[Lowell Goudge]

I have been looking at the low cost (?) fisheye lenses, and there seem to be 3 different lenses but are they really different.

there is the samyang / bower / pro-optic 8mm, the vivitar 7 mm and the Opteka 6.5mm

they all show 12 inch close focusing and 180 degree FOV, so what, other than bragging rights is different?

the pro optic and opteka seem to be $50-70 less and the vivitar is $20 more than the samyang/bower lens.

all seem to be available in KA mount.

are the coatings different? is the amount of distortion different? or are they all the same optical design. (the vivitar for sure is mechanically , at least cosmetically, different)

[jeffrey r]

Putting the Vivitar aside for a moment, the others are all the same lens. There have been a few discussions about this line recently, and a bunch of us have picked up the Rokinon version for about $250 from Overstock. It's a really good lens if you want to dabble in fisheye and not break the bank, while still getting the "A" setting for metering in the camera. I bought the cheapest version I could find, which was the Rokinon.

As to the Vivitar, your post makes it seem like you don't think it is the same lens, but from what I recall, it is the same lens (maybe a cosmetic difference or other minor difference, but essentially the same exact lens, just paying a bit more for the Vivitar Series 1 designation). I can't say for sure though.

[Lowell Goudge]

Putting the Vivitar aside for a moment, the others are all the same lens. There have been a few discussions about this line recently, and a bunch of us have picked up the Rokinon version for about $250 from Overstock. It's a really good lens if you want to dabble in fisheye and not break the bank, while still getting the "A" setting for metering in the camera. I bought the cheapest version I could find, which was the Rokinon.

As to the Vivitar, your post makes it seem like you don't think it is the same lens, but from what I recall, it is the same lens (maybe a cosmetic difference or other minor difference, but essentially the same exact lens, just paying a bit more for the Vivitar Series 1 designation). I can't say for sure though.

I looked at all the options when I bought a 85mm F1.4. all but the vivitar are identical in every detail but the engraving of the name plate. The Vivitar definitely has different moldings and grips, but I suspect was identical optically to all other 85's.

the difference in the 6.5 to 8mm fisheye lenses is similar. They all look identical except the vivitar, which again has it;s own moldings etc.

The question I really have is how can they claim 3 different focal lengths, and what do you get, aside from a more recognizable name, with the vivitar.

[jeffrey r]

For all intents and purposes, they're all the same lens. Just that some of the companies did funky things with the focal length description to distinguish their version, and Vivitar is trying to bank on their Series 1 brand name.

See:

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/70440-opteka-6...ns-pentax.html

and

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/63836-samyang-...heye-lens.html