Variation Facts and Fallacies

Lens sharpness is widely discussed on the internet, so it shouldn’t come as any surprise that lens softness is also a major topic. However, my experience both as a photographer and as the owner of a lens rental business has shown me that much of this discussion is based on a fallacy. So just what is it reasonable to expect from a lens and how doggedly should you pursue the ‘best copy?’

Fallacy:

  • Noun - "an error in reasoning resulting in a misconception or presumption"

A bit of background

When I started in photography most of the forums I learned from had at least one thread a day about someone’s 'soft lens.' They knew the lens was soft because their camera worked 'fine' with all their other lenses. After a few years of running a rental business, though, I found myself in the following situation three or four times a week:

'The lens you sent me front-focuses, it's not good.'
'OK, we’ll overnight you a replacement.'

Only to find, when the first lens came back, that all our tests suggested it was perfectly fine. And the customer is very happy with the replacement lens - apparently, this one is 'fine.'

So what causes this problem? It's rather simple, actually. The fallacy here is the definition of 'fine.' Most people assume that 'fine' means, 'perfectly calibrated.' It became apparent to me that cameras and lenses are not perfectly calibrated, but rather, they all have some variation. That realisation shouldn’t have been shocking; every manufactured product has variation, why should cameras and lenses be any different?

For the next several years I continued to investigate this issue, writing articles about it as I went. Reading all of them now is an overly-long exercise and I’ve learned a lot since I began writing on this subject. So it seems time to put a summary article together.

Manufacturing variation affects all lenses from all brands – the only difference is the tolerance levels considered acceptable.

Some Semantics

In most online discussions, things derail when different people understand the same terminology differently. Discussions of lens quality are particularly prone to that, so let me define the terms as I intend to use them.

A soft or bad copy is a copy of lens X that clearly does not perform as well as other copies of lens X.  There are bad lenses out there. They happen.  

A design choice affects all the copies of Lens X. Every lens has some design choices made that we may not like.

Copy/sample variation is a slight difference that can be detected between different copies of lens X, or different copies of Camera B. Copy variation is detectable, but usually not significant (compared to a bad copy which is always significant).

The Search for the Holy Lens Grail

Before we go further, there are some people that should probably stop reading here. If you ever think 'for $1,500 I demand perfection,' this is not the article for you, it will just get you upset. The laws of physics are not suspended, nor are techniques of manufacturing altered, just because you demand it be so. If you enjoy The Quest for the Perfect Lens and other fantasy games, just move along and save yourself the aggravation of being administered this particular dose of reality.

Why Variation is Inevitable

First, I should mention that the problem has received more attention in recent years, oddly enough, because our equipment has improved so much. A 6MP crop-sensor camera didn’t expose the flaws in a lens that now, a 24MP full-frame camera makes painfully obvious. Better lenses contribute too: when a lens had four really soft corners it was hard to tell if one side was worse than the other. On a newer lens with sharp corners the difference may be instantly obvious.

It’s probably not a coincidence that photographer and blogger Lloyd Chambers brought attention to the fact that camera mounts aren’t always perfectly parallel to the sensor when he was testing Zeiss ZF 21mm lenses on a 24MP Nikon D3x. There's every chance it would not have been apparent if he had been shooting a lesser lens on a lesser camera.

The key thing to realize is that the problem is not limited to one brand, one type of lens, or even just SLR gear. Landscape photographer Joseph Holmes found significant variation in medium format lenses and focusing. Testing website SLR Gear found a batch of 50mm lenses that were all softer on the right side than the left. At Lensrentals we found a group of 300mm f/4 lenses from the same serial number run almost all suffered electrical failures. Why is this so?

Manufacturing Tolerances

Manufacturing tolerances are just that: a range of acceptable values, not an exact point. In other words, what is specified as a 1/4 inch diameter screw may be anything between 0.247 inches and 0.253 inches in diameter (see this chart from an internationally-renowned industrial fastener manufacturer). The machines that make them can’t be more accurate than that at reasonable cost.

Did you know that every time a glass manufacturer makes a run of a given optical glass, the refraction index and dispersion vary a tiny bit? The glass manufacturer furnishes a melt sheet to the lens manufacturer so they can make tiny adjustments in thickness or curvature of that element to compensate for the differences.

The glass is probably a tiny source of variation compared to the other components that make up a lens or camera. In addition to the multiple glass elements, there are clips, shims, and grips that hold them in place within the lens. There are helicoids, barrels, gears, and rings move them around to focus. Electrical motors and circuit boards tell them what to do, and, as Chambers has shown us, even the lens mount that connects the lens to the camera is a source of variation. 

Cross-section of a Zeiss 21mm lens. Note all of the clips, shims, and barrels holding the elements in position.

Many, if not most, of those components are outsourced to other companies or factories. A change in subcontractor could result in a slightly different part being supplied. Something as simple as a set of ribbon cables more likely to crack or a solder that is slightly less conductive being used on a circuit board could result in significant changes to a camera or lens.

If you delve into the manufacturer’s parts lists (when you can get them) you’ll find they take these variations into account and plan for them within a given tolerance range. For example, if you need to replace the front element of your Nikon 14-24mm lens (part # 1K104-xxx) you need to replace the adjustment washer behind it with one of five specific thicknesses - each copy of the lens requires a slightly different thickness for proper spacing of the front element to focus sharply.

