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04-30-2013, 11:53 AM   #1
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Laboratory tests versus Real-life usage: Are Pentax lenses being misrepresented?

This matter has been touched on by others before, but I believe it may be beneficial to re-examine it by a different approach. I put together some of the salient info/evidence that we have concerning three well-known Pentax lenses, presenting them as actual case studies, as it were. The idea is to allow the reader to easily correlate the data, do some analysis and come to some conclusions.

I do this mainly for the following four categories of people:

a) There may be some users of Pentax lenses who after reading online reviews of their lenses come away feeling perplexed and underwhelmed, now doubting their lenses and wondering if perhaps they made a wrong purchasing decision
b) There may be some who feel a certain sense of injustice at how Pentax lenses are being misrepresented in a negative way by some online lens reviews
c) There may be prospective buyers of Pentax lenses who have received good recommendations from trusted friends using Pentax glass, having also been well impressed after seeing pictures taken using those lenses, but after reading online reviews now feel not so sure
d) There could be people planning to change systems entirely (wishing to enter Pentax), or others just starting off and wanting to build up a Pentax system, who are impressed with the Pentax bodies; but having read online lens reviews of Pentax glass come away with a general impression that these are somewhat sub-par in their performance. In categories (c) and (d), it would be a shame if they subsequently turned away from a lens(es) which potentially could have given them many years of enjoyment
e) You may be able to think of other categories

In each of the case studies below you will detect a clear disconnect - something just doesn't add up when comparing the verdict given via technical testing versus what is being experienced in real-world usage.


Case 1: FA77 f1.8 Limited

This famous Pentax lens received an unremarkable 3.5/5 stars from Photozone (PZ) in terms of optical performance. PZ went on to conclude that "Optically it doesn't offer much beyond the mainstream in this class but don't misunderstand this as something negative because moderate fix-focal length tele lenses tend to be great performers." PZ also questioned the high asking price.

In short, PZ does not view this lens as particularly remarkable.

And yet, users of the FA77 worldwide know for a simple fact that this is a one-of-a-kind lens - a lens capable of producing pictures of exquisite beauty, rendering subjects with remarkable vividness and lending a magical, classy "polish" to the overall image difficult to obtain otherwise. Indeed as a portrait lens it is widely regarded by many Pentaxians as having practically no equal, period.

What is remarkable - and scary - is that the PZ review seems to not have detected any of the above traits, so highly prized by those who know the lens well. No wonder then that PZ questions the asking price - but we know that in life, a tool this remarkable will naturally cost more. Certainly the sample photos included in the PZ review do not exhibit the traits just described.

And while PZ cannot see anything particlularly outstanding about this lens, on the other hand we have Michael Johnston from Luminous Landscape in 2002 calling this lens "the best autofocus lens in the world".

Hence we see a clear disconnect somewhere.


Case 2: DA35 Macro f2.8 Limited

PZ declares that this lens "does not excel".

Yet Michael Johnston in reviewing this lens in 2008 concludes that "It ranks right up there with the best lenses I’ve ever used in any format."
An Optical Paragon - photo.net

Some might conclude that Johnston is really nothing more than a Pentax-fan, and this biases his judgment. Granted. But it would be equally valid to propose that here is a man with deep and varied photographic experience, with access to various lenses from diverse manufacturers - including the best and costliest - and moving on from 2002 to 2008 has found another lens worth writing home about; and it just happens to be another Pentax. Thus it is not necessarily correct to conclude that he is merely "pro-Pentax."

Further, if you click on the link you will note that the review was actually co-written with Carl Weese, another experienced photographer. In fact, both of them are actually "trading notes", sharing what they have independently discovered after having used the DA35 Limited for some period of time. Like Michael, Carl is equally blown away. So this is clearly no "pro-Pentax" party here. What we're seeing is real-world photographers, putting a lens to real-world usage, and learning (over time) its capabilities and character, with both coming away thoroughly impressed.

As a matter of fact, Weese's methodology for "testing" a lens is particularly enlightening - he states: "My “tests” really consist of heading out the door to use a new piece of equipment for the kinds of pictures I like to make, and then see how it does. If I run into something that looks like a problem—say obvious barrel distortion or color fringing—I’ll run a specific test to nail down that issue. For the most part I don’t do tests that aren’t really just attempts to make pictures."

