Sunday, February 14, 2021

DOFIS: Minor update

Just a quick post to discuss a couple of tweaks to DOFIS and how to use the information it displays in the non-LV, Quick Shooting screen.

DOFIS now alerts you to switch to M mode, as DOFIS works best in this mode:

I've also tweaked what DOFIS shows in the Quick Shooting screen:

Here we see an additional blur being shown in brackets, before the usual blurs that show the infinity defocus blur, the diffraction blur and the total blur at infinity.

The new blur field, 30um above, is simply a reminder of the overlap blur that is being used when focus bracketing: noting that this overlap blur gets adjusted if you switch on diffraction aware in DOFIS. The 30um shown above indicates that I've switched diffraction aware off, ie the blur being shown is my ML CoC setting of 30um.

On a Full Frame sensor I recommend the base overlap, ie before diffraction is accounted for, be set to 30um and on an APS-C format sensor to 20um. You can certainly use a smaller overlap criterion, however, the cost is more focus brackets.

As an illustration, the following landscape workflow is one way to use DOFIS, ie from near to far:

  • Compose and set the aperture/exposure you wish to use, ie to minimise diffraction, but maximise image quality, and ensure the best photon capture, eg ETTR with/without Dual-ISO
  • Focus on the closest part of the near field object that you wish to see in focus and review the DOFIS feedback and decide if one image is acceptable, ie are you are focused at/beyond the hyperfocal.
  • In the above we see we are focused at 80cm and that the infinity defocus and total blurs are much bigger than the overlap (CoC) blur, as we are focused at less than the hyperfocal (the overlap/CoC value). All we need to do is take an image (or an exposure bracket set) and follow DOFIS's advice, ie look at how many focus brackets it is telling us we need to take and using the colours (green and red: see the last post) to set the next focus until we have captured our focus bracket set, including, if you wish, a zero defocus blur shot at the 'measured infinity', ie where Canon is still measuring distance and the defocus blur reporting is at/near zero.
As usual I welcome any feedback on DOFIS, either here or on DOFIS's Magic Lantern forum page.

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