Re: simple-as-dirt focus calibration method

On 8 April 2012 11:34, Charles Robinson wrote: > On Apr 7, 2012, at 23:19, Miserere wrote: > >> Well Charles, now that Phase Detect focusing agrees with Contrast >> Detect focusing, and assuming CD focusing is correct, you now have the >> enviable task of making sure manual focusing agrees too! If

Re: simple-as-dirt focus calibration method

On Apr 7, 2012, at 23:19, Miserere wrote: > Well Charles, now that Phase Detect focusing agrees with Contrast > Detect focusing, and assuming CD focusing is correct, you now have the > enviable task of making sure manual focusing agrees too! If an > autofocused image doesn't look focused through t

Re: simple-as-dirt focus calibration method

Well Charles, now that Phase Detect focusing agrees with Contrast Detect focusing, and assuming CD focusing is correct, you now have the enviable task of making sure manual focusing agrees too! If an autofocused image doesn't look focused through the viewfinder, you'll have to install some shims or

Re: simple-as-dirt focus calibration method

On 04/04/2012 12:56 PM, Bryan Jacoby wrote: Can anybody explain the origin of lens-related phase detection AF errors? Pixel peeping. -- William Robb -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the

Re: simple-as-dirt focus calibration method

On Apr 4, 2012, at 15:18, wrote: >> but I do know that some of my lenses needed calibration and some didn't! > > The proof of all this obviously will be in the images. > I agree! I was in a hurry to make an appointment last night and couldn't really run any testing beyond "shoot and

Re: simple-as-dirt focus calibration method

but I do know that some of my lenses needed calibration and some didn't! The proof of all this obviously will be in the images. Kenneth Waller http://www.pentaxphotogallery.com/kennethwaller - Original Message - From: "Charles Robinson" Subject: Re: simpl

Re: simple-as-dirt focus calibration method

You spoke my thoughts exactly, George.   Jack From: George Sinos To: Pentax-Discuss Mail List Sent: Wednesday, April 4, 2012 11:32 AM Subject: Re: simple-as-dirt focus calibration method OK, I just looked it up.  If I understand it correctly, the default focusing mode for live view is based

Re: simple-as-dirt focus calibration method

On 4/4/2012 2:06 PM, Matthew Hunt wrote: On Wed, Apr 4, 2012 at 2:01 PM, George Sinos wrote: I'm not sure what is being accomplished here. How do you know which of the two focusing methods techniques is errant? Live View is correct, by definition. It's based directly on the imaging sensor.

Re: simple-as-dirt focus calibration method

On Apr 4, 2012, at 14:27, George Sinos wrote: > OK, I found my answer, and some animated examples here. > > Cl. Thanks! > The short story is that phase-detection measures the error and tells > the lens which direction an

Re: simple-as-dirt focus calibration method

That applet is a great explanation of how phase detection AF works, but I don't think it explains lens-to-lens variation in AF. On Wed, Apr 4, 2012 at 3:27 PM, George Sinos wrote: > OK, I found my answer, and some animated examples here. >

Re: simple-as-dirt focus calibration method

OK, I found my answer, and some animated examples here. The short story is that phase-detection measures the error and tells the lens which direction and how far to move to get into the correct position. It's faster, but depend

Re: simple-as-dirt focus calibration method

On Wed, Apr 4, 2012 at 2:32 PM, George Sinos wrote: > If that's true people should be saying this "camera body back-focuses > with this lens" instead of the more commonly phrased "this lens has a > back-focus problem." I can't say I understand exactly why this is, but phase detection AF errors c

Re: simple-as-dirt focus calibration method

OK, I just looked it up. If I understand it correctly, the default focusing mode for live view is based on contrast as detected by the imaging sensor. Focusing through the optical system uses a separate phase detection sensor. I guess the method assumes that the live view, contrast-based autofoc

Re: simple-as-dirt focus calibration method

On Wed, Apr 4, 2012 at 2:01 PM, George Sinos wrote: > I'm not sure what is being accomplished here.  How do you know which > of the two focusing methods techniques is errant? Live View is correct, by definition. It's based directly on the imaging sensor. -- PDML Pentax-Discuss Mail List PDML@p

Re: simple-as-dirt focus calibration method

rom: Christine Nielsen > To: Pentax-Discuss Mail List > Cc: > Sent: Wednesday, April 4, 2012 7:55 AM > Subject: Re: simple-as-dirt focus calibration method > > A chore I have put off for a while, too.  And I think my FA-50 1.4 > could use a little calibrating... I would love

Re: simple-as-dirt focus calibration method

-Discuss Mail List Cc: Sent: Wednesday, April 4, 2012 11:12 AM Subject: Re: simple-as-dirt focus calibration method I think that should work (and does indeed sound like a simpler way to go about it), but I'd still want to use a flat surface for the target. There's no guarantee that the AF

Re: simple-as-dirt focus calibration method

On Apr 4, 2012, at 12:00, John Celio wrote: > That sounds super easy! I will give that a shot today. My FA50 1.4 has > always had a horrible back-focus issue on just about all my dSLRs, so > it'll be great to finally have that sorted. Thanks for sharing! > I'm sure we'll all appreciate a follow-

Re: simple-as-dirt focus calibration method

That sounds super easy! I will give that a shot today. My FA50 1.4 has always had a horrible back-focus issue on just about all my dSLRs, so it'll be great to finally have that sorted. Thanks for sharing! John -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_p

Re: simple-as-dirt focus calibration method

On Apr 4, 2012, at 10:35, Collin Brendemuehl wrote: > Wouldn't the results be affected by the # of AF sensors in use? > What does your AF "Select AF Point" say? > >From my list of instructions: "2. Set up camera on tripod with center focus point selected." > I wonder how an AF lens can be in e

Re: simple-as-dirt focus calibration method

Wouldn't the results be affected by the # of AF sensors in use? What does your AF "Select AF Point" say? I wonder how an AF lens can be in error if the sensor is aligned with the ground glass and film/sensor plane. What am I missing? Sincerely, Collin Brendemuehl "He is no fool who gives what

Re: simple-as-dirt focus calibration method

Yeah..me too. Probably readying their needles as I (two finger) type. ;-) Jack - Original Message - From: Christine Nielsen To: Pentax-Discuss Mail List Cc: Sent: Wednesday, April 4, 2012 7:55 AM Subject: Re: simple-as-dirt focus calibration method A chore I have put off for a while

Re: simple-as-dirt focus calibration method

I think that should work (and does indeed sound like a simpler way to go about it), but I'd still want to use a flat surface for the target. There's no guarantee that the AF sensor is locking on exactly the same part of the scene as the live view AF, so a wine bottle (with a curved surface) might

Re: simple-as-dirt focus calibration method

A chore I have put off for a while, too. And I think my FA-50 1.4 could use a little calibrating... I would love for it to be this simple... I await the bubble-poppers... :) -c On Wed, Apr 4, 2012 at 10:37 AM, Charles Robinson wrote: > I don't know why I never thought of doing it this way... >

simple-as-dirt focus calibration method

I don't know why I never thought of doing it this way... My FA-50 1.7 has always given me "surprisingly soft" results and I've always suspected that the focus needed to be calibrated but never had the time. In the kind of low-light situations where I use it, manual focus is as dodgy as auto.