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Sigma 28-105mm F2.8-4

Reviews Views Date of last review
12 50,736 Mon May 23, 2016
Recommended By Average Price Average User Rating
83% of reviewers $100.08 6.82
Sigma 28-105mm F2.8-4

Sigma 28-105mm F2.8-4
Sigma 28-105mm F2.8-4

There are several incarnations of the Sigma 28-105mm:

sigma 28-105mm f4-5-6 UC ii.
Sigma 28-105mm f3.8-5.6 UC iii
Sigma 28-105mm F2.8-4
Sigma 28-105 2.8-4 DG

Weight 14.3 oz
Viewing angle 23.3-75.4
Magnification 1/5.5
Minimum focus 19.7" (50mm)
Dimensions D 3" x L 5.1"
Diaphram 8 blades
Lens construction 12 elements in 10 groups
Filter 72mm
Min. aperture F22
Mount Type: Pentax KAF2 (w/ in-lens AF)
Price History:

Add Review of Sigma 28-105mm F2.8-4
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Site Supporter

Registered: February, 2013
Location: Houston TX
Posts: 258
Lens Review Date: May 23, 2016 I can recommend this lens: Yes | Price: $53.00 | Rating: N/A 

Pros: When it is good - it is very good
Cons: When it is bad - it is awful
Camera Used: K1    Autofocus: 7   

There is a wide range of ratings for this lens. They are all correct. This is perhaps the most bizarre lens I have ever used.

On the K-1 wide open at 28mm an entire clown car full of photographic problems show up and drive around in your picture. By 50mm things have settled down - as you might expect in the middle of the zoom range. At 105mm wide open the lens is well behaved but soft - making it an attractive lens for full frame portraits - since the full resolution capability of a K-1 can be brutal in exposing every tiny flaw in a human face.

Closing the lens down to the f8 to f11 region results in very solid performance from the lens - colors look better, resolution is much better. But the bizarre nature of the lens is still there; at these f-stops the wide angle and telephoto ends of the zoom solidly outperform the middle of the zoom range. A behavior I have never seen before in a zoom lens, and the opposite of the wide open behavior of the lens.

I would have to give this lens a variable rating of 4.5-8.5 on a K-1 - which averages out to 6.5 - or about the average of the other reviews. Here it is at 28mm and f2.8 and then at 28mm and f8.
New Member

Registered: October, 2013
Location: Naples
Posts: 10
Lens Review Date: November 2, 2013 I can recommend this lens: No | Price: $30.00 | Rating: 4 

Pros: Cheap, can be used in dangerous situation of reportage! Good focal escurtion on film.
Cons: Low quality in optical performance and built.
Sharpness: 4    Aberrations: 4    Bokeh: 5    Handling: 4    Value: 6   

A very low quality lens, may be a good zoom to shot in those situation where you can risk the integrity of the lens, and it's more importante to take home the "shoot" than any regardi in qality of the immage. It may be a good "hight risk" reportage.
Junior Member

Registered: January, 2012
Posts: 36
Lens Review Date: August 4, 2013 I can recommend this lens: No | Price: $180.00 | Rating: 2 

Pros: Uhm, ehm...
Cons: Soft, terrible colors and overall rendition
Sharpness: 4    Aberrations: 4    Bokeh: 4    Handling: 6    Value: 3   

I got this lens in a bundle with an FM2n... (yes, I'm guilty) and tried it on my film cameras.

Results were absolutely unpleasant, hence my very low rating.

Veteran Member

Registered: February, 2013
Location: Melbourne
Posts: 2,524
Lens Review Date: May 13, 2013 I can recommend this lens: Yes | Price: $35.00 | Rating: 7 

Pros: Was cheap , Does a decent job
Cons: Some what soft
Sharpness: 5    Aberrations: 8    Bokeh: 8    Handling: 8    Value: 8   

I got mine from a camera swap meet , attached to a pentax MZ-5n for the princely sum of $35 Australian ... This lens has been on my K5 ever since then .
Yes it does back focus , and thankfully you can tune the K5 to eliminate the back focus . I also find the lens to be a little soft ( focus ) . I dont know how much I would need to spend to get a better lens ?

