This is one in a series of posts on the Fujifilm GFX 100S. You should be able to find all the posts about that camera in the Category List on the right sidebar, below the Articles widget. There’s a drop-down menu there that you can use to get to all the posts in this series; just look for “GFX 100S”.
On DPR, someone posted some anecdotal photographs that suggested that with long lenses, shutter shock on the GFX 100 was lower _ I almost said significantly lower, but then again it was an uncontrolled, low-N test so it’s hard to ascribe significance. I realized that I hadn’t done much at all with shutter shock on the GFX 100xs cameras, figuring, as is the case with the GFX 50S, that electronic first curtain shutter (EFCS, or, in Fuji’s notation, EF) pretty much made shutter shock not worthy worrying about.
I decided to construct a close-to-worst-case test. I took the following gear:
- GFX 100S
- Fuji 250 mm f/4 lens
- Fuji 1.4X teleconverter
- C1 cube
- RRS 4-series carbon fiber legs
And set it up in portrait orientation, which is the worst case for the GFX shutter, which travels in the short direction.
Here’s the target:
My indicator of sharpness is the vertical slanted edge on the left. Using an edge that runs parallel to the long side of the sensor is again a worst-case situation. If focus error with AF-S is smaller than the shutter shock variations that we’re looking for, using AF to focus each frame would be the way to go here, to avoid any change of the infamous Fuji GFX focus drift issue. I ran a test. focus variation with AF-S was far greater than the kinds of differences I expected to see between the electronic shutter (ES) and EFCS.
Darn. I need to use manual focusing. I focused once at the beginning of the series.
I decided to shoot 16 shots in each of ES, EFCS, and mechanical shutter, with the lens wide open, giving my f/5.6. I did the EFCS series first, with the shutter actuations 2 seconds apart. I picked a shutter speed of 1/30 second, which is close to the worst case for this kind of test,
I developed the images as follows:
- Lightroom 10.2
- Default settings except as noted below
- Sharpening turned off
- White balanced to gray of slanted edge.
I analysed the slanted edge with Imatest, looking for the MTF50.
Why are there two EF (or EFCS) datasets? That’s my way of checking for focus drift. The order of testing was EF, ES, M, and EF again at the end. YOu can see that the EF bookends provide essentially the same results, which indicates to me that there was no material focus drift.
ES wins. Why? It could be that it’s better in isolation, or it could be that the 2 seconds between shots wasn’t enough time for the vibrations to die down. I ran another test with 10 seconds between shots.
This time, I did a series with EFCS, then one with ES, then another with EFCS, and the final one with ES.
It looks like the improvement in ES is real, and not just from leftover vibrations from earlier shots.
We can look at some of the individual MTF curves. to get an assessment of the 250/4 wit a 1.4x TC. This is the sharpest shot in the first ES series with the 10-second delay:
This is not a super-sharp combination, but then again, what lens really shines with a TC?
We can also look at chromatic aberration:
The red is sharper than the green and the green is sharper than the blue, but it looks like there is very little shift.