• site home
  • blog home
  • galleries
  • contact
  • underwater
  • the bleeding edge

the last word

Photography meets digital computer technology. Photography wins -- most of the time.

You are here: Home / GFX 100 / Transfocal bokeh — 45-100/4 on GFX 100S

Transfocal bokeh — 45-100/4 on GFX 100S

July 18, 2021 JimK Leave a Comment

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”. Since it’s more about the lenses than the camera, I’m also tagging it with the other Fuji GFX tags.

There are two important aspects to bokeh. It seems most people, when they hear the word, think immediately of the look of parts of the scene that are for out of focus. That’s a good thing to think about when buying, selecting, or using a lens, but the, ahem, focus, of today’s post is going to be on another aspect of bokeh: the characteristics of the lens in reddering subjects that are nearly in focus. The way the lens handles the change from sharply in focus to definitely out of focus is important in the look that the camera and lens give to three-dimensional subjects closer than landscape distances.

The MTF Mapper returns information about the line spread function (LSF), which can be thought of as the radial component of the point spread function (PSF).* The PSF defines the image-forming behavior of the lens. Looking at the PSF yields the same information as looking at the modulation transfer function; the difference is that the PSF is in the space domain, and the MTF is in the frequency domain (thanks to Joseph Fourier, 1768-1830). Sometimes the frequency domain is the way to look at things. Other times, you’re better off staying in the space domain. Trying to assess the rendering qualities of a lens in the space domain seems to work better. For one, it’s pretty easy to do it in a way that allows you to visualize the color effects. For another, do to looking at out of focus distant spectral highlights, we are more or less used to looking at PSFs.

The below image was made at 45mm and f/4, using a radial edge near the right side of the image. The vertical direction is the shift of the focal plane with respect to the plane of the sensor. Focus distance runs from top to bottom, with front-focused at the top and back-focused at the bottom. The horizontal axis a heavily-magnified view of distance in the sensor plane. The colors are highly approximate; I just assigned the raw channels to their respective sRGB channels.

45-100 at 45mm, f/4, right side, radial edge

This shows a little longitudinal chromatic aberration (LoCA).

45-100 at 45mm, f/4, right side, tangential edge

The tangential edge shows lateral chromatic aberration (LaCA). Note the blue to the left of the edge when the edge is in focus.

 

45-100 at 45mm, f/5.6, right side, radial edge

 

45-100 at 45mm, f/5.6, right side, tangential edge

 

The LaCA doesn’t go away when you stop down a stop.

45-100 at 45mm, f/8, right side, radial edge

 

45-100 at 45mm, f/8, right side, tangential edge

 

There is still LaCA.

At 60 mm focal length:

45-100 at 60mm, f/4, right side, radial edge

 

45-100 at 60mm, f/4, right side, tangential edge

 

45-100 at 60mm, f/5.6, right side, radial edge

 

45-100 at 60mm, f/5.6, right side, tangential edge

 

45-100 at 60mm, f/8, right side, radial edge

 

45-100 at 60mm, f/8, right side, tangential edge

At 100 mm focal length:

45-100 at100mm, f/4 right side, radial edge

 

45-100 at 100mm, f/4 right side, tangential edge

 

45-100 at 100mm, f/5.6 right side, radial edge

 

45-100 at 100mm, f/5.6 right side, tangential edge

 

45-100 at 100mm, f/8 right side, radial edge

 

45-100 at 100mm, f/8 right side, tangential edge

 

 

 

GFX 100, GFX 100S, GFX 50S

← Off-axis LoCA of Fuji 45-100/4 on GFX 100s Actual vs calculated depth of field for the 45-100/4 GF on the GFX 100S →

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

July 2025
S M T W T F S
 12345
6789101112
13141516171819
20212223242526
2728293031  
« Jun    

Articles

  • About
    • Patents and papers about color
    • Who am I?
  • How to…
    • Backing up photographic images
    • How to change email providers
    • How to shoot slanted edge images for me
  • Lens screening testing
    • Equipment and Software
    • Examples
      • Bad and OK 200-600 at 600
      • Excellent 180-400 zoom
      • Fair 14-30mm zoom
      • Good 100-200 mm MF zoom
      • Good 100-400 zoom
      • Good 100mm lens on P1 P45+
      • Good 120mm MF lens
      • Good 18mm FF lens
      • Good 24-105 mm FF lens
      • Good 24-70 FF zoom
      • Good 35 mm FF lens
      • Good 35-70 MF lens
      • Good 60 mm lens on IQ3-100
      • Good 63 mm MF lens
      • Good 65 mm FF lens
      • Good 85 mm FF lens
      • Good and bad 25mm FF lenses
      • Good zoom at 24 mm
      • Marginal 18mm lens
      • Marginal 35mm FF lens
      • Mildly problematic 55 mm FF lens
      • OK 16-35mm zoom
      • OK 60mm lens on P1 P45+
      • OK Sony 600mm f/4
      • Pretty good 16-35 FF zoom
      • Pretty good 90mm FF lens
      • Problematic 400 mm FF lens
      • Tilted 20 mm f/1.8 FF lens
      • Tilted 30 mm MF lens
      • Tilted 50 mm FF lens
      • Two 15mm FF lenses
    • Found a problem – now what?
    • Goals for this test
    • Minimum target distances
      • MFT
      • APS-C
      • Full frame
      • Small medium format
    • Printable Siemens Star targets
    • Target size on sensor
      • MFT
      • APS-C
      • Full frame
      • Small medium format
    • Test instructions — postproduction
    • Test instructions — reading the images
    • Test instructions – capture
    • Theory of the test
    • What’s wrong with conventional lens screening?
  • Previsualization heresy
  • Privacy Policy
  • Recommended photographic web sites
  • Using in-camera histograms for ETTR
    • Acknowledgments
    • Why ETTR?
    • Normal in-camera histograms
    • Image processing for in-camera histograms
    • Making the in-camera histogram closely represent the raw histogram
    • Shortcuts to UniWB
    • Preparing for monitor-based UniWB
    • A one-step UniWB procedure
    • The math behind the one-step method
    • Iteration using Newton’s Method

Category List

Recent Comments

  • Michael Angelo on Nikon Z7 focus shift shooting
  • Erik Kaffehr on Visualizing lens aberrations — why do it?
  • Eugene on Don’t fixate on the bad stuff
  • Jonby on How focus-bracketing systems work
  • JimK on Of fidelity, photography, audio, and wine
  • JimK on Of fidelity, photography, audio, and wine
  • AVN on Of fidelity, photography, audio, and wine
  • Markus on In photography, and in life, work and joy can, and should, coexist
  • JimK on Fuji 120/4 GF at 1:1 with tubes — visuals
  • Christopher Roberton on Fuji 120/4 GF at 1:1 with tubes — visuals

Archives

Copyright © 2025 · Daily Dish Pro On Genesis Framework · WordPress · Log in

Unless otherwise noted, all images copyright Jim Kasson.