Modifying the DA* 60-250mm F4 for Full Frame

Optical Test: Vignetting

The main reason to modify the baffle is to remove the black corners which appear using the 60-250mm in full frame. In this section we will evaluate the vignetting with both replacement baffles and compare it with vignetting obtained in APS-C mode with the original baffle.

The following charts illustrate the vignetting at different apertures and focal lengths. The original baffle was also tested, both in APS-C and full frame crop modes, to provide comparison points.

Vignetting at 60mm

At 60mm, vignetting is superb when the lens is used in APS-C mode. In full frame, the original baffle does not generate black corners but vignetting is still strong. Results are better with both modified baffles, with the best values obtained with the round baffle.

Vignetting at 250mm

Results are different at 250mm. As expected, in APS-C mode vignetting is again kept very much under control. However, using the original baffle in full frame mode shows why it is necessary to modify the lens. Our chart shows 5 EV of vignetting, but for all practical purposes it means that corners are black and there is no information available in these zones.

Using the modified baffles improves results dramatically. While in absolute terms the vignetting is still strong wide open, these values will be easy to correct in post-processing. Again, the round baffle yields better results.

The next images show the vignetting at various focal lengths and apertures for both baffles. They give an idea of what to expect in real-life scenarios.

Vignetting at 60mm

APS-C Original baffle, FF Round baffle Cutout baffle
F4
F5.6
F8
F11

Vignetting at 250mm

APS-C Original baffle, FF Round baffle Cutout baffle
F4
F5.6
F8
F11

Verdict

The baffle modification meets its main objective, which is to remove the black vignetting generated by the APS-C baffle when used in full frame mode. While higher than usual, the remaining vignetting is not a problem in general use, and is easy to automatically correct via software.


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