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08-01-2012, 08:56 AM - 2 Likes   #1
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A close-focusing, fast 28mm shootout: Sigma 28/1.8 vs Vivitar 28/2

I just found this little Vivitar in a second-hand shop, picked it up, and immediately thought to compare it to my Sigma 28/1.8 which I use all the time. According to the bestiary, this is a Komine-made model. So yeah, let's see what we've got:

The contestants:



Vivitar 28mm 1:2.0 MC Close Focus Wide Angle
8 elements in 7 groups
Minimum focusing distance: 23 cm
Maximum magnification: 1:5
Aperture: 6 blades, f/2-f/16
Filter size: 49 mm
Weight: 280 g

Sigma 28mm 1:1.8 EX DG
10 elements in 9 groups
Minimum focusing distance: 20 cm
Maximum magnification: 1:2.9
Aperture: 9 blades, f/1.8-f/22
Filter size: 77 mm
Weight: 500 g

Now, obviously, the Sigma is a modern lens with "A" mode on the aperture ring as well as autofocus, and is therefore quite a bit more convenient to use on a modern camera. It also focuses closer. However, it is a lot bigger and heavier than the Vivitar! Not only that, but seeing as there are few (inexpensive) options for fast lenses in the 28 mm range, and given how useful this focal range is as a walk-around lens on an APS-C DSLR -- especially when the lens does close-focus -- the Vivitar could be potentially interesting for many Pentax DSLR owners.

All these pictures were shot on a K-5 on a tripod, manually focused in zoomed-in LV mode. RAW processed in Lightroom, default settings. No attempt made to correct exposure. The shutter speed was the same for a given aperture with both lenses.

Brick wall series (sharpness test):

Sigma:
f/1.8
f/2
f/2.8
f/4
f/5.6
f/8
f/11

Vivitar:
f/2
f/2.8
f/4
f/5.6
f/8
f/11

As uninteresting as brick walls are, here they allow us to note a couple of things right away:
  • While both lenses are nominally 28mm, the Sigma has a slightly wider field of view.
  • The Vivitar seems to let in slightly more light at the same shutter speed and aperture, i.e. exposes brighter.
  • The Sigma has slightly more contrast and seems to render colours a bit warmer, but beware that the differing exposures exaggerates this effect. Equalize the exposures and they're much closer.
  • The Vivitar is visibly sharper in the corners, right up to about f/8. In the center, I find they're pretty much equal.


Close-focus/bokeh test:
In this test, I focused the Vivitar to its absolute closest point and then adjusted the Sigma to match. The focus point looks to be a bit further back on the Sigma. Sorry about that. Remember that the Sigma CAN focus quite a bit closer than this, but I wanted to level the playing field.

Vivitar:
f/2
f/2.8
f/5.6

Sigma:
f/2
f/2.8
f/5.6
  • Again, we can see that the Vivitar lets in a little bit more light and has a different field of view -- the camera was not moved between the lens change.
  • The bokeh on the Vivitar is a little busy (check out the "KR-10" writing in the f/2 sample) owing to the mere 6 aperture blades. The Sigma is smoother with its 9 blades.
  • I much prefer the calmer rendering of the Sigma in the f/2 image. Already by f/2.8, I don't really have a clear preference.
  • Both lenses display a little CA/PF. It is not really a big deal and gone by f/5.6.

So, a conclusion from this very unscientific test? Well, draw your own, if you want. The Sigma has better bokeh and focuses quite a bit closer, but the Vivitar is actually slightly sharper overall. If I had to sell one of these I would keep the Sigma, but the Vivitar seems to be a great lens for its size and price. I got it for $65 with a Ricoh KR-10, a Rikenon 50/2, Soligor C/D 80-200, bag and flash.

EDIT: Oh yeah. The Sigma had a Hoya UV filter on, the Vivitar nothing. So keep that in mind. It didn't even occur to me until right now.


Last edited by Erik; 08-01-2012 at 09:03 AM.
08-01-2012, 09:50 AM   #2
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I sure know which I'd rather have in my pocket Thanks for the report!
08-01-2012, 10:11 AM   #3
Zav
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QuoteOriginally posted by jimr-pdx Quote
I sure know which I'd rather have in my pocket
Easy, only one of them can fit in a pocket!
08-01-2012, 02:53 PM   #4
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Thanks for doing this test! I own the Sigma 28mm EX DG f/1.8 and have enjoyed it (despite it's size) and have often wondered how it stacked up to the old 28mm f/2 manual focus lenses out there, and in particular the Komine variants.

Regarding this:

QuoteOriginally posted by Erik Quote
The bokeh on the Vivitar is a little busy (check out the "KR-10" writing in the f/2 sample) owing to the mere 6 aperture blades. The Sigma is smoother with its 9 blades.
It's a common misconception that the number of aperture blades is what determines bokeh quality. What determines bokeh quality is primarily the optical design of a lens, with the aperture blades merely affecting the shape of the out-of-focus highlights (especially point source highlights). You can absolutely guarantee that the aperture blades have nothing to do with bokeh when a lens is fully open because the blades are completely retracted and it's a perfect circle of an opening! So for the Komine lens at f/2, the number of aperture blades matters naught. (And for the Sigma, it matters little since the opening is still very circular, though especially so with 9 blades.) I'm happy to see I like the bokeh of the Sigma more than the Komine.

I did allow myself to recently explore the 24mm prime territory (which doesn't really compete with 28mm) by picking up a Tokina 24mm f/2.8 (the Komine 24mm typically go for too much, esp. considering my Sigma 28mm f/1.8 was only $330 when new). I'm curious how it will compare, but I was impressed that the minimum focus difference of the Tokina 24mm is 7.5 inches (vs. 7.9 inches for the Sigma). And the Tokina doesn't even call itself 'macro' or 'close focus'!

08-02-2012, 12:22 AM   #5
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Original Poster
QuoteOriginally posted by nater Quote
It's a common misconception that the number of aperture blades is what determines bokeh quality. What determines bokeh quality is primarily the optical design of a lens, with the aperture blades merely affecting the shape of the out-of-focus highlights (especially point source highlights). You can absolutely guarantee that the aperture blades have nothing to do with bokeh when a lens is fully open because the blades are completely retracted and it's a perfect circle of an opening! So for the Komine lens at f/2, the number of aperture blades matters naught. (And for the Sigma, it matters little since the opening is still very circular, though especially so with 9 blades.) I'm happy to see I like the bokeh of the Sigma more than the Komine.
Yeah, of course, I don't know what I was thinking there. In some other pics I took with the Vivitar, the 6-blade aperture did make some pretty unpleasing highlights when stopped down to I think f/5.6 or f/8, that's why I was thinking of the blades when talking about the bokeh.
08-02-2012, 06:29 PM   #6
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I've had both, and preferred the small size of the Vivitar over the Sigma, despite the latter's many advantages. However the Sigma 30/1.4 seems to me an even better lens, with a reasonable size and very nice IQ in the center. Of course, you lose a few mm of wideness, and the minimum focus distance is pretty long.
08-02-2012, 09:01 PM   #7
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A flare comparison would be interesting. I have this older Sigma: Sigma 28mm f/1.8 Aspherical II Lens Reviews - Sigma Lenses - Pentax Lens Review Database and it's not great with flare, but neither is my Vivitar 28/2 Kiron non-close-focus. The size difference is a killer for me. If this newer version needed a hood, I'd sell it and look for a KA version of the close-focus.
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