel Clemens. |
#14
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Dpreview does away with formal resolution tests in their reviews
On Wed, 02 May 2012 17:43:29 -0400, Alan Browne
wrote: On 2012-05-02 05:52 , Eric Stevens wrote: I was considering only the movements likely to be encountered in normal use. I'm not quite sure how you could obtain 10 degrees rotation during any exposure sufficiently short for any stabilisation system to have any effect. In fact, I don't think any stabilisation system could cope with 10 degrees of rotation. In the limited space inside a camera, the compensation is probably no more than a degree (maybe more, probably less) in any axis. There are commercial and military stabilization systems for various cameras and sensors that cope with much more. They are larger and often extremely expensive. And how do you compensate for rotation about the axis of the lens? Rotate the sensor (with all it's connections)? Regards, Eric Stevens |
#15
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Dpreview does away with formal resolution tests in their reviews
On Wed, 02 May 2012 17:41:54 -0400, Alan Browne
wrote: On 2012-05-01 21:29 , Eric Stevens wrote: On Tue, 01 May 2012 15:51:17 -0400, Alan Browne wrote: On 2012-04-30 22:55 , Eric Stevens wrote: On Mon, 30 Apr 2012 19:13:56 -0400, Alan Browne wrote: On 2012-04-30 11:58 , RichA wrote: http://www.dpreview.com/reviews/olympusem5/ Very nice stabilization system (pitch, roll, yaw, y, z). I suspect only the X and Y rotational axiis matter much. Translation (y,z) are a lot of it (same as the Sony system). The weakness of that is pitch and roll is also present. Yaw is a lesser concern. When you depress the shutter you can easily roll the camera a little. Along the lens axis, if not well balanced, is the other concern (pitch). Pitch movement of the lens axis is the same as roll around the X axis. Not that it matters much, but to my (aviation based) reckoning : x is along lens axis, y is right and z is down. So pitch is about the y axis, roll about the x axis and yaw around the z axis. Thence the the translation axes are along: y (right left) and z (down up) and x (out in) - but not existent in the Oly sensor system for good reason. My point is that roll only matters if it deflects (as distinct from rotates) the lens axis. The lever effect of a long lens axis (to the subject) makes such movements critical. In the case where the camera pitches down, the ability to translate in z (move the sensor) is as important as tilting the sensor in pitch. But at the same time, the camera is likely to roll to the right and back (shutter depress) and the ability to roll the sensor about the lens axis is also important.. Unlike the Sony system (y and z only) the Oly system adds 3 more corrections. That is what I was referring to as advantageous. Pitch is corrected by rotation about what you define as the 'y' axis. Yaw is corrected by rotation about what you define as the 'Z' axis. If I am correct, any camera correcting pitch and yaw has always employed rotation about the y and z axes. Roll correction about what you define as the 'x' axis implies rotation of the sensor about the x axis. I'm not sure how they can do that. Regards, Eric Stevens |
#16
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Dpreview does away with formal resolution tests in their reviews
Alan Browne wrote:
On 2012-04-30 11:58 , RichA wrote: http://www.dpreview.com/reviews/olympusem5/ Very nice stabilization system (pitch, roll, yaw, y, z). I use the Gitzo stabilization system :-) BugBear |
#17
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Dpreview does away with formal resolution tests in theirreviews
On Wed, 02 May 2012 06:54:35 -0700, RichA wrote:
On May 2, 5:52Â*am, Eric Stevens wrote: On Wed, 02 May 2012 01:02:35 -0400, John A. wrote: On Wed, 02 May 2012 13:29:03 +1200, Eric Stevens wrote: On Tue, 01 May 2012 15:51:17 -0400, Alan Browne wrote: On 2012-04-30 22:55 , Eric Stevens wrote: On Mon, 30 Apr 2012 19:13:56 -0400, Alan Browne wrote: On 2012-04-30 11:58 , RichA wrote: http://www.dpreview.com/reviews/olympusem5/ Very nice stabilization system (pitch, roll, yaw, y, z). I suspect only the X and Y rotational axiis matter Â*much. Translation (y,z) are a lot of it (same as the Sony system). The weakness of that is pitch and roll is also present. Â*Yaw is a lesser concern. Â*When you depress the shutter you can easily roll the camera a little. Â*Along the lens axis, if not well balanced, is the other concern (pitch). Pitch movement of the lens axis is the same as roll around the X axis. My point is that roll only matters if it deflects (as distinct from rotates) the lens axis. The lever effect of a long lens axis (to the subject) makes such movements critical. So if the camera is spinning about the lens axis so as to turn, say, ten degrees during the exposure, that will make no difference to the shot so long as said axis itself doesn't move? I was considering only the movements likely to be encountered in normal use. I'm not quite sure how you could obtain 10 degrees rotation during any exposure sufficiently short for any stabilisation system to have any effect. In fact, I don't think any stabilisation system could cope with 10 degrees of rotation. Regards, Eric Stevens It can't. You'd have to have something like they use in the fire control system of tanks to deal with that. I don't think it would fit in the camera. The gun (main armament) in a tank is a little larger and has to cope with much greater movement than that which occurs in a camera. -- Neil Reverse ‘a’ and ‘r’ Remove ‘l’ to get address. |
#18
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Dpreview does away with formal resolution tests in their reviews
On Thu, 03 May 2012 05:49:02 -0500, "C. Neil Ellwood"
