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Sigma Mini Wide 28mm F2.8

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3 27,166 Mon August 1, 2016
Recommended By Average Price Average User Rating
100% of reviewers $25.00 8.00
Sigma  Mini Wide 28mm F2.8

Sigma  Mini Wide 28mm F2.8
Sigma  Mini Wide 28mm F2.8
Sigma  Mini Wide 28mm F2.8

First versions of the Miniwide, introduced in 1978 according to Pics show two different looks, pics 1, 3 show the common or normal one. Was made with all the mounts of the era including P-KM and M42.

Some of these suffer a technical mount problem, as described in this thread. The aperture lever guard for some reason is misaligned with the aperture lever, the result is that the lens won't mount on some Pentax DSLR's because the guard bumps against the SDM autofocus contacts. The necessary solution is to remove, or at least prune down, the errant guard. This is easy to do - it's only plastic.
Haze is also quite frequent: often on the 3rd element from the front. Even if difficult to see it normally adversely affect images. Not a difficult fix: take off the front barrel (loosen small grub screw on the side, unscrew); unscrew the flat ring holding the front element in (friction device) and remove front element; unscrew a ring holding the second group in (fingernails may suffice) and shake out the group; haze is normally on the very concave inner surface, a solvent like acetone shall clean it off.

Focal Length: 28mm
Filter Size: 52mm
Focus throw: 180
Maximum aperture: 2.8
Minimum aperture: 22
Iris: 6 blades;
Close focus to 1:4.5
weight: ~205g

Sigma product development engineer Yasuhiro Ohsone talks about the development of sigma 28mm lenses.
Mount Type: Pentax K
Price History:

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Registered: May, 2015
Location: Hampshire
Posts: 892
Lens Review Date: August 1, 2016 I can recommend this lens: Yes | Price: $15.00 | Rating: 8 

Pros: Can be found at a very reasonable price
Cons: Not too much
Sharpness: 8    Aberrations: 7    Bokeh: 8    Handling: 8    Value: 9    Camera Used: K-5   

I compared this version 1 Sigma lens against a Pentax-M 28mm F3.5 and found it to have;
Closer focussing.
Obviously faster aperture.
Not as good to my eyes.
The images seem quite good in strong sunlight (see images) but lacking in contrast when the light is flatter. This makes the images seem to be not quite as sharp as the Pentax. Maybe they are not but the file sizes of JPEGs are pretty similar.
Mine had no aperture lever guard and no sign of there having been one fitted.

If you want a 28mm F2.8 and see a Sigma version 2, that might be even better than this one. If you see one of these version 1, chances are it will be cheap enough to be worth buying. I find it good enough for a 28mm lens but there are better ones as evidenced by the Pentax 28mm F3.5.

My first image taken with this lens and a crop to show colour and sharpness in good light.

New Member

Registered: June, 2016
Posts: 12

1 user found this helpful
Lens Review Date: July 30, 2016 I can recommend this lens: Yes | Price: $20.00 | Rating: 9 

Pros: Sharp, Contrasty
Cons: Flare, plastic aperture ring, haze is a common
Sharpness: 9    Aberrations: 8    Bokeh: 9    Handling: 8    Value: 10    Camera Used: NEX-5   

After going through half a dozen of those lenses here is the thing: there are two versions of Sigma Mini Wide 28mm.
  • Older one with narrow font on name plate and serial numbers appeared to start with 2 and 3.Just my observation, I do not know exact cut out number. These lenses are inferior, huge CA and often uncleanable haze to the glass. My advice is to avoid those. Top left picture. Any Vivitar is better than this one.
  • Newer one, with wide font on name plate. These are the greatest. Very easy to service. All of them I had got flawless after full internal cleaning. Serial numbers appeared to start with 4. Look for those. I'm yet to find another 28mm under $50 that is as good. Top right on the picture. If you attempt to clean one - be aware that 3 rear elements all held by single nut and bunch of spacers. Once unscrewed - it all falls out. Be careful to register orientation of elements. It is easy to flip them and you will have headache to find the right order.
  • And to the bunch, just to compare, Mini Wide II. If you can get one clean - you are lucky. These are very good performers, BUT they are pretty much unserviceable. Though lens appeared to be metal on the outside, optical assembly barrel is plastic and some lens nuts are plastic as well. Everything welded together with solvent or glue. Even rear nut which is metal is smudged in glue. soaking this lens in solvent is out of the question. I will be no longer pursuing those, not worth the trouble. Even if you get clean one and it get moldy later - it's a goner, I think.
Worth to mention: all of those I've purchased of eBay. Only 2 sellers mentioned haze. The fact is that ALL of these lenses I've purchased had haze. To be fair - I was hunting for best deals. Maybe this is the price I have to pay. But considering their age it is probably systematic issue and you should not count on getting one without haze. Be ready to do full CLA to it.

Pictures below are from latest eBay listings and I did not purchase those exact once. I hope nobody object to use of those images?

The following info is mostly for those who will look to purchase old Mini-Wide in unknown condition. Sharing my experience. Yours may vary.

From gathering info about it, this lens appeared to be better than most 28MM. I was hunting it for a while. Got 2 of them, both original, not v2. Apparently there is typical problems with them to be aware off.

First test reveal that both lenses are hazy. It was rear surface of front doublet, second group accessible from the front. Both of them. Front surface on third group is clean and pristine. Go figure?
Interesting note: I think first lend had much worse lateral CA in the corners than second one. It was hazy but clear enough to see that. I can hardly imagine what can cause such CA difference in those copies?

Back to haze: difference was that in first lens haze has dried. In second it appeared as micro droplets that still wet. This is clearly visible from the back with bright front illumination. When cleaning first lens with alcohol or acetone those hazy spots flaked off leaving micro craters on glass. Glass looks clean and in good shape when wet. As it dries - haze returns. It took high magnification microscope to realize that glass is pitted and damaged irreparably. I'm guessing that coating has pure metal in it that corroded and pulled glass with it. Just a guess.
Better luck with second lens. Haze was on the exactly same surface, but appeared as oily micro beads. Once again, front of third group, in the same cavity as front doublet, is perfectly clean. Cleaning doublet with acetone return lens to perfect condition.

It took me a wile to figure out how ot take it apart: Turn focus to macro, this will expose set screw. Use jewelers screwdriver to unscrew it. Then you may unscrew whole rim by bare hands. After that there is access to glass nuts. No slots for spanner in those, so you need rubber grip to go deeper. No other tricks. Takes one minute to get to front doublet.
Careful with cleaning, edge paint easily thinned by either, alcohol or acetone. Don't get edge wet.

Even though one lens is damaged beyond repair, I will keep it as spare for the front and rear glass.

After cleaning second lens haze completely gone. No halo or glow.

Working lens is beautiful, sharp and contrasty, minimal wide angle distortions.
It is prone to internal reflection flare when shot against pointy light source, not too bad.

Very nice lens, if yo can get one in good shape.

Good luck!

Sigma Mini Wide.28mm, wide open (2.8)

1:1 crop

Wide open. Focus on the center horizon (Empire State Building). Lateral CA really good on this copy!
New Member

Registered: November, 2012
Location: Southern California
Posts: 7
Lens Review Date: August 12, 2013 I can recommend this lens: Yes | Price: $40.00 | Rating: 7 

Pros: captures light well
Cons: not as sharp as I hoped
Sharpness: 7    Aberrations: 7    Bokeh: 7    Handling: 8    Value: 8   

It's a nice little 28mm 2.8 if you want to save some money, but I wouldn't recommend it for professional shoots.

I shoot video as well, and I normally use it when I want to create a dreamy yet hazy feel.

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