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Distortion fix formula/workflow for Tokina 12-24 AT-X Pro f/4?

 
 
k-man
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      04-29-2006

> The Tokina 12-24 is in the database, but maybe not against the dslr
> model that you are using. It is there for Nikon, but I don't see it for
> Canon. If you tell PTlens that you are using a Nikon, then it should be
> very close - although the sensor size is different. (strikes me as kind of
> odd, because I couldn't lay my hands on a Tokina with Nikon mount, but the
> Canon mount ones seem reasonably readily available). What PTLens is
> *exceptional* for is easy correction of more complex distortion patterns,
> such as the "moustache" pattern seen on many of these newer small sensor
> ultra w/a zooms, and wide/telephoto (17 or 18 to xx or xxx) zooms at the
> wide end. Another interesting use for it, is to load an image of a grid
> pattern at 3:2 ratio, then see what all the lenses you might have ever
> wanted to own are really like for distortion (assuming that the PTlens
> databse is correct - which it seems to be for the lenses that I own). You
> see it in "reverse" once "corrected" of course, but there are a few
> surprises there. Distortion on some coveted (but older design) w/a prime
> lenses is sometimes quite bad, and some of these newer zooms are very
> good.
>


Yep, the Tokina *is* in the database. Strange, I can't figure out why
I didn't see it in there last night and I chose Nikon D70s. Maybe I
had more beers than I thought.

Thanks again for your help!

Kevin

 
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k-man
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Posts: n/a
 
      04-29-2006

> >>k-man wrote:

>
> >>>Hi:

>
>
> >>>I recently bought a Tokina 12-24 AT-X Pro f/4. Nice lens, especially
> >>>given the price. It's got some noticeable distortion, though,
> >>>particularly at the wide end. Anyone with any experience with this
> >>>lens care to share a workflow or Photoshop (I'm using CS at the moment)
> >>> formula that they've used or are using to help correct the distortion?
> >>> I've done a few by hand and it's not too terribly painful. But with
> >>>working with a lot of images of course any help is most welcome.

>
>
> >>>Thanks!
> >>>Kevin

>
>
> >>http://epaperpress.com/ptlens/

>
>
> > Looks pretty slick. The Tokina's not in the database. But it looks
> > like I can submit photos for generating calibration and correction
> > values. Good tool.

>
>
> > Thanks.
> > Kevin

>
>
>
> The Tokina 12-24 is in the database, but maybe not against the dslr
> model that you are using. It is there for Nikon, but I don't see it for
> Canon. If you tell PTlens that you are using a Nikon, then it should be
> very close - although the sensor size is different. (strikes me as kind of
> odd, because I couldn't lay my hands on a Tokina with Nikon mount, but the
> Canon mount ones seem reasonably readily available). What PTLens is
> *exceptional* for is easy correction of more complex distortion patterns,
> such as the "moustache" pattern seen on many of these newer small sensor
> ultra w/a zooms, and wide/telephoto (17 or 18 to xx or xxx) zooms at the
> wide end. Another interesting use for it, is to load an image of a grid
> pattern at 3:2 ratio, then see what all the lenses you might have ever
> wanted to own are really like for distortion (assuming that the PTlens
> databse is correct - which it seems to be for the lenses that I own). You
> see it in "reverse" once "corrected" of course, but there are a few
> surprises there. Distortion on some coveted (but older design) w/a prime
> lenses is sometimes quite bad, and some of these newer zooms are very
> good.
>


Yep, the Tokina *is* in the database. Strange, I can't figure out why
I didn't see it last night, not even for my Nikon D70s. I must have
had more beers than I thought.

Thanks again for your help.

Kevin

 
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Go-dot
Guest
Posts: n/a
 
      04-29-2006
On Sat, 29 Apr 2006 08:15:45 -0500, "2" <(E-Mail Removed)> wrote:

><(E-Mail Removed)> wrote in message
>news:(E-Mail Removed) roups.com...
>
>> It is not a failing of the lens nor program, it's inherent
>> to rectilinear wide angle images.

