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Dpreview does away with formal resolution tests in their reviews



 
 
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  #11  
Old May 2nd 12, 05:40 PM posted to rec.photo.digital.slr-systems,rec.photo.digital
John A.[_2_]
external usenet poster
 
Posts: 1,551
Default 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  
Old May 2nd 12, 10:41 PM posted to rec.photo.digital.slr-systems,rec.photo.digital
Alan Browne
external usenet poster
 
Posts: 12,640
Default 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  
Old May 2nd 12, 10:43 PM posted to rec.photo.digital.slr-systems,rec.photo.digital
Alan Browne
external usenet poster
 
Posts: 12,640
Default 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  
Old May 3rd 12, 01:32 AM posted to rec.photo.digital.slr-systems,rec.photo.digital
Eric Stevens
external usenet poster
 
Posts: 13,611
Default 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  
Old May 3rd 12, 01:40 AM posted to rec.photo.digital.slr-systems,rec.photo.digital
Eric Stevens
external usenet poster
 
Posts: 13,611
Default 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  
Old May 3rd 12, 09:23 AM posted to rec.photo.digital.slr-systems,rec.photo.digital
bugbear
external usenet poster
 
Posts: 1,258
Default 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  
Old May 3rd 12, 11:49 AM posted to rec.photo.digital.slr-systems,rec.photo.digital
C. Neil Ellwood
external usenet poster
 
Posts: 33
Default 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  
Old May 3rd 12, 09:49 PM posted to rec.photo.digital.slr-systems,rec.photo.digital
Eric Stevens
external usenet poster
 
Posts: 13,611
Default 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  
Old May 3rd 12, 10:05 PM posted to rec.photo.digital.slr-systems,rec.photo.digital
Alan Browne
external usenet poster
 
Posts: 12,640
Default 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  
Old May 3rd 12, 10:09 PM posted to rec.photo.digital.slr-systems,rec.photo.digital
Alan Browne
external usenet poster
 
Posts: 12,640
Default 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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