Teardown: Sigma 35mm f/1.4 DG HSM Art by LensRentals.com

[TWI by Dustin Abbott]

I'm not surprised that the Sigma doesn't have any lens element adjustment. These third party manufacturers have to save cost in order to offer the lens at a relatively attractive price. Being able to assemble the lens 'as is' must be a decent saving in production but from the lens rentals variability graphs it looks like Sigma haven't mastered the consistent assembly that Canon have achieved with say the new 50mm STM.

I bet if Lens Rentals disassembled one of the new Tamron primes they would find the same thing - decent enough construction but straightforward.

I would be very interested in that teardown. The weather sealing is supposed to extend to seals at all the proper points, and I'd like to see a third party confirmation of that.

 

[Bdube]

I really have to wonder if Sigma doesn't have a tuning option at the factory. My thought is that if they have a pre-assembly check then they could estimate which individual elements work together well and then group them up.

Unless that's still overthinking it and they're actually confident enough to assemble lenses with nothing but a final "pass/fail" QC check.
In interviews the Sigma CEO did mention higher failure rates with the Glbal Vision line.

The funny thing is the variation doesn't seem to affect reviews. In a way they're right not to bother if the worst copies are still very sharp.

It's possible to match fabrication errors in elements to each other, but it is difficult and requires expensive sorting. Each element gets measured anyway, but for example if the front element's radius of curvature is too small, the focal length becomes shorter but the aberrations also change. It requires a thorough study of the lens system to match errors in a way that is constructive. The errors of alignment, at least in the art series lenses produced thus far, are quite a bit larger than the errors of the elements.

 

[infared]

I love the work that Roger does. It's always so vital to the craft!
I think that it's fantastic that the Canon 35mm f/1.4LII is so incredible optically and physically. Actually stunning....part of the asking price is justified just by the consistency of each lens to "hit the mark".
I picked up my Sigma for under $800 overseas. I can't justify the $1800 for a 35mm prime..(wish that I could), but clearly that lens is worth its price...and it would seem that my lens is worth its price.
What's cool about this situation is that if a great image was shot with both lenses simultaneously ....the image quality difference in reality is moot. Academic. The image would come through in both instances. That is pretty cool.
I wonder how the build on the Sigma holds up to the Canon 35mm f/1.4L I? I'm curious now...since even that lens is still commanding $1100, currently.....

That is somewhat true (re image quality), but the new Canon is definitely in another league. Think Canon L to Otus. The 35L II has better contrast, color, and overall resolution, and I find that images just look more "special". The drawing is better with the L lens, though that probably won't show up on any chart testing. I've been using the lenses side by side in my review process, and for critical moments I find myself reaching for the Canon every time.

I think if I had both lenses size-by-side that I would be reaching for the Canon EVERY time. ... But I am happy to know that a lens that is less than half the price holds up so well optically to the Golden Fleece. I look forward to your review. I am interested to see the comparison of the bokeh of the two lenses especially in the transition zone...I bet the Canon is impressive.

 

[Larsskv]

I love the work that Roger does. It's always so vital to the craft!
I think that it's fantastic that the Canon 35mm f/1.4LII is so incredible optically and physically. Actually stunning....part of the asking price is justified just by the consistency of each lens to "hit the mark".
I picked up my Sigma for under $800 overseas. I can't justify the $1800 for a 35mm prime..(wish that I could), but clearly that lens is worth its price...and it would seem that my lens is worth its price.
What's cool about this situation is that if a great image was shot with both lenses simultaneously ....the image quality difference in reality is moot. Academic. The image would come through in both instances. That is pretty cool.
I wonder how the build on the Sigma holds up to the Canon 35mm f/1.4L I? I'm curious now...since even that lens is still commanding $1100, currently.....

That is somewhat true (re image quality), but the new Canon is definitely in another league. Think Canon L to Otus. The 35L II has better contrast, color, and overall resolution, and I find that images just look more "special". The drawing is better with the L lens, though that probably won't show up on any chart testing. I've been using the lenses side by side in my review process, and for critical moments I find myself reaching for the Canon every time.

I am happy you point this out. I don't think MTF charts is a proper tool to evaluate the quality of a lens. It tells quite a bit, of course, but your real world testing are way more important to me. Looking forward to your review of the 35 L II!