Jump to content

21 SEM quality control issues?


onasj

Recommended Posts

Advertisement (gone after registration)

First, I think the 21 SEM is (capable of being) one of the best wide angle lenses in the Leica M line. It’s very sharp wide open, super contrasty, well-corrected, tiny, and (by Leica standards) a good bargain.

 

But as I recently completed my quest to find a good copy of the 21 SEM, I noticed, and experienced firsthand, evidence that there might be a QC issue with the production of this lens.

 

The first copy I purchased new online from a major online camera retailer. That copy was decentered in an obvious way— one corner was much softer than the other three, and the coma was highly asymmetric and differed greatly in tangential vs radial shape depending on which corner of the image one was examining. Indeed, my 28 lux at 1.4 was substantially sharper near the edges and corners than the 21 SEM at 3.4, despite the MTF curves implying the opposite should be the case. I showed the retailer photos demonstrating the problem and returned the lens for a full refund.

 

I didn’t make much of this issue since no manufacturer is perfect and mistakes happen. But then I noticed an unusual number of people in this forum posted their experience with purchasing a defective 21 SEM.

 

I ordered a second copy through my local Leica store. When I tested it side-by-side for more than an hour with their floor model (which was a much older copy of the same current design), I was surprised to find that the old copy was noticeable sharper than the new copy! And the new copy also showed signs of asymmetric corner softness, though it wasn’t as pronounced as the badly decentered copy I purchased online.

 

Needless to say, I ended up buying the floor model copy, and the lens has been performing much better than my first copy, especially outside the center region of each image.

 

It’s possible that I was just unlucky, twice, but I’m sharing my experiences in case anyone else is looking for a new copy of this outstanding lens. Perhaps an assembly jig is misaligned in the factory? In any case, prospective buyers might want to test carefully before buying.

 

I should also note that I own quite a few M lenses purchased recently and I have had zero problems with any of them besides the cases above.

Edited by onasj
  • Like 3
Link to post
Share on other sites

First, I think the 21 SEM is (capable of being) one of the best wide angle lenses in the Leica M line. It’s very sharp wide open, super contrasty, well-corrected, tiny, and (by Leica standards) a good bargain.

 

But as I recently completed my quest to find a good copy of the 21 SEM, I noticed, and experienced firsthand, evidence that there might be a QC issue with the production of this lens.

 

The first copy I purchased new online from a major online camera retailer. That copy was decentered in an obvious way— one corner was much softer than the other three, and the coma was highly asymmetric and differed greatly in tangential vs radial shape depending on which corner of the image one was examining. Indeed, my 28 lux at 1.4 was substantially sharper near the edges and corners than the 21 SEM at 3.4, despite the MTF curves implying the opposite should be the case. I showed the retailer photos demonstrating the problem and returned the lens for a full refund.

 

I didn’t make much of this issue since no manufacturer is perfect and mistakes happen. But then I noticed an unusual number of people in this forum posted their experience with purchasing a defective 21 SEM.

 

I ordered a second copy through my local Leica store. When I tested it side-by-side for more than an hour with their floor model (which was a much older copy of the same current design), I was surprised to find that the old copy was noticeable sharper than the new copy! And the new copy also showed signs of asymmetric corner softness, though it wasn’t as pronounced as the badly decentered copy I purchased online.

 

Needless to say, I ended up buying the floor model copy, and the lens has been performing much better than my first copy, especially outside the center region of each image.

 

It’s possible that I was just unlucky, twice, but I’m sharing my experiences in case anyone else is looking for a new copy of this outstanding lens. Perhaps an assembly jig is misaligned in the factory? In any case, prospective buyers might want to test carefully before buying.

 

I should also note that I own quite a few M lenses purchased recently and I have had zero problems with any of them besides the cases above.

 

I don`t know, but I find it hard to believe that this particular lens should be any different from Leica lenses in general. The quality control should be the same for all lenses. I know of more instances than one where persons I know personally have bought a brand new lens (and not the 3.4/21) only to discover that it does not perform and have had it replaced by a new copy. The quality control procedures are not perfect, it seems.   

 

 

Link to post
Share on other sites

Onasj,  I have experienced the same issues over the years with several M lenses.  I learned in my early Leica years, to always buy from a reputable dealer or now Leica Stores to test the lens in the store first before buying it.  If the dealer won't let you do this, (which would be quite strange if its a Leica dealer) then take your business elsewhere.  Even though the lenses are built by hand in small batches and go through quality controls, errors happen.  It only takes a second for someone not paying attention to the production, quality control...or suffering from a hangover, fight with the wife or dog etc., to cause errors.   It happens with cars and most anything these days.  Most recently, I intended buy a new 28mm Elmarit-M and tested 2 in the store...both failed for decentering before buying the third copy that was perfect.  The Leica Store staff in San Francisco was most helpful as always with my in store testing.  If you buy mail order, just remember do not to fill out the warranty card, call for a return authorization and send it back for a refund.  So, I always recommend test the lens before buying it or test it immediately for flaws if bought online.  r/ Mark  

