[stevebrot]

I just found this on the LensAlign site:

Does LensAlign work for manual focus lenses? / LensAlign / Knowledge Base - Michael Tapes Design Support

I have reviewed this thread and still am not sure what your issue is or even how you are attempting to acquire focus. Here are few bullet points:

• You should evaluate focus at maximum aperture
• There is some risk of focus shift on stop-down, but that is usually off-set by greater DOF
• You may evaluate focus accuracy using the LensAlign or any of a number of other (usually better) methods
• Proper diopter adjustment is useful when attempting manual focus using the optical viewfinder
• Manual focus of fast lenses using the Pentax stock focus screen is an exercise in futility due to poor precision (can't get the same focus point twice in a row). What shows as sharp in the viewfinder at f/1.2 is probably not in focus at the sensor.
• AF focus confirm with fast lenses is also an exercise in futility due to an effective aperture of only f/5.6 for the AF system. As with the point above, it is difficult to get the same focus point twice in a row.
• Inaccurate focus using the viewfinder focus screen is corrected by shimming the screen
• It is not possible to do per lens calibration of the PDAF for non-AF lenses
• Live view is your friend for critical focus with fast lenses. Ditto for a split-image or S-type focus screen.

Have fun with your f/1.2 lens.


Steve

[tabl10s]

What's better than LensAlign?

[stevebrot]

What's better than LensAlign?

For AF system calibration

For cameras that have focus peak in live view, a variation on the procedure below is my preference. Although a Nikon camera is used in the example, it is easily applied to a Pentax camera with features such as your K-3. Use focus peaking in magnified live view on your K-3 as the standard.

Youtu.be

Youtu.be

The discussion on youtube even includes a link to a decent printable target. For your convenience:

http://www.testcams.com/DotTune/CrossHatch_Target.png

or

Camera Lens Testing- Sharpness, Chromatic Aberration and Distortion - Bob Atkins Photography

The advantages are:

• A known in-focus image is your start point
• Inherent variability of the AF system is accounted for
• Fast
• Free

FWIW, a similar method is automated in the Magic Lantern software often used by Canon shooters.

Manual Focus Adjustment Check

Focus peaking in live view against a flat target is also great to confirm focus screen adjustment. The procedure is less rigorous than the DotTune method above, but consists instead of using focus peaking in live view as a standard and checking the split image for agreement.


Steve

[tabl10s]

D.T. is rough!