|
Fujinon XF 27mm f/2.8 (Fujifilm) - Review / Test Report - Analysis |
|
Lens Reviews -
Fujifilm X
|
|
Page 2 of 3
Distortion
Fuji relies on image auto-correction for many of their lenses and this also applies to the Fujinon XF 27mm f/2.8. Most users will enjoy fully corrected images thus distortions are nothing to worry about. The original characteristic shows a 2.1% barrel distortion which isn't all that bad either.
If you move your mouse cursor over the image you can switch to the corresponding "raw" results.
Vignetting
The auto-correction is also active for vignetting. JPEG images show a rather moderate light falloff of 0.8EV (f-stops) at f/2.8. As usual the vignetting decreases when stopping down and it's not really relevant anymore from f/5.6 onward.
Uncorrected RAWs show a very different situation with a rather massive falloff of 2EV at max aperture and still 1EV at f/4. The problem is mostly gone at f/5.6 and hardly noticeable from f/8 onward.
MTF (resolution)
The Fujinon delivered very impressive results in the MTF lab. This is especially true for the image center which is pretty much outstanding straight from f/2.8 all the way up to f/8. The outer image region is already very good at f/2.8 and f/4 but the quality is boosted to really unprecedented heights at f/5.6 and f/8. Diffraction has a higher impact from f/11 onward although the setting remains easily usable.
The centering quality of the tested sample was good albeit not stellar.
Please note that the results were obtained from uncorrected RAWs. The quality of the (distortion-)corrected images depends on the specific converter so we decided to avoid this discussion here.
Please note that the MTF results are not directly comparable across the different systems!
Below is a simplified summary of the formal findings. The chart shows line widths
per picture height (LW/PH) which can be taken as a measure for sharpness.
If you want to know more about the MTF50 figures you may check out the corresponding
Imatest Explanations
Field Curvature
The MTF curve above shows the characteristic on the focus field. However, the Fujinon has a bit of an issue with field curvature so it's not as flat as it should be - the MTF chart below reflects this characteristic. Interestingly the issue isn't all that pronounced at f/2.8 but increases the more you stop down. When evaluating "flat" test targets, the indicated border quality is still very good albeit not quite as impressive anymore. The minor image bit beyond our "extreme corner" target is also somewhat softer than the chart indicates so it makes sense to stop down a bit for achieving the best results across the image frame.
A flat field MTF isn't overly accurate since even tiny centering defects - which are just normal - can spoil the results quite a bit.
Chromatic Aberrations (CAs)
At around 0.2px lateral CAs (color shadows at hard contrast transitions) are very minor and nothing to worry about.
|
