Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
02-08-2008, 07:08 PM   #16
Veteran Member
distudio's Avatar

Join Date: Jul 2007
Location: Sydney
Photos: Albums
Posts: 445
QuoteOriginally posted by ricardobeat Quote
Pentax also claims the sensor is able to compensate for rotation, unlike other IS systems. Very useful for supressing "shutter press" shake.
The SR mechanism can rotate and can be controlled to rotate (used to set fixed sensor rotation) but I don't believe that the SR system actively counters for rotation, if you can find a Pentax publication where it specifically says this I'd love to see it.

02-08-2008, 07:18 PM   #17
Inactive Account




Join Date: Jul 2007
Location: London
Posts: 1,067
Hi Rob

I believe Ricardobeat is entirely correct when he states that:

QuoteQuote:
Pentax also claims the sensor is able to compensate for rotation, unlike other IS systems.
Which would appear to contradict your opinion that:

QuoteQuote:
I don't believe that the SR system actively counters for rotation
That is, unless I've misunderstood the intention of what you were actually saying ?

Best regards
Richard
02-08-2008, 07:32 PM   #18
Veteran Member
distudio's Avatar

Join Date: Jul 2007
Location: Sydney
Photos: Albums
Posts: 445
QuoteOriginally posted by Confused Quote
Hi Rob

I believe Ricardobeat is entirely correct when he states that:



Which would appear to contradict your opinion that:



That is, unless I've misunderstood the intention of what you were actually saying ?

Best regards
Richard
As I said find a statement where Pentax say the SR counters for rotation. All I meant was that the mechanism is capable of rotation and can be controlled to rotate the sensor by a fixed amount, not that it actively counters body rotation during SR operation.
02-08-2008, 08:20 PM   #19
Pentaxian
falconeye's Avatar

Join Date: Jan 2008
Location: Munich, Alps, Germany
Photos: Gallery
Posts: 6,863
QuoteOriginally posted by distudio Quote
As I said find a statement where Pentax say the SR counters for rotation. All I meant was that the mechanism is capable of rotation and can be controlled to rotate the sensor by a fixed amount, not that it actively counters body rotation during SR operation.
distudio, thank You for the informative answer given earlier.

Why did I ask for the number of axes the gyros can measure? Because there can only be two differences between hand-held Eigen modes and tripod Eigen modes: frequency and type. As long as the frequency stays well below Eigen frequencies it should work. But tripod vibration may use different types of modes (e.g., rotational rather than translational etc.). And then it may fail even if frequency is low.

Note that tripod, in particular stable tripods, have high Eigen freqency!

distudio, thanks for the comment on drift. You are right, that alone may be a killer, i.e., if the system behaves non-linear for minuscule shake.

Some posters here quoted the number of axes the sensor can be moved by. It is x-trans, y-trans, and z-rot within the sensor plane. That's as many axes as possible given the constraint that the sensor better stays in the focus plane That wasn't my question, though. It was about the number of axes the gyro can measure and I doubt that it is more than two (rotational x and y of the camera body and no translations). But distudio and me do not seem to know facts about this. But if there is no third gyro for rotational z, the SR won't be able to compensate for body rotation along the lens axis.


Last edited by falconeye; 02-08-2008 at 08:26 PM.
02-09-2008, 07:59 AM   #20
Pentaxian
falconeye's Avatar

Join Date: Jan 2008
Location: Munich, Alps, Germany
Photos: Gallery
Posts: 6,863
QuoteOriginally posted by falconeye Quote
Why did I ask for the number of axes the gyros can measure?
Update:
I got additional info about the gyro sensors in K10D by private mail.
They seem indeed to be Murata's ENC-03R GYROSTAR sensors and there seem to be exactly two of them, measuring angular velocity (not acceleration!) around the following two axes, both perpendicular to the lens axe:
- vertical
- horizontal
Their center point (location of sensors) is in the lower and front part if the right hand grip, below the infrared sensor.

The gyro sensors output is specified for in between 0.3 Hz and 1 KHz only. But this does not mean much because we don't know the sensor's magnetic drive specification.

BTW, there is not enough information gathered to rotate the sensor except if there is a third gyro sensor at a completele different location within the camera body. Thre is no indication for this, though.
02-18-2008, 04:45 PM   #21
Veteran Member




Join Date: Aug 2007
Location: Brazil
Posts: 377
This says nothing about DSLRs, but may be a hint: Pentax selects InvenSense for image stabilization

Look for "rotational": http://www.pentaxslr.com/pdf/Pentax_SR_system_explanation1.pdf

I remember before buying my K100D of reading somewhere about how the SR system in it was the only one able to compensate for the shutter press movement... can't find it now though.
02-18-2008, 09:14 PM   #22
Veteran Member
distudio's Avatar

Join Date: Jul 2007
Location: Sydney
Photos: Albums
Posts: 445
QuoteOriginally posted by ricardobeat Quote
This says nothing about DSLRs, but may be a hint: Pentax selects InvenSense for image stabilization

Look for "rotational": http://www.pentaxslr.com/pdf/Pentax_SR_system_explanation1.pdf

I remember before buying my K100D of reading somewhere about how the SR system in it was the only one able to compensate for the shutter press movement... can't find it now though.
It's still only a dual plane rotational sensor and it was destined for use in the P&S range, the K10D definitely uses the Murata product that I mentioned above.
02-21-2008, 09:09 AM   #23
New Member




Join Date: Dec 2007
Location: Harrisburg, Pennsylvania
Photos: Gallery
Posts: 18
I use my 600mm with SR and a tripod. Did many tests with and without. It works when I use slow shutter speed and hendhold. If I use 2 s delay or remote, SR is not needed.