For the price I paid , I really cant complain , it is a decent lens , again I dont have (?) good glass to compare to , especially as most photographers consider anything under $200 bargain basement . I will say , if you find one at a good price ( get it ) , at the very least it would be a good back up lens ( you do have a back up lens ? ) .

Besides the back focus and the lens being slightly soft ( to me )

Image was taken @ 105mm and F8 with back focus corrected 2 points ...

Around f8 the image begins to sharpen , but I still feel its a little soft ( perhaps the subject is to soft ? )

Anyhow , if you find this lens ( I see them from time to time on **** ) at a good price and in good condition , it might be worth a bite !
Senior Member

Registered: July, 2011
Location: Mississippi
Posts: 282
Lens Review Date: April 24, 2012 I can recommend this lens: Yes | Price: $35.00 | Rating: 8 

Pros: cheap, decent build quility, great focal range, fast focus
Cons: stiff zoom function, back focus problem, poor CA control at times
Sharpness: 8    Aberrations: 6    Bokeh: 8    Handling: 6    Value: 8   

This is more a review for this particular copy, so you version maybe better or worse.

I think the reason this lens gets poor reviews for wide open shooting is that it tends to back focus slightly, making the images seem "soft". I doubt most would ever know this or even how to test it least with mine anyway. I have yet to test it on another body, or against a like copy, but on my KX, it back-focuses from 28-40mm or so, and from f2.8-f4. All, I might add in less than ideal light indoors. More extensive testing is needed to determine true functionality. Each time I was able to beat the auto focus by switching to manual. Every other aspect of this lens is typical Sigma quality..........neither having any major flaws or spectacular performance. Overall, I rate this a solid 7.5-8 especially if you can pick one up for a good price as I did, I would not hesitate to get one!!!

Upon further testing and calibration to my camera, I've revised a few things. 1st, this has fairly poor CA control sometimes when not using a lens hood and the Bokeh is improved now that I got the focus problem fixed. Below, in the first two is a few un-altered shots right off the camera showing some of the CA problems..........easily fixed in post of course and hence why I Still give it an overall 7.5-8. Most pics come out very pleasing to the eye with great color rendering, saturation, and sharpness right off the SD card. Just beware when not using a lens hood, that CA can creep up on you without notice. Couple others showing typical great results. Along with a link to more test shots........all, completely un-edited!!!

Tested with a K100D-s, and had the same back focus with my KX it renders very saturated, natural, vibrant colors with good resolution/sharpness up to f11 or so once calibrated to camera. Never seen the CA/PF on the k100d as I did with my KX, so I decided to bump that review up a notch...........still believe this is a very solid 8 overall, once you find how to easily calibrate the lens to your camera.

Click here to see all test shots:
Veteran Member

Registered: July, 2009
Location: Mount Joy, PA
Posts: 542

1 user found this helpful
Lens Review Date: February 17, 2012 I can recommend this lens: Yes | Price: $110.00 | Rating: 8 

Pros: Light weight for its size, image quality
Cons: Unusual filter size, a-typical zoom ring operation for PK
Sharpness: 8    Aberrations: 8    Bokeh: 8    Handling: 7    Value: 9   

It's a shame a buyer can't find more examples of this lens breed, considering it offers strong value for the money and exhibits very few serious weaknesses. In many ways, the value of this lens has steadily improved over the years because of the advances in DSLR technology.

I bought my copy of this lens after convincing myself I needed something with more reach than my Pentax DA* 16-50mm as a walk-around lens. I paid about $110 and it turned out to be a lucky investment. I was meant to take photos at a relative's vow-renewal ceremony when the DA* lens SDM crapped out on me. Not only did the Sigma's improved range come in handy, but the image quality was far better than I could have hoped for in such a situation.