  • Like 2
Link to post
Share on other sites

Your experiences have been mine also, except that I find variation in all but a few lenses.  In addition to testing for sharpness and symmetry Leica M lenses have rangefinder adjustment that could be a source of issues.  Occasionally, a lens when shot will stand out as exceptional, a perfect sample, this happened to me with a 24mm S lens, a store sample that could not be sold. Testing four other copies and finding them all inferior.  Months later I was able to buy the sample.  In two cases I have found samples that matched so closely to be indistinguishable, a pair of 135mm Tele-Elmars manufactured 20 years apart (iirc), the second was a pair of 35 FLE's that were manufactured in the same batch with serial numbers very close.  It's easy to choose a lens when one sample is superior, two similar lenses can drive one to madness looking for any nuance of difference.  Single sample reviews (most are) on the internet can be subject to these variations.  Roger Cicala in his blog will post mtf curves for multiple samples and show the variation, a wide band results rather than a nice thin line provided by the manufacturer.   

  • Like 1
Link to post
Share on other sites

I wouldn't be so quick to suggest the presence of a QC problem.

 

1. None of us presumably know enough about lens design or manufacturing to be able to say conclusively whether the sample variation is normal.  The more relevant question is whether the sample variation you have discovered is within Leica's accepted tolerance.  

2. If it is within Leica's accepted tolerance then it probably is not reasonable to expect more for the price.  Leica strives for very high quality standards and I'm sure they set the tolerance according to what is economical given cost. What look like very small improvements to you at the margin may in reality double or triple the cost of manufacturing.

3. If it is outside of Leica's accepted tolerance then it should have been a reject.  But one or two rejects don't make a QC problem.  There is some statistical likelihood that a very small fraction of defective units can get passed inspection to make it to the hands of the consumer. I'm sure in such a situation Leica would be very happy to send a replacement unit.  

4. I doubt any of us would be under served by something that passes the intended standards set by Leica, defective units that slip through notwithstanding .  

5. Just because we pay Leica prices doesn't mean we should expect perfection.  Why else do the cine lenses cost so much more?  Expensive is relative.  

6. If there really is a QC problem, which by the way will require a large enough sample to determine with statistical confidence, rest assured that Leica will know before we do from the repair / return numbers.  I'm sure meetings will be called and heads will get summoned.  They are not a firm that takes quality lightly.

 

First, I think the 21 SEM is (capable of being) one of the best wide angle lenses in the Leica M line. It’s very sharp wide open, super contrasty, well-corrected, tiny, and (by Leica standards) a good bargain.

But as I recently completed my quest to find a good copy of the 21 SEM, I noticed, and experienced firsthand, evidence that there might be a QC issue with the production of this lens.

The first copy I purchased new online from a major online camera retailer. That copy was decentered in an obvious way— one corner was much softer than the other three, and the coma was highly asymmetric and differed greatly in tangential vs radial shape depending on which corner of the image one was examining. Indeed, my 28 lux at 1.4 was substantially sharper near the edges and corners than the 21 SEM at 3.4, despite the MTF curves implying the opposite should be the case. I showed the retailer photos demonstrating the problem and returned the lens for a full refund.

I didn’t make much of this issue since no manufacturer is perfect and mistakes happen. But then I noticed an unusual number of people in this forum posted their experience with purchasing a defective 21 SEM.

I ordered a second copy through my local Leica store. When I tested it side-by-side for more than an hour with their floor model (which was a much older copy of the same current design), I was surprised to find that the old copy was noticeable sharper than the new copy! And the new copy also showed signs of asymmetric corner softness, though it wasn’t as pronounced as the badly decentered copy I purchased online.

Needless to say, I ended up buying the floor model copy, and the lens has been performing much better than my first copy, especially outside the center region of each image.

It’s possible that I was just unlucky, twice, but I’m sharing my experiences in case anyone else is looking for a new copy of this outstanding lens. Perhaps an assembly jig is misaligned in the factory? In any case, prospective buyers might want to test carefully before buying.

I should also note that I own quite a few M lenses purchased recently and I have had zero problems with any of them besides the cases above.

Edited by cpclee
Link to post
Share on other sites

Advertisement (gone after registration)

I've churned through a lot of Leica lenses over the years (too many for sure) and I think it is reasonable to say that no two of the same model are exactly the same. In my experience, if you sell a good one you rarely get such a good one when you buy another. The moral (that I have belatedly discovered) is that if you have a good example of a particular lens, don't sell it unless you are certain you will never be buying another.

