Vivitar (Kobori) 120-600mm f5.6/8 passes the test

[xkaes]

I wanted to determine if my new PIXCO Minolta-to-Maxxum/Sony/a-mount adapter gets infinity focusing correct -- since it has glass in it to allow this. Since that's hard to do with a wide-angle or normal lens, I opted to test it with a LONG lens. I decided against most of my long lenses because they are designed to focus slightly passed infinity. The longest lens that I have that does NOT focus passed infinity is a Vivitar (Kobori) 120-600mm f5.6/8 two-toch zoom. With the PIXCO adapter attached it turns into a 144-720mm f6.7/9.5 zoom.

I was not only pleasantly surprised that it gets infinity focusing perfectly, but the quality is amazing. Close focusing is 13 feet which is rather amazing for a 720mm lens. The close-focusing on my Vivitar (Perkins-Elmar) 800mm f11 CAT is 25 feet. The PIXCO will turn that into a 960mm f13.

[Attila]

[Ultrapix]

By the way, shorter the lens, more evident any lack of precision in getting perfect focus on infinity

[stevemark]

[xkaes]

Your eye-sight is better than mine. With my 12mm Heliar lens wide-open, everything is in focus. With a 720mm lens, there's just a sliver.

[Alsatian2017]

[xkaes]

Here are three reviews from users at the PENTAX FORUM. None of them have anything bad so say -- except for the size and weight, of course

"It really surprised me, I expected severe fringing and only find it slight for a manual focus lens of any type from this era. For grins I used a 2x teleconverter from atop a bluff in Illinois near Grafton of a building near Earth City in Missouri (that's 1200mm and the equivalent of 1800mm on a 1.5 crop factor). It worked but imagine compacting miles and miles and miles of dust, pollution, and particles into a flat scene? I used a 1.5x to capture shots on tow barges along the Mississippi river and they were very detailed and crisp. I used it at 75 feet to capture hawks and was impressed. I think it easily outperforms the Sigma 170-500mm in IQ."


"I live in sunny South Africa, and very bright days are quite plentiful.
I can't do more than 10 shots at a time handheld because of the weight.
When I use a tripod, it has to be standing on a soft surface, to prevent movement.
Used it on some moon shots successfully just resting on a chair back, on amazing settings!
Got better results than Sigma 150-500 F5-6.3 on a D90 Nikon"


"It's a much better lens than I thought it was going to be, But you need a tripod to really get great pictures from it. PF is to be expected with these old, long zoom lenses. But it is easy to fix on Photo Shop. There isn't any lens creep and it focuses and zooms very smooth but I did get a almost new copy that was stored for a long time."

[Alsatian2017]

[xkaes]

There are only four reviews on the Pentax Forum, and all four reviewers gave it an 8 out of 10 for sharpness. Pretty good for a none APO zoom. From the quick results I've seen with mine, I'd give it a 9.

If you're not happy with yours, for whatever reason, you ought to sell it.

It sure is a monster though.

I might get lucky and nab a Sigma 170-500mm. If I do, I'll have to run some comparative tests

[Alsatian2017]