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Sigma UC 28-70mm F3.5-4.5 | | | | Sharpness | | | Aberrations | | | Bokeh | | | Handling | | | Value | | | Autofocus | |
| | Reviews | Views | Date of last review | | 4 | 32,747 | Mon April 6, 2020 | |  | | Recommended By | Average Price | Average User Rating | | 100% of reviewers | $26.75 | 5.75 | | | | 
supersize
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| Author: | | New Member Registered: June, 2017 Posts: 15 | | Review Date: April 6, 2020 | Recommended | Price: $7.00
| Rating: 7 |
| Pros: | 2-touch, good enough for 5x7s and on-screen work | | Cons: | for the price - nothing | | Sharpness: 7
Aberrations: 7
Bokeh: 7
Handling: 8
Value: 9
Camera Used: P30 and Micro 4/3
Autofocus: 1
New Or Used: Used
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My copy was essentially "free" as it came with a secondhand P30 that I bought to keep my Pentax film camera capability going into the future. In the multi-coated era there were few makers still producing 2-touch zoom lenses - but this Sigma was kept going up to the switch to autofocus. As so many 1-touch zooms are now sufferring terrible lens creep as the internal rubber seals and washers deteriorate, there is an added value in finding 2-touch zooms if the image quality is good enough for the task intended.
For medium resolution work this lens is fine - for sure, there are problems when scaled up but remember this was a lens designed for home slide projection or "snapshot" prints - and it does that well...even today.
In the modern era we can correct the barrel distortion at wide-angle in photoshop. At wide-angle in bright light we will be at f8-11, so any edge softness has gone. In dark exposures - the edge softness at wide apertures is less visible in your compositions. At the telephoto end - the edge softness with the aperture wide open works to help concentrate the composition on the centre or at the "intersection of the thirds"...and there is enough smooth "bokeh" to make it a useful composition effect.
As with all zooms - there are lots of air/glass or glass/glass interfaces inside so it makes sense to get the best possible lens hood. In the digital era I find those 3-position rubber ones excellent as you can alter the position to suit the zoom perspective.
It has the "sigma" colour cast - and I like it - as others have said - it can be paired with the inexpensive and easy-to-find 70-210 equivelent as a "matched set".
- On film - this is a good alternative to carrying a 28, 35 and 50mm lens when you are travelling light with 400asa negative film.
- On APS this is a "35-105mm equivalent" lens - good as a walk around companion to a Pentax DSLR if you want to view the images on screen or print to album size.
- On Micro 4/3 the 2-touch control gives you an excellent "50-135mm" equivalent video lens - and the smooth focus and zoom controls are a great bonus here.
- If image quality is paramount - then a 1970s single coated prime lens (with a matched lens hood) beats near any zoom lens on any format sensor digital camera.
Construction
This lens is metal - but still lightweight - so I guess it is an aluminium construction. As with all the 1980-90s sigmas, the white lens lettering wears off easily. It has a very "light touch" feel to it - you can control focus and zoom with a single finger. This is similar to the Pentax 28-80 feel but very different to a Nikon style zoom, which has much more friction and so feels "more positive" in comparison.
Would I prefer a Vivitar series 1 or a Tokina ATX spec alternative? Why yes....but not at the prices paid for a "amateur spec" sigma zoom.
Are there any "cheap" mid-range zooms that I prefer as an alternative ? - well at the
| | | | | | | New Member Registered: March, 2019 Posts: 3 | | Review Date: June 1, 2019 | Recommended | Price: $40.00
| Rating: 4 |
| Pros: | Nothing at all really | | Cons: | sloppy action, soft especially in corners | | Sharpness: 6
Aberrations: 7
Bokeh: 7
Handling: 4
Value: 4
Camera Used: Canon A-1
New Or Used: Used
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I bought this after having a lense stolen. It's been a disappointment and will be sold in due course. It's very soft until you get down to f8, especially in the corners and even then it can't compete with my older Pentax-A zoom. The macro is ok, but still very soft. Probably ok for a portrait lense but nothing else.
Handling is meh, with a smooth action but there is noticeable fore and aft play in both rings, especially the focus ring, and the whole action feels sloppy. This makes it difficult to be sure of an accurate focus and I have left it sitting in the case in favour of my Pentax and Tamron lenses.
I've used this on my Canon A-1 as it's a CFD mount, but the same lense is made in several different fittings including Pentax.
Avoid even if cheap.
| | | | | New Member Registered: November, 2013 Posts: 14
1 user found this helpful
| | Review Date: May 21, 2016 | Recommended | Price: $35.00
| Rating: 6 |
| Pros: | sharp enough | | Cons: | much flare, poor bokeh | | Sharpness: 7
Aberrations: 6
Bokeh: 4
Handling: 6
Value: 5
Camera Used: k200 kx sfx mz5 z20p
Autofocus: 7
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not my taste.
- cheap optical construction
-- much flare
O sharpness stopped down ok, not so in the corners
- for beginners ok
I*ve sold it
vivitar, soligor, and tokina are better in this range
| | | | | Inactive Account Registered: June, 2010 Location: Manila, Philippines Posts: 4
1 user found this helpful
| | Review Date: December 3, 2010 | Recommended | Price: $25.00
| Rating: 6 |
| Pros: | Good range, Sharp | | Cons: | Flare | |
This lens served as my everyday, walk-around lens for more than a year now... Coupled with it's 70-210mm UC counterpart, they served as the "Batman & Robin" for my old, trusty K-7... 
Good range, sharpness is ok, but flares a lot... But that's what the hood's for!
Not recommended for the AF enthusiast, solely because it is a manual focus lens...
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