Sunstar rendering and Flare resistance
Here is an aperture series from f/2.8 until f/11 in 1/2 stop increments showing the Voigtlander 90/2.8 APO-SKOPAR's sunstar shape.
This lens is equipped with 10 straight aperture blades which yields 10-point sunstars. The aperture mechanism allows for perfectly round specular highlights not only wide open but also at f/4 and f/22. This allows one to shoot into a light source at these apertures and get a blurred effect. However, stopping the aperture down to f/8 or f/9.5 (most defined), sunstars will be well-defined. Basically you get the best of both words.
So far, flare resistant looks to be well above average. I have pointed the lens directly to the sun and at many angles against light and do not see much ghosting nor veiling. I will test this further and compare it to the Leica 90AA, but it seems that flare resistance is a strength for this lens.
f/2.8 (absence of sunstar definition)
ILCE-7RM3A Voigtlander 90mm F2.8 APO-Skopar lens 90mm 1/80s 100 ISO +0.3 EV
f/3.3
ILCE-7RM3A Voigtlander 90mm F2.8 APO-Skopar lens 90mm 1/60s 100 ISO +0.3 EV
f/4 (absence of sunstar definition)
ILCE-7RM3A Voigtlander 90mm F2.8 APO-Skopar lens 90mm 1/50s 100 ISO +0.3 EV
f/4.8
ILCE-7RM3A Voigtlander 90mm F2.8 APO-Skopar lens 90mm 1/40s 100 ISO +0.3 EV
f/5.6
ILCE-7RM3A Voigtlander 90mm F2.8 APO-Skopar lens 90mm 1/25s 100 ISO +0.3 EV
f/6.7
ILCE-7RM3A Voigtlander 90mm F2.8 APO-Skopar lens 90mm 1/15s 100 ISO +0.3 EV
f/8 (Nice definition with a slight spill over)
ILCE-7RM3A Voigtlander 90mm F2.8 APO-Skopar lens 90mm 1/13s 100 ISO +0.3 EV
f/9.5 (Optimal aperture for clean and well defined sunstars)
ILCE-7RM3A Voigtlander 90mm F2.8 APO-Skopar lens 90mm 1/10s 100 ISO +0.3 EV
f/11
ILCE-7RM3A Voigtlander 90mm F2.8 APO-Skopar lens 90mm 1/5s 100 ISO +0.3 EV