[kypfer]

Would it be possible to implement in-camera focus-bracketing by shifting the sensor fore and aft, or is there insufficient movement in this plane to be useful?

[ehrwien]

Would it be possible to implement in-camera focus-bracketing by shifting the sensor fore and aft, or is there insufficient movement in this plane to be useful?

I don't think that would work. The lens will still be focussed on the same plane, but you'll just be leaving the plane where the image gets focussed to on the sensor's side, all you'd get would be the same image but less focussed everywhere (?)

[mctaveck]

I would be happy to just have the first.

Me too. Aperture bracketing is not a great help to increase the DOF, to me , Not as a real focus bracketing

Danilo

[phoebus]

Would it be possible to implement in-camera focus-bracketing by shifting the sensor fore and aft, or is there insufficient movement in this plane to be useful?

The sensor only moves up, down, left, right and rotate. There is no fore/aft adjustment - that axis is only affected by focussing, not shake reduction.

AFAIK to get focus stacking to work, precise control of the focus is required. Olympus has it in their more recent flagship models, but only with certain lenses. I believe all the current Olympus lenses are focus-by-wire, but not all can be used for stacking. I suspect the Pentax PLM lenses would be capable - if the camera firmware was available. ie the camera can command an absolute focus position, not just closer or further as required by normal auto-focus..

[kypfer]

The sensor only moves up, down, left, right and rotate. There is no fore/aft adjustment - that axis is only affected by focussing, not shake reduction.

Gotcha
I'd misinterpreted the "5 axis of correction" … lost count of one of the rotations

[kwb]

Would it be possible to implement in-camera focus-bracketing by shifting the sensor fore and aft, or is there insufficient movement in this plane to be useful?

I don't think that would work. The lens will still be focussed on the same plane, but you'll just be leaving the plane where the image gets focussed to on the sensor's side, all you'd get would be the same image but less focussed everywhere (?)

ehrwien, kypfer's idea is basically all correct.

Shifting the sensor would work if the camera can translate the sensor along the center axis of the lens with enough range. See my cartoon, far subject is projected in front of the sensor (red lines) while near subject behind the sensor (blue lines). That's the primary reason why out-of-focus subjects are blurred, i.e. a point on the subject doesn't become a point on the sensor. But you can shift the sensor back or forth to focus on near or far subjects, respectively. (Note: Color of lines doesn't have anything to do with color of light in this cartoon.)

However, even if there's a camera that supports this kind of sensor motion using SR-type mechanism, usefulness of such a feature for macro focus stacking will be limited by the range of the sensor motion. If you want to achieve the depth of field D, your sensor should move by roughly D*M*M where M is the optical magnification (M=1 for 1:1, M=2 for 2:1 etc.). If you can only move the sensor by 1mm (which I consider is a huge motion), as D*M*M=1mm, the maximum depth of field achievable by the sensor motion is 1mm for 1:1 and 0.25mm for 2:1. FYI honey bees are about 15mm long.

[phoebus]

Gotcha
I'd misinterpreted the "5 axis of correction" … lost count of one of the rotations

The 'five-axis' is meaning pitch, roll and yaw rotation and up/down, left/right shift. The missing one is fore/aft shift. The marketing blurb is not particularly clear, but as I understand it:

a. Sensor up/down movement counters pitch rotation and up/down shake
b. Sensor left/right motion counters yaw rotation and left/right shake
c. Sensor rotation clockwise/counterclockwise counters roll rotation

a and b are also used microscopically for pixel-shift and with larger steps for composition adjustment.
c is used for horizon correction.
a, b and c for astrotracer.

[Pikachu]

We need this useful feature in Pentax cameras and require its addition in all models, where it is possible!

[Medex]

I don't think that would work. The lens will still be focussed on the same plane, but you'll just be leaving the plane where the image gets focussed to on the sensor's side, all you'd get would be the same image but less focussed everywhere (?)

No, the focus plane will shift a little if the sensor plane will be slightly changed. But this is impractical, because IBIS allows only very very small movement forth/back, - the space is just enough to not stuck sensor plate between walls of metallic cage that holds magnets.

[mlag]

If this were added on the K-3III, it surely would have been on the feature list at some point. Part of the problem, at least in terms of implementation, is with allowing arbitrary steps to support the various use cases for stacking; noting, of course that such is usually done using automated rail hardware. (That last might provide some explanation why in-camera support is not offered.)

Steve

One could imagine selecting two focus points with the 4way dial and a number of steps as input...
I think the biggest problem for in camera focus stacking is focus breathing , most lenses change the viewing angle slightly when refocusing over some distance, becoming a complication for joining the stack of images.... With a rail the focus point is kept steady, hence also the viewing angle... so rail avoids the problem.

As it differs per lens and focus distance, the camera can’t judge if requested focus range and steps makes sense (=will yield good stacked images...). One could say this is the photographers responsibility, but it can make the feature impopular if it fails too often due to hard to understand lens variations...

I think postprocessing would be best out of the camera..., too time consuming I guess.

[mlag]

AFAIK to get focus stacking to work, precise control of the focus is required. Olympus has it in their more recent flagship models, but only with certain lenses. I believe all the current Olympus lenses are focus-by-wire, but not all can be used for stacking. I suspect the Pentax PLM lenses would be capable - if the camera firmware was available. ie the camera can command an absolute focus position, not just closer or further as required by normal auto-focus..

Focus breathing might also be the reason to limit it to specific lenses. Some lenses zoom in or out a bit when changing focus ...depends on the focus implementation in the lens. If the zoom effect is more pronounced, the matching of stack images gets difficult....

https://photographylife.com/focus-breathing
Explains how to check if a lens has focus breathing...