There are numerous other variable-sized spacers and parts for every lens (most lenses have variable thickness spacers in at least three different places). In many lenses even the lens mount comes in several thicknesses or with shims so that the image focuses properly on the sensor. As someone who has to shim lenses fairly frequently, I can assure you it can be done close to perfection, but not perfectly. When a 0.06mm shim is indicated, we often have the choice of 0.05mm or 0.07mm shims - close, but not perfect.

Similarly, the lens must be electronically calibrated. The circuit boards inside each lens with its own AF motor contain adjustment screws to calibrate the frequency and current of the electronic pulses sent to the motor used to move the lens during focusing. Manufacturers don’t build in this adjustment because every lens is exactly the same; they build it in because every lens is slightly different and adjustments are necessary. And by the way: the factory manual gives an acceptable range for the adjustment, something like 150 +/- 2 KHz.

Frequency and voltage adjustment variable resistors on the printed circuit board inside a Canon EF lens.

It’s not my purpose to list every source of variation in a given copy of a lens or camera body. They are far too numerous. But just to give an idea of some major ones:

  • A lens has eight to 23 elements, each of which may vary slightly in its spacing from the other elements, centering along the axis of the lens, and tilting from right angles to the axis of the lens.
  • The focusing and zooming elements must move certain distances front to back within the lens and during their travel their tilt or centering may vary slightly.
  • The barrels and helicoids, and various slots in them, must machined so that the elements are not only aligned properly within them, but they are aligned properly with other barrels.
  • The lens mount may not be perfectly parallel to the camera’s sensor.

For everything on the list there is a slight variation within an allowable tolerance. You can demonstrate this for yourself if you have some friends (or camera club members) and can get several copies of the same lens. Mount a camera to a tripod and focus on a target that is very visible in live view at 10X magnification. Then, just change from one lens to another and watch the target be a bit off center in different directions with each lens. Just a bit for most lenses, but you might find one that's off target by half of the screen or so. 

Camera bodies are no different than lenses with regard to variation, and in fact could be even more problematic. Is the sensor perfectly parallel to the lens mount? Is the AF sensor properly calibrated to the imaging sensor? Is the AF mirror exactly aligned and angled in relation to the AF sensor? The list goes on and on. And in every case the camera is made nearly perfect, but not exactly perfect.

Lens-Camera Matching

During, and at the end of, the assembly process, the lenses and cameras are tested to make sure they are within the manufacturer’s specifications. If they are out-of-spec and get by quality control, then someone, somewhere gets a truly bad camera or lens. It doesn’t happen frequently, but it happens. When it does, it isn't a subtle call; it's very obvious the lens is bad. In mass-produced elements, quality control is likely to be conducted on a 'sample' basis - only one in every ten or every hundred units will be checked.

But even the cameras and lenses that meet specifications are still going to vary slightly. Many people think, 'I’ll try eight lenses and take the best one.' The reality though is that the only sensible definition of 'best' is 'best with the camera body you are using,'. This is because there is plenty of room for variance in the behavior of bodies, too.

Let’s consider just the lens mount as a theoretical example. First, we say the lens mount of a camera must be parallel to the sensor with a range of +/ - 0.05 degrees (I have no idea what an acceptable range is, I only know that they cannot consistently be made perfectly parallel). Then, let’s say camera A's lens mount has a tilt of 0.04 degrees to the right. Lens #32 has a tilt of 0.04 degrees to the left. The two tilts would cancel each other out, all would be magical, and the owner would write sonnets on the various forums praising his lens.

But let's say he sells his lens to someone whose camera's lens mount has a tilt of 0.03 degrees to the left. The lens and camera now both tilt to the left and the new owner may say, 'the lens you sold me is a bad copy, it’s horribly soft on the sides.'

And this is just tilt. The mounts may also vary in thickness. There is variation, too, in autofocus systems. Certainly more than there is in lens mounts. Through-the-viewfinder manual focus will also vary (you might be surprised to know that viewfinder focusing screens are shimmed by hand). Even exposure metering varies slightly from camera to camera, and requires recalibration if it’s out of specification.

The bottom line is every lens varies slightly, in several respects. And every camera varies slightly too, in a number of different ways. A given lens on four different cameras will behave slightly differently on each of them, and four different copies of the same lens will each perform slightly differently on a given camera body. How differently? Well the short version is you probably will notice the differences if you’re a 'pixel-peeper'. If you use cameras and lenses to take pictures, though, it would be very unlikely you’d notice normal variation, even with large prints. The one exception might be high quality wide aperture lenses because the narrow depth of field may make subtle differences apparent.

So how much of a difference does this make? Click here to read page 2

The views and opinions expressed in this article are those of the author and do not necessarily reflect the views and opinions held by dpreview.com or any affiliated companies.

Comments

Total comments: 231
123
PatrickP
By PatrickP (Nov 27, 2011)

Wide angle zoom lens may be an exception.

I tested 3 different copies of Nikon 16-35mm f/4G VR on my D700, only one of them does not display severe de-centering : with the two other copies one (or more) of the corners are significantly softer than the other corners at f/4. it was shocking to say the least.

