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Sigma 28-105mm F3.8-5.6 UC III

Reviews Views Date of last review
5 40,312 Fri February 14, 2020
Recommended By Average Price Average User Rating
100% of reviewers $52.50 8.40
Sigma 28-105mm F3.8-5.6 UC III

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

Lens Construction: 12-13
Angle of View: 75.4~23.3
Minimum Aperture: 22-32
Minimum Focusing Distance: 0.5m(19.7 inches)
Magnification: 1:5.6
Filter Size: 62mm
Hood mount: Bayonet
Dimensions (WxL): 71x72.5mm(2.8x2.85 inches)
Weight: 275g(9.7oz)
Mount Type: Pentax KAF2 (w/ in-lens AF)
Price History:

Add Review of Sigma 28-105mm F3.8-5.6 UC III
Sort Reviews by: Date | Author | Rating | Recommendation | Likes (Descending) Showing Reviews 1-5 of 5
New Member

Registered: July, 2012
Posts: 14
Lens Review Date: February 14, 2020 I can recommend this lens: Yes | Price: None indicated | Rating: 8 

Pros: light weight, rapid auto-focus, excellent sharpness, FF compatible
Cons: not WR
Sharpness: 9    Aberrations: 9    Bokeh: 9    Handling: 9    Value: 9    Camera Used: K1ii    Autofocus: 6    New Or Used: Used   

I got his lens as a 'kit lens' substitute for my K1ii after reading the previous reviews on this forum.
I got it from an auction site on a Pentax camera and both were in pristine condition.
The glass is clean and the general apperance is also 'like new'.
Here is a hand held test shot with the lens at full zoom (105mm) on the K1ii using TAv, 1/250s at f/8 and auto focus.
The first is the full camera jpg with no PP and after that is the subject in the centre of the same image viewed at 100%.

I think this second image displays the good resolution available with both this lens and the K1ii
New Member

Registered: September, 2017
Posts: 7
Lens Review Date: August 28, 2018 I can recommend this lens: Yes | Price: $50.00 | Rating: 10 

Pros: sharpness,IQ,weight,IF
Cons: none
Sharpness: 9    Aberrations: 8    Bokeh: 9    Handling: 10    Value: 10    Camera Used: K-5    Autofocus: 8    New Or Used: New   

Very good performer lens for such low cost.
New Member

Registered: April, 2013
Posts: 20

2 users found this helpful
Lens Review Date: July 25, 2013 I can recommend this lens: Yes | Price: $50.00 | Rating: 8 

Pros: IQ, useful range, Internal focusing, non rotating front element, price
Cons: AF can hunt, manual focus ring a little sloppy, 28mm low end
Sharpness: 8    Aberrations: 9    Bokeh: 6    Handling: 6    Value: 10   

Fallen on hard times and as such money is very short. Want to keep the hobby going so had to take some extreme budget measures. The Sigma 28-105 UC-III was one of them. Sold my beloved Tamron 17-50 2.8 XR and Pentax DA 55-300, raised a load of money and settled for the Sigma. Not expecting anything really, just as long as it provided a picture.

As it happens i love it. The focus is quite snappy most of the time, it can hunt a little bit in poor light but other than that its pretty much on a par with my other lenses. The manual focus ring is one of the negatives, at least on my sample. It's a bit loose and sloppy, which is a real shame because its very quick to manually focus.

The optics are good to very good. I miss the Tamron 17-50, can't deny that but Sigma provides a really good image, even wide open. It's obviously pretty slow at 3.8-5.6 but you can work with that. Working at F8-F11 the lens provides a very sharp image and i love using it for landscapes. It's also great as a walk about lens, you just have to work your feet a bit more due to the not so wide 28mm on APS-C. I just found it a little bit restrictive at a car show where there wasn't the room to move and 28mm wasn't wide enough. Found myself more restricted to detail shots. It's worth keeping the 18-55 kit lens handy as well.

The lens has some great features that wouldn't expect to find on a cheap lens. The internal focusing, non-rotating front element, metal mount, quick manual focus with large manual focus ring and decent petal hood are all very welcome indeed. This all makes for a very good value lens, in fact, impossible to mark it as anything other than 10/10 for value.

This lens gets double thumbs up from me and i would definitely recommend it to a friend. But i would like some premium glass again one day.
Veteran Member

Registered: February, 2013
Location: Lometa, TX
Posts: 402
Lens Review Date: June 11, 2013 I can recommend this lens: Yes | Price: $50.00 | Rating: 9 

Pros: Good build,fair reach, ease of use,sharpness, good bang for buck
Sharpness: 10    Aberrations: 9    Bokeh: 8    Handling: 10    Value: 10   

I bought this lens, just wanted a little more reach than the 18-55mm kit lens has for everyday use. I am very happy with the sharpness and overall image quality. The lens is well built and has a nice feel on the camera. For the money You just can't go wrong in my estimation. I use many lenses on a variety of Pentax DSLR's and would highly recommend this lens for the money.
Senior Member

Registered: March, 2010
Location: NE Florida
Posts: 130
Lens Review Date: March 18, 2010 I can recommend this lens: Yes | Price: $60.00 | Rating: 7 

Pros: Light weight, useful zoom range, decent build and IQ, internal focus
Cons: A little on the slow/dark side, zoom ring turns opposite direction from the norm

This lens surprised me. It is somewhere between kit lens and high quality, but seems to average even below a kit lens price. As with most lenses in this category, you can always get sharper images by stopping down, but it is a rather slow/dark lens, so you are limited a bit on that. I haven't noticed any distortion throughout the zoom range. Autofocus is quite fast, and despite other reviews elsewhere for other mounts, it is not very loud. Internal focus is a nice touch. When zooming you have to rotate the ring in the opposite direction of the typical norm. That can take some getting used to -- not sure if more or all Sigma lenses are like this (?).

Overall a good, inexpensive lens. I have found it very useful as a walk-about lens and good on vacations. At this price, it is practically disposable if something should happen to it, yet still takes very nice images.
Add Review of Sigma 28-105mm F3.8-5.6 UC III

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