  • Like 3
Link to post
Share on other sites

I’m asking in the spirit of the theory of “the market for lemons”. Akerlof is a Nobelist and the spouse of Janet Yellen.

 

https://en.m.wikipedia.org/wiki/The_Market_for_Lemons

 

Interesting. I am an economics and of course familiar with Akerlofs work. I doubt all lenses offered for sale are lemons, though (although the massive price fall on a one week old lens is a mystery). 

Link to post
Share on other sites

First time i complained about Leitz QC was in the eighties and i have not the feeling that things got significantly better since then. Now i rely on my serious dealers to check bodies and lenses before delivery. I prefer checked-in-box to new-in-box but it's just me. 

Link to post
Share on other sites

@wattsy when you say “you rarely get such a good one when you buy another”, are you talking about new or used?

  

I’m asking in the spirit of the theory of “the market for lemons”. Akerlof is a Nobelist and the spouse of Janet Yellen.

https://en.m.wikipedia.org/wiki/The_Market_for_Lemons

I was referring mainly to new. The Akerlof theory is interesting but to the extent that I have sold many good lenses (only to buy inferior new examples of the same lens at a later date) I don’t think my experience fits the model.

Link to post
Share on other sites

In some Leica lenses (such as the current 50 Lux and the 21 SEM), I have found massive sample variation. Real MTFs of the bad ones would not come even close to the published MTFs. 

I do not care whether this is within Leica's tolerances or not. I find it unacceptable.

 

The Akerlof theory does not apply imo: The employees in the stores usually have no clue whether the one sample they have in stock is good or bad.

Some buyers of bad samples probably never find out...

Link to post
Share on other sites

Interesting. I am an economics and of course familiar with Akerlofs work. I doubt all lenses offered for sale are lemons, though (although the massive price fall on a one week old lens is a mystery). 

 

I can say of my own experience that the last 6 Summicron asph 75mm lenses I have had in my possession, all of them were "lemmons". The only used 75mm summicron lenses there are on the market, are the ones sold by their owners, because of the bad sharpness at infinity. Maybe a lot of them thought it was their own fault and that the lens was not good for them , because they were not capable of handeling their specimen, but the search for a used 75mm led me to this conclusion. Of all the people I speak that want to keep their 75mm , all of them have a perfect specimen. 

  • Like 1
Link to post
Share on other sites

I can say of my own experience that the last 6 Summicron asph 75mm lenses I have had in my possession, all of them were "lemmons". The only used 75mm summicron lenses there are on the market, are the ones sold by their owners, because of the bad sharpness at infinity. Maybe a lot of them thought it was their own fault and that the lens was not good for them , because they were not capable of handeling their specimen, but the search for a used 75mm led me to this conclusion. Of all the people I speak that want to keep their 75mm , all of them have a perfect specimen. 

 

With the 75mm Cron I was lucky. The second sample I tried was perfect. I'll never sell it.

  • Like 1
Link to post
Share on other sites

I can say of my own experience that the last 6 Summicron asph 75mm lenses I have had in my possession, all of them were "lemmons". The only used 75mm summicron lenses there are on the market, are the ones sold by their owners, because of the bad sharpness at infinity. Maybe a lot of them thought it was their own fault and that the lens was not good for them , because they were not capable of handeling their specimen, but the search for a used 75mm led me to this conclusion. Of all the people I speak that want to keep their 75mm , all of them have a perfect specimen. 

 

Not good. Many years ago I took an interest in Alpa and lenses, especially the legendary Switar 1.9/50, which probably was on par with the comparable Leica lenses at the time. As I recall, I had 3 or 4 before I got one which was good. I have not sold it! 

Link to post
Share on other sites

Roger Cicala, from LensRentals, has written many good articles on lens variations, across brands, backed up by strict optical testing. Anyone interested should check out his work. His lens tear downs are also quite revealing in terms of build quality.

 

They stock and rent the 21 SEM, but I don't know how it stacks up against their other lenses.

 

Jeff

Link to post
Share on other sites

Another issue is: When a new lens out of the factory has had a knock of some kind; it's fallen ( in his box ) during transport. Could this influence the lens in such way, that there is a difference in sharpness in the corners between two lenses? 

  • Like 1
Link to post
Share on other sites

I bought the new Canon 1.4/35mm IS II for my SL, this lens is now supposedly the best 35mm available. I read tests of this lens and the competition such as Sigma Art, for example here:

https://www.lensrentals.com/blog/2015/11/lensrentals-reviews-the-canon-35mm-f1-4l-ii-lens/

 

This guy tests many similar lenses and often reports average scores, and for example comparing the Sigma Art and the Canon, probably Canon has a slight upper hand but this does not mean that all Canon specimens are better than the Sigma, as internal variation is greater than the difference between the two makes. However, based on what many of you report here, this is hardly what we discuss, or?

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...