| Author: | | Pentaxian Registered: April, 2009 Location: Madrid, Spain Posts: 10,911
1 user found this helpful
| | Review Date: February 10, 2016 | Recommended | Price: $20.00
| Rating: 8 |
| Pros: | Small, light, quite sharp, well-built | | Cons: | Could be sharper wide open, doesn't work on my SFXn, bad design of lens hood | | Sharpness: 8
Aberrations: 9
Bokeh: 8
Handling: 9
Value: 9
Camera Used: K3, MZ-6
Autofocus: 8
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This is a small, light general-purpose zoom. It's well built for an AF lens, about the level (if a little better) than the Pentax 18-55mm kit lens.
It's at 28mm when fully extended and 70mm when retracted, which I like because it means the lens is at it's smallest at the long end, so good for portraits. The front element turns when focusing and, because the hood locks onto the rotating end of the lens, if you don't disengage the AF when adding/removing the hood then you'll force the AF motor and potentially damage it. That's a very poor design decision and it's a bit annoying to have to remember to disengage the AF every time.
The lens is soft wide open at 28mm and doesn't really become acceptable until f/4, then it's better at f/5.6 and more so at f/8. By 35mm it's already much better wide open (f/3.5) and usable. From 35mm onwards the lens is quite sharp wide open, but benefits from being stopped down. Still, it's usable wide open for most of the range. The lens never gets really, really sharp no matter how much it's stopped down (my benchmark for sharpness is the DA 35mm limited) but it's pretty good.
For some strange reason this lens autofocuses fine on all my film and digital cameras except the SFXn. I assume there's a software/firmware incompatibility between the lens and this specific camera model.
Overall I like the lens, it's a solid performer though due to the focal length and speed I use it more on my AF film cameras than on digital. On film it's extremely useful and is the only zoom I've used that I would consider using in place of a handful of primes. On digital it's OK but the focal length isn't so useful.
Here are a couple of photos taken at 28mm on film. Don't let my poor scanning put you off - this is really just to show the angle of view.
Kodak Colorplus 200, MZ-6 031a by Jonathan MacDonald, on Flickr
Kodak Colorplus 200, MZ-6 025a by Jonathan MacDonald, on Flickr
Here's one more shot to show the size difference between this lens and a Sigma zoom with the same focal length but constant f/2.8 throughout the range. The size (and weight) difference is huge.
Pentax MZ-6 with Sigma UC 28-70mm f/2.8 - f/4 & MZ-5N with Sigma EX DF 28-70mm f/2.8 by Jonathan MacDonald, on Flickr
| | | | | | | Site Supporter Registered: October, 2009 Location: Denver, Colorado Posts: 2,030
1 user found this helpful
| | Review Date: July 22, 2012 | Recommended | Price: $58.00
| Rating: 9 |
| Pros: | Build Quality, Sharpness, Color Rendition | | Cons: | For The Price, None | | Sharpness: 9
Aberrations: 8
Bokeh: 9
Handling: 9
Value: 10
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This is a review of the Sigma 28-70mm f/2.8-4.0 UC M/F zoom.
This is a small, well-built short zoom that does a lot of things well, and for a modest price.
The zoom and focusing action is firm but not overly stiff. It stays where you put it. The M/F ring is far forward and takes some getting-used-to. Once your fingers (and brain) sort it out, no problem.
The color rendition is beautiful, dare I say "Pentax-Like"? Warm and clean, especially with the blue hues and softer colors. It doesn't have the overy bright "Pop" of some newer zooms and primes. Contrast is above average.
Edge to edge sharpness is very good at all focal lengths I've tried and resolution is excellent.
EV seems to be near-perfect with a slight under-exposure in bright, high contrast scenes. Overall, a 9 +.
Bokeh is remarkably good for a budget zoom, especially at wider apertures.
Here are some samples, the close-up bee shot is a 100% crop of a flower shot similar to the black + white photo.
https://www.pentaxforums.com/forums/members/20870-rbefly/albums/5408-sigma-28-70/
Ron
| | | | | New Member Registered: May, 2012 Location: Brasov, Romania Posts: 5 | | Review Date: May 26, 2012 | Recommended | Price: $60.00
| Rating: 9 |
| Pros: | Very good all-around, clear, nice colors, cheap, solid build | | Cons: | big, little bit heavy | | Sharpness: 9
Aberrations: 9
Bokeh: 9
Handling: 7
Value: 9
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Good lens for low light use. Zoom range is great, sharp enough for a beginner. I bought an old copy, is very sharp for a manual focus lens. I cleaned the dust from the inside.
Obiectiv bun pentru lumina slaba. Plaja de magnificare e buna, suficienta pentru un amator. E un obiectiv vechi, e precis la focalizare pentru unul cu focus manual. A trebuit sa-l curat de praf in interior, pentru cine se incumeta la aceasta operatiune recomand o surubelnita PH 0 (in cruce) si multa rabdare.
| | | | | New Member Registered: April, 2012 Posts: 4
1 user found this helpful
| | Review Date: April 10, 2012 | Recommended | Price: $95.00
| Rating: 9 |
| Pros: | Very good all-rounder | | Cons: | Focus time may be a bit lengthy | | Sharpness: 10
Aberrations: 8
Bokeh: 10
Handling: 9
Value: 9
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This 28-70 f/2.8 - 4 UC was tested on a Pentax K-x. The results speak for itself, quite sharp (especially at f/8) and is a quite good all-round lens. If you're a beginner or someone looking for a good lens, start with this lens. It's quite a lot of value for money.  | | | | | | | Pentaxian Registered: April, 2011 Location: Lost in translation ... Posts: 18,076 | | Review Date: October 29, 2011 | Recommended | Price: None indicated
| Rating: 8 |
| Pros: | Sharp after a couple steps down, Ap ring ... | | Cons: | Noisy AF, rotating front element while focusing ... | | Sharpness: 8
Aberrations: 8
Bokeh: 8
Handling: 7
Value: 8
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Bonjour,
First of all, please note that my lens is AF ... you cannot miss hearing it. It's a 55 mm filter mount, seven blades and what seems to be a P KAF 2 all metal mount.
I picked up a used copy of this lens about 8 months ago and it looks like I may have made a good deal. Why? Well, I just stumbled upon its reference in the most recently published equipment pricing guide of the French photo magazine "Chasseur d'Images" : 95 Euros / 125 Euros / 140 Euros for a copy in "excellent" condition (Listed as "SIGMA - Gammes anciennes - Zooms 24 x 36 - AF UC 28-70 mm f2.8/4").
After buying it, I tried to "Google" some info about this lens and found very little (?). Some possible links were: http://www.dyxum.com/lenses/Sigma-28-70-F2.8-4-UC_lens272.html - & - http://www.photographyreview.com/cat/lenses/35mm-zoom/sigma/28-70mm-f-2-8-4-...5_3128crx.aspx ... but, the sample review photos are different and a few reviews make mention of a plastic mount which is not the the case for my lens. So, basically I'm not too sure about anything here. Any help would be appreciated.
Overall, I kind of like this lens, but I have really not spent a lot of time with it to test extensively, etc. But what I have shot has been quite good once the lens is stopped down a couple of times. I find it rather soft at low end and wide open, but that made for some interesting low light portrait shots of my kids.
"Allez, bon courage! Jean le Frog"
PS - Here's a previous post about this lens ... https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/143696-info-si...-f2-8-4-a.html | | |
;)
;)
