Where the sharpness comes from: A tour of Sigma’s factory

Some people are happy to shoot with lenses and think only of the results, but it can also be fascinating to think about how such complex, precision pieces of engineering are made. Some insight is provided by Dave Etchells over at Imaging Resource, who has just posted a story about his visit to Sigma’s factory in Aizu, Japan. Etchells follows the process from shaping the lens surfaces, to polishing, assembly and testing.

However, no matter how hard you try, you can’t make every lens perfect – as Lensrentals Roger Cicala explains in his recent blog post. He looks at lens production from the perspective of manufacturability and engineering tolerances, and what’s done to mitigate against the unavoidable inconsistencies they bring.

Lens polishing at Sigma’s Aizu factory – photo from Imaging Resource

The two articles make an interesting pair – the efforts made to make a lens as ‘perfect’ as possible and the reasons why that’ll always be just out of reach.

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Etchell’s tour and write-up of the Sigma factory is excellent. I’m very impressed with my Sigma lens and after seeing the complex and time consuming manufacturing process I’m surprised Sigma lenses don’t cost more, a lot more.


Japanese has extremely high standard of QA.


sharpness comes from discipline!


Amazing read. We are lucky to be able to buy these lenses at such reasonable prices. Very good item, a must read indeed.


It IS possible to produce best possible series of lenses. Zeiss are currently proving it with its coming HQ lenses. They will beat every currently FF lens.


If Zeiss ever manage to beat 20 year old Nikon prime glass, they will be doing an amazing job.

Ralf B

… and thinking of DPR’s future, how come I find more and more sources of good digital photography elsewhere compared to 8 years ago? A lens rental site disclosing the quality assurance process they run on their lens stock makes for a better read than found on this site here for quite some time!
Diversity isn’t the only key to survival, Simon. Remember where this site came from…so hats off for the courage to actually link to the good stuff over at IR and Lens Rental. A good service to your web site visitors (= customers)!

In that context: Thanks for NOT linking to rumor sites, that “service” is taken care of by forum rumor mongers to an over-saturating degree 🙁

Ralf B

Hats off to Dave! Reading his post made me feel like having been there myself.
Now give him and Simon Joinson some more sake and let them negotiate a joint venture of IR and DPR …


After watching the tour of the factory and knowing about the processes and precision that they (and others too) need to abide by, I kind of wonder why a 16 element 2.8 ED etc piece of optical precision glass can cost 400$ and a pair of Gucci or Rayban sunglasses with a SINGLE piece of UV-protected plastic can cost the same?


Probably because the Gucci or Rayban label costs $399 to produce.


Great inside what really goes into a lens cost. Yes, it is
– expensive optical glass ~proportionally to its weight
– polishing of the sufrace – proportionally to surface areas of the lenses
– coating – ~proportionally to surface areas of the lenses
– assembly – ~proportionally to number of elements

Smaller, lighter lenses are also cheaper to make – don’t fool yourself thinking otherwise.


Sheesh, “insight”.


peevee1 – you forgot about one thing: Higher precision = higher price.
So if you want really high quality lens that’s small at the same time (for example – because it’s used on a small size sensor like m4/3) than it’s price will be higher.
That’s why all these 50s are cheaper on DSLRs than CSCs – noone cares much about small size and the sensor is large, so you can allow yourself some more… freedom in manufacturing in order to pull the price down.

Mr Fartleberry

I want to believe … but the fact is no one is abandoning their Canikony lense in any class to use the Sigma. Unless they’re a shill like I’ve seen in the Canadian photo press.

Nothing against Sigma but your past history follows you around. It’s just not a simple case of throwing your shittty underwear in the wash with a sheet of Bounce and think you’ll come out smelling like …. mountain meadow.


You are living way in the past. Sigma in no way resembles the company it once was, and that has been the case for many years now.

Just look at the build quality of Sigma’s cameras, for example. They are top notch and as good as anything out there. Then consider the truly revolutionary picture quality their cameras are capable of. They are the only camera maker that has done anything truly significant to increase image quality.

Finally, is it really necessary to use disgusting toilet metaphors to make your point?


“past history follows you around”….
I think Sigma right now is an excellent example of how a company can turn around from a bad reputation by doing an exceptional job. They’re not just making lower quality, cheaper versions of common lenses anymore. Recently, they’ve put out:
-18-35/1.8: no other manufacturer has a f/1.8 zoom
-35/1.4: as good as (or better than) first party versions for a lower price
-USB dock: adjust lenses without having to ship them off
And that adds to their already strong portfolio with lenses like the 120-300/2.8 (no one else has a 300/2.8 that zooms back)
In terms of lenses, Sigma right now is on track to beating first party manufacturers at their own game. If they continue to play it right, Sigma could come out smelling like mountain meadow.


