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Dpreview does away with formal resolution tests in their reviews



 
 
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  #21  
Old May 4th 12, 12:13 AM posted to rec.photo.digital.slr-systems,rec.photo.digital
Eric Stevens
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Posts: 13,611
Default Dpreview does away with formal resolution tests in their reviews

On Thu, 03 May 2012 17:05:40 -0400, Alan Browne
wrote:

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.


But these don't normally bend sideways. I wonder how they do it?

Regards,

Eric Stevens
  #22  
Old May 4th 12, 01:42 AM posted to rec.photo.digital.slr-systems,rec.photo.digital
Savageduck[_3_]
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Posts: 16,487
Default Dpreview does away with formal resolution tests in their reviews

On 2012-05-03 16:58:13 -0700, John A. said:

On Fri, 04 May 2012 08:49:23 +1200, Eric Stevens
wrote:

On Thu, 03 May 2012 05:49:02 -0500, "C. Neil Ellwood"
wrote:

On Wed, 02 May 2012 06:54:35 -0700, RichA wrote:


Le Snip

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.


IIRC they actively (or passively?) encourage it in the projectile.


To answer the question regarding encouraging rotation of the
projectile, there have been some changes in the manner tank guns gain
accuracy. Up until 1986 the M1 Abrams used the Royal Ordnance L52/M68
105mm rifled canon which proved inadequate.

In 1986, the upgraded M1A1 received the Rheinmetall L44/M256 120mm
smoothbore cannon. That is the gun currently found on all of the
upgraded Abrams tanks and the fine German Leopard 2.

The standard ammo most used is the kinetic energy penetrator type
M829/A2/A3 or Armor-Piercing, Fin-Stabilized, Discarding Sabot (APFSDS)
round. Rotation is not required, shear acceleration is all that is
needed to get that dart down range to punch through most anything.

It also fires the M830A1 High Explosive Anti-Tank, (HEAT) round which
also employs a sabot surrounding the primary submunition, no rifling
required.

Then it gets very nasty when it comes to engaging personnel with the
M1028 anti-personnel canister (APC) cartridge which delivers 1098
tungsten balls in a shotgun effect which is lethal out at 600 meters.

The latest projectile the M1/A1 Abrams and Leopard 2 are firing is the
XM1111 Mid-Range Munition Chemical Energy round or MRM-CE. This is a
guided munition using a dual mode seeker combining imaging IR and
semi-active laser guidance.
Guess what, no rifling is needed for the APC or MRM-CE.

Having said all of that the British Challenger 2 uses the L30A1 120mm
rifled gun, which still spins those English versions of the APFSDS
rounds, with their specialized "high explosive squash head" HESH rounds
down range.


--
Regards,

Savageduck

  #23  
Old May 4th 12, 10:15 PM posted to rec.photo.digital.slr-systems,rec.photo.digital
Alan Browne
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Posts: 12,640
Default Dpreview does away with formal resolution tests in their reviews

On 2012-05-03 19:13 , Eric Stevens wrote:
On Thu, 03 May 2012 17:05:40 -0400, Alan Browne


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.


But these don't normally bend sideways. I wonder how they do it?


"bend"? Nothing about bending, it's just degrees of articulation.

For example a z-y translation table mounted on a x-axis rotation table
mounted on a z, y axis tilt table. Probably driven by piezo actuators
which can make tiny, precise, repeatable movements. The magic is in
making it all very thin such that it fits and the two tilt axis' result
in the center of the sensor not changing the focal length when activated.

--
"A person with a new idea is a crank until the idea succeeds."
-Samuel Clemens.


  #24  
Old May 4th 12, 10:17 PM posted to rec.photo.digital.slr-systems,rec.photo.digital
Alan Browne
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Posts: 12,640
Default Dpreview does away with formal resolution tests in their reviews

On 2012-05-03 16:49 , Eric Stevens wrote:
On Thu, 03 May 2012 05:49:02 -0500, "C. Neil Ellwood"


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.


There are limits to any comparison across systems.

--
"A person with a new idea is a crank until the idea succeeds."
-Samuel Clemens.


  #25  
Old May 4th 12, 11:35 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 2012-05-04 17:55 , John A. wrote:
On Fri, 04 May 2012 17:15:26 -0400, Alan Browne
wrote:

On 2012-05-03 19:13 , Eric Stevens wrote:
On Thu, 03 May 2012 17:05:40 -0400, Alan Browne


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.

But these don't normally bend sideways. I wonder how they do it?


"bend"? Nothing about bending, it's just degrees of articulation.

For example a z-y translation table mounted on a x-axis rotation table
mounted on a z, y axis tilt table. Probably driven by piezo actuators
which can make tiny, precise, repeatable movements. The magic is in
making it all very thin such that it fits and the two tilt axis' result
in the center of the sensor not changing the focal length when activated.


I wonder how much range the tilt has and if the firmware can be hacked
to set it manually.


Don't know and I haven't heard of any DSLR's being hacked. (Not to say
there aren't any, just doesn't interest me).

Presumably any camera for which firmware can be updated can be hacked.
Set you alarm clock for very early in the morning...

--
"A person with a new idea is a crank until the idea succeeds."
-Samuel Clemens.


