So... how can I tell if the expensive lens I bought is a good copy?

People regularly report that there is variance in the performance of
Sigma lenses. Canon lenses ALSO vary, and I'm sure Nikon does too...
so the lens you buy might be a dud.

I've even heard that some pros will buy 6 copies of a lens, like a
500mm, test them, and then return 5, keeping the best one.

How the heck can a person evaluate a new lens purchase to find out if
it is a good copy, without having an optics lab... and objectively
(without subjective guesswork)? Can ordinary folks do this, or do you
have to be some kind of expert?

Archibald

"Archibald" wrote in message
...
People regularly report that there is variance in the performance of
Sigma lenses. Canon lenses ALSO vary, and I'm sure Nikon does too...
so the lens you buy might be a dud.

I've even heard that some pros will buy 6 copies of a lens, like a
500mm, test them, and then return 5, keeping the best one.

That's known as an Urban Legend. Realistically no one buys $50,000
worth of 6 lenses
including big two way shipping charges- even if the supplier would
take back the 5 unpacked beand new lenses.


How the heck can a person evaluate a new lens purchase to find out
if
it is a good copy,

When you take home the lens and try it out under the conditions you
normally shoot with.
Try different f stops. Also try some shots using your camera on a
tripod or stand to eliminate lens problems that appear as camera
shake.
Examine the images closely. If there are no significant visual
problems with the results like partially blurred images, out of focus
corners or edges or any unusually poor results return the lens.
I almost always buy Nikon lenses and find it extremely, extremely rare
that a lens I bought was not good.


without having an optics lab... and objectively
(without subjective guesswork)? Can ordinary folks do this, or do
you
have to be some kind of expert?

Archibald

"Frank Arthur" wrote in message
.. .

"Archibald" wrote in message
...
People regularly report that there is variance in the performance of
Sigma lenses. Canon lenses ALSO vary, and I'm sure Nikon does too...
so the lens you buy might be a dud.

I've even heard that some pros will buy 6 copies of a lens, like a
500mm, test them, and then return 5, keeping the best one.

That's known as an Urban Legend. Realistically no one buys $50,000 worth
of 6 lenses
including big two way shipping charges- even if the supplier would take
back the 5 unpacked beand new lenses.


How the heck can a person evaluate a new lens purchase to find out if
it is a good copy,

When you take home the lens and try it out under the conditions you
normally shoot with.
Try different f stops. Also try some shots using your camera on a tripod
or stand to eliminate lens problems that appear as camera shake.
Examine the images closely. If there are no significant visual problems
with the results like partially blurred images, out of focus corners or
edges or any unusually poor results return the lens.
I almost always buy Nikon lenses and find it extremely, extremely rare
that a lens I bought was not good.


without having an optics lab... and objectively
(without subjective guesswork)? Can ordinary folks do this, or do you
have to be some kind of expert?

Archibald


Hi folks.

I thought a Sigma telezoom was good until :
- the first one wouldn't stop down from full aperture and
- the second one shed a screw head from its mount into my camera body.

This was years ago but then
- a Sigma 105mm macro was noisy and slow to focus and it was too easy to
catch the focussing ring and put it into Manual Mode while the lens's
focussing switch was in Auto Mode.

I also had a Vivitar (there's a name from the past) macro lens that was
outperformed in terms of sharpness by my Canon 70-210 zoom.

I now routinely check new lenses for sharpness across the range of apertures
and focussing distances. I'm not too concerned about absolute performance,
all I want is sufficient sharpness and lack of distortion for me to enjoy
viewing my photos.

Regards, Ian.

On Mar 24, 11:40 am, Archibald wrote:
People regularly report that there is variance in the performance of
Sigma lenses. Canon lenses ALSO vary, and I'm sure Nikon does too...
so the lens you buy might be a dud.

I've even heard that some pros will buy 6 copies of a lens, like a
500mm, test them, and then return 5, keeping the best one.

How the heck can a person evaluate a new lens purchase to find out if
it is a good copy, without having an optics lab... and objectively
(without subjective guesswork)? Can ordinary folks do this, or do you
have to be some kind of expert?

Archibald

Depends on the lens. You'll pay $1000+ for an old Olympus 18mm f3.5
but wide open, it likely will look worse than a good, current digital
lens of the same effective focal length. If you have a decent normal
lens, that you know is good, you could compare it against it.
Download and print a resolution chart and take some images, wide open,
stopped down, etc.

"Joseph Meehan" wrote in message
...

"RichA" wrote in message
...
On Mar 24, 11:40 am, Archibald wrote:
People regularly report that there is variance in the performance
of
Sigma lenses. Canon lenses ALSO vary, and I'm sure Nikon does
too...
so the lens you buy might be a dud.

I've even heard that some pros will buy 6 copies of a lens, like a
500mm, test them, and then return 5, keeping the best one.

How the heck can a person evaluate a new lens purchase to find out
if
it is a good copy, without having an optics lab... and objectively
(without subjective guesswork)? Can ordinary folks do this, or do
you
have to be some kind of expert?

Archibald

Depends on the lens. You'll pay $1000+ for an old Olympus 18mm
f3.5
but wide open, it likely will look worse than a good, current
digital
lens of the same effective focal length. If you have a decent
normal
lens, that you know is good, you could compare it against it.
Download and print a resolution chart and take some images, wide
open,
stopped down, etc.