I would favorably compare this lens to any of the DSLR-era Pentax kit and DA / DA L lenses. The construction is solid, yet the lens is lightweight. It balances nicely on my K-5 with battery grip. The zoom ring is well damped and moves smoothly. The focus ring is a bit lifeless, although it doesn't bother me. My main complaint about the handling of the lens is that the zoom ring turns in the opposite direction of Pentax glass to zoom in and out. It's certainly no deal-breaker, but can take some getting used to if the photographer normally uses Pentax or Tamron equipment, both of which operate the same way.

The front element of the Sigma lens requires a 72mm filter which is an a-typical size compared to Pentax lenses (they are usually 58/67/77mm). This means the Sigma probably won't be able to share filters with the rest of your collection. Again, not a huge problem, but certainly less convenient than it could be.

Sharpness on the Sigma 28-105mm is slightly better than the Pentax kit lenses. I would say the edge-to-edge performance is better and more even across all apertures and focal lengths than most lenses except for the top-dollar, premium variety. This was a nice surprise when I was relying on the lens after the DA* failed. One could argue the corner sharpness is a bit soft when used wide-open at the longest focal length. Still, it improves nicely after stopping down one notch. The center sharpness remains high through the range. I would not hesitate to use this lens as an impromptu portrait lens. I've used the lens more than once at weddings.

The barrel distortion at 28mm is a bit disappointing. I can't measure the effect, but I would say the distortion is in line with Pentax's DA 18-55mm 3.5-5.6 II lens when both lenses are set at their respective widest focal lengths. The Sigma might still have some slight barrel distortion at 35mm, but it clears up at all higher settings.

I'm happy to say my Sigma 28-105mm 2.8-4.0 displays only light-to-moderate chromatic aberrations. I've seen some purple fringing in strong contra-lighting conditions, but what lens doesn't?

All-in-all, the Sigma is a great lens. I sincerely believe it deserves an average 8.5 rating. Sure, it would be nice if the lens were wider or had a quieter auto-focus system. Nevertheless, the improvements in higher ISO performance among DSLRs allow the Sigma to show off its nice telephoto range with good image quality at wider apertures. The used-market asking price of this lens is relatively low, but its availability is rare. Many strengths and few true weaknesses make the Sigma 28-105mm 2.8-4.0 lens a nice addition to any photographer's arsenal! A good value, indeed.
Senior Member

Registered: August, 2010
Location: Leeds
Posts: 152
Lens Review Date: January 9, 2011 I can recommend this lens: Yes | Price: $135.00 | Rating: 8 

Pros: Good general purpose lens, nice pictures
Cons: distortion at 28mm, zoom creep, bit heavy

I should say that I haven't done any careful tests or anything. But I am certainly happy with the pictures I took with this lens, and generally I really liked this lens.

Occasionally I would like it to be a bit wider, but I really like the 28-105 range (on a digital camera) - nice for a walkaround lens, and good for photographing people.

The main downsides are that it is a bit heavy and mine had zoom creep. In the end, I sold it planning to replace it with the Pentax 28-105 3.2-4.5, because it is lighter and is also meant to be a better lens.

However, I bought two copies of the Pentax and had problems with the auto-focus of both (see my review of that lens), so sent them both back.

