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Adjust for Wide Angle lens distortion

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February 11, 2005 11:33:15 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Is there a way in Photoshop to adjust for the distortion when
using a wide angle lens (e.g. 17mm)?

Thanks...
Anonymous
February 11, 2005 11:33:16 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

billh <billh@nospam.att.net> wrote:

> Is there a way in Photoshop to adjust for the distortion when
> using a wide angle lens (e.g. 17mm)?
>
> Thanks...

There's some software designed for panoramas and other image stitching,
called PanoTools. It's free, and it's being packaged by about a zillion
different people. One of the things it's designed to do is adjust for
lens distortion. There are PS plugin versions of it. Start here:
<http://panotools.sourceforge.net/&gt;.
Anonymous
February 11, 2005 6:11:46 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

On Fri, 11 Feb 2005 08:33:15 GMT, billh <billh@nospam.att.net> wrote:

>Is there a way in Photoshop to adjust for the distortion when
>using a wide angle lens (e.g. 17mm)?
>
>Thanks...
>
Use freetransform and skew, and crop.

ken
Related resources
Anonymous
February 11, 2005 7:06:39 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

"billh" <billh@nospam.att.net> wrote in message
news:420C6DAC.7BE5D2C7@nospam.att.net...
> Is there a way in Photoshop to adjust for the distortion when
> using a wide angle lens (e.g. 17mm)?

Yes, download the free PTlens plugin for Photoshop at:
http://www.epaperpress.com/ptlens/index.html
Also download the "PTlens helpers" and "Profiles" from their download
page.

Bart
February 11, 2005 8:43:39 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Bart van der Wolf wrote:

> "billh" <billh@nospam.att.net> wrote in message
> news:420C6DAC.7BE5D2C7@nospam.att.net...
> > Is there a way in Photoshop to adjust for the distortion when
> > using a wide angle lens (e.g. 17mm)?
>
> Yes, download the free PTlens plugin for Photoshop at:
> http://www.epaperpress.com/ptlens/index.html
> Also download the "PTlens helpers" and "Profiles" from their download
> page.

Thanks Paul & Bart... Looks promising!

Bill
Anonymous
February 12, 2005 1:19:42 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Ken Ellis <kenellis@nycap.rr.com> wrote in
news:0hip011g74r2e0lht8a83j8dva7mmngv0g@4ax.com:

>>Is there a way in Photoshop to adjust for the distortion when
>>using a wide angle lens (e.g. 17mm)?
>>
>>Thanks...
>>
> Use freetransform and skew, and crop.

Hmmmm ... how?


/Roland
Anonymous
February 12, 2005 1:45:58 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

"Roland Karlsson" <roland_dot_karlsson@bonetmail.com> wrote in message
news:Xns95FAED4ED1580klotjohan@130.133.1.4...
> Ken Ellis <kenellis@nycap.rr.com> wrote in
> news:0hip011g74r2e0lht8a83j8dva7mmngv0g@4ax.com:
>
>>>Is there a way in Photoshop to adjust for the distortion when
>>>using a wide angle lens (e.g. 17mm)?
>>>
>>>Thanks...
>>>
>> Use freetransform and skew, and crop.
>
> Hmmmm ... how?
>
It's all there in "Help"
I tried it after seeing this post and it's just great for getting rid of
converging verticals.
Anonymous
February 12, 2005 7:26:32 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

On 11 Feb 2005 22:19:42 GMT, Roland Karlsson
<roland_dot_karlsson@bonetmail.com> wrote:

>Ken Ellis <kenellis@nycap.rr.com> wrote in
>news:0hip011g74r2e0lht8a83j8dva7mmngv0g@4ax.com:
>
>>>Is there a way in Photoshop to adjust for the distortion when
>>>using a wide angle lens (e.g. 17mm)?
>>>
>>>Thanks...
>>>
>> Use freetransform and skew, and crop.
>
>Hmmmm ... how?
>
>
>/Roland

If you can't get it with the help, let me know and i'll try to explain
it. It's fairly easy.

