Lens quality control

Started Sep 24, 2013 | Discussions thread
parallaxproblem
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Re: Lens quality control
In reply to ProfHankD, Sep 26, 2013

ProfHankD wrote:

parallaxproblem wrote:

Yes, here's my experience with a (well two actually) decentered SEL16/2.8 lenses... and Sony's total disinterest in doing anything about it:

http://www.dpreview.com/forums/post/52107652

I know this isn't what you want to hear, but I've seen far worse than this. The comparably small lenses on many "prosumer" compact cameras often have at least this much badness.

Maybe, but the number of decentered examples of the 16/2.8 appears surprisingly high for a discrete lens.  Sony must be aware of this and really should not be 'fobbing-off' poor quality samples onto their customers in this way!

The 16mm f/2.8 was a pretty nasty little design problem; honestly I don't think Sony was up to it at the time. We all know that Sony was leaning heavily on Tamron to extend the Minolta line that they acquired

I think Minolta was the one who got Tamron involved by rebadging their 28-70/2.8 and 17-35/2.8-4 designs as KM lenses (I use the 17-35 on my A900 and it's not a bad lens at all) a few years before the Sony acquisition or even the relationship with Sony (though I think Sony have a big stakeholding in Tamron?). The reason Konica-Minolta needed to do this was... again... problems with their offshored Chinese plant not being able to produce what they needed!

and Zeiss to provide high-end options,

The relationship with Zeiss goes back further than the Minolta acquisition...  the Cybershot 707 (launched 2001) had a Zeiss-badged lens on it, as did a number of their other early P&S cameras

but the E-mount's APS-C sensor with a short flange distance was very new territory -- especially for making a low-cost pancake that would work with a fisheye adapter, etc.

NEX in the start seems to have been a small project with a team of young designers...  now it has suddenly become part of the core strategy and on the way I guess the original team members have by now all been elbowed out of the way by a bunch of ambitious 'corporate suits' (I missed out an 'h' somewhere in that word)

Lens design probably took a back seat at that time as they were likely focusing more on 'concept'

The UW and Fisheye adaptor options however were a masterstroke - what a shame the implementation was so 'so-so'

Most new lenses are variations of old SLR lenses -- computer optimization experiments starting with an existing design -- but I don't think there was an obvious starting point for this lens. I think this is why Sony's been slow coming out with new E-mount lenses...

Is lens design really so difficult these days?  Don't you just need to pump a few reflective/refractive indexes into a MathCad model and out pops your answer?  Optics is a very well established field and there are no 'mysteries' there and so I would imagine (I have never done it myself) optical design is just a case of chosing between compromises of cost/quality etc?  Not like the old days where they would have to spend ages and lots of money actually making prototypes to test the optical design at the initial stages

I would suspect that the problems were much more ones of dealing with the new production plant (and then dealing with the production plant once it found itself becoming a sub-marine production plant) and a big political mess within Sony as the DSLR and mirrorless factions fought it out amongst themselves over what the future of each line was likely to be!  Add to that clear confusion on Sony's part over who they wanted to sell NEX cameras to and what sort of lenses they needed to support that and you get...  well... pretty much what we've seen happening over the years since NEX was released

and I actually think slowly coming out with better lenses as Sony's design expertise with E-mount grows is better for all.

A redesign of the 16/2.8 which can still use the UW and fisheye converters but has less production variance and maybe better edge/corner performance might be welcome

As would the 30/2 pancake (Samsung lens design + 7mm flange distance offset?) people have been begging for since the NEX range was launched

Sadly Sony are now on a 'big, expensive zoom' trip, which is strange considering they are about to jump into FF and that APS-C will become the 'budget line'

Aside from the design challenges, take a look at LensRentals tear-down of the 16mm f/2.8. It is designed as a very straightforward assembly -- by which I don't mean the parts are simple, but that there aren't any adjustments. If a part is a little out of tolerance, the lens will be too.

Yes, that is what the Sony tech told me as well... that he had no opportunity to adjust my lens, but that he could have maybe done something to make it better if it had been an Alpha mount lens instead

I saw the tear-down article before and I think they also do the same to an Olympus 17mm lens.  I know that lens doesn't have a particularly good reputation for IQ, but I haven't heard complaints about decentering with it (though I haven't been looking too hard) so it would appear that Oly don't have these construction quality issues

Expect better in the future....

Maybe, but the decentered Zeiss 16-70 samples aren't giving many grounds for confidence... 

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