Update: I'm continuing to research this issue, with mixed results:
-- Since my X-Pro 1 doesn't have an intervalometer or a remote terminal, I built a test stand that lets me use a hobby-type servomotor as a "robo-finger" to release the shutter repeatably. I used an Arduino microcontroller to trigger the "robo-finger" and then time the number of milliseconds until the X-sync terminal closes. This gave me a large series of measured lag figures.
-- I also ran a series of trials using the video timing method Cass used in his original report. Although the actual lag numbers were slightly different, the video method gave overall results similar to those from the test stand.
-- In both types of testing, I consistently measured a slightly longer lag time at small apertures than at larger apertures, confirming Cass' and others' experience.
-- However, I was NOT able to reproduce the extremely long (~500ms) and variable lag times documented by Cass in his test (and experienced by me in real-world usage.) My lag times at a given aperture never varied more than 20ms or so, which I considered reasonable given that I'm using a low-precision servo.
-- I began to wonder if my original experience wasn't simply a one-off quirk or possibly caused by another factor such as a slow memory card. So this past Saturday, with another batch of subjects to photograph, I decided to try using the X-Pro again. It performed normally for about the first 250 shots, when suddenly I was hit by a long, unpredictable lag again. It was easily perceptible, and was causing me to miss peak actions that I had had no trouble capturing just a few moments before.
-- I turned the X-Pro off and back on and the lag went back to normal; after a few more shots, however, the problem returned, and continued to return intermittently during the rest of the session. Eventually I found that I could seemingly predict when it was going to happen by listening to the sound of the lens aperture motor as I half-depressed the release: If I heard a softer-than-normal sound, or no sound, I would get the long, unpredictable lag. When this happened, I could usually clear it (although not always) by re-locking the focus point and trying the release again. This at least saved the subjects some extra work, because we could abort an attempt when excess lag seemed likely.
-- Unfortunately, I was concentrating so hard on working with the subjects that I didn't pay close attention to what might have been triggering the problem. However, I'm thinking now that there must be specific combinations of settings or operating sequences that put the X-Pro into this "long-lag" mode.
Cass has documented focusing direction as a trigger factor for the Fuji models he tested, but I wasn't able to reproduce that effect with the X-Pro on my test stand. My next task is to figure out what does trigger the effect, so I can evoke it consistently enough to measure.
For those who aren't interested, feel free to ignore this whole thread, which I admit has gotten somewhat esoteric. However, this variable lag is a very serious issue for anyone who wants to use Fuji for peak action -- it's possible to adapt to a fairly long lag as long as it's consistent, but a lag that varies inconsistently makes it almost impossible to "lead" your subject successfully.
So if anyone else has experience or measurements that will help us pin down when this effect occurs and what's likely to cause it, please chime in!
Note: Attached is an example from Saturday's session, when the X-Pro was cooperating. Catching the arms, legs and hair at the right position requires anticipating the peak moment, which is almost impossible if the lag varies by hundreds of milliseconds from shot to shot...
View attachment 4634
-- Since my X-Pro 1 doesn't have an intervalometer or a remote terminal, I built a test stand that lets me use a hobby-type servomotor as a "robo-finger" to release the shutter repeatably. I used an Arduino microcontroller to trigger the "robo-finger" and then time the number of milliseconds until the X-sync terminal closes. This gave me a large series of measured lag figures.
-- I also ran a series of trials using the video timing method Cass used in his original report. Although the actual lag numbers were slightly different, the video method gave overall results similar to those from the test stand.
-- In both types of testing, I consistently measured a slightly longer lag time at small apertures than at larger apertures, confirming Cass' and others' experience.
-- However, I was NOT able to reproduce the extremely long (~500ms) and variable lag times documented by Cass in his test (and experienced by me in real-world usage.) My lag times at a given aperture never varied more than 20ms or so, which I considered reasonable given that I'm using a low-precision servo.
-- I began to wonder if my original experience wasn't simply a one-off quirk or possibly caused by another factor such as a slow memory card. So this past Saturday, with another batch of subjects to photograph, I decided to try using the X-Pro again. It performed normally for about the first 250 shots, when suddenly I was hit by a long, unpredictable lag again. It was easily perceptible, and was causing me to miss peak actions that I had had no trouble capturing just a few moments before.
-- I turned the X-Pro off and back on and the lag went back to normal; after a few more shots, however, the problem returned, and continued to return intermittently during the rest of the session. Eventually I found that I could seemingly predict when it was going to happen by listening to the sound of the lens aperture motor as I half-depressed the release: If I heard a softer-than-normal sound, or no sound, I would get the long, unpredictable lag. When this happened, I could usually clear it (although not always) by re-locking the focus point and trying the release again. This at least saved the subjects some extra work, because we could abort an attempt when excess lag seemed likely.
-- Unfortunately, I was concentrating so hard on working with the subjects that I didn't pay close attention to what might have been triggering the problem. However, I'm thinking now that there must be specific combinations of settings or operating sequences that put the X-Pro into this "long-lag" mode.
Cass has documented focusing direction as a trigger factor for the Fuji models he tested, but I wasn't able to reproduce that effect with the X-Pro on my test stand. My next task is to figure out what does trigger the effect, so I can evoke it consistently enough to measure.
For those who aren't interested, feel free to ignore this whole thread, which I admit has gotten somewhat esoteric. However, this variable lag is a very serious issue for anyone who wants to use Fuji for peak action -- it's possible to adapt to a fairly long lag as long as it's consistent, but a lag that varies inconsistently makes it almost impossible to "lead" your subject successfully.
So if anyone else has experience or measurements that will help us pin down when this effect occurs and what's likely to cause it, please chime in!
Note: Attached is an example from Saturday's session, when the X-Pro was cooperating. Catching the arms, legs and hair at the right position requires anticipating the peak moment, which is almost impossible if the lag varies by hundreds of milliseconds from shot to shot...
View attachment 4634