I would agree that would be some good advice if Archibald was
interested in photographing resolution charts, but if he is
interested in photographing his son on the football field moving and
if that is a stabilizing lens, he is not going to get much useful
information from a photo of a static chart a few feet away from his
lens.

Rich, try to say this every morning for the next week.
"Photography is an art where the artist uses tools. The art created
is a result of the artistic ability of the artist, not the tools he
uses." I know this is true because I bought a set of "Pablo
Picasso's brushes on the internet and I could not do as well as he
did with those brushes.

Probably because you didn't buy Pablo Picasso's paints & Pablo
Picasso's Canvas and the Pablo Picasso instruction book..


--
Joseph Meehan

Dia 's Muire duit

On Mar 24, 5:29 pm, "Joseph Meehan"
wrote:
"RichA" wrote in message

...



On Mar 24, 11:40 am, Archibald wrote:
People regularly report that there is variance in the performance of
Sigma lenses. Canon lenses ALSO vary, and I'm sure Nikon does too...
so the lens you buy might be a dud.

I've even heard that some pros will buy 6 copies of a lens, like a
500mm, test them, and then return 5, keeping the best one.

How the heck can a person evaluate a new lens purchase to find out if
it is a good copy, without having an optics lab... and objectively
(without subjective guesswork)? Can ordinary folks do this, or do you
have to be some kind of expert?

Archibald

Depends on the lens. You'll pay $1000+ for an old Olympus 18mm f3.5
but wide open, it likely will look worse than a good, current digital
lens of the same effective focal length. If you have a decent normal
lens, that you know is good, you could compare it against it.
Download and print a resolution chart and take some images, wide open,
stopped down, etc.

I would agree that would be some good advice if Archibald was interested
in photographing resolution charts, but if he is interested in photographing
his son on the football field moving and if that is a stabilizing lens, he
is not going to get much useful information from a photo of a static chart a
few feet away from his lens.

Rich, try to say this every morning for the next week. "Photography is
an art where the artist uses tools. The art created is a result of the
artistic ability of the artist, not the tools he uses."

I see idiot Rockwell has brainwashed you too.

On Mar 25, 9:41 am, "Rita Berkowitz" wrote:
Archibald wrote:
People regularly report that there is variance in the performance of
Sigma lenses. Canon lenses ALSO vary, and I'm sure Nikon does too...
so the lens you buy might be a dud.

I've even heard that some pros will buy 6 copies of a lens, like a
500mm, test them, and then return 5, keeping the best one.

Yeah, I bought one 500/4L IS USM and I really got a winner on my first try!
I ended up selling the piece of **** and got the Nikkor version for $2K
more.

How the heck can a person evaluate a new lens purchase to find out if
it is a good copy, without having an optics lab... and objectively
(without subjective guesswork)? Can ordinary folks do this, or do you
have to be some kind of expert?

Just buy Nikon lenses.

Rita

Just to put the messages back where the OP intended them to go.

On Mon, 24 Mar 2008 15:21:03 -0400, "David Ruether"
wrote:


"Archibald" wrote in message ...

People regularly report that there is variance in the performance of
Sigma lenses. Canon lenses ALSO vary, and I'm sure Nikon does too...
so the lens you buy might be a dud.

I've even heard that some pros will buy 6 copies of a lens, like a
500mm, test them, and then return 5, keeping the best one.

How the heck can a person evaluate a new lens purchase to find out if
it is a good copy, without having an optics lab... and objectively
(without subjective guesswork)? Can ordinary folks do this, or do you
have to be some kind of expert?

Archibald

Here are methods I use, at www.donferrario.com/ruether/lens-testing.htm,
and why I do not use some other commonly used methods. As for
variability of lenses in the Nikkor line, you may find this interesting:
www.donferrario.com/ruether/slemn.html. You may notice that more
extreme lenses (wide range zooms, especially ones including WA, and
wides that have "floating elements") lead in variability. Generally, long and
fast (or expensive, slower, or shorter) teles vary the least among samples.
I have seen huge variability in samples in some well known lines, but with
a few exceptions, not much in the Nikkor line of lenses. BTW, trying
to remove subjectivity from the process of lens evaluations is, I think,
not the most useful way to go (at least after you have established that
a lens is well aligned and up to *your* standards for edge/corner
performance at the stops and shooting conditions of interest to you).
There are no perfect lenses - so you choose from among a bunch
of compromises what will best work for you. I buy from a good dealer
that offers "painless" returns/exchanges, and I CHECK FOR DEFECTS
IMMEDIATELY, while I can still do something about a poor sample
beyond selling it on eBay. I'm still surprised when a pro shooter friend
doesn't bother to do this, and then asks me something like, "Do the
lower left corners of these prints shot with XYZ lens look soft to you?",
usually about a year after the expensive purchase...

Thanks, David.

You have obviously thought about the subject, and I appreciate you
sharing with us what you learned.

Archibald

["Followup-To:" header set to rec.photo.digital.slr-systems.]
Rita Berkowitz wrote:
Archibald wrote:

People regularly report that there is variance in the performance of
Sigma lenses. Canon lenses ALSO vary, and I'm sure Nikon does too...
so the lens you buy might be a dud.
[...]
Just buy Nikon lenses.

Note to OP: Rita's religion is that Nikon's **** doesn't stink,
Canon is the arch-enemy, and facts don't matter. Rita has not
yet learned to practise religion in private, or at least in
Nikon-temples.

-Wolfgang