Re: Anyone else shooting a Samyang/Rokinon 135 have this issue?
Finally formalized a flare test and the results, as I already expected, look pretty dismal. One doesn't appreciate the expertise of CZ to suppress stray light until the third-party lens steps up to the plate. In this area, the Rok 135 is generally mediocre in a 1950s Leitz kind of way, allowing many photons within the frame to spray all over the sensor. However, matters are much more severe when a light source gets in the frame, or within about 30° of the optical axis. Then we observe all manner of veiling glare, flare, and hot spots. The mix of effects will depend on the entry angle and f-stop. For some reason, many effects are only visible via LiveView while the OVF shows little.
I narrowed this report to one angle that gets past the OEM hood. Without the hood, troubles are visible and worse over a large angle. Light source was a double-AA Maglite placed on an arm which could be swung to explore different angles. Also on a swinging arm were barndoors to improve on the hood.
Row 1 shows flare at different f-stops with OEM hood installed and the Maglite taking maximum advantage. Row 2 shoulds vast improvement with barndoors conforming tightly to the frame. Row 3 shows Maglite and barndoors removed.
Inspecting the light path with barndoors installed leads me to believe the problem is reflection of stray light off the barrel interior behind the iris. This could be fixed with flocking and a rectangular baffle. Of course, that would incur engineering costs that we bottom-feeders avoid. While the Rok is otherwise a mind-bending performer, there is an argument for upgrading to the CZ Aposonnar 135/2.
Feb 14, 2017 at 06:20 AM
Previous versions of rico's message #13921166 « Anyone else shooting a Samyang/Rokinon 135 have this issue? »
