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

Reviews Views Date of last review
6 43,834 Sun July 5, 2020
Recommended By Average Price Average User Rating
100% of reviewers $52.50 8.17
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 1-6 of 6
Junior Member

Registered: March, 2013
Location: Strasburg, Ohio, USA
Posts: 48
Lens Review Date: July 5, 2020 I can recommend this lens: Yes | Price: None indicated | Rating: 7 

Pros: Sharp! Light weight.
Cons: Lens mount broke!
Sharpness: 9    Aberrations: 9    Bokeh: 6    Handling: 10    Value: 10    Autofocus: 10    New Or Used: New   

I have to see a full view of this lens, including the mount to submit an accurate review.

We were on our way to shoot 7/4/20 fireworks last night when the lens suddenly separated from the camera! Seems like the rear lens mount is plastic! If this is actually the case, I find it hard to recommend the lens to anyone.

Images are great but how would you feel if your lens suddenly just fell off your camera?!

(Now living in North Port, Florida)
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: 11
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.
Site Supporter

Registered: February, 2013
Location: Lometa, TX
Posts: 403
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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