Voigtlander Apo-Lanthar 65 mm f/2 Aspherical 1:2 Macro
8. Vignetting
| A7R II, APS-C, f/2.0 | A7R II, APS-C, f/2.8 |
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The moderate brightness loss is clearly visible only at the maximum relative aperture where it reaches 27% (−0.93 EV). On stopping down to f/2.8 and f/4.0 that problem is eliminated as the vignetting decreases to 10% (−0.32 EV) and 7% (−0.21 EV) respectively.
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After progressing to the full frame sensor the problems are more serious and there are more of them – let’s glance at photos below.
| A7R II, FF, f/2.0 | A7R II, FF, f/2.8 |
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| A7R II, FF, f/4.0 | A7R II, FF, f/5.6 |
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At the maximum relative aperture in the very corners of the frame you lose over half of light - the actual result is 54% (−2.26 EV). The light fall-off problem still remains bothersome by f/2.8 where it reaches 34% (−1.19 EV). You can start talking about moderate values by f/4.0 and f/5.6, where we got the following results: 25% (−0.83 EV) and 20% (−0.66 EV) respectively.
Further stopping down didn’t provide any distinct effects. The values we got by f/8 and f/11 both amounted to 19% (−0.60 EV).
| Sony A7R II, JPEG, f/2.0 |
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Below we present averaged out values of brightness loss shown in concentric circles as you move further away from the frame centre. The numerical value for every image, expressed in percents, shows the area limited from the top and right by 100% and from the bottom by the presented curve. The area indicates how much light overall is lost due to the vignetting effect. Please don’t mix these percentages with the values given at the beginning of the chapter because they aren’t directly connected.