rgds

Ken
Anonymous
February 12, 2005 12:54:41 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Ken Ellis wrote:
> On 11 Feb 2005 22:19:42 GMT, Roland Karlsson
> <roland_dot_karlsson@bonetmail.com> wrote:
>
>> Ken Ellis <kenellis@nycap.rr.com> wrote in
>> news:0hip011g74r2e0lht8a83j8dva7mmngv0g@4ax.com:
>>
>>>> Is there a way in Photoshop to adjust for the distortion when
>>>> using a wide angle lens (e.g. 17mm)?
>>>>
>>>> Thanks...
>>>>
>>> Use freetransform and skew, and crop.
>>
>> Hmmmm ... how?
>>
>>
>> /Roland
>
> If you can't get it with the help, let me know and i'll try to explain
> it. It's fairly easy.
>
> rgds
>
> Ken

Isn't barrel correction one of the primary requirements? Is that in
Photoshop?
(Yes, it is in Paint Shop Pro, as is a rather handy perspective correction
tool).

Cheers,
David
Anonymous
February 12, 2005 1:45:19 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

"David J Taylor" <david-taylor@invalid.com> wrote in news:376231F5865icU1
@individual.net:

> Isn't barrel correction one of the primary requirements? Is that in
> Photoshop?

No it is not IMHO. You can correct perspective in Photoshop,
but not distorsion (without a plugin).

Some here wants to tell me how it is simply done in Photoshop.
If they can, then I stand corrected :) 


/Roland
Anonymous
February 12, 2005 3:48:43 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

On 12 Feb 2005 10:45:19 GMT, Roland Karlsson
<roland_dot_karlsson@bonetmail.com> wrote:

>"David J Taylor" <david-taylor@invalid.com> wrote in news:376231F5865icU1
>@individual.net:
>
>> Isn't barrel correction one of the primary requirements? Is that in
>> Photoshop?
>
>No it is not IMHO. You can correct perspective in Photoshop,
>but not distorsion (without a plugin).
>
>Some here wants to tell me how it is simply done in Photoshop.
>If they can, then I stand corrected :) 
>
>
>/Roland

I beleive you can acheive some similar results with the "sphere"
filter in photoshop - filter>distort>sphere (or spherize) where 0 is
no effect and +/- would debarrel and barrel ...lol

rgds

Ken
Anonymous
February 12, 2005 4:02:49 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Roland Karlsson wrote:

> Ken Ellis <kenellis@nycap.rr.com> wrote in

>>Use freetransform and skew, and crop.
>
>
> Hmmmm ... how?

You've been led to the well. Pump your own water.

--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.
Anonymous
February 12, 2005 7:14:39 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Ken Ellis <kenellis@nycap.rr.com> wrote in
news:vbur01p0g1cpdt5u5kmo6l7hdktfje0rq7@4ax.com:

> I beleive you can acheive some similar results with the "sphere"
> filter in photoshop - filter>distort>sphere (or spherize) where 0 is
> no effect and +/- would debarrel and barrel ...lol

Yes - you may be able to use that filter. It is not easy and
it is not certain that you can. You only have a slider for
amount - and lens distortion is somewhat more complex than that.
OK - I missed that filter.

But - that was not really my point. At least two posters claimed
that you could fix distortion easily with skew and distort. I
asked them to show me how.


/Roland
Anonymous
February 13, 2005 1:10:43 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Alan Browne <alan.browne@freelunchVideotron.ca> wrote in news:culgc5$7fc$1
@inews.gazeta.pl:

>>>Use freetransform and skew, and crop.
>>
>>
>> Hmmmm ... how?
>
> You've been led to the well. Pump your own water.

According to my knowledge you cannot use free transorm, skew and crop
to correct distortion. You have to have some kind of non linear
transform to do that.

So - I think that I have been led to a useless well.

Please show me that I am wrong?


