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Sigma EX DF 28-70mm F2.8 Review RSS Feed

Sigma EX DF 28-70mm F2.8

Reviews Views Date of last review
8 54,142 Mon April 8, 2019
Recommended By Average Price Average User Rating
63% of reviewers $222.50 6.88
Sigma EX DF 28-70mm F2.8

Construction: 12 groups, 15 elements
FOV: 75.4 to 34.3 degrees
Minimum apeture: f32
Minimum focus distance: 0.4m or 15.7in
Magnification: 1:4.2
Filter size: 77mm
Dimensions: 83.6 x 101.2mm or 3.3 x 4.0in (D x L)
Weight: 645g or 22.7oz
Mount Type: Pentax KAF2/KAF (screwdrive AF)
Price History:

Add Review of Sigma EX DF 28-70mm F2.8
Sort Reviews by: Date | Author | Rating | Recommendation | Likes (Descending) Showing Reviews 1-8 of 8

Registered: April, 2009
Location: Madrid, Spain
Posts: 10,897
Review Date: April 8, 2019 Not Recommended | Price: $150.00 | Rating: 2 

Pros: Looks good
Cons: Sharpness, image quality, weight, size, poor quality control, fragile despite it's heft

I bought this lens used with the intention of using it mostly on AF film cameras but maybe occasionally on digital. I was very disappointed with the lens and took around two years to sell it (at a loss).

The lens is big and very heavy and balances poorly on digital and film cameras. The weight would suggest good build quality but unfortunately that's not true. Despite not being used, just sitting on my lens shelf, it spontaneously developed a fault - the focusing was extremely stiff below ~3m, too stiff for any focus motor to move.

Now for the optical quality - my copy was badly de-centred and produced soft images even on APS-C. Stopped down (not what you buy an f/2.8 lens for) image quality was still poor.

I really don't have anything good to say about this lens other than that it looks cool, which is hardly a reason to buy it. It's very much a lemon of a lens. I have a much smaller, lighter and optically far superior Sigma 28-70mm f/2.8-4 which I use as a normal zoom for film (and occasionally on digital).

Definitely one to avoid.
New Member

Registered: July, 2018
Posts: 1
Review Date: August 1, 2018 Recommended | Price: $180.00 | Rating: 9 

Pros: Sharpness, low distortion.
Cons: Durability ?
Sharpness: 9    Aberrations: 8    Bokeh: 8    Handling: 9    Value: 8    Camera Used: FF, K-1    Autofocus: 8    New Or Used: Used   

This lens has a suitable optical formula for full frame or film. This model lacks the distortion and soft edges common in many 24-70mm models

Unlike a lot of modern 24-70mm and 28-75mm, this lens generates good, crisp edge to edge sharpness stopped down a bit. The detail on FF is excellent. Sharpness is very good to excellent beyond F/5.6. Colour and contrast is vibrant. Distortion is slight.

Unlike some super sharp macro lenses, sharpness at F/2.8 does not bite. Sharpness steadily improves to very good as you stop down. There is very slight softness in the extreme corners at all apertures.

Handling is a little front heavy, but manual focus, for narrow depth of field shots, is intuitive and nicely weighted.

This model is optimised for close up studio work. A good lens, if you can get a lightly used copy.

Registered: March, 2010
Location: Chiang Mai, Bologna, Amsterdam
Posts: 1,198

1 user found this helpful
Review Date: October 13, 2017 Recommended | Price: $200.00 | Rating: 9 

Pros: cheap, good contrast/colors
Cons: relatively fragile
Sharpness: 8    Aberrations: 7    Bokeh: 8    Handling: 8    Value: 10    Camera Used: K-1    Autofocus: 9   