>
>It is inherent to a cheap, compromise designed "rectilinear" lens. That is
>one crummy lens.
>

This clown, aka "2", has no idea what he is talking about. One should
just ignore his ignorant ravings. He's obviously clueless about
photography and optics.

The "distortion" being discussed is indeed normal for true projection
(i.e. straight lines in reallity remain so in the image). When using a
flat image plane (i.e. film and/or current CMOS/CCD sensors) you have
a choice of either straight lines and "distorted" heads or curved
lines and "normal" heads. (You can't change the laws of physics,
captain!) Such "distortion" is more properly referred to as wide angle
persepective.

One potential solution would be the use of a digital sensor with a
spherical, rather than flat surface (think of the retina in one's
eye).

However, the use of such a sensore would be limited to wide angle use
as it would present servre problems to normal/telephoto lenses unless
the curvature of the sensor could be made to vary as the focal length
of the lens in use. Also, the manufacturing of such a device is well
beyond current capabilities.

I use PTLens (mentioned elsewhere); the current version of the
database includes the Tokina 12-24 for the Canon 350D - both of which
I own and use. PTLens is easily corrects the slight barrel distortion
produced by the Tokina.

Nothing can "correct" the wide angle distortion you are referring to
without inducing a significant fisheye effect.

 
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Paul J Gans
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Posts: n/a
 
      04-30-2006
k-man <(E-Mail Removed)> wrote:
>> k-man wrote:
>> > Hi:

>>
>> > I recently bought a Tokina 12-24 AT-X Pro f/4. Nice lens, especially
>> > given the price. It's got some noticeable distortion, though,
>> > particularly at the wide end. Anyone with any experience with this lens
>> > care to share a workflow or Photoshop (I'm using CS at the moment)
>> > formula that they've used or are using to help correct the distortion?
>> > I've done a few by hand and it's not too terribly painful. But with
>> > working with a lot of images of course any help is most welcome.

>>
>>
>> > Thanks!
>> > Kevin

>>
>>
>>
>> http://epaperpress.com/ptlens/
>>


>Looks pretty slick. The Tokina's not in the database. But it looks
>like I can submit photos for generating calibration and correction
>values. Good tool.


The Tokina *IS* in the data base. I've got the same lens and
use the same program. The version I downloaded was updated
as of late April. You may need to download a new data file.

----- Paul J. Gans
 
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Paul J Gans
Guest
Posts: n/a
 
      04-30-2006
2 <(E-Mail Removed)> wrote:
><(E-Mail Removed)> wrote in message
>news:(E-Mail Removed) roups.com...


>> It is not a failing of the lens nor program, it's inherent
>> to rectilinear wide angle images.


>It is inherent to a cheap, compromise designed "rectilinear" lens. That is
>one crummy lens.


My my...

I rather like mine.

---- Paul J. Gans



 
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k-man
Guest
Posts: n/a
 
      04-30-2006

> The Tokina *IS* in the data base. I've got the same lens and
> use the same program. The version I downloaded was updated
> as of late April. You may need to download a new data file.
>
> ----- Paul J. Gans
>
>


Yep, I had written in my last post that I had found the lens in the
database. Thanks, though.

Do you find that PTLens does the trick for you for your Tokina?

Kevin

 
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bjw@mambo.ucolick.org
Guest
Posts: n/a
 
      04-30-2006
Go-dot wrote:
> On Sat, 29 Apr 2006 08:15:45 -0500, "2" <(E-Mail Removed)> wrote:
> ><(E-Mail Removed)> wrote in message
> >
> >> It is not a failing of the lens nor program, it's inherent
> >> to rectilinear wide angle images.

> >
> >It is inherent to a cheap, compromise designed "rectilinear" lens. That is
> >one crummy lens.


The picture on the PTLens page is a sample (from a
fisheye) to show off the program. It's certainly not from
the Tokina mentioned in the subject line.