/Roland
Anonymous
February 13, 2005 6:51:01 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

On 12 Feb 2005 22:10:43 GMT, Roland Karlsson
<roland_dot_karlsson@bonetmail.com> wrote:

>Alan Browne <alan.browne@freelunchVideotron.ca> wrote in news:culgc5$7fc$1
>@inews.gazeta.pl:
>
>>>>Use freetransform and skew, and crop.
>>>
>>>
>>> Hmmmm ... how?
>>
>> You've been led to the well. Pump your own water.
>
>According to my knowledge you cannot use free transorm, skew and crop
>to correct distortion. You have to have some kind of non linear
>transform to do that.
>
>So - I think that I have been led to a useless well.
>
>Please show me that I am wrong?
>
>
>/Roland


Well...With the free transform..etc you can approach converging lines,
etc; also you can rotate the pic like a 3d object and correct it that
way too...and the sphere filter will definately do what a debarrelizer
does (per se)...so betwean all that i suspect that you have to tinker
with them to get what you want....because what's to say what is
distorted..and what isn't. You'll make that decision when you pinch
and pull and tug on the thing; and change it...what "distortion" are
you trying to fix?

rgds

Ken
Anonymous
February 13, 2005 2:58:31 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Ken Ellis wrote:
[]
> Well...With the free transform..etc you can approach converging lines,
> etc; also you can rotate the pic like a 3d object and correct it that
> way too...and the sphere filter will definately do what a debarrelizer
> does (per se)...so betwean all that i suspect that you have to tinker
> with them to get what you want....because what's to say what is
> distorted..and what isn't. You'll make that decision when you pinch
> and pull and tug on the thing; and change it...what "distortion" are
> you trying to fix?

It sounds a lot more complex than the equivalent Paint Shop Pro 9 steps:

- step 1, apply barrel correction, needs one number

- step 2, apply perspective correction. Draw four lines on your picture
showing what elements comprise a rectangle, and tick Apply.

Perhaps it's easier than it sounds once you have experience of the tools
in Photoshop.

Cheers,
David
Anonymous
February 13, 2005 6:41:12 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Roland Karlsson wrote:

> Alan Browne <alan.browne@freelunchVideotron.ca> wrote in news:culgc5$7fc$1
> @inews.gazeta.pl:
>
>
>>>>Use freetransform and skew, and crop.
>>>
>>>
>>>Hmmmm ... how?
>>
>>You've been led to the well. Pump your own water.
>
>
> According to my knowledge you cannot use free transorm, skew and crop
> to correct distortion. You have to have some kind of non linear
> transform to do that.
>
> So - I think that I have been led to a useless well.

Not as far as I know. I've used Image|Transform|Perspective to correct
architecture shots from a 20mm lens. (Okay, that's not 'freetransform' but it's
in the same transform menu).

To be clear, it can correct for the perspective error; it cannot correct for
known 'flatfield' error of the lens.

http://www.aliasimages.com/images/ManoirLorraineLR00090...
http://www.aliasimages.com/images/ManoirLorraineLR00090...

Best to 'squeeze' the wide part to narrow than to stretch the narrow to wide.

Cheers,
Alan

--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.
Anonymous
February 13, 2005 7:19:59 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Ken Ellis <kenellis@nycap.rr.com> wrote in
news:ekit01p1h0pk2b4fr74j8u0qvu0nchdd7v@4ax.com:

> Well...With the free transform..etc you can approach converging lines,
> etc; also you can rotate the pic like a 3d object and correct it that
> way too...and the sphere filter will definately do what a debarrelizer
> does (per se)...so betwean all that i suspect that you have to tinker
> with them to get what you want....because what's to say what is
> distorted..and what isn't. You'll make that decision when you pinch
> and pull and tug on the thing; and change it...what "distortion" are
> you trying to fix?

I know how to fix distortion. I do it with panorama tools.
And I now know that there is a sphere tool in Photoshop,
although it looks more like a toy than a real tool.

I is just that some here said to me that I could use crop, skew
and free transform to do it. And when I asked how, they said
that it is now up to me as I have been led to the water hole.
I think it is sux big time to pretend being expert and pointing
at some tools - when you are wrong. And I also think it sux
big time to not admit that you are wrong.

Note Ken - that nothing what I write here fits you. Your replies
have been helpful. Others was just nonsens.


