Thursday, August 25, 2022

QDFS: a further refinement

After playing with the 'get magnification' option that QDFS now contains, I realised I could take the idea further and turn the feature into a more dynamic tool.

Thus the latest version of QDFS now has the following menu:

#lensmag = 0 "Get Mag" {Off On Dynamic}

If you select Off, QDFS uses the registered magnification(s) of the lens.

If you select ON and, at your focus reference, press SET, you will get on screen feedback on the magnification (make sure the console is switched on in the QDFS menu). This magnification can then be to used in the QDFS script, meaning that the Canon distance reporting, from the sensor, comes into alignment with QDFS distance reporting. Note, that with this option the magnification doesn't change until you change the value in the script.

The new, Dynamic, option gives you full control over QDFS in real time, such that you can dynamically decide to align QDFS and Canon at any distance, and the magnification that is needed will get used instantly, ie you will see the change.

This feature is of value when, say, you focus on a subject and wish to know the focus distances either side of the point of focus. Having dynamically set the magnification in the QDFS model, the distance feedback will be the 'best you can get'.

Anytime you use the feature, make sure you stop focusing just as the Canon lower (L) reporting in the console changes.

If you are doing deep focus stacking, I recommend you calibrate at or just short of the hyperfocal.

So, like a stopped watch, that is always right twice a day, QDFS focus distance reporting from the sensor and Canon's reporting from the sensor are always the same at two focus distances: the minimum focus distance and at the calibration distance. In between QDFS uses a thin lens model to estimate the focus distances from the sensor: noting that lens extension is not modeled ;-)

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

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