Viltrox AF 15 mm f/1.7 Air
5. Chromatic and spherical aberration
Chromatic aberration
On the one hand the combination of f/1.7 aperture and a wide angle of view suggested that the tested lens might experience some problems with correcting both variants of chromatic aberration. A low price was another point indicating that there might be slip-ups ahead. At the same time, despite low pricing, the producers were able to include as many as three elements made of ED glass and three others made of low refractive index glass. Finally I suppose the special elements performed as they should and, overall, there are no serious problems with aberrations, and the photos below show it well.Near the maximum relative aperture you can notice slight colouring of images situated far away from the depth of field but this effect is not especially pronounced and it is reduced very quickly on stopping down the aperture.
 |
Now let's check how the Viltrox AF 15 mm f/1.7 Air corrects lateral chromatic aberration – an appropriate graph you can find below.
Please Support UsIf you enjoy our reviews and articles, and you want us to continue our work please, support our website by donating through PayPal. The funds are going to be used for paying our editorial team, renting servers, and equipping our testing studio; only that way we will be able to continue providing you interesting content for free. |
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Here the situation is even better than in case of the longitudinal variant. At all aperture values you land below 0.04% and it means the aberration is very low everywhere. At the same time by f/2.8 you can notice the local maximum, mentioned by us in the previous chapter. It limited the speed of the resolution increase with the initial stopping down of the aperture.
In the category of both chromatic aberration variants the Viltrox AF 15 mm f/1.7 Air once again surprised us very nicely and, once again, deserves to be praised.
| Fujifilm X-T2, RAW, f/1.7 | Fujifilm X-T2, RAW, f/2.8 |
|
|
Spherical aberration
In first photos of this chapter you can notice slight focus shift. During stopping down the depth of field shifts slightly toward greater distances.Effect of a similar scale you can observe in defocused circles of light reached before and behind the focus. A slight influence of spherical aberration is noticeable in a shape of a soft edge in the first circle and a slightly brighter rim of the second one.
It's clear that the producer of the tested Viltrox didn't correct spherical aberration in a perfect way, leaving it on a moderate level.
| Fujifilm X-T30, f/1.7, before | Fujifilm X-T30, f/1.7, after |
|
|