This says a lot! Test charts are all fine and good, but there is a very real need to thoroughly evaluate a lens under real world picture-taking situations. Indeed, the only instance where we could legitimately say that technical tests alone are adequate is when we have bought a lens solely for taking pictures of test charts - which nobody does of course!

So again, a disconnect is apparent between lab tests and real-world findings.

Case 3: FA43 f1.9 Limited

This lens has been tested twice by PZ, and the amount of controversy generated has been considerable. Bottomline, PZ is "still not impressed by this lens".

It is not my intention to get into all that here, but note that Lenstip, another online lens test site, is even more thorough than PZ, going into things like astigmatism, light transmission and coma (the latter yielding a very bad result).

Yet neither PZ nor Lenstip seem to be aware (certainly they do not mention it) that the designer of this lens, Jun Hirakawa, had very clear design intentions when creating this lens, and one of the things he did for example was to deliberately leave certain optical parameters only partially corrected in particular axes.

One cannot help but wonder if such design decisions are at least partially responsible for the lens' "poor showing" in test-charts, yet creating absolutely stunning images in real-life usage!

Again, the test pictures in PZ and Lenstip do little to showcase what this lens is truly capable of. Users familiar with this lens know it to have stunning colour rendition, an almost startling "3-D" rendering of subjects, and micro-contrast of the highest order - among many other virtues relevant to picture-taking. Yet these aspects are hardly if at all mentioned in most technical reviews, let alone measured quantitatively!

Interestingly enough, Steve Huff evaluates this lens - and he does so by way of actual real-world usage - and comes away impressed.
The Pentax K5 Digital Camera Review | STEVE HUFF PHOTOS

All of this is not to say that the FA43 Limited is in anyway a "soft" lens - by f2.8 it is certainly very sharp, rising to nearly insane levels at f4.0. I do not need to measure my copy of this lens to verify it - I see it plainly evident in my pictures taken!

But that's the whole point isn't it? A lens is so much more than just sharpness alone! As Carl Weese put it in his review of the DA35 Limited: "Once we pass a certain threshold of “sharp enough,” though, sheer resolution isn’t anywhere near as interesting as other aspects of lens performance."

I believe that the more we stop obssessing about sharpness per se, and look instead into other aspects of a lens' character and rendering, the richer and deeper will be our appreciation of the pictures taken.

Indeed looking at some of the older B&W pictures taken back in the days of manual-focus lenses, it becomes apparent that some of the shots weren't even perfectly in focus - so much for sharpness! And yet many of these pictures have tons of character, and really "speak"!

------------------------

And so we conclude. If as a reader you find yourself in any of the categories of people mentioned at the beginning, know for sure that technical testing of a lens has its rightful time and place, but user experience is every bit as weighty, and often more relevant, since the latter is born out of real-world photo-taking situations.

We could easily go on forming more case studies, but I judge three as being quite adequate. And the fact that all three examples given are Limited lenses - Pentax's premium glass - makes it all the more alarming, for it would appear that several reputable lens review sites seem quite unable in their testing to capture the heart and soul - the very magical essence - that makes these lenses so very highly regarded and prized worldwide!

To put it quite simply, technical lens tests have their usefulness, but they certainly cannot give us the full picture - pun intended!

04-30-2013, 11:58 AM   #2
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Hmm, I think you're trying to say that photozone's tests aren't worth much. I'd agree with that

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04-30-2013, 01:10 PM   #3
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I think that Photozone is worth more than DXO Mark's assessment of lenses, where each lens is assigned a number, which can then be flogged by the happy or disappointed fans. At least Klaus on Photozone puts down his reasons for liking (or disliking) a lens. The FA 43 is a pretty expensive normal lens, that isn't quite as fast as the typical normal lenses (ranging usually between f1.4 and f1.8). If it is a focal length that works for you, then it is very sharp and has interesting out of focus rendering. In point of fact, Photozone has liked the DA limiteds better than the FA limiteds. I can understand why. While I own both the FA 31 and FA 77, they are pretty highly priced for what they are. Yes, you get some pixie dust with them that maybe Nikon lenses are lacking, but a Nikon 85 f1.8 will run you 200 plus less than the FA 77 f1.8.
04-30-2013, 01:35 PM   #4
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It seems to me that a lot of lab tests concentrate mainly on sharpness and technical issues. Lines of resolution, percentage of vignetting, degrees of barrel distortion curvature, those sort of things. These are numbers, things you can measure, quantify, and chart.

