Update To My Fujifilm Pre-Shot Feature Post

Catching the decisive moment of an airborne trespasser! (click to enlarge)

Just a quick update on the Pre-Shot feature found in Fujifilm's X-T3.  I first wrote about this feature here.  To get some background on the feature, what it can do and how it can help you not miss peak action, you may want to read it before reading this post.

I don't like to do things halfway and that is how I felt after my first experiments with the Pre-Shot feature.  The feature worked.  I familiarized myself with how to use it, but I felt really didn't fully understand everything about it.  Time to finish the job for my own knowledge and for yours.

Since Fujifilm does not give us any settings to directly control the Pre-Shot feature, I felt I needed to dive deeper into it to better understand the one variable that is available and how it affects the outcome, not just that it does work as Fujifilm intended.

That one variable when using Pre-Shot is you can set the burst speed (FPS) in your camera.  Two settings are non-negotiable, use of the electronic shutter and setting the camera on a (CH) continuous high frame rate.  What you can change is the number of frames per second with the camera's electronic shutter when using CH.  That FPS is settable to 8, 11 or 20 FPS.  What I didn't know after my first experiments was if changing the frame rate changed the number of buffered exposures captured before fully pressing the shutter and how long before the shutter is fully pressed are those buffered images being captured.  To fully understand Pre-Shot, I wanted to know these two things also.

I set up an experiment.  I thought I would photograph the stop watch on my mobile phone as an easy way to measure both.  If I tried to press the shutter at a specified time, such as at the 5, 10, 15, 20 second marks, I could measure how long before fully pressing the shutter images would be buffered and also give me the number of images buffered.  However, my ability to press the shutter exactly at a specified point (reaction time) as well as knowing the shutter delay (the time it takes for the camera to actually open the shutter after pressing the shutter button) would also have to be calculated as that would affect my ability to calculate both of these parameters.  

I first calculated my average reaction time coupled with the actual actuation of the shutter after pressing the button.  That averaged 0.12 seconds.  Pretty quick.  Knowing that number now allowed me to calculate the number of images buffered and how long they were being buffered before pressing the shutter.

 Here are my general findings.  These findings are not absolute as the "human factor" is involved, but estimates as close as I could come to accurately and consistently determining the two aspects of this short experiment.

     FPS        Number of Images Buffered         Time captured before full shutter press

       8                     6-7 (varied in the tests)                about 1/2 second
      11                    8-9 (varied in the tests)                about 2/3 second
      20                     20  (consistently)                         about 1 second

These are my general findings.  At best, the camera will buffer 20 images upon half press of the shutter and record about a full second of time before you fully press the shutter.  That makes sense since CH is set for 20 FPS.  

Setting your camera to record 20 FPS will give you the best chance of capturing the precise moment in peak action.  Lesser frames per second, with fewer images made, could cause you to miss it.  The only caveat is that this feature uses the electronic shutter which means there could be some slight distortion when panning or with a moving subject.

Hope this helps those of you who are interested.  I now feel better than I fully understand this feature and am prepared to make the best settings on my camera when I need to use it.

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Thanks for looking. Enjoy! 

Dennis A. Mook 

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