Samyang AF 85 mm f/1.4 FE/RF
5. Chromatic and spherical aberration
Chromatic aberration
One glance at crops below and it's obvious the Samyang AF 85 mm f/1.4 FE has slight problems with longitudinal chromatic aberration. Blurry areas, especially those by f/1.4, show a bit of colouring. Still, it must be clearly said this problem is not very serious especially as it decreases swiftly on stopping down the aperture to f/2.0 and f/2.8. |
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In this case there are no problems almost at all. There are no pronounced differences between the edge of the APS-C sensor and the edge of full frame; in both cases that aberration level increases a bit from 0.03% to about 0.05% on stopping down the aperture. Still you deal here with low and very low values so the performance in this category shouldn't worry you at all.
It's also worth mentioning that the results are very similar to the performance of the more expensive Sony FE 85 mm f/1.4 GM which aberration values ranged from 0.03 to 0.06% as well.
| A7R II, RAW, f/1.4 | A7R II, RAW, f/8.0 |
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Spherical aberration
One close look at first photos, shown in this chapter, and you know the lens will have a lot of problems with spherical aberration. The depth of field moves toward greater distances on stopping down the aperture - the effect is very distinct especially when you compare f/1.4 and f/2.8 images. It's nothing else but the famous 'focus shift' connected to spherical aberration.Is that aberration also visible in defocused circles of light reached behind and before the focus? Let's have a look at photographs below.
| A7R II, f/1.4, in front of | A7R II, f/1.4, behind |
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Here the problem is visible at its fullest – the circle before the focus features soft edges and their brightness decreases distinctly as you move away from the centre. The circle behind the focus has a very distinct, bright rim. Images presented above are an almost textbook spherical aberration example and it is clear the Samyang AF 1.4/85 FE doesn't correct it as it should. Its performance in this category should be considered a slip-up.