> The "distortion" being discussed is indeed normal for true projection
> (i.e. straight lines in reallity remain so in the image). When using a
> flat image plane (i.e. film and/or current CMOS/CCD sensors) you have
> a choice of either straight lines and "distorted" heads or curved
> lines and "normal" heads. (You can't change the laws of physics,
> captain!) Such "distortion" is more properly referred to as wide angle
> persepective.
>
> One potential solution would be the use of a digital sensor with a
> spherical, rather than flat surface (think of the retina in one's
> eye).
>
> However, the use of such a sensore would be limited to wide angle use
> as it would present servre problems to normal/telephoto lenses unless
> the curvature of the sensor could be made to vary as the focal length
> of the lens in use. Also, the manufacturing of such a device is well
> beyond current capabilities.
>
> I use PTLens (mentioned elsewhere); the current version of the
> database includes the Tokina 12-24 for the Canon 350D - both of which
> I own and use. PTLens is easily corrects the slight barrel distortion
> produced by the Tokina.
>
> Nothing can "correct" the wide angle distortion you are referring to
> without inducing a significant fisheye effect.


Actually, the sensor shape doesn't really have anything to
do with it. As long as the _output_ - the print or image on
your monitor - is flat, you have a choice of fisheye or
rectilinear distortion, or things in between. But you can't
make a distortion free wide angle image on a flat surface.
It's just like the way the Mercator map projection makes
Greenland look bigger than South America, even though
it's not. In the real world, our brain's visual processing
compensates for these distortions so that we think we're
seeing a wide angle distortionless view.

Panoramas with cylindrical perspective, like those from
asembling multiple shots or from a swing lens camera,
offer a natural looking perspective but make off-center
straight horizontal lines curved. If you can avoid these lines
in your picture they look pretty natural. Also huge prints
mounted like a cyclorama (cylindrical room with 180-360
degree print on the wall) look good because they
bypass the problem of making a flat print.

 
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2
Guest
Posts: n/a
 
      04-30-2006
"Go-dot" <nospam@comcastnospamnet> wrote:

> This clown, aka "2", has no idea what he is talking about. One should
> just ignore his ignorant ravings. He's obviously clueless about
> photography and optics.


Oh, am I? I've been a photographer for almost forty years. I have spent more
time behind a lens than you have been on earth. I KNOW Biogons. I USE
Biogons. I also use the rest of the line. So far, digital folks are pretty
much ****ed when it comes to Biogon lenses, but that will eventually be
fixed when your sensors grow up.


 
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2
Guest
Posts: n/a
 
      04-30-2006
"Paul J Gans" <(E-Mail Removed)> wrote in message
news:e32st9$k7i$(E-Mail Removed)...
>2 <(E-Mail Removed)> wrote:


>>It is inherent to a cheap, compromise designed "rectilinear" lens. That is
>>one crummy lens.

>
> My my...
>
> I rather like mine.


I get it: If at first you do not succeed, just lower your standards.


 
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Go-dot
Guest
Posts: n/a
 
      05-01-2006
On Sun, 30 Apr 2006 18:54:16 -0500, "2" <(E-Mail Removed)> wrote:

>"Go-dot" <nospam@comcastnospamnet> wrote:
>
>> This clown, aka "2", has no idea what he is talking about. One should
>> just ignore his ignorant ravings. He's obviously clueless about
>> photography and optics.

>
>Oh, am I? I've been a photographer for almost forty years. I have spent more
>time behind a lens than you have been on earth. I KNOW Biogons. I USE
>Biogons. I also use the rest of the line. So far, digital folks are pretty
>much ****ed when it comes to Biogon lenses, but that will eventually be
>fixed when your sensors grow up.


This clown just prooves my point; in fact he's pretty clueless in
gerneral. By his claim, he's spent twenty years behind the lens before
he becam a photographer. (Yes, I have personally comercially
processed E-3 and C-22 films, Super-X films and other things long,
long gone from this earth).

A wise man once told me never to wrestle with a pig. You both get
dirty, and the pig enjoys it. This pitiful troll now enters my kill
file. PLONK.

 
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