Probably 8 would be the right vote, but i want to compensate the previous vote (4). Why review a lens that is obviously damaged? And why in the wrong place (it was a DG, this is the DF from film time!).
My example had a problem: quite strong vignetting, especially at the wide end.
Then it started getting stuck at the minimum focusing distance. Brought it to a repair shop and found that the focusing sleeve was bent. Probably it was already damaged when i purchased the lens second hand, and it got worse after photographing in a dusty environment.
After the repair the lens works more than fine. A very good option for those who prefer to use high-end primes with the K-1, but still want a cheap zoom when required.
Among f/2.8 zooms, it's one of those with the best price/performance ratio, together with the Tamron 28-70mm (which is somewhat more expensive, though).
AF works fine with the K-1. A little noisy, as all screwdrive types, but fast and precise. This is the second version in a long line of Sigma 2.8/28-70mm, and the last from film times, as far as i remember. Considering it was not designed for digital, i've been surprised by the high contrast and the intensity of the colors. Fringing is also well controlled, much better than many film-era zooms.
According to my personal experience, and taking into account some user reviews i've read, i think that most of the high-speed Sigma zooms that either show excessive softness, strong vignetting or heavy CA, are actually damaged.
I guess that the barrel of many Sigma zooms, especially f/2.8, is not robust enough for the heavy weight of the glass elements.
I had a similar experience with the modern 2.8/24-70mm EX DG Macro (non HSM) that i'm using these days.
I bought it when i was abroad, and asked a friend to open the parcel at home and check the lens.
It looked in spotless conditions, so i released a positive Ebay feedback.
About five months later i came back home and found that the objective had optical and mechanical problems not dissimilar from those of the other one.
I sent it to Sigma Italy official repair center, and i was told that it needed the replacement of both focusing and zooming hardware.
Now it works flawlessly with my K-1, and has the updated firmware... but the repair was expensive!
In practice both my f/2.8 full frame Sigma zoom required rather expensive repairs, even if both showed no signs of external damage (no dropped lenses, no hard knocks, possibly a rather mild concussion leaving no traces, likely when the lens was fully extended).
I suggest to buy this kind of zooms only if you can test the lens, and eventually return it if defective.
If everything is OK, both are good choices. A recent version of the 24-70mm is better, but the 28-70mm DF gives the most bang for the buck.
I still have my DF, and i still hate the procedure to disengage AF, but i would use it in place of the 24-70mm EX DG if there is a serious risk to damage the lens. After using the DF at the Burning Man festival, famous for the terrible environmental conditions, no silt/dust entered the camera. OK, it's not WR, but i was impressed.
I think a little dust got it while focusing, though the glasses weren't affected. When i got it from the repair center it was like new. Smooth and clean.
It still has a hint of vignetting, i can't find any other major fault. All in all, it's a great lens, considering the price.

Here is a sample of the nice colors/contrast. Slightly cropped because the original had some vignetting (it was shot with the K-1 and the lens still had to be repaired):

Junior Member

Registered: July, 2012
Location: Perth, Australia
Posts: 42
Review Date: October 7, 2017 Not Recommended | Price: $150.00 | Rating: 5 

Pros: constant f2.8. Good for a paperweight
Cons: soft
Sharpness: 4    Aberrations: 6    Bokeh: 7    Handling: 7    Value: 5    Camera Used: k1    Autofocus: 7    New Or Used: 7   

I have the APO DG version as part of a bundle of four lenses and obtained cheaply.

I had heard some versions were not the greatest optics and after testing on my K1, I then done further home work to find that this one is a bit of a dog.

It actually works ok for close up and portrait lens but otherwise I either have a very poor version or the DG is not good as indicated by overall scores here.

I intend to try it using flash at a night club job I have coming up and believe this might bring out the best of it's limited qualities.

I may send it to CR kennedy's in Melbourne for a tune up and clean to see if it can improve the performance a little.
New Member

Registered: November, 2013
Posts: 14

1 user found this helpful
Review Date: March 12, 2015 Not Recommended | Price: $300.00 | Rating: 5 

Pros: in the center good sharpness
Cons: wide angle wide open not so sharp in the corners
Sharpness: 6    Aberrations: 5    Bokeh: 6    Handling: 8    Value: 5    Camera Used: k-5, k-x    Autofocus: 9   

for such an expensive lens I am looking forward to best results in CA's and corner sharpness. My item was really disappointing in this matter. Even stopped down to f 6.7 not really fully sharp in the corners and visible CA's WITH WIDE ANGLE:

My cheaper lenses with f3.5-4.5 wide open has better results (perhaps productiuon mistake)

Veteran Member

Registered: December, 2007
Location: Prague
Posts: 1,199

1 user found this helpful
Review Date: December 4, 2011 Recommended | Price: $250.00 | Rating: 8 

Pros: bokeh, sharpness, solid construction
Cons: loses contrast badly when shooting against light sources
Sharpness: 9    Aberrations: 10    Bokeh: 10    Handling: 6    Value: 7   

Bad design, well implemented Bad beacuse it is bad when bright light hits the lens in certain angle you suddenly take a picture that is like in a fog. If the lens hood was done in same style as Canons great 24-70/2.8 the lens would sustain these situations much better.
AF is not as positive as with other lenses I have, but certainly not bad - again if you are not shooting against bright light.
I like the bokeh, total lack of abrations and good sharpness. Only the contrast could be better - this would be a great lens, if it had the SMC or other good coatings.