If wide angle shots are your bread and butter, the moral of the lesson is buy at least 3 copies of the wide lens you want and cherry pick one. it definitely was worth it.

1 upvote
Dominique Dierick
By Dominique Dierick (Dec 1, 2011)

Had the same with my copy of the 16-35 which I bought to complement my (very sharp) 14-24 which is prone to raindrops :) It showed decentering. Took it back to the shop, got another copy, no problem. Had the same with a 10-24 DX by the way, even worse de-centering. The second copy was fine too. Quality control nowadays... :(

0 upvotes
aris14
By aris14 (Nov 27, 2011)

How come and so many readers here ignore elementary principles of manufacturing?
The same stands everywhere...
Your 200 ps car may deliver from 192 to 208 ps and believe me the manufacturers will never tell u that...It is also rather rare your car to deliver 201 ps.... Usually delivers less!

0 upvotes
Simon97
By Simon97 (Nov 27, 2011)

One reason I like primes. Zooms are obviously more complex with the extra movements and elements that are necessary to make them work. This, coupled with plastic parts that seem to require wider tolerances, make for a better chance to get a dog. And that I have.

I love the silky smooth focus rings of the old metal lenses and the no wiggle when you shake it rigid body. I must say that after collecting numerous types of these lenses, sometimes two or three copies of the same lens, I never had one that was soft on one side or had some other quality issue.

0 upvotes
photo nuts
By photo nuts (Nov 27, 2011)

I once had a 35 f/2 prime lens that was plain awful. Sent it to the service center and they acknowledged the lens was totally out of whack. Nothing to do with AF calibration. It was a totally different lens after servicing.

0 upvotes
Larry Winters
By Larry Winters (Nov 26, 2011)

When the camera manufacturers started including a back/front focus adjustment feature in their camera's that was an admission there were indeed focus problems between many lenses and cameras..That fact is not a FALLACY!!!

This added feature has saved the camera makers from repairing literally thousands of returned lenses...They initially didn't listen or care about customer complaints about focus issues until they were swamped with returned lenses, based on what customers had learned from reliable sources...Had it not saved the camera makers money they still wouldn't care...

It's always about the money and that't not a fallacy either!!!

5 upvotes
BJN
By BJN (Nov 30, 2011)

It was an admission that with digital cameras, many users can and do pixel peep looking for any issue no matter how minor. In fact, I believe that modern lenses for digital cameras got sharper because the buyers are more critical. The technology of "fixing" the lens in-camera or non optionally in raw has reversed that trend for some camera systems (Micro Four Thirds for example).

Micro focus adjustments are a real benefit, not a sign of the apocalypse. I suspect that the feature is rarely used, and improper use probably causes manufacturers to spend more time and money dealing with pixel peepers who aren't quite clear about how to do micro adjustments.

Yes, it's all about money. If you demand a high level of precision, you should be prepared to pay much more than consumer product prices for your camera gear and its maintenance.

1 upvote
jack1a
By jack1a (Dec 5, 2011)

Here here, however the focus adjustment dosen't fix the problem so they failed again

Comment edited 21 seconds after posting
0 upvotes
Corpy2
By Corpy2 (Nov 26, 2011)

... somewhere gets a truly bad camera or lens. It doesn’t happen frequently, but it happens. When it does, it isn't a subtle call; it's very obvious the lens is bad."

Not necessarily. One can have a lens that is significantly more out of spec than a "normal" lens, but not to the point that it is "very obvious." In fact, it is much more likely that a lens would be out of spec by a significant margin, but not "very obviously," than that it would be out of spec "very obviously," for several reasons:

1) Lenses that are "very obviously" out of spec are much more likely to be spotted and removed from distribution before they are, well, distributed.

2) Lenses that are only out of spec by a significant margin are more likely to occur than lenses that are "very obviously" out of spec, from a statistical perspective.

Comment edited 25 seconds after posting
0 upvotes
mpetersson
By mpetersson (Nov 26, 2011)

Very interesting article. Like someone said below, microadjust should be standard in all DSLR:s, a lot of the complaints could be eliminated. It's one thing to turn my old analog Leica M3 in for calibration with a specific lens, but with a DSLR we should be past that, especially since the technology is included in a lot of the more expensive cameras.

That said, I have never encountered a "lemon" or sent a lens back or to be calibrated.

1 upvote
photo nuts
By photo nuts (Nov 27, 2011)

MA that does not allow for adjustment at both ends of a zoom lens is useless. Only some Olympus cameras and the upcoming 1DX have more sensible implementation.

0 upvotes
BJN
By BJN (Nov 30, 2011)

It's not useless for zooms it's just imperfect. And adding a second adjustment for the wide and the tele end of the zoom range just begs for another for the middle. Varifocus action isn't the same for every zoom design.

0 upvotes
Renard DellaFave
By Renard DellaFave (Nov 26, 2011)

http://www.ted.com/talks/lang/en/kathryn_schulz_on_being_wrong.html
I thought I understood how this lens would work...and then something else happened instead.

0 upvotes
DonM999
By DonM999 (Nov 26, 2011)

Very thorough analysis.
Of course, it doesn't take away the wonderful feeling you get when all the stars are lined up in your favor and you find a great combination of camera body and lens that works great for you.
And yes, I realize that being a fussy customer is not going to make it happen any more often.

