Saturday, July 31, 2021

M3 Landscape Bracketing Script: latest UI tweaks

Following some testing in the field, I've tweaked the UI in the M3 Landscape Bracketing Script, to better meet my needs.

You can now show/hide the CHDK histogram, whilst in ALT mode, by simply toggling the INFO button.

At script start up the UI now looks like this:

In the above we see three info groups in the script's top bar. We also see the CHDK histogram is switched off, ie I have this as the setting in the script's menu, as we can now quickly show it at anytime.

The left hand group shows focus position information, including how many focus brackets are required to get to the defined overlap hyperfocal distance. In the above, we see the camera is positioned at 154cm and that this is beyond the hyperfocal.

The middle group now shows exposure information. In the above we see that, relative to the last reference exposure, there is a 0.0Ev difference, ie we haven't changed exposure yet. We also see that we are at an exposure of 0.5s. If exposure survey mode is set to off, this group will show the focal length and the shutter speed.

Finally we see the right hand group shows the depth of field information. I personally have the DoF option set to 'both', as this shows the near/far defocus DoFs (ie no diffraction) if the focus position is less than the hyperfocal, and the near defocus DoF and the infinity blur, if the focus position is greater than the hyperfocal. In addition, as I have infinity blur diffraction aware set to on, the display above shows the total infinity blur, ie the defocus blur at infinity convolved with the diffraction blur, in quadrature.

Let's now switch on the histogram, by pressing the INFO button:

Here we see the CHDK histogram in log mode.

Let's now change exposure by changing the shutter speed:

In the above we see the shutter speed has changed to 3.2s and that, as exposure survey mode is enabled, we see the Ev feedback, ie the exposure difference between the last zero exposure, ie start up or half shutter press (HSP), and the current exposure. This feature is useful when you are undecided on what exposure bracketing approach to use. For instance, set the exposure for the shadows, do a HSP, and then an auto ETTR, by pressing the RIGHT key. You now will have the scene's dynamic range, which will help inform your exposure bracketing selection.

For example, in this next image we see I've set the exposure for the shadows and carried out a HSP, as the Ev feedback is zero:

In the next image we see I've pressed the auto ETTR button, the RIGHT button, and the script has calculated that the ETTR exposure is 2s, ie a 0.7Ev delta on the shadow exposure: a low dynamic range scene that requires no exposure bracketing.

We also see that I remain focused at 154cm and that the near defocus DoF is at 670mm with an infinity total blur, including diffraction, of 14 microns.

Finally, having decided I only need a single exposure, I will set focus for the nearest object of interest and see what focus bracketing I need, if any:

We can see that the nearest object is at 250mm and that this requires 3 focus brackets to cover the depth of field from the current position to the hyperfocal, plus an infinity shot as informed by the infinity blur feedback. We also see, in the right hand info group, that the near defocus DoF is at 224mm and the far defocus DoF is at 287mm.

To focus bracket, I could use the auto mode, with the script driving the lens, or carry out the focus bracketing manually, with the script providing feedback as to when to take the focus brackets.

The latest version of the M3 Landscape Bracketing Script may be downloaded from the right hand link.

Here is a test image I just took: with a little wind movement. Six focus brackets at the same exposure to cover up to the hyperfocal, plus an infinity ETTR bracket for the sky. All captured automatically in camera, and blended in Photoshop.

As usual I welcome any feedback on this post or any of my posts.

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