This is one in a series of posts on the Fujifilm GFX 100. 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 100”. Since it’s more about the lenses than the camera, I’m also tagging it with the other Fuji GFX tags.
I’ve been posting a lot recently about the 120 mm f/4 GF macro lens for the GFX. I found it a good performer at 1:2, at minimum focusing distance (MFD) with no extension tubes, but that it had really soft edges and a lot of focus curvature at MFD with 36 mm of tubes. In this post, I tested it at 1:1 with a 45 mm tube,a and found it credible on-axis but soft on the right edge of the frame. I reported those results numerically. I know that some people like images better than charts, so here is a visual look at the phenonium, using the time honored sharpness target of a banknote.
I tested 4 setups, all at an indicated f/4:
- 45mm tube at minimum focusing distance(MFD), which gives 1:1 magnification.
- Two 18mm tubes at MFD
- One 18 mm tube at MFD
- No tubes at MFD, which gives 1:2 magnification
Here are full-frame images of the 1:1 shots for navigation purposes. The images were created by Helicon from 150-capture sequences:
Here are center crops for all 4 cases, at about 150% magnification
Conclusion: in the center you don’t lose much image-field sharpness as you add the tubes, and you gain object-field sharpness.
On the center right edge:
Conclusion: on the right edge you lose a lot image-field sharpness as you add the tubes, and you appear to lose object-field sharpness.
In the corner:
Conclusion: same as for the edge: you lose a lot image-field sharpness as you add the tubes, and you appear to lose object-field sharpness.