Comment edited 10 minutes after posting
0 upvotes
Superka
By Superka (Nov 26, 2011)

I would be happy no see something like rating of manufacturer.
Once I had a deal with 2 examples if decenter softness of Tamron 17-50/2.8

http://www.flickr.com/photos/superka_01/2916517937/sizes/o/in/set-72157602227398671/

And only 3rd was symmetrical, thou not sharper then kit 18-55 lens. I don''t know whether I would buy Tamron ever.

3 upvotes
micahmedia
By micahmedia (Nov 26, 2011)

Ooch, I feel your pain. I'm dealing with this right now too. I'm also not sure how a lens this messed up passes QA. Maybe it wasn't one tested? How extra would it cost to test every lens?

Ideal situation: we can pay extra for guaranteed calibrated copies. Except the manufacturers would never do this, since it would mean admitting that a bunch of copies were "bad".

2 upvotes
Superka
By Superka (Nov 26, 2011)

Thank you for your article! It is the best! Now everyone would afraid of buying not only new lens, but new body, also!

3 upvotes
robneil
By robneil (Nov 26, 2011)

Thank you very much for this excellent article. It will save me a great deal of (unnecessary) stress in the future. In the past, I have agonised occasionally over "soft" lenses (and spent more money than necessary in fruitless attempts to cure them) but now understand the pointlessness of seeking perfection.

As sdyue says, "a good dose of reality check". Thanks again.

1 upvote
Sdaniella
By Sdaniella (Nov 26, 2011)

:)
a good dose of reality check for those unaccustomed to 'soft' images especially from the advent of much higher MP cameras.

0 upvotes
Hank3152
By Hank3152 (Nov 26, 2011)

I enjoy all of your articles and often bookmark and forward the links to those that find "flaws" in their gear...........they seem to quickly clear up any misconceptions they have about "soft" lenses ..........thanks for your time & effort.......

0 upvotes
osage_archer
By osage_archer (Nov 26, 2011)

Thanks for a good article! For me this has helped clarify and reinforce what I already suspected, but did not have the time nor the equipment nor the skill to determine for myself. I guess I'm lucky that for me, so far, all my lenses have fallen into the "acceptable" category for sharpness and performance.

0 upvotes
BPJosh
By BPJosh (Nov 26, 2011)

Agree, this is the best article to come from DPReview, I mean Roger Cicala, so far!

0 upvotes
RCicala
By RCicala (Nov 26, 2011)

Thank you so much for the kind words -- but I can't take all of the credit. Richard Butler was instrumental both in the idea of a summary article and in editing it. He put in so much work that I asked him to list himself as co-author. He wouldn't do so, but he should have.

Roger Cicala

0 upvotes
Gil Knutson
By Gil Knutson (Nov 26, 2011)

Well, then... a most heartfelt, and sincere Thank You to both of you for putting this all into perspective. Most of us who have used cameras for decades really "knew" all this, but have probably chosen to ignore it... much to our regret.

Personally, I found it most beneficial to have it pointed out that, really, the auto-focus is probably the single biggest contributor to unhappy results, all other things being equal.

As well, and as is kind of stated, a bad lens is a bad lens and is more than likely very obvious... the other variables on the other lenses may disappear into the background noise. :)

0 upvotes
satureyes
By satureyes (Nov 26, 2011)

Well.. I've owned a fair few lenses and never sent one back - I have Canon and Leica glass and I've never experienced an issue with any of them.
Perhaps I'm lucky - but if i was to go by people whining on forums about 'soft copies' then I'd be forever adjusting and not shooting.

No client of mine - or publisher of my photos has complained they are 'soft copies'

0 upvotes
Biggstr
By Biggstr (Nov 26, 2011)

An excellent article. As I learned in Six Sigma training, managing statistical variance is the essence any manufacturing process. Different lens (and camera) manufacturers will have different standards for these variances ... what is acceptable and what is not. The ones with the tightest tolerances will have fewer bad lenses on the street and (we can assume) less variance among copies. Tighter tolerances cost money; lenses with tighter tolerances will cost more than lenses with wider tolerances. Hence, it is no accident that lenses from certain manufacturers have better reputations than others and that many lens manufacturers have different lens series based on quality and cost. You get what you pay for!

2 upvotes
Earthlight
By Earthlight (Nov 26, 2011)

Thank you! It is good to have a voice of reason to stop the madness. I have always wondered how the same people always get boatloads of "unusably soft" lenses. I have only bought one lens that was DOA right out of the box in all my years of photography. My other lenses just work work work.

Earthlight

Comment edited 31 seconds after posting
2 upvotes
Earthlight
By Earthlight (Nov 26, 2011)

And yes, this is the BEST article in dpreview so far. I wish the standards were a bit higher. More stuff of this quality, thank you.

5 upvotes
tpg77
By tpg77 (Nov 26, 2011)

The best article I've read on the subject. It is clear, detailed and easy to understand. Every photographer should read it.

7 upvotes
kkcheong
By kkcheong (Nov 26, 2011)

Why no micro adjust in every dSLR? Manufacturer are bad people for not giving us the basic function.

6 upvotes
Mr Fartleberry
By Mr Fartleberry (Nov 26, 2011)

Finally a good write up on the subject. Now will someone explain to me why so many Nikon 24-70s grind or growl when zoomed.