Pentax's strengths seems to come from things like color rendering which do not lend themselves to numeric measurement. If you can't slap a number on it, you can't compare it with other lenses on a chart and they're not going to put it in the review at places like that. Not to mention that ultimate sharpness isn't necessarily desirable in portrait lenses, but they use the same test procedures because it's all they know how to do.

04-30-2013, 01:48 PM   #5
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Nice review. I think its spot on, because it agrees with me

This is why I read the reviews here by people that actually use the lens on a camera pointed at something other than a mannequin or a B&W chart with hypnotism symbols on it. I don't always agree with folks here but I know that most actually take the darn lens out and use it and then write about it. Not to pick on anyone but some of the official reviews here have left me a bit confused, like the ones mentioned from PZ. When a new product is released and Adam and the crew get it before anyone else I read their take on it to learn, but I have always waited until actual members have reported on it in the field before committing to buying one myself.
04-30-2013, 01:54 PM   #6
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I find PZ's tests conform to my experience fairly well. Perhaps fairy dust is in the mind of the beholder.

I have seen images on this site from these Pentax lenses that supposedly do something special in rendering. I do not see it.
04-30-2013, 01:55 PM   #7
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Lots of reviews are based on a single sample, which may or may not be typical. You need a number of samples to get the whole picture - just look at LensRentals tests
04-30-2013, 02:02 PM   #8
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For an informed decision,
I've found it best to factor in
a mix of (subjective) user reviews
and (objective, but sometimes flawed) technical tests.

For example, I bought the DA 35 Ltd,
rather than the FA 31 or 35 that Photozone rated higher,
and have not regretted that decision after three years of intense use.

04-30-2013, 02:02 PM   #9
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QuoteOriginally posted by civiletti Quote
I find PZ's tests conform to my experience fairly well. Perhaps fairy dust is in the mind of the beholder.

I have seen images on this site from these Pentax lenses that supposedly do something special in rendering. I do not see it.

I'll give you and example from PZ - the 40 Limited. All the actual empirical tests of the lens were excellent or above average. The only area they were not pleased with was Bokeh and there is NO technical test - its all personal taste and preference. Technically the lens is a solid performer. They also commented on the excellent workmanship by "elves" that put the diminutie lens together. Then they wrote this conclusion (Fair Use under Copyright):

"The Pentax SMC DA 40mm f/2.8 exhibits a quite harmonious optical performance combined with excellent build quality. It is capable to produce impressively sharp images across the frame straight from the max. aperture. Distortions are marginal and CAs are a non-issue. Vignetting is visible at f/2.8 but not a show-stopper. The bokeh (out-of-focus blur) is slightly sub-average and bokeh fringing can be an issue at very large apertures. The lens does also suffer from a focus shift when stopping down - this can have an impact in close focus scenarios.

The biggest "problem" of the lens is not quality but its application. It is a comparatively slow lens and not faster than many zooms. Classic "normal" lenses are about as good at comparable apertures but with a lot more potential for low light and shallow depth-of-field photography ... at a lower price. Some users may argue with its size and weight but even with the DA 40mm f/2.8 a DSLR is not a pocketable camera. That all said it remains an very good performer and as such it is a welcome addition to the Pentax lens lineup"

