Vivitar 28 f2 5 đánh giá

Well, this Minolta MC mount lens looks nearly brand new. Here it is on my A7RII via a Fotasy MD-to-M adapter and a TechArt Pro LM-EA7:

It's a funny-looking little lens. I don't know why they needed to shout in UPPERCASE LETTERING on the front ring, but they did. The front sticks out more than it seems like it should, but the whole lens is quite small and the focus rings turns smoothly enough to blend in nicely with Minolta MC Rokkors. The focus goes wonderfully close in one continuous movement. It's not hard to see why this lens has a lot of fans....

I have not yet done formal testing of this lens -- after all, I just got it this afternoon.

It also has been raining much of the day. However, that didn't stop me from informally testing it out. All the following are OOC JPEGs with no postprocessing beyond scaling to 1500x1000. Let's see how it does....

Alvin looks about how he should. Contrast is a bit low and the trees in the distant background are a little busy-looking, but sharpness isn't a problem and neither is flare. While I'm in my office, let's see how good it is close up....

f/2, quite close up

That's way better than I expected for close-up wide open.

My Buck Rogers poster has faded, but it still makes a good detail target. The bokeh both before and after the focus point look fairly smooth, but there is a little double-image effect (nissen bokeh) after the focus point.

These 3D-printed bracelets show good sharpness and nice bokeh.

Perhaps this shot of one of our camera arrays makes the bokeh issue most obvious: the lens has slightly overcorrected spherical aberration, which makes the bokeh closer than the focus point beautiful, but the bokeh farther away show some outlining. To be precise, the out-of-focus point spread function (OOF PSF) has a fairly thick bright ring, but the ring itself has a somewhat diffuse edge, so it actually looks fairly smooth unless there is a really bright point light source.

f/2

At a more normal distance, my machine room looks good wide open, with crisp sharpness for the in-focus area and nice, soft, bokeh for the closer wires.

At infinity, everything looks quite good. Straight lines also stay fairly straight.

Let's see how it does back home....

f/2

Well, close-up is awesome outside. The bokeh here are much better than average.

At a distance, stopped down to f/5.6, things are as crisp as one could hope:

f/5.6 (focus fairly close; opposite shore to the right is out of focus)

At a more in-between distance outdoors:

Things still look sharp where in focus, but distant bokeh actually look very smooth because the OOF PSF isn't large enough to show the bright ring distinctly.

Finally, a couple of flower photos indoors:

f/2

f/2

Ok, so what's the verdict?

This is really an outstanding lens. The close focus is remarkably useful and, combining that with f/2 and a decent OOF PSF, this lens can produce bokeh that are way better than most 28mm lenses can deliver. Where things are in focus, they're sharp -- even wide open. Stopping down even a little improves the already-modest vignetting, and immediately improves both contrast and colors. Colors aren't bad even wide open, but they get a little more accurate and slightly colder when stopped down. Distortion is minimal, and I really don't see any flare problems either.

I only tested this on FF, but 42MP FF gives a clear indication that sharpness is more than sufficient for APS-C use without a focal reducer. The LM-EA7 was fairly quick to autofocus it, although I found it worked even better for the LM-EA7 to merely tweak manual focus... a nice bonus for a manual-focus lens.

So, in sum, it's an "A+" for both build and image quality. I still prefer the IQ of my MC Rokkor 28mm f/2.5 over it, but there's really nothing to complain about here and the faster aperture and close focus make this lens more versatile. This easily could end up being the 28mm I use most often....