1 upvote
Ho72
By Ho72 (Nov 26, 2011)

As someone who's been involved in manufacturing for 35+ years, I understand variation in both the manufacturing and assembly processes all too well. It's really no small achievement that mass-produced items are nearly identical, within microns, on a consistent basis. Modern machining and measurement methods, both computer controlled, are largely responsible, but credit must also be given to the engineers who design things that are "manufacturable", at least most of the time. :)

I've had one bad lens out of the dozens I've bought. It was well regarded and tested OK out of the box, but then it stopped being able to acquire critical focus in the middle of a shooting session. Apparently something within the lens shifted after it passed its initial shakedown. Sent it back and that was that (always know your dealer's return policy before the purchase).

Bad lenses are rare, but the people who examine them with anal zeal are not and this article won't cure them, sad to say.

3 upvotes
Dan Ortego
By Dan Ortego (Nov 26, 2011)

...'Bad lenses are rare, but the people who examine them with anal zeal are not and this article won't cure them, sad to say.'

So very true, especially in a hobby that attracts the most anal-OCD masters of the universe. Yes, I am including myself in this group.

3 upvotes
Sosua
By Sosua (Nov 26, 2011)

'anal zeal' - love it haha - you're right though - the quest for perfection will not be put in perspective by this article for the anal and zealous...

0 upvotes
mlackey
By mlackey (Nov 29, 2011)

"...anal zeal..." is a perfect choice of words.

Mike

0 upvotes
SteveHageman
By SteveHageman (Nov 29, 2011)

Well done, thanks....

0 upvotes
Kriekira
By Kriekira (Nov 26, 2011)

Excellent article. Thanks to the author, and to DPR.

1 upvote
C. Farrington
By C. Farrington (Nov 26, 2011)

Even the gauges used to measure parts have tolerances so even the measuring devices aren’t perfect. Physical Perfection along with beauty can never be truly attained only an approach toward it can be made.

1 upvote
Nigel Wilkins
By Nigel Wilkins (Nov 26, 2011)

Thanks for an excellent article, well written. It certainly held my attention from start to finish, which is an achievement in itself.
As for the subject, I'm constantly surprised at how people haven't realised the concept of manufacturing tolerances. Maybe I take it for granted, having started my working life in manufacturing. I'd just like to add, the same concepts apply to everything ever manufactured (the brakes on your car!), so for anyone worrying about tolerances, I'd suggest the ones used in lens manufacture move towards the bottom end of the concerns list.

2 upvotes
PixLator
By PixLator (Nov 26, 2011)

One of the best article I've read.
Thanks!

0 upvotes
MPA1
By MPA1 (Nov 26, 2011)

Very true.

I have found that the better the lens in terms of where it fits in a camera maker's range, the less likely it is to have issues.

None of my pro 2.8 Nikkors have ever been out in any way I can notice. I have one consumer lens - a 28-300 5.6 and in comparison it sucks big time.

It focuses so slowly in comparison and so much less accurately that I rarely use it and will get round to selling it.

I do not believe that there is anything wrong with it - it was just serviced by Nikon Japan so should be at factory spec. I just don't like the results.

0 upvotes
AndyGM
By AndyGM (Nov 26, 2011)

> Occasionally, an acceptable lens mounted to an acceptable
> camera combine their variations in a way that makes
> them unacceptable together.

This statement suggests 2 things:

1. A judgement has been made about acceptable variation in the combined system (camera body + lens)

2. The acceptable variation on just the lens or just the body is too lenient, as it doesn't take into account the combination of 2 worse case pieces

Roll 2 dice. A score of 2 or 12 (two 1's or two 6's) is unacceptable.

Now roll 1 die. Let us say its score would be unacceptable IF there is any chance the roll of a second die would make the combined score unacceptable. Therefore the first die CANNOT be a 1 or a 6.

At the moment, the manufacturers are having a wager that the combination of 2 worst case pieces will come up so infrequently, they can handle it in aftersales and it wont affect their reputation.

0 upvotes
Bob Meyer
By Bob Meyer (Nov 27, 2011)

Yes, but there's another factor to consider: cost. The additional cost of controlling tolerances such that two components never combine to exceed overall acceptable system tolerances is very high. The additional cost of each "9" (e.g., 99.99% vs. 99.9%) in performance is not linear.

Controlling a component to a tolerance of, for example, .025" may easily be 10 times the cost of controlling it to .05". For the relatively few cases that combine in a bad way, it's probably not cost effective to try to prevent it. Would you pay 10% more for your bodies and lenses to guarantee that never happens? In a competitive industry, when you know your competitors won't do that, you can't afford to do it either.

1 upvote
jonte0
By jonte0 (Nov 26, 2011)

And DPR forum post intensity dropped 43%

1 upvote
dopravopat
By dopravopat (Nov 27, 2011)

Looks like they moved here to this article. :-) Btw. it looks promising, I will read it tomorrow, going to bed now...

Comment edited 26 seconds after posting
0 upvotes
benincolorado
By benincolorado (Nov 26, 2011)

great article!

This is totally in-line with my personal view on the topic, because so far I never had any issues with neither my new lenses nor my used lenses that I bought.