02-21-2008, 09:36 AM   #24
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,346
QuoteOriginally posted by Confused Quote
Hi again

Here is a previous quote from Lowell:
QuoteQuote:
While people have written in that if you are on a tripod there is no need because the camera is stable, I am not sure that they have ever looked through a 500mm-1000mm lens on a tripod. There is all sorts of vibration, much of it very high frequency. This is why lots of pros use a sand bag to weight down the tripod.
Richard I'm glad some people actually remember what I post.
QuoteQuote:
Best regards
Richard

As another point to raise, Manfretto makes a "long lens support" which is an extendible tube with a small bnall head on one end (for the camera body tripod mount), and a clamp on the other to clamp to a tripod leg. THis works very effectively to take out vibration at the tripod head which on long lenses is on the lens mount.
02-22-2008, 11:11 AM   #25
Inactive Account




Join Date: Jul 2007
Location: London
Posts: 1,067
Hi again Lowell

FWIW I hadn't heard of such a device before as I'm not personally into extreme telephoto photography myself, but for those others who might be interested, here's a link to the Manfrotto product that you mentioned

Large Image Adorama Sku#BG3252.JPG

Best regards
Richard
02-22-2008, 12:36 PM   #26
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,346
QuoteOriginally posted by Confused Quote
Hi again Lowell

FWIW I hadn't heard of such a device before as I'm not personally into extreme telephoto photography myself, but for those others who might be interested, here's a link to the Manfrotto product that you mentioned

Large Image Adorama Sku#BG3252.JPG

Best regards
Richard
Richard

thanks for the link

FWIW, the effectiveness is not limited to such extreme lenses. I use it with my Sigma 70-200 f2.8 and 2xTC. It takes a lot of vibration out

Also, I use it with a slightly different orientation in terms of camera and tripod. I insure that the camera splits (if possible) the two rear legs of the tripod, and have the support come off at an angle. usually going down to the left. this cancells out not only vertical but a large degree of lateral motion. If the support goes streight down, it does nothing against lateral motion,
02-22-2008, 03:41 PM   #27
Inactive Account




Join Date: Jul 2007
Location: London
Posts: 1,067
Hi again Lowell

Bet you don't half get some funny looks from the occasional passer-by when using this contraption........lol !

Still, when all's said & done, your pictures come out OK, so the last laugh is probably on them.....

Best regards
Richard
06-04-2009, 06:45 PM   #28
Pentaxian
Class A's Avatar

Join Date: Aug 2008
Location: Wellington, New Zealand
Posts: 9,036
QuoteOriginally posted by ricardobeat Quote
Pentax also claims the sensor is able to compensate for rotation, unlike other IS systems. Very useful for supressing "shutter press" shake.
As others have said already the sensor could rotate potentially. However, in actual fact the K-7 is the first model to actually exploit this.
The Imaging Resource Review of the K-7 says:
QuoteQuote:
For a while now, we've been under the impression that Pentax's Shake Reduction systems not only compensated for vertical and horizontal movement of the camera, but for rotation about the lens axis as well. As it turns out, this in fact wasn't the case, the misunderstanding apparently tracing back to a translation error on documentation for the original K-100D.
06-04-2009, 11:56 PM   #29
Site Supporter




Join Date: Mar 2008
Location: Prince George, BC
Photos: Gallery
Posts: 2,269
Only with the K-7 can the Pentax SR work in 3 axes. All previous versions of SR were 2 axes only. My own experience with star trail photos at night on a tripod is that SR is a bad idea, likely due to the intermal frequencies that the SR cannot handle properly that others have mentioned. So if my K20D is on a solid tripod, SR is off. Otherwise, it is always on unless I want an intentionally blurred photo.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, dslr, photography, reduction, telephoto
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
M42 lens' & shake reduction Big Bob Troubleshooting and Beginner Help 11 06-14-2009 06:49 AM
F series zoom lens & Shake Reduction calicojack Pentax SLR Lens Discussion 3 02-22-2008 08:25 AM
Best long (affordable) telephotos? Finn Pentax SLR Lens Discussion 16 10-12-2007 01:44 PM
K10D, Shake Reduction & Tripod switch79 Pentax DSLR Discussion 28 04-19-2007 06:18 PM
Shake reduction & camera life Brew1brew Pentax DSLR Discussion 9 09-27-2006 05:58 AM



All times are GMT -7. The time now is 09:57 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top