wrote: On Wed, 02 May 2012 06:54:35 -0700, RichA wrote: On May 2, 5:52*am, Eric Stevens wrote: On Wed, 02 May 2012 01:02:35 -0400, John A. wrote: On Wed, 02 May 2012 13:29:03 +1200, Eric Stevens wrote: On Tue, 01 May 2012 15:51:17 -0400, Alan Browne wrote: On 2012-04-30 22:55 , Eric Stevens wrote: On Mon, 30 Apr 2012 19:13:56 -0400, Alan Browne wrote: On 2012-04-30 11:58 , RichA wrote: http://www.dpreview.com/reviews/olympusem5/ Very nice stabilization system (pitch, roll, yaw, y, z). I suspect only the X and Y rotational axiis matter *much. Translation (y,z) are a lot of it (same as the Sony system). The weakness of that is pitch and roll is also present. *Yaw is a lesser concern. *When you depress the shutter you can easily roll the camera a little. *Along the lens axis, if not well balanced, is the other concern (pitch). Pitch movement of the lens axis is the same as roll around the X axis. My point is that roll only matters if it deflects (as distinct from rotates) the lens axis. The lever effect of a long lens axis (to the subject) makes such movements critical. So if the camera is spinning about the lens axis so as to turn, say, ten degrees during the exposure, that will make no difference to the shot so long as said axis itself doesn't move? I was considering only the movements likely to be encountered in normal use. I'm not quite sure how you could obtain 10 degrees rotation during any exposure sufficiently short for any stabilisation system to have any effect. In fact, I don't think any stabilisation system could cope with 10 degrees of rotation. Regards, Eric Stevens It can't. You'd have to have something like they use in the fire control system of tanks to deal with that. I don't think it would fit in the camera. The gun (main armament) in a tank is a little larger and has to cope with much greater movement than that which occurs in a camera. And they don't worry about rotation about the axis of the barrel. Regards, Eric Stevens |
#19
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Dpreview does away with formal resolution tests in their reviews
On 2012-05-02 20:32 , Eric Stevens wrote:
On Wed, 02 May 2012 17:43:29 -0400, Alan Browne wrote: On 2012-05-02 05:52 , Eric Stevens wrote: I was considering only the movements likely to be encountered in normal use. I'm not quite sure how you could obtain 10 degrees rotation during any exposure sufficiently short for any stabilisation system to have any effect. In fact, I don't think any stabilisation system could cope with 10 degrees of rotation. In the limited space inside a camera, the compensation is probably no more than a degree (maybe more, probably less) in any axis. There are commercial and military stabilization systems for various cameras and sensors that cope with much more. They are larger and often extremely expensive. And how do you compensate for rotation about the axis of the lens? Rotate the sensor (with all it's connections)? In the Oly case, the amount of rotation is small. The entire sensor package is mounted on the articulation system. It's the articulation system that moves. The connection from that to the camera electronics would most likely be flexible-printed circuit. -- "A person with a new idea is a crank until the idea succeeds." -Samuel Clemens. |
#20
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Dpreview does away with formal resolution tests in their reviews
On 2012-05-02 20:40 , Eric Stevens wrote:
On Wed, 02 May 2012 17:41:54 -0400, Alan Browne wrote: On 2012-05-01 21:29 , Eric Stevens wrote: On Tue, 01 May 2012 15:51:17 -0400, Alan Browne wrote: On 2012-04-30 22:55 , Eric Stevens wrote: On Mon, 30 Apr 2012 19:13:56 -0400, Alan Browne wrote: On 2012-04-30 11:58 , RichA wrote: http://www.dpreview.com/reviews/olympusem5/ Very nice stabilization system (pitch, roll, yaw, y, z). I suspect only the X and Y rotational axiis matter much. Translation (y,z) are a lot of it (same as the Sony system). The weakness of that is pitch and roll is also present. Yaw is a lesser concern. When you depress the shutter you can easily roll the camera a little. Along the lens axis, if not well balanced, is the other concern (pitch). Pitch movement of the lens axis is the same as roll around the X axis. Not that it matters much, but to my (aviation based) reckoning : x is along lens axis, y is right and z is down. So pitch is about the y axis, roll about the x axis and yaw around the z axis. Thence the the translation axes are along: y (right left) and z (down up) and x (out in) - but not existent in the Oly sensor system for good reason. My point is that roll only matters if it deflects (as distinct from rotates) the lens axis. The lever effect of a long lens axis (to the subject) makes such movements critical. In the case where the camera pitches down, the ability to translate in z (move the sensor) is as important as tilting the sensor in pitch. But at the same time, the camera is likely to roll to the right and back (shutter depress) and the ability to roll the sensor about the lens axis is also important.. Unlike the Sony system (y and z only) the Oly system adds 3 more corrections. That is what I was referring to as advantageous. Pitch is corrected by rotation about what you define as the 'y' axis. Yaw is corrected by rotation about what you define as the 'Z' axis. If I am correct, any camera correcting pitch and yaw has always employed rotation about the y and z axes. The K-M system moved the sensor in translation only along the y and z axis' to correct for camera "movement". I don't recall if the sensing was solely in the same axis' or if it included rotation and an estimate of translation offset. Roll correction about what you define as the 'x' axis implies rotation of the sensor about the x axis. I'm not sure how they can do that. Sense it (gyros). Rotate the sensor in opposition (keep it 'still' wrt to the scene). As I say in the other recent post the image sensor is mounted on an articulation base with 5 axis freedom (3 angular, 2 translation). -- "A person with a new idea is a crank until the idea succeeds." -Samuel Clemens. |
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