Im VERY happy with both my Sigma lenses….cant say the same thing about the Tamron though


Well, I don’t know – all Tamron lenses I got are there only because Sigma has even worse products.
There are right now only 4 outstanding lenses from Sigma. They’re still long way from beating crap out of Tamron. And most likely – till than Tamron will catch up and beat them again.

Though definitely – Sigma knows where’s a warm spot in Photographers soul and right now – that’s where they’re aiming. With a great success as you can see from chlamchowder’s post.

Ernest M Aquilio

The Sigma 35mm and 50mm are on my camera 90% of the time. They are truly great lenses.


In my days of engineering and working with molding, extrusion and tooling of materials, even though it was Medical devices, I can relate to much of the article. A hand made prototype could prove a great design. Then came the real hard part: repeatability in an automated process. Which involved a different team of engineers and technicians skilled in the art.

Hopefully this article sheds some light on why a good Quality Assurance department can make the difference in a respected product. That if you do get a lemon, just exchange it for another. It happens.


I think that applies to all manufacturing, i worked for nine years in commercial printing,
We made carton boxes of all shapes and sizes for companies, from boxes for fake limbs down to small candy boxes, cereal boxes and so on, many designs look good on paper but the machinery cant handle everything.
issues that can come up are “width of the box vs height” to long and narrow it wont go through properly (we did a ton of DIY to fix so many issues),
the thickness of the carton (to thin it would rip, to thick it would refuse to go through)
The color used (if it was to wet or the wrong color used it would smudge all over and be ruined),
what kind of coating is on the carton? (if the coating was not good enough we had to use another type of glue)

And so many things could go wrong because of the designs and so many did, we however rarely had to turn down a job.

Model Mike

Fascinating, splendidly written article. Go, Sigma!


Very cool article! While I am a long time Nikon fan (only Sigma experience was with an old 100-300 I didn’t care much for), I am willing to give Sigma another try after reading this article.

four under

There was a time I wouldn’t have taken a Sigma lens for a gift. Those days are long gone though, they have some great products now.


That was a great read. Sigma – shaking it up!


What about the cameras?


I own two of them, the DP 1 and 2 Merrill series cameras. No matter how many pictures I take I am truly stunned every time I develop a raw image from them. No other camera and lens has done that for me. Staggering picture detail and quality. They just need to make the Foveon sensors more sensitive to improve high ISO performance.


I think more important would be to drive the price down than getting better high ISO – I would buy a great low-ISO camera in an instant, but not for these prices.


Never been a big fan of Sigma lenses, or any of the third party makers to be honest.
My Nikkors have always seemed better built and drawn nicer images.


Some of our OEM lenses are made by the third party manufacturers and the OEMs have sold third party designs as “their own.” I wouldn’t thrown Tokina, Tamron and Sigma under the bus.


Yep, the best of Sigma, Tokina and Tamron lenses are as well built as anything out there. The best built and finished lens I ever owned was a Tokina ATX lens. It was also the sharpest.

All major camera and lens manufacturers make lenses of varying quality, both in build and image quality. The cheapest built lenses I have owned were Canon. The cheapest of the Nikons look no different.


Sigma is now testing every single lens? That’s one impressive statement of intent.


Basically they have to to take advantage of the super sharp Foveon sensors.


Good info and glad they didn’t stick you with the dinner bill. The part about them rejecting a lot of lenses that don’t quite measure up was very interesting because with so much automation, I’m sure it’s tempting to give everything a pass.


Neat stuff. Looks high-tech and old school. We all remember grinding a telescope mirror as kids. Fantastic article by Dave and kudos to DPReview for linking it.


“We all remember grinding a telescope mirror as kids?!”

I most certainly don’t. I’ve never even seen a telescope mirror except on TV, much less ground one.

Roland Karlsson

Agree!! I have never done it either. Had some plans though. Would have been fun to look at Jupiter with the help of a home made mirror 🙂


“I most certainly don’t. I’ve never even seen a telescope mirror except on TV, much less ground one.”

Maybe you’re too young? There used to be a time when science experiment kits used to be sold so kids could do a lot of things that our upside down world today no longer allows. The 70s were the peak for such things. Now you can’t even get a decent toy in a Cracker Jacks box for fear of some idiot giving their child something to choke on.

Mark Roberts

What a great report… I was delighted to see it written with a human perspective, not just technical.


The Dave Etchell piece was very interesting. I read and enjoyed the whole thing. Much better than those superficial u-tube things we get everywhere now.


i also liked the last part.. when it ended with sushi!


a good footnote to the relationship between lens price and aperture area (surface area of all lens elements here).


A very comprehensive and well written exposition. Well worth reading.


Sigma is a company in ascension,and It’s nice to witness someone shaking up the Japanese paradigm ..

Source Article from http://www.dpreview.com/news/2013/09/20/where-the-sharpness-comes-from-a-tour-of-sigmas-lens-factory-manufacturing