Thanks for this article, it should be (and I'm sure it will be) spread widely in forums.

1 upvote
Tom Bird
By Tom Bird (Nov 26, 2011)

sharpness is overrated anyhow.

the more sharpness-fanatic the mediocre the photographer. cause he's nothing to give but sharpness. no decisive moments, no composition, no nothing.

and the sharpness is not his but the manufacturer's.

so, in real, he himself has nothing to give. that's why he´s so aggressive, mostly.

0 upvotes
JakeB
By JakeB (Nov 26, 2011)

Hello again, Tom. Here you are with more generalities.

Once again you confuse the compositional and technical qualities of an image.

Once again it needs to be pointed out that both elements are important. If we can only have one (a false choice), then of course the compositional should take precedence. But if that image lacks sharpness, then it distracts from the well-composed subject matter.

I think you'll find avoiding simplistic black or white statements will give you a more accurate view of most topics.

1 upvote
Tom Bird
By Tom Bird (Nov 27, 2011)

Wrong.
Most of Henri Cartier Bressons pictures wouldnt make the cut in this forum - not sharp enough.
it such simple.

0 upvotes
Neil Morgan
By Neil Morgan (Nov 26, 2011)

On top of this is that people on forums who have a bad copy of anything will make the most noise and really make thing seem far worse than reality.
For instance if 90% of people were happy with their lenses then they just use them. Another 9.99% get on a forum and show images.
Then 0.01 percent of people in the world get a bad copy, look on the forum to see if someone else has a bad copy too and then others start pixel peeping and pretty soon everyone gets paranoid about getting a bad copy or the lens now has this baggage "did u get a good copy?"
So also then there is a totally false truth because if most of those people who have a bad copy go to the forum and post and are vocal about how bad things are and the rest who have a good copy dont care, then this vocal minority suddenly becomes overwhelming.
In reality 100x1000 of lenses have been sold and there are many happy people with just a few duds.
Not too mention the forum trolls that seek to enhance a bad rep for their own gain.

2 upvotes
backfocus
By backfocus (Nov 26, 2011)

A really compelling article! What are a the take home messages?

1) You will easily discern the real bad copy: serious decentering, back-/frontfocus ....

2) Owners of an acceptable lens-body combination just have to stand the inevitable random scatter ...

My 2Cnt: He is so right! If you experience about 25% randomly unacceptable focused shots, you will greatly improve your yield by taking a second independently focused shot. The probability of both shots being bad diminishes: 0.25X0.25 :). And by the way, just stop pixel peeping, life is too short

Comment edited 1 minute after posting
0 upvotes
Eric Glam
By Eric Glam (Nov 26, 2011)

Great article.
This only goes to show that fixed lens cameras should be considered more often.

Take for example the likes of Fuji X100, Fuji X10 and Canon S100.

I'm pretty sure that Fuji matches the camera's body to the right lens before it is affixed to the body permanently - so that a certain combo produces satisfactory results. Right?

0 upvotes
Gerardjan
By Gerardjan (Nov 26, 2011)

great article mate, and certainly an article one can understand! Thanks.
And now let's go out and take some pictures.
Regards
Gerard

Comment edited 31 seconds after posting
1 upvote
MICHAEL_61
By MICHAEL_61 (Nov 26, 2011)

Very interesting. My conclusion: in order to buy a lens, get as many copies as you possibly can tested on your camera (preferably 10 at least) to choose the best one of them.

3 upvotes
Kartika Sari
By Kartika Sari (Nov 26, 2011)

I always test the lens i'm going to buy at the camera store :)

2 upvotes
Sosua
By Sosua (Nov 26, 2011)

10 copies! Haha, perhaps if I had assistants to do such things.

I think you are missing the moral of the story however - its not to scare users about all the possible variation, rather that if its bad, you will KNOW about it.

Just enjoy taking photos.

0 upvotes
Tom Bird
By Tom Bird (Nov 26, 2011)

ive never tested any lens and never felt ive got an unsharp copy. no unfunctional canon 1d m3 either. how comes?
ps: im a pro for 25 years.

0 upvotes
Jon_F
By Jon_F (Nov 26, 2011)

Me as well... never tested one... and never detected that I had a bad copy. I've never really pixel peeped either though...

0 upvotes
Pete Berry
By Pete Berry (Nov 26, 2011)

Well TomB and JonF, half of the four Canon "L" lenses I've owned in past years were clearly defective from the get-go (17-40 and 24-105), with a distinctly soft side seen (but only if you looked!) in prints larger than 8.5x11, and above 4x mag. on the LCD - pixel-peeping, if you wish. My Nikon F lenses of the 60's were much more uniform in their quality as seen in my 16x20 B&W's.

Not to care at all about taking the minimal time it takes to look for lens softness is kinda like the lazy woodcarver who never sharpens his tools, and tolerates the rough outcome as "the nature of the wood", or other such drivel.

Pro or not, you folks admittedly don't look very closely and must not print very large, deal with picky photo editors (that would be all of them), or have been jackpot lucky with all your lenses - a most unlikely situation...

