I added a review of my newly-acquired Vivitar 7/3.5 lens to the Pentax lens database. For posterity, I’ve copied the review below:
I’m no stranger to fisheyes – I have owned several fisheyes in at least four formats (Sony NEX, m4/3, regular 4/3, Pentax) and once the honeymoon is done, I usually get rid of the fisheye.
The Vivitar 7/3.5 may be the exception (though I am still in the honeymoon phase right now).
Manual fisheyes on most other formats tend to be problematic due to manual aperture control and lack of data from the lens, but with Pentax, the ‘A’ setting provides aperture control, so I can compose and ‘focus’ with the lens wide open, along with getting aperture data in my output files. This is a major plus.
The lens is sharp when stopped down – this is typically true of most manual fisheye lenses anyway. In fact, the optimal would be f/8 or f/11, but I’ve found f/5.6 to be perfectly usable, however, with a fisheye, I want the deepest depth of field possible, so I try to use f/11. I’ve found that with f/8 and up, I can easily achieve starburst effect with light sources, so this is a plus if that’s what you’re after. I inadvertently captured some starbursts below:
Now, as far as focusing, I lucked out and the focusing guide on the lens is accurate, though realistically, when the lens is stopped down to f/11, I can set any focus and everything will be sharp, but I do my best to approximate distance to subject anyway. Below, I think I focused to infinity at f/11, but did it really matter?
True, the Vivitar 7/3.5 is just a rebranded Samyang/Rokinon/etc 8/3.5 fisheye, but I actually owned the Rokinon 8/3.5 for another format and the build and ‘feel’ of the Vivitar 7/3.5 is significantly better. However, the Rokinon that I owned in the past never had accurate focus and I couldn’t adjust the focus using the hack that’s circulating online…
Downside – the lens is not compact, but this is expected. When I had m4/3, I owned the Samyang/Rokinon 7.5/3.5 fisheye and the 9mm fisheye bodycap lens and that was lots of fun – I could put my camera in really unique places (like inside my refrigerator) and get some awesome shots:
Similarly, the Samyang/Rokinon 7.5/3.5 for m4/3 (and it’s identical twin, the Samyang/Rokinon 8/2.8 for NEX) were minuscule compared to the Vivitar 7/3.5…
However, my goal for 2017 is just to have a 2-lens kit with my K-3, and I think I’m going to keep the Vivitar 7/3.5 and the Sigma 50/2.8 macro as part of this kit. I’ll sell the other lenses to keep me honest…