Lens review
2011-05-25
Canon EF-S 18-55 mm f/3.5-5.6 IS II
7. Coma and astigmatism
In the case of the cheapest, low-end constructions with poor quality casing the astigmatism is often not the measure of the optics build quality but the casing build quality of a given specimen. That off-axis aberration is very sensitive to any improper slopes of the optical elements toward the axis and in the most shabbily build instruments these are very frequent after all.
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In the case of the tested lens’s predecessor the astigmatism was well-corrected and it amounted just 6%. A bit worse performance of the specimen, tested here, can stem from the fact that the astigmatism reaches a noticeably higher level of 11%.
