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Lens review

Fujifilm Fujinon XF 18 mm f/2 R

14 September 2012
Szymon Starczewski

8. Vignetting

As we’ve already found out in the chapter about the distortion, the lens has noticeably different fields of view on RAW and JPEG files. What’s more, after the test of the Fujinon XF 35 mm f/1.4R we know that, even when the fields are similar, the X-Pro1 body corrects the vignetting on JPEG files on its own. It is obvious then that the vignetting should be checked both on RAW and JPEG files. The first tell us something about the optics of the lens, the second – about the competence and abilities of the Fujifilm programmers.

The thumbnails, presented below, show a comparison of vignetting levels by different aperture values and for both types of files.

JPEG RAW
f/2.0 f/2.0
Fujifilm Fujinon XF 18 mm f/2 R - Vignetting Fujifilm Fujinon XF 18 mm f/2 R - Vignetting
f/2.8 f/2.8
Fujifilm Fujinon XF 18 mm f/2 R - Vignetting Fujifilm Fujinon XF 18 mm f/2 R - Vignetting
f/4.0 f/4.0
Fujifilm Fujinon XF 18 mm f/2 R - Vignetting Fujifilm Fujinon XF 18 mm f/2 R - Vignetting

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In the case of using JPEG files the vignetting won’t be especially bothersome. At the maximum relative aperture the brightness loss in the frame corners amounts to just 19% (-0.60 EV). On stopping down by one stop makes this aberration decrease to the value of 15% (-0.48 EV). Further stopping down doesn’t produce any significant improvement – at every aperture value we can gain just about 1%.

If you have even the foggiest idea about optics, such results, concerning a „pancake” lens with a quite good aperture fastness of f/2.0, must seem to you unreal. The actual vignetting level can be determined only after analyzing RAW files. The results are typical for “pancakes” so significantly high. Although, praising the tested Fuji a bit, I must say they are hardly record-breaking.

At the maximum relative aperture the vignetting is 44% (-1.69 EV) - a high level, clearly noticeable in real life photos. It is often the case of the “pancakes” that the stopping down is not very effective when it comes to lowering the vignetting level and here we deal with a similar situation. By f/2.8 the light fall-off in the frame corners reaches 39% (-1.43 EV), by f/4.0 it decreases to 34% (-1.19 EV) and by f/5.6 to 30% (-1.02 EV). On further stopping down you can’t see any measurable influence on the vignetting.

Fujifilm Fujinon XF 18 mm f/2 R - Vignetting