0 upvotes
Tom Bird
By Tom Bird (Nov 27, 2011)

"My Nikon F lenses of the 60's were much more uniform in their quality as seen in my 16x20 B&W's."

you pixel-peeped them at 100%, then?
you would have been surprised ...

ps: my agency sells my pics every day. must be those incompetent editors and customers all over the world who never look closely and buy crap ...

Comment edited 2 minutes after posting
0 upvotes
OneGuy
By OneGuy (Nov 26, 2011)

My wife is fat, a lousy cook, and keeps a messy house. So I find your article nice and even inspirational. Now I hafta call for a replacement or get my money back -- or chalk it up to the imperfect world where the ideal can only be found through the eye of a perfect lens.
Cheers,

2 upvotes
Nigel Wilkins
By Nigel Wilkins (Nov 26, 2011)

Oh no, we're sharing wives!!

1 upvote
bigdaddave
By bigdaddave (Nov 26, 2011)

Interesting stuff

Comment edited 32 seconds after posting
0 upvotes
Humberto_Yaakov
By Humberto_Yaakov (Nov 26, 2011)

the most comprehensive article I had the pleasure to read on the subject.
thanks for it, it was very useful.

0 upvotes
HarrieD7000
By HarrieD7000 (Nov 26, 2011)

Very good story. You are telling things, I somewhere had in my mind, but could not prove. I could not even find the right words to tell. Your equipment did help you to by that. And you have written some great articles. Thanks for this in depth article. It is of great help for me. Will be in my mind every time I buy a lens.

0 upvotes
Debankur Mukherjee
By Debankur Mukherjee (Nov 26, 2011)

Nothing is perfect under the microscope !! ...... and the same applies to our photographic industry.......

0 upvotes
boho
By boho (Nov 26, 2011)

you are saying that I should lower my standards in order not to harm your business. aren’t you?

you must have guts mr.

Comment edited 21 seconds after posting
1 upvote
HowardinOregon
By HowardinOregon (Nov 26, 2011)

Lower standards, absolutely not. Read Lightroom above and you'll understand my point. To state it alternatively; human inventions have limits and tolerances, thus, if you expect perfection you'll be disapointed. Everything you purchase carries with it a warrantee of merchantability. This means it should do the thing it was designed to do, and if it doesn't get a refund or exchange. But don't expect perfection.

3 upvotes
Gerardjan
By Gerardjan (Nov 26, 2011)

Even I, who's mother tongue is not English, can answer:
"No stupid, that's not what I am saying!"

3 upvotes
Rick Knepper
By Rick Knepper (Nov 26, 2011)

So, in conclusion, don't blame Lensrental.com (or Amazon/DPR for that matter) for a lens that does not perform well on your camera.

This article states nothing new that a few years of buying lenses should have told you already but leads the newbie to a conclusion found down the path of abject obedience and maybe unintentionally provides fodder for fanbois whose manhoods are threaten by reports that their favorite lens ain't all dat.

Let's say you rent a lens from Lensrental.com (or buy a lens from Amazon/DPR) and it front focuses on your camera but not on the test cameras at Lensrental? What are you to do?

Writing an article that positions one as an expert in a field is a common and acceptable business practice. However, a conflict of interest is almost always present. Good can still come of it if one is wary of the pitfalls.

Comment edited 1 minute after posting
0 upvotes
Teila Day
By Teila Day (Nov 26, 2011)

boho I'm actually amazed at how you can infer "lower my standards in order not to harm your business..." from the article as it mentions nothing of the sort.

The article merely lends an understanding to a reality about lenses and cameras in the context of reasonable tolerances. If you expect (and recognize) what's reasonable (a lens that's in tolerance but not necessarily optimized for your particular camera), then you'll be better equipped mentally to detect the truly unexpected (an obviously bad lens). The article isn't saying do nothing after paying $2k for a "bad" lens. The article merely details why lenses are often perceived as "bad".

Regardless what business the writer's in (selling/renting lenses) the facts about lenses and cameras have not changed.

Comment edited 9 minutes after posting
0 upvotes
JakeB
By JakeB (Nov 26, 2011)

@ Rick. if you stopped stamping your foot like a spoilt child you might take on board the writer's point about manufacturing tolerances.

Of course if you receive a genuine bad copy, you should return it for a replacement. In other cases the suggestion is that you should micro-adjust the lens.

Or do you really think the writer is just making excuses? Such an attitude would suggest you haven't understood the article very well.

2 upvotes
jzzmusician
By jzzmusician (Nov 26, 2011)

Great article. One of the best I've read here.

2 upvotes
HowardinOregon
By HowardinOregon (Nov 26, 2011)

How novel: things, like mankind itself are imperfect. The Hubble space telescope mirror needed replacement even though it cost millions of dollars and was the most precisely engineered optic element in history.

Imperfect creation notwithstanding, we posses free will to endeavor to greater heights. Witness the accomplishments of Bach, Einstein, Michael Jordan and Salk-Sabin. But with that come measuring tools and improved insight to reveal flaws. Concomitant is the demand for perfection. The author, taking the human condition into account, warned us of this.

We demand greater, more innovative and clever assemblies to reach the euphoria we experienced once upon a time. I too would like a car that gets the equivalent of 100mpg, 0-60 in 3 seconds, seats 5 adults comfortably, has every electronic device imaginable, can manuever better than an F22, and almost never needs service.

There remains a lot we can learn from our forefathers, chief among them our own humanity.