Currently, not sure if I will buy this lens again, or one of the other pentax 28-105s, or just go without a 28-105. (I do have an F 35-70, which I like.)
Junior Member

Registered: May, 2009
Location: Charlotte, North Carolina
Posts: 27
Lens Review Date: July 27, 2010 I can recommend this lens: Yes | Price: $70.00 | Rating: 7 

Pros: Reasonably sharp, good solid build, fast
Cons: Noisy focus, front element coating fragile

Got mine off of a popular auction site while looking for some portrait glass for my K10D. This lens is fast considering its size, and build seems very solid. My focus ring 'zings' as it moves across its range quite audibly. It is loud enough that people turn and look at the local strobist meetup. The coating on the front element of my copy seems to be deteriorating around the extreme edges. The hood is sturdy and painted with a non-reflective coating on the inside. My copy is very sharp when stopped down out to about 90mm. At 28mm and 105mm it is soft in the corners, but very nice in the center.
Inactive Account

Registered: June, 2010
Location: Toronto
Posts: 4
Lens Review Date: June 29, 2010 I can recommend this lens: Yes | Price: $99.00 | Rating: 8 

Pros: sharp, bright, excellent !Q
Cons: zoom is a bit sticky

This has become my go-to lens. It produces noticably better images than my 55/1.8 prime or any other lenses i have tried.

Seems to be well built but is light and handles well. It feels nicely proportioned to the K20 body.

Bottom line - Love it, it's a keeper.
Senior Member

Registered: August, 2008
Location: St. Louis, MO
Posts: 139
Lens Review Date: March 26, 2010 I can recommend this lens: Yes | Price: $175.00 | Rating: 8 

Pros: Fast and great value for the money
Cons: Not as sharp as more expensive glass
Sharpness: 7    Bokeh: 6    Handling: 8    Value: 9    Autofocus: 7   

Because this lens isn't seen all that often it's frequently overlooked, but it's a fine piece of glass as long as you realize there must be some allowance at this price point. For the money it's an amazing value. I have taken many great pictures with it. It's amazing that for this price you can get a F2.8 lens that stops down only to F4 when zoomed out to 105mm.
The lens seems pretty clear to me and I have used it quite a lot without ever having to deal with any mechanical or optical problems. It was my standard walk-around lens when I first switched to Pentax. However, on a crop sensor camera it's not quite wide enough for typical indoor use with my family. I do less optical quality compared to the better glass in my bag, but it's not extreme.
For an outdoor walk around lens, this is one of the best values for the money, it's just not easy to find and at this price point you always lose some optical quality.
Veteran Member

Registered: July, 2009
Location: Saffron Walden, Essex
Posts: 362
Lens Review Date: March 7, 2010 I can recommend this lens: Yes | Price: $80.00 | Rating: 8 

Pros: Speed, sharpness, fast focus
Cons: Barrel distortion at wide end, slightly softer at long end, zoom creep

Don't often see this lens around so when a used copy appeared at my favorite used camera shop for a mere 49 I snapped it up. I was pleasantly surprised! It is sharp wide open in the middle of the zoom range, and slightly less sharp wide open at the short and long ends of the range. It sharpens up nicely at all focal lengths when stopped down one stop. It's f2.8 until around 35mm, f3.5 until around 70mm, f4 to 105mm.

The only real flaw in this lens is significant barrel distortion at 28mm, probably quite easy to correct but still a bit of a hassle. A lesser problem is that it also loses a bit of sharpness at 105mm - it's still good, but not as good as it is at 70mm. This copy also suffers from slight zoom creep when pointed directly downwards.
Veteran Member

Registered: September, 2008
Location: Houston Tx.
Posts: 1,876
Lens Review Date: December 15, 2008 I can recommend this lens: Yes | Price: $199.00 | Rating: 7 

Pros: Crisp clean shots edge to edge
Cons: Aperture ring hard to turn at times if you shoot manually

I purchased this lens back in '99 for my ZX50 as an upgrade for the kit lens. The aperture ring malfuctioned a while after the warrenty expired; I had no AE functions whatsoever in th A position. So I had to shoot manually. Since I shoot weedings ocassionally, exposure was not an issue with the flash. This year, I purchased my K10D and once again, after a couple of years not using the lens, same problem. But one day the ring became hard to turn and now I have all of my AE functions which still work as of this posting. It is probably a minor problem that can be easily fixed. Other than that, it is a great lens.
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