BTW I did compare the lens with the very popular Tamron 28-75. This one has less aberations and a lot nicer bokeh. Also the built quality seems better. In everything else the Tamron wins. Finally I decided to buy the Sigma instead of Tamron. Suited me better.
Veteran Member

Registered: June, 2007
Location: Sydney, Australia
Posts: 2,891
Review Date: April 30, 2010 Recommended | Price: $250.00 | Rating: 8 

Pros: Excellent low light performer, nice intermediate zoom range
Cons: a little soft wide-open, hefty lens, zoom ring a fraction stiff.

From what I can see ... it has no focusing faults (no FF or BF in my copy).

So far I have noticed it can be a little soft wide-open (although that changes with my EF 530 DG Super flash bounced off the ceiling/wall).

This is a hefty lens ... but i am getting used to the weight of it though.

Will edit this report as soon as I can test this out more and have a good look at images.

Mine is an older version of the lens ... not sure on the year though.
Veteran Member

Registered: September, 2008
Location: Adelaide, South Australia
Posts: 677

3 users found this helpful
Review Date: April 6, 2010 Recommended | Price: $300.00 | Rating: 9 

Pros: Good IQ, fast, very sharp at the upper end
Cons: Heavy
Sharpness: 9    Aberrations: 8    Bokeh: 9    Handling: 9    Value: 9    Camera Used: K-1 (& K200D & K5)    Autofocus: 8   

I bought the DF (means dual focus apparently - since it has a ring to disengage the AF like the Tamron 90) version of this lens in August 2009 as part of a run out deal (the store had bought up all the remaining copies in Australia)

This is late film era lens from about 2002-2003 and as a result a bit heavy (645g) - but if the mythical FF Pentax dSLR arrives it will have a home (I know a guy with an MZ that bought one and loves it). However, it has a constant f2.8 aperture at all zoom focal lengths, and that big chunk of glass at the front means it focuses quite fast.

There were good reviews of it around the web, and a few mixed in here with its younger sibling the DG version (lighter and smaller).

Its also very solidly built (NOTE: see the update of the update at the end of this review) - the zoom and focus rings feel tight and smooth. Its a pleasure to use. The filter diameter is 77mm - the same as my Sigma 10-20mm f4. Watch out for the lens hood though - the 28-70mm hood will cause grief on your 10-20mm as its longer.

Having used it extensively for a month whilst on holiday I can say that IQ is very good to excellent. There is no discernable CA or vignetting in my experience. It can be little soft at full aperture, but from f4 up its sharp. Its not too bad at f2.8 though - no worse than any other zoom.

Colour and contrast are good - it needs very little PP to get well balanced images.

Bokeh is smooth and pleasing as you can clearly see in here

It is a bit limited in range, with the wide focal length being 42mm (35mm equivalent) to a useful 105mm (35mm equivalent) at the upper end. So its normal to moderate telephoto FOV.

However, as a portrait lens at the 70mm end, its great and very sharp (embarrasingly so according to my daughters - I won't post the photos ).

At the lower end, it can be appear a bit soft unless you use the old trick of focusing at the upper end, and zooming back. For that reason, I've down graded it a little - but I still find it useful.

[click on any image to see it full size]

To show what I mean about sharp - particularly in close, look at

and a little further away look at

Its pretty good at 28mm - just be careful with focus

One other great use I found for it is on the end of extension tubes - the zoom ring acts as a focus ring and produces images like this

Overall, this is a good solid lens with good IQ and colour. If you can find one of these, get it - its worth the investment!

UPDATE Jan-2017 :
I am now using this on the K-1. It still performs well, but now there is the widish 28mm to the short tele 70mm
Still sharp, focuses faster, and in low light is a gem
The bonus - now you have the shallower DOF

Here are a few images from a recent low light shoot (a market and a live music gig)
Poh by Chris, on Flickr
Weight by Chris, on Flickr

Lollipop Lollipop...... by Chris, on Flickr

Blue song by Chris, on Flickr
Bassman singing by Chris, on Flickr

Update on my update - April-2017
  • I accidentally dropped the lens once (in a camera bag on the camera) about 0.5m. The weight of the lens bent the mount and bent the focus helicoid (an internal slotted bar). It was repaired and seemed ok.
  • However, on a subsequent occasion it must have been knocked (I don't know how) and the helicoid again bent requiring repair
  • It has done it again after 6 months. I will not repair it a 3rd time.
The helicoid is thin aluminium and may have metal fatigue. Due to the mass of the lens, the front element mass and the weakness in the helicoid I am retiring the lens and finding a new one (Pentax HD WR 24-70mm f2.8 and Tamron 28-75mm IF are calling me).

My warning to any owner of the lens is don't drop it, and ensure the lens is set to infinity when in your bag (retracts the lens)
Add Review of Sigma EX DF 28-70mm F2.8

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