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”.
In the last post, I looked at the field flatness/corner sharpness of the Fujifilm 23/4 and 30/3.5 lenses on the GFX 100S, and found them flat and sharp enough for distant landscape and aerial use. But there’s a problem with those lenses for aerial photography, and that’s the focusing. They are focus by wire lenses, and there’s no way to lock the focus plane in one place. In addition, Fuji GFX lenses suffer from infrequent, but problematical focus shift over time. Together, that means that the only semi-practical way to focus the lenses is by using automatic focusing. However, aerial photography means dealing with vibration and low contrast subject matter, which confuses AF.
The standard way to do aerial photography is to take a piece of gaffer tape and tape the focusing ring at the infinity position. I got to thinking about finding a way to make a wide angle manual focusing lens work on the GFX 100S. I decided that combining the Zeiss 15 mm f/2.8 ZF.2 with the Metabones NF-GFX 1.26 Expander would give me a 19 mm lens that had a chance of being sharp in the corners.
I put the lens on the expander and the expande ron the camera, grabbed a tripod, and went out to make some test shots.
Uh-oh. The lens wouldn’t focus on a tree 100 meters away. It focuses fine out to 20 meters or so.
I put the Zeiss 100 mm f/2 Apo-Makro on the expander. It wouldn’t focus to infinity either.
It turns out this is adjustable. I’ve fixed it, and I’ll now run the test.