1 upvote
Dan Tong
By Dan Tong (Nov 26, 2011)

Another excellent thoughtful article that should be a "must read" for everyone involved in photography.

Thanks,

Dan

3 upvotes
Peter Waldvogel
By Peter Waldvogel (Nov 26, 2011)

There are really lensese out there that DO overcome some of the old physics issues and the design and production choices that some companies make are really annoying.

Take the 17-55 2.8 by Nikon and compare it to the 24-70 2.8 - One is DX and the other FX, but for their counterpart cameras they are basically designed for the same kind of photography and the 24-70 is a much better lens!!! It can produce very sharp images from edge to edge even at 24mm, where as the 17-55 cannot.

I think it's reasonable for Nikon users, especially professionsals to criticize Nikon for this and if I ever start shooting for money again, I hope Nikon will address (what I see as) the huge design flaws in the 17-55!

0 upvotes
MaikeruN
By MaikeruN (Nov 26, 2011)

But that wasn't the point of this article.

0 upvotes
Tom Bird
By Tom Bird (Nov 26, 2011)

no. the 17-55 is for hobbyists, quality- and cost-wise. the 24-70 is for professionals. if you decide to use your 17-55 as a professional, then blame yourself.

0 upvotes
JakeB
By JakeB (Nov 26, 2011)

I'm a big fan of the Nikon 24-70mm, but on DX it is soft in the corners at 24mm at f2.8. It also suffers from obvious (though easily correctible) distortion at that fl.

It's still Nikon's best midrange zoom, of course. Just not "perfect."

0 upvotes
CameraLabTester
By CameraLabTester (Nov 26, 2011)

Tolerances.

A mighty word in terms of the arrangement of optical elements in a lens.

Plastic and metal have a great divide in providing chassis and structural stability to the contraption.

1 upvote
Malcolm L
By Malcolm L (Nov 26, 2011)

In 44 years of fairly serious photography I have gotten 1 "bad" lens out of 12 I currently own. It was pretty obvious, I sent it back. The next one was also bad. The store would only replace that one if I signed a waiver that that was the last replacement. I foolishly did and got a third bad copy - I since have given that one away (to someone who is happy with it). All the other 12 have been more than good enough for me printing at up to 17X22. And I only judge the quality in a print.
Malcolm

0 upvotes
Tom Bird
By Tom Bird (Nov 26, 2011)

most people NEVER ever print in their lifetime. so they judge onscreen, 100%. and they dont know what they-re doing. the sharp single pixel is their aim, not a wow-picture.

0 upvotes
JakeB
By JakeB (Nov 26, 2011)

You are confusing two different elements, Tom, or at least presening us with a false choice; a well-composed photograph of an "interesting" subject, and an image with good image quality.

Of course we want the former, but if image quality isn't high, that can detract from the "wow" picture. Both are important.

Viewing at 100% on a properly calibrated IPS monitor of at least 24 inches is an accurate way to assess image quality.

A properly calibrated monitor is necessary for high quality color-accurate printing.

0 upvotes
oscarvdvelde
By oscarvdvelde (Nov 26, 2011)

I have to admit that I am probably such person. I rarely print. I just have little use for printed images. However, I do pay a lot of attention to get the best compositions. Yet I greatly enjoy looking at all the details viewing the images 100% on the screen. A sharp image at the pixel level gives the a greater sense of reliving the scene and allows for further cropping, if desired. Why would I accept a quite soft 100% view that would "would not matter" when printed? Cropping seems very useful in wildlife, bird, macro, and street photography.

I'm always surprised how certain professional photographers tell others to buy the most expensive lenses, always use tripod, mirror lockup, etc, but then despise that people subsequently are enjoying their sharp pictures also at 100% on the screen. If this is how most people enjoy their photos, which is very demanding on equipment, this drives the market for better (lower tolerance) new lenses and cameras, right?

Excellent enjoyable article!

0 upvotes
Octane
By Octane (Nov 26, 2011)

All I can say is thank you for this article!

The variations in AF is something I have noticed myself. Yes every camera focuses a little different each time you let it focus on the same subject. But I can tell from experience that there is a noticeable difference in the amount of variation in cameras. Entry level cameras have a 'large' tolerance, prosumer cameras a smaller tolerance and pro level cameras have a very small amount of variation.

tighter tolerances are more expensive in terms of production which explains the higher prices for professional level cameras and lenses.

Comment edited 4 minutes after posting
0 upvotes
mick232
By mick232 (Nov 26, 2011)

That article sums it up pretty well. What I miss is a clear statement that AF adjustment is a must-have feature in today's cameras, no matter in what price category. Unless some pressure builds up from customers, manufacturers will continue to withhold that feature from lesser bodies. That's why I think awareness about that topic must be raised.

6 upvotes
Antony John
By Antony John (Nov 26, 2011)

Thank you for sharing your vast experiences with us Roger. I for one can rest easier seeing the sharpness variables put succinctly together and having to accept that there's noting perfect in this life.
As kids we shot Brownies and Instamatics and were happy with the results - a memory to be shared and cherished. Now we have moved on to sharpness, artistic content et al which in the end are probably forgotten after the initial 'wow that's nice' for those of us non-professionals anyway.

1 upvote
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