Originally posted by kypfer Is that cropped? I only ask because when I use my Peleng 8mm the corners are vignetted.
No cropping at all on that shot, and don't recalling seeing vignetting with my copy. I did crop a couple of other shots I took today with that lens, but only to improve composition.
I don't know how similar all of the versions of the Samyang f3.5 8mm are. I know, besides the original Samyang, there are also Rokinon and Bower versions. You have a Peleng. Samyang clones also get labeled Phoenix, ProsPec, and others. It's assumed that the optical design of all is the same, but there are at least small appearance differences. I believe that Samyang and Rokinon versions of the 8mm have removable hoods, but mine can't be removed. Are there differences in manufacturing quality standards among the different clone labels that might allow a copy which vignettes get through? I don't know.
*** You aren't using your Peleng 8mm on a full-frame digital Pentax are you? So far as I know all of the versions of the lens are designed to work on Cropped Sensor digital cameras only, and would be guaranteed to give a lot of vignetting on full-farme, but not just in corners.
Are you only getting vignetting with certain apertures? I mainly shoot my copy from wide-open to f8. Maybe it does vignette a bit when stopped down more.
One other thing could affect my copy is that, I purchased mine as a Canon mount version and I converted it to Pentax K. There is a rather large registration distance difference between those two mounts. If my K-mount is still extended back a hair, that could reduce vignetting slightly I suppose.