Precisely how is its size a negative? Because dSLRs are not pocketable? Again, impressively sharp from max aperture, no distortions to speak of, CAs a "non-issue", incredibly well built, minimal vignetting - and they they want to argue that there's no need for the lens because you can get an f2.8 zoom that covers the 40mm range? They present themselves as all about the empirical data and "tests" but at the end of the day they offer incredibly subjective assessments in their conclusions that often are at odds with their own numbers in the actual tests they say they venerate.
04-30-2013, 02:07 PM - 1 Like   #10
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QuoteOriginally posted by KDAFA Quote
And while PZ cannot see anything particlularly outstanding about this lens, on the other hand we have Michael Johnston from Luminous Landscape in 2002 calling this lens "the best autofocus lens in the world".
Yep, in 2002 - I bet in the 11 years since that statement his sentiments have changed. I use photozone and lenstip, when looking at both, the numbers match up nearly identical on the MTF charts percentage wise for matching lenses. For me, 90% of my lens choices or buying decisions are influenced or weighed strongly on lens resolving power [MTF's], this is the starting point that indicates the quality of the optics.
04-30-2013, 02:10 PM   #11
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The whole thing is reminiscent of the audio product review philosophical divide. The Absolute Sound tends toward the subjective, we hear discussions of the "blackness" of the absence of signal and of other qualities of the sound akin to wine reviews. Back in the day Audio was far more technically oriented, with measurements galore. Stereophile sort of straddles the fence, with lots of measurements, graphs, charts, etc, but also a good discussion of the quality of the output, or the sound. Stereophile does have some resident "golden ears" who maintain that anyone who can't hear the difference in cables is hardly worthy of consideration, and that double-blind tests are inadequate for reviewing audio gear.

It would be interesting to see a double-blind test in photo gear, shots made on the same camera but with different but comparable lenses. How many of us could correctly identify the taking optic? For example, if one could adapt a Nikon or Canon 50mm f1.2 to a K5 and compare its output to the Pentax 50mm f1.2 how many of us could identify the lens better than 50% of the time? No peeking at the EXIF data!
04-30-2013, 02:17 PM   #12
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QuoteOriginally posted by Docrwm Quote
I'll give you and example from PZ - the 40 Limited. . . . Some users may argue with its size and weight but even with the DA 40mm f/2.8 a DSLR is not a pocketable camera.
I read this as "Some users may argue [in favor of the DA 40 Ltd based on] . . . its size and weight"
--- as compared with a nifty fifty or (Robert's example) a good zoom.

QuoteOriginally posted by Docrwm Quote
Precisely how is its size a negative?
So I don't think the Limited's size is being considered a negative here.

(Although I believe that some users do regard
at least the DA 40 XS as too small,
if not the DA 40 Ltd.)
04-30-2013, 02:20 PM   #13
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QuoteOriginally posted by grhazelton Quote
It would be interesting to see a double-blind test in photo gear, shots made on the same camera but with different but comparable lenses. How many of us could correctly identify the taking optic? For example, if one could adapt a Nikon or Canon 50mm f1.2 to a K5 and compare its output to the Pentax 50mm f1.2 how many of us could identify the lens better than 50% of the time? No peeking at the EXIF data!
We often have that kind of test offered by users on this forum.
Although it's hard if you only see the web image,
and don't open up a full size version.
04-30-2013, 02:34 PM   #14
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QuoteOriginally posted by lytrytyr Quote
I read this as "Some users may argue [in favor of the DA 40 Ltd based on] . . . its size and weight"
--- as compared with a nifty fifty or (Robert's example) a good zoom.



So I don't think the Limited's size is being considered a negative here.

(Although I believe that some users do regard
at least the DA 40 XS as too small,
if not the DA 40 Ltd.)
I see your point but would argue that in context "a dSLR is not pocketbook" the implication is clearly - so why have a lens this small and therefore its size is not a plus in its favor.
04-30-2013, 02:38 PM   #15
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QuoteOriginally posted by grhazelton Quote
....It would be interesting to see a double-blind test in photo gear, shots made on the same camera but with different but comparable lenses. How many of us could correctly identify the taking optic? For example, if one could adapt a Nikon or Canon 50mm f1.2 to a K5 and compare its output to the Pentax 50mm f1.2 how many of us could identify the lens better than 50% of the time? No peeking at the EXIF data!
I agree. I find the cooking shows on TV a snooze mostly because the judges know who cooked the food, and their comments often indicate they are judging the two entrants based on their perception of the cook and not solely based on the food they ate. I see the same thing all the time in reviews of camera gear. Ok, for usage reviews you really have to know what you have in your hands. But for reviews of output there is no reason that the Canon - Nikon - Pentax equivalents can't shoot the same images, be put side-by-side and judged without labels telling which is which.
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