Fujifilm GFX100S/100 FOCUS BKT: Workaround for Failure to Reach Infinity Focus
Related: focus stacking, Fujifilm, Fujifilm GFX100S, Fujifilm medium format, Fujifilm mirrorless, medium format, Roy P
re: Fujifilm GFX100S/100 FOCUS BKT Feature still has can’t-reach-infinity-focus Bug dating back to 2019
UPDATE May 30: for how well the feature works to avoid this issue, see Fujifilm GFX100S Focus BKT 'Auto' Mode: Usage and Example.
Roy P writes:
Do you suppose the GFX100S is not missing the final few shots to reach infinity, but perhaps going several shots beyond infinity?
I did a quick test today. I can’t quite go to a mile away, but looking from my front yard down my street, the farthest I can see is about 1200 to 1300 feet away. That’s about 300-330 meters. I set the near point 1 m away, and the far point to “infinity” on the lens, as far as it would go. It took 203 shots, but what I noticed was the last frame with the farthest features in my scene, a tall tree, was frame #192. In the frames 193-203, the sharpness of the most distant features actually got progressively worse. So for my focus-stacking, I used only frames 1-192, and it came out pretty darned well.
So if you are looking at the last couple of frames in your focus bracketing series and seeing the distant features “at infinity” were not sharp, can you work backwards from there and see if those same distant features become actually sharper in frames that are about 90% of the way to the end?
DIGLLOYD: if the camera proceeds in the series “past infinity” then the extra frames can just be discarded. That’s not the issue, other than the minor hassle of figuring out the last frame that is needed.
The issue is not going past infinity, aborting even before the designated frame count is reached. For example: I would set a frame count of, say, 10 frames. I’d initiate the process, and the camera would only take 1 or 2 frames, then stop. The last frame would be focused perhaps 100 meters out, far short of INF focus.
In many situations, I would repeatedly see the GFX100 take a single frame when a dozen or more were needed, with the most distantly focused frame still badly blurred at distance (focused much closer than INF). Sometimes it would take 2 or 3, but again maybe a dozen were needed.
Fujifilm GFX100: Bug and Issues with the FOCUS BKT Feature, How to Mitigate
Fujifilm GFX100: Using the FOCUS BKT Feature for Focus Stacked Images
Possible workaround for failure to get to INF
The Fujifilm GFX100S and presumably the GFX100 with latest firmware have an mode whereby one sets the near point and far point and just lets the camera figure out the frame count. This differs from manual mode where the near-focus point is chosen, and the camera takes frames up to the frame count, which in practice means getting several frames focus past infinity (when things are working as they ought).
If the feature works as it ought, then setting the far point at infinity focus should ensure getting a full series from near to far.
