Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
12-31-2014, 07:39 AM   #46
Pentaxian
Oldbayrunner's Avatar

Join Date: Mar 2013
Location: Havre de Grace, MD
Posts: 1,219
Good grief, I give up.. I could care less who he is, go back to write to "Labnut" on dpreview and tell him he is full of beans on his probable sensor correction circuitry low pass filter. Regardless there isn't one and the only low pass filter associated with image blurr is the anti-alias filter.

12-31-2014, 07:53 AM   #47
Pentaxian




Join Date: Dec 2010
Location: Ontario
Photos: Gallery
Posts: 2,285
QuoteOriginally posted by Oldbayrunner Quote
Good grief, I give up.. I could care less who he is, go back to write to "Labnut" on dpreview and tell him he is full of beans on his probable sensor correction circuitry low pass filter. Regardless there isn't one and the only low pass filter associated with image blurr is the anti-alias filter.
You're the one who claimed he was implying that the AA filter may impact SR:

QuoteOriginally posted by Oldbayrunner Quote
Perhaps before you jump to that conclusion you may wish to read the full report from P. Smith. Read it very thoroughly and carefully you just might gain some more insight. In his testing he mentions some cause due to possible Low Pass Filter, remember neither your K5 lls nor the K3 have one.
Though your post has mysteriously vanished. I was just trying to clear up this misconception.
12-31-2014, 07:59 AM   #48
Pentaxian
kh1234567890's Avatar

Join Date: Sep 2010
Location: Manchester, UK
Photos: Gallery
Posts: 2,327
QuoteOriginally posted by Gimbal Quote
Alright, the sensor is lifted AFTER the mirror is up, but before the shutter opens.
But what do you mean by "except when in live view"? The mirror has to be lifted to enable live view.
What I meant is that in live view the sensor is moved continually whereas in viewfinder view the movement only starts after the mirror up point in time.

As for the presence or absence of a LP filter in the movement servo loop - this will be taken care of simply by the mass of the sensor stage, there will be a limit to how fast you can move/accelerate this by the positioning magnets.
12-31-2014, 08:03 AM   #49
Pentaxian
Oldbayrunner's Avatar

Join Date: Mar 2013
Location: Havre de Grace, MD
Posts: 1,219
QuoteOriginally posted by Gimbal Quote
They don't mention anything about a battery either so... But perhaps that is because that isn't necessary in order to describe the SR function, just as every filter or capacitor actually used ins't mentioned.
And according to this https://www.google.se/patents/US20080013939 patent there are no filters at all except the optical ones.
Yep, in the US patent filed July 12, 2007 and published Jan. 17 2008 your referencing via google doesn't mention anything;

http://images2.freshpatents.com/pdf/US20080013938A1.pdf

HOWEVER in the updated US patent filed March 7, 2008 and published Sept 18 2008 I referenced it clearly does.

Anti-shake Apparatus

I looked at both and since the latest Patent is based in the most current filing and provides more detailed information that is what I referenced.

Here is the circuitry show me a low pass filter reference;



Last edited by Oldbayrunner; 12-31-2014 at 08:15 AM.
12-31-2014, 08:17 AM   #50
Pentaxian




Join Date: Apr 2007
Location: Sweden
Posts: 1,883
As I said, I bet that there is a low pass filter there somewhere before the A/D converter, even if it isn't mentioned in the patent. And that is because if you feed an A/D converter with frequencies higher then half the sampling rate you will get problems. That is a fact, even if it isn't mentioned in the patent.
So either they omit it from the patent as it is an electronic design thing and not part of the SR invention, or the selected gyro sensor has a built in low pass so no extra filter is needed.

Anyhow, why are we debating this?
01-01-2015, 03:01 AM   #51
Pentaxian
kh1234567890's Avatar

Join Date: Sep 2010
Location: Manchester, UK
Photos: Gallery
Posts: 2,327
QuoteOriginally posted by Gimbal Quote
So either they omit it from the patent as it is an electronic design thing and not part of the SR invention, or the selected gyro sensor has a built in low pass so no extra filter is needed.
The InvenSense gyros which Pentax use have a programmable LP filter.
01-01-2015, 04:42 AM   #52
Pentaxian




Join Date: Apr 2007
Location: Sweden
Posts: 1,883
Do you know exactly which type of gyros they use?
01-01-2015, 03:36 PM   #53
Veteran Member
Flugelbinder's Avatar

Join Date: Nov 2014
Location: Toronto - missing the ocean
Posts: 466
Original Poster
The 55-300 just got here, and now (at the long end in the dark) the SR is necessary... and visible...

