Friday, February 12, 2021

DOFIS: 2021 Uplift

I wrote my Depth Of Field Information Script (DOFIS) as I wished to know about focus on my 5D3.

I believe the DOFIS lens model is the best you can have, without having access to lens CAD design details, ie it uses a split/thick lens model and accounts for pupil magnification.

DOFIS will give you information on: where you are focused; what the infinity blurs are at that focus (defocus, diffraction and total blurs); the depths of field (either relative to the focus or as an absolute from the sensor plane); how many brackets you will need to take to get to the hyperfocal; if you are beyond the hyperfocal; and where to focus next when focus bracketing.

So what more I could I need out of DOFIS?

Up until now DOFIS only provided you all the above information if you are in LV. If you wished to use the view finder, then you needed to come out of LV.

So, I'm pleased to say that DOFIS now works outside of LV, albeit restricted to M mode for now.

Like ML, which enhances the non-LV Quick Shooting (QS) screen with additional info, eg see the battery info and colour temperature below, DOFIS now displays focus information in the Canon QS screen eg:

In the above screen capture we see DOFIS at start up, with the DOFIS info bar being black with white text, showing the point of focus and the defocus/diffraction/total blurs in microns.

In this release of DOFIS I've restricted the information to focus position and infinity blurs, ie not depth of field information.

Whenever DOFIS doesn't have a point of focus reference, eg a 'base' image hasn't been taken, or the aperture or focal length changes, you will see the above presentation, ie white on black.

As soon as you take an image the QS screen will change to look something like this:

Here we see the same focus position (35cm) and the same infinity blur information, but enhanced by DOFIS info area turning yellow, showing the current focus is the same as that of the last captured image, and with an additional piece of information that gives you an estimate of the number of focus brackets to get to the hyperfocal.

If you now start to refocus, the information displayed reflecting your focus position (either moving away or towards infinity), the infinity blurs, and the number of brackets required to get to the hyperfocal will change, as will the colour of the bar according to whether you have a positive (green) or negative (red) focus overlap with the last image you took eg:

You can return to the last image's focus position at anytime, ie refocus until the bar is yellow.

Thus, all you need to do is refocus until you see a red bar, then back off to a green bar.

Once you go beyond the hyperfocal, you can then use DOFIS to inform your infinity focusing, eg:

Here we see that in this bracketing sequence I took a final image at 4.25m, which DOFIS tells us is beyond the hyperfocal, giving me a infinity defocus blur of 3 microns, which, with an F/10 diffraction blur of 13, gave me a total (convolved) blur at infinity of just over 13um.

Finally you can switch off the DOFIS QS display by switching the Focus Bracketing off in the DOFIS menu.

As usual I welcome any feedback on DOFIS, especially being used on cameras other than the 5D3; and any ideas about making DOFIS better.

The latest version of DOFIS, which has been developed on a 5D3, may be downloaded from the right, but the QS feature may not work in a non-DSLR, eg an EOSM appears to not report focus when the QS screen is showing. Finally, if things don’t seem to work with your ML camera, then feel free to tweak the script, eg the position of the DOFIS box on the QS screen. 

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