Saturday, April 15, 2023

QDFS: update

This post is to record the latest tweaks to my Quasi Depth of Field Script (QDFS). 

I wrote the M3 (only) QDFS to complement my Landscape Bracketing Script, that is optimised for auto focus and exposure bracketing. QDFS being targeted at more manual shooting.

Exposure bracketing in QDFS is restricted to either carrying out a Canon set AEB capture or a two bracket QDFS capture from a base ETTR, either with a Tv or ISO shot.

In the latest version (downloadable from the right), I've added the ability to dynamically reset the following menu items:

#coc = 15 "CoC (um)" [5 30]
#brak = 0 "X bracket mode?" {ISO Tv}
#isoval = 0 "X Bracketing Value" {Canon ETR+1Ev ETR+2Ev ETR+3Ev ETR+4Ev ETR+5Ev}
#sleep_time = 0 "Delay (s)" [0 10]

Enabling edit mode is simply achieved by focusing 'beyond' infinity, ie where there is no useful Canon lens info, but the lens count is still being indexed or has maxed out. This location is a place where you don't want to be, as you have no way of knowing the focus state. Because of QDFS’s edit mode, you will never focus ‘beyond’ infinity. If QDFS reports 0 micron infinity blur, then you are at the Canon reported infinity.

The updated button controls look like this:

Note that you can press Left or Right buttons to set an ETTL or ETTR exposures. The ETTR auto setting is based on the top 1/10 Ev and the ETTL exposure is set at about -7.4Ev down from fully saturated, ie the first 25 bins of the histogram. Also by pressing the Info button you can toggle through the various Canon screens, where you can change Canon settings such as the AEB and display the Canon histogram etc, according to how you have set up the Canon display options.

These are the release notes embedded in the script


* This Quasi Depth of Field Scale script only runs on the M3 with the XIMR version of CHDK, ie CHDK 1.7

* The script provides visual feedback for manual deep focus bracketing, ie not for macro focus bracketing

* It also provides two exposure bracket options from an ETTR exposure (ISO or Tv) and one from whatever Canon AEB is set

* The script first tests to see if a Canon AEB is set. If not the script then looks at the ISO/Tv ETTR bracketing options. Canon meaning whatever AEB is set on the Canon side, or not

* Repeatedly pressing the INFO button will cycle through the Canon screens, including the Canon histogram: which will be active via touch.

* Here you can change the AEB for example

* The script was mainly written for wide angle lenses and specifically the EF-M 11-22mm ;-)

* Although mainly EF-M lenses can be used, you can add other lenses, eg TS-E 24mm II

* An estimate of the front principal location can be found from subtracting the QDFS MFD (displayed in the console) from the Canon reported MFD

* Changing focal length will reset the DoF scale

* Switching out of ALT mode will exit the script

* Switching the console on in the script's menu will provide additional feedback, eg the lens stepper count and the Canon lower and upper focus bounds

* You can reposition the console, including switching it off, by pressing the UP button

* If you are focused beyond the hyperfocal, the DoF Scale will display the infinity blur in microms (on the right of the DoF scale)

* The infinity blur info will disappear if you focus beyond the Canon 'data infinity', when you enter edit mode: using the LEFT, UP, RIGHT & DOWN buttons

* If selected, the number of brackets to the hyperfocal is also shown on the right, as you focus short of H/3

* If Focus is selected in the Display menu, then an ESTIMATE of the focus distance from the sensor is displayed: this can be compared to the Canon reported distance and the mag tuned as required

* Pressing the MENU button will toggle the bar on and off, eg as an aid to composing

* Pressing the INFO button will toggle through the various Canon displays

* Pressing the ZOOM-IN button will reset the realtive Ev feedback and show the current DoF on the top on the DoF scale

* A long press of the ZOOM-IN button will toggle between showing focus info on the right or % of the histogram in the top 1/10 stop

* Pressing the RIGHT button will ETTR, and pushing the LEFT button will ETTL. ETTR and ETTL thresholds can be changed in the code.

* If things don't look right either do a HS press, or change focal length to reset things or restart the script or the camera ;-)

* Further info on the script may be found on my blog, including dynamic focus calibration when the script is running

Release 1.34

April 2023

The following are a few M3 screen captures illustrating the latest version of the script.

In the above we see the QDFS menu, where you can set your defaults, some of which can be dynamically edited.

In the above we see one way to set up QDFS. The top screen capture shows that the focus distance is being reported on the right, as we are less that the hyperfocal, the red bar. This reporting can be reconfigured in the menu to show the near depth of field and infinity blur.

Where as on the bottom screen we see that once we are focused passed the hyperfocal, the display changes to show the infinity blur.

In the above we see that the AF Frame button has been pressed to register the current focus (white bar) and set the current exposure as the 0Ev (shown in the console area, along with the current lens position count and the total (max) count, the Canon upper and lower reported distances, the focus relative to the hyperfocal, and the exposure relative to the exposure on start up or the registered exposure.

In the above we see that focus has changed and that the current DoF, relative to the registered (or last image captured) focus is green, indicating a positive overlap at the set CoC (which is dynamically adjustable).

In the above we see that the current focus has a focus gap (red) relative to the last registered/captured image.

In the above we see that the CHDK histogram has been toggled on, via the AE Lock button. Note that as we can display both the Canon and CHDK histograms, it is best to set the CHDK histogram to log mode. We also see the right hand side info has changed to a %, which shows the ETTR state in the top 1/10 Ev. This ETTR info is realised by doing a long press of the AE Lock. To display the focus info again, simply do another long press. There are three regions that get reported. A 0% means just that, ie the top 1/10 of a stop has zero histogram data. If the top 1/10 of a stop contains less than 1% of the histogram, then the actual count is shown. Finally, if the top 1/10 of a stop has greater than 1% of the histogram, then the % is shown.

In the above we see the console area has been repositioned by pressing the UP button, which moves the console up until it is not shown. Pressing further repositions the console at the bottom. A long press of the UP button will switch off the console and another long press will show it in the bottom position.

In the above we see that we have focused 'beyond' infinity and thus entered the edit mode. Here we can change exposure bracketing options by pressing the Left, Up, Right or Down buttons, to adjust the CoC value, set ISO or Tv bracketing, and change the start delay when capturing images.

Finally in the above we see the impact of changing aperture, here to F/22. Changing focal length, aperture or CoC will dynamically reconfigure the depth of field bar.

As usual I welcome any feedback/comments on the above or any of my posts.

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