01-02-2015, 12:12 PM   #54
Pentaxian
KevinR's Avatar

Join Date: Jan 2010
Location: Cape Town, South Africa
Photos: Gallery | Albums
Posts: 646
QuoteOriginally posted by kh1234567890 Quote
....As for the presence or absence of a LP filter in the movement servo loop - this will be taken care of simply by the mass of the sensor stage, there will be a limit to how fast you can move/accelerate this by the positioning magnets.
I tend to support this view. The inertia mass of the sensor will tend to act as a low pass frequency filter to the system. I'm a little out of my depth on the electronics side, but on the mechanical vibration side, a little more up to speed. The sensor will act as a variant of a driven mass-spring harmonic oscillator, and with these, the response amplitude tends to:
i) the forcing amplitude as the driving frequency ratio (driving/natural) tends to zero
ii) to zero as the driving frequency ratio over the natural frequency is significantly greater than 1.
Therefore it is necessary to eliminate spurious low freq inputs to moving the sensor, but unnecessary on the high freq side assuming the system is appropriately "tuned" to the underlying physic characteristics. Since the eletro-magnetics will only be so powerful as to achieve the necessary force but not to powerful as to be heavy and burn power, the system is likely fine without a low-pass filter on the gyro-sensors.

In addition, I suspect the gyros will also have an upper useful limit and they might simply clip the data in the digital circuit.
01-02-2015, 04:00 PM   #55
Pentaxian
kh1234567890's Avatar

Join Date: Sep 2010
Location: Manchester, UK
Photos: Gallery
Posts: 2,327
QuoteOriginally posted by KevinR Quote
The sensor will act as a variant of a driven mass-spring harmonic oscillator
And presumably the AA filter simulation jitter then exploits a natural mechanical resonance node at a frequency way above that of the positioning/anti-shake servo loop response.
01-04-2015, 10:41 AM   #56
Loyal Site Supporter
pacerr's Avatar

Join Date: Jan 2008
Location: Henry, TN
Photos: Gallery | Albums
Posts: 2,850
QuoteOriginally posted by kh1234567890 Quote
And presumably the AA filter simulation jitter then exploits a natural mechanical resonance node at a frequency way above that of the positioning/anti-shake servo loop response.
But only if the Coriolis-effect module has been calibrated for the northern (or southern?) hemisphere using the correct latitude (within 6-furlongs +/- 3 meters) within the past fortnight though.
01-05-2015, 07:08 AM   #57
Pentaxian




Join Date: Apr 2007
Location: Sweden
Posts: 1,883
QuoteOriginally posted by pacerr Quote
But only if the Coriolis-effect module has been calibrated for the northern (or southern?) hemisphere using the correct latitude (within 6-furlongs +/- 3 meters) within the past fortnight though.
Well obviously.
03-06-2015, 01:53 AM   #58
New Member




Join Date: Mar 2015
Posts: 1
I'm a newbie, so i can't open new topic, please help me with a big problem with K5 shake reduction:

Link to my big problem :

It seems to shake reduction error, when i open liveview, it isn't stable, when i shoot with slow speed ( about 1/20 ), it's blur. In my country, there is a little shop to repair pentax, please tell me how to fix it, and how much if i repair it? Thank you so much.
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, couple, dslr, filter, frequency, iso, issue, k-5, k-5 ii, k-5 iis, k5, mirror, move, pentax k-5, sensor, sensor movement, shutter, sr, view
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
SR mmjoshi Pentax DSLR Discussion 24 04-03-2013 01:27 AM
SR question Wingincamera Pentax K-5 9 02-03-2013 10:51 AM
SR sounds UncleRed Pentax Q 3 01-11-2013 06:49 AM
Should SR noise occur when SR is off? amoringello Pentax K-5 5 11-29-2010 06:03 PM
In-Body SR vs. In-Lens SR Pros and Cons? uchinakuri Troubleshooting and Beginner Help 32 09-23-2010 09:42 PM



All times are GMT -7. The time now is 05:59 PM. | See also: NikonForums.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