  #26  
Old May 5th 12, 12:15 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 Fri, 04 May 2012 17:15:26 -0400, Alan Browne
wrote:

On 2012-05-03 19:13 , Eric Stevens wrote:
On Thu, 03 May 2012 17:05:40 -0400, Alan Browne


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.


But these don't normally bend sideways. I wonder how they do it?


"bend"? Nothing about bending, it's just degrees of articulation.

For example a z-y translation table mounted on a x-axis rotation table
mounted on a z, y axis tilt table. Probably driven by piezo actuators
which can make tiny, precise, repeatable movements. The magic is in
making it all very thin such that it fits and the two tilt axis' result
in the center of the sensor not changing the focal length when activated.


A flat printed circuit ribbon can bend which movement can cope with
tilting of the sensor. Rotation of the sensor about it's central axis
seems to require a lateral shearing movement of the printed circuit. I
am puzzled as to how they managed to fit a suitably flexible run of
printed circuit into the limited space within the camera.

Regards,

Eric Stevens
  #27  
Old May 5th 12, 12:29 AM 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 2012-05-04 19:15 , Eric Stevens wrote:
On Fri, 04 May 2012 17:15:26 -0400, Alan Browne
wrote:

On 2012-05-03 19:13 , Eric Stevens wrote:
On Thu, 03 May 2012 17:05:40 -0400, Alan Browne


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.

But these don't normally bend sideways. I wonder how they do it?


"bend"? Nothing about bending, it's just degrees of articulation.

For example a z-y translation table mounted on a x-axis rotation table
mounted on a z, y axis tilt table. Probably driven by piezo actuators
which can make tiny, precise, repeatable movements. The magic is in
making it all very thin such that it fits and the two tilt axis' result
in the center of the sensor not changing the focal length when activated.


A flat printed circuit ribbon can bend which movement can cope with
tilting of the sensor. Rotation of the sensor about it's central axis
seems to require a lateral shearing movement of the printed circuit. I
am puzzled as to how they managed to fit a suitably flexible run of
printed circuit into the limited space within the camera.


I suggested that as a means, not the means. Go buy one and open it up.

--
"A person with a new idea is a crank until the idea succeeds."
-Samuel Clemens.


  #28  
Old May 5th 12, 12:30 AM 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 2012-05-04 19:15 , Eric Stevens wrote:
On Fri, 04 May 2012 17:15:26 -0400, Alan Browne
wrote:

On 2012-05-03 19:13 , Eric Stevens wrote:
On Thu, 03 May 2012 17:05:40 -0400, Alan Browne


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.

But these don't normally bend sideways. I wonder how they do it?


"bend"? Nothing about bending, it's just degrees of articulation.

For example a z-y translation table mounted on a x-axis rotation table
mounted on a z, y axis tilt table. Probably driven by piezo actuators
which can make tiny, precise, repeatable movements. The magic is in
making it all very thin such that it fits and the two tilt axis' result
in the center of the sensor not changing the focal length when activated.


A flat printed circuit ribbon can bend which movement can cope with
tilting of the sensor. Rotation of the sensor about it's central axis
seems to require a lateral shearing movement of the printed circuit. I


The connection from table to table does not imply a single ribbon -
though it may depending on how the ribbon is layed out, cut and folded.


--
"A person with a new idea is a crank until the idea succeeds."
-Samuel Clemens.


  #29  
Old May 5th 12, 03:21 AM posted to rec.photo.digital.slr-systems,rec.photo.digital
[email protected]
external usenet poster
 
Posts: 210
Default Dpreview does away with formal resolution tests in their reviews

On Sat, 05 May 2012 11:15:55 +1200, Eric Stevens wrote:

On Fri, 04 May 2012 17:15:26 -0400, Alan Browne
wrote:

On 2012-05-03 19:13 , Eric Stevens wrote:
On Thu, 03 May 2012 17:05:40 -0400, Alan Browne


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.

But these don't normally bend sideways. I wonder how they do it?


"bend"? Nothing about bending, it's just degrees of articulation.

For example a z-y translation table mounted on a x-axis rotation table
mounted on a z, y axis tilt table. Probably driven by piezo actuators
which can make tiny, precise, repeatable movements. The magic is in
making it all very thin such that it fits and the two tilt axis' result
in the center of the sensor not changing the focal length when activated.


A flat printed circuit ribbon can bend which movement can cope with
tilting of the sensor. Rotation of the sensor about it's central axis
seems to require a lateral shearing movement of the printed circuit. I
am puzzled as to how they managed to fit a suitably flexible run of
printed circuit into the limited space within the camera.


I used to work on 2-way FM radios (walkie-talkies) and sometimes they would fold
the flex circuit ribbon at a right angle before inserting into a connector,
which allows a ton of movement in ANY direction. (not that movement within the
radio was necessary, but removing modules was made easier.) Radios, without the
battery, have been smaller than DSLRs for years,

  #30  
Old May 12th 12, 08:34 PM posted to rec.photo.digital.slr-systems,rec.photo.digital
Ben Brugman
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Posts: 271
Default Dpreview does away with formal resolution tests in their reviews

"Alan Browne" wrote in message
...


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).


Translation of the sensor (as the Sony system) is used to counteract the yaw
and pitch (rotation) of the camera.

To my knowledge it is not used to counteract the translation of the camera
itself.
That would be usefull for closeup situations, but not for general usage.

Ben

 




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