Re: [Leica] Lens test and the PLTC

[Stephen Gandy <Stephen@CameraQuest.com>]

Erwin Puts wrote:

> To 'test' lenses all stopped down to 5.6 and then shooting handheld, is not
> the most meaningful act and conclusions based on these results are bound to
> be valueless.

Valueless to who ?  Based upon what criteria ?  For What uses ?

The human tripod and the human focusing system are not the best or most precise,
they vary from human to human example.   If someone wants to test their own
lenses, to find out what their own lenses will do in the photog's personal
shooting environment, its essential part of the test includes real world picture
taking to introduce these added variables into the equation.   Some photogs are
much steadier than others,  a variable which Published Lens Tests has no way to
account for.


> It has been repeated so often, that at 5.6 all current and
> well corrected lenses perform very well and whatever differences in fine
> detail rendition and micro contrast are available, the handheld shooting, by
> vibration and focusing inaccuracy will degrade these differences. I know
> that many persons assume that a practical user test in normal shooting
> situations is to be preferred as it seems to simulate the normal use of a
> lens. In a way it does and if the user is satisfied wih such a test, any
> argument or proof that a lens from one of the 4 or 5 topmarques is better/as
> good/not as good as another one is a pleasurable but futile way of killing
> time.

Reading lens tests indeed often are a futile waste of time, especially when they
are of someone else's lenses.

I personally believe any test performed by the lens owner, even if badly done,
is of a much higher value to that photog  than any published lens test of that
lens type, simply because photog needs to know what THEIR lens will do for them,
not someone else's test results with another lens.

The lens in the photog's bag may or may not perform like the one in the
published test:   the photog's lens could be better, the same, or worse,
invalidating the value of making general conclusions from a published lens
test.   As many have noticed, published lens tests from different sources often
disagree, for precisely this reason.

Think a minute about it.  If new lenses were consistent right off the assembly
line, wouldn't all lens tests of a particular lens have the same results?   The
results often are not the same, which of course invalidates detailed conclusions
from a single test sample.

Lenses can vary from sample to sample, and the older the lenses, the more likely
the samples will vary.   Beware of any classic lens test which does not
specially state the lens was cleaned and collimated before testing.     I have
yet to see any published lens test which averages the test results of a larger
enough sample group, so that the final results can be reasonably believed to an
accurate average of lens performance.   Another problem is not testing randomly
bought  lenses, and instead borrowing lenses from the distributor or
manufacturer -- which means the tested lenses may be specially selected
samples.   Modern Photography used to make a point of only testing randomly
purchased cameras and lenses,  never samples sent from the distributor or
manufacturer.    Another problem is not using standard linear measures to
describe lens characteristics.  How on earth can the "micro contrast" or
"detail rendition" of one lens be compared to another, if there is no standard
defined unit of measurement ??    Lens test without standard measurements become
a mass of opinion -- which is fine,  but hardly scientifically accurate.

Not sure about the rest of the world, but in America in the middle 1950's,
Modern Photography and Popular Photography started publishing resolution tests.
They were popular, and best of all, they helped sell lenses for their
advertisers. Time and advertising has marched on, with so called new and better
lens tests, for more and more expensive lenses. Lens makers, being in the
business of making sales, love anything and everything that help them sell more
lenses.    So do camera dealers,  lens tests are great sales tools.

The Published Lens Test Cult is much like a religion,  in that it takes a leap
of faith to believe that the lens you will buy will give results like the
tested lens.    OK, I will agree that published lens tests are useful for
determining GENERAL qualities of a lens, but not exact qualities, which you will
have to test your own lens for.  But then, GENERALLY, its accurate to say that
modern lenses are usually better than older designs, so why bother with
Published Lens Tests?

To me,  Published Lens Tests Deification  shows the believer's attempt to
justify financial investment:  to themselves, to their pocketbook,  and to their
family.   Photogs may not be able to see the differences between their old lens
and their new lens in their own work, but at least they can have the new lens
test to justify their newest expenditure.    I suspect another reason for
Published  Lens Test Cultists interest in using  "the best lenses,"  is to
divert attention from the quality of their work.   If their own  work lacks
something, at least they can still make the claim "I shoot with the best lenses"
(a better solution is photography classes).

In my opinion, beware of any photog who holds up some one else's lens test of  a
lens they do not own,  to show how well their own lens will perform, instead of
showing their own work.    Another danger sign is framed lens tests on the wall.

No doubt these views will be roundly criticized by card carrying members of the
PLTC (Published Lens Test Cult), so be it.  At least this post offers a
dissenting opinion to the PLTC -- a viewpoint rather rare on the LUG.

To borrow from the NRA,  "Lenses do not shoot Pictures, People shoot Pictures."

Stephen  Gandy