/Roland
Anonymous
February 13, 2005 7:20:00 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Roland Karlsson wrote:

> Ken Ellis <kenellis@nycap.rr.com> wrote in
> news:ekit01p1h0pk2b4fr74j8u0qvu0nchdd7v@4ax.com:
>
>
>>Well...With the free transform..etc you can approach converging lines,
>>etc; also you can rotate the pic like a 3d object and correct it that
>>way too...and the sphere filter will definately do what a debarrelizer
>>does (per se)...so betwean all that i suspect that you have to tinker
>>with them to get what you want....because what's to say what is
>>distorted..and what isn't. You'll make that decision when you pinch
>>and pull and tug on the thing; and change it...what "distortion" are
>>you trying to fix?
>
>
> I know how to fix distortion. I do it with panorama tools.
> And I now know that there is a sphere tool in Photoshop,
> although it looks more like a toy than a real tool.
>
> I is just that some here said to me that I could use crop, skew
> and free transform to do it. And when I asked how, they said
> that it is now up to me as I have been led to the water hole.
> I think it is sux big time to pretend being expert and pointing
> at some tools - when you are wrong. And I also think it sux
> big time to not admit that you are wrong.

Tsk, tsk. See my other reply. And example. Imperfect though it is (not
knowing the lens distortion) it works.

Cheers,
Alan

--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.
Anonymous
February 13, 2005 7:22:24 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

"David J Taylor" <david-taylor@invalid.com> wrote in news:378tn7F59eu60U1
@individual.net:

> It sounds a lot more complex than the equivalent Paint Shop Pro 9 steps:
>
> - step 1, apply barrel correction, needs one number
>
> - step 2, apply perspective correction. Draw four lines on your picture
> showing what elements comprise a rectangle, and tick Apply.
>
> Perhaps it's easier than it sounds once you have experience of the tools
> in Photoshop.
>

You are perfectly right. Photoshop has no built in distortion correcter.
It neither has any easy to use perspective correction. The method you
describe for perpective correction is several times more convenient.

If you have Photoshop, and want to work with it efficiently, you have to
get some plug ins.


/Roland
Anonymous
February 13, 2005 7:22:25 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Roland Karlsson wrote:

> "David J Taylor" <david-taylor@invalid.com> wrote in news:378tn7F59eu60U1
> @individual.net:
>
>
>>It sounds a lot more complex than the equivalent Paint Shop Pro 9 steps:
>>
>>- step 1, apply barrel correction, needs one number
>>
>>- step 2, apply perspective correction. Draw four lines on your picture
>>showing what elements comprise a rectangle, and tick Apply.
>>
>>Perhaps it's easier than it sounds once you have experience of the tools
>>in Photoshop.
>>
>
>
> You are perfectly right. Photoshop has no built in distortion correcter.
> It neither has any easy to use perspective correction. The method you
> describe for perpective correction is several times more convenient.

Image -> Transform -> Perspective. (Not a plugin). Easy to use.


--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.
Anonymous
February 13, 2005 8:28:13 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

"Alan Browne" <alan.browne@freelunchVideotron.ca> wrote in message
news:cuofjl$3ma$2@inews.gazeta.pl...
> Image -> Transform -> Perspective. (Not a plugin). Easy to use.
>
..

There is no such function on my copy of Photoshop 8 CS.
Anonymous
February 14, 2005 1:05:43 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

So anyway.... There's alot of tools in potoshop. I'm no expert..but i
suspect you might be able to create an action that would give
you a vanilla correction.

Fundamentally, it's a loaded question, because imo you are paying for
that "distortion" by going wide angle - it's what it does. The best
correction might be using a longer lens - or factor, and making a pan.

I have wished for a composite of both effects...which i suppose will
entail me learning how to fix parts of the pic - like the right and
left sides of a wide angle shot where everything is streched; but
maintain the distortion in center field.

But..if i was to stick to the point - the original question - then the
mentioned "familly" of controls is the answer. You can get in there
and tweek the heck out of them..and that seeming complexity
- that contol - is what ya pay for. It's why alot of folks use the
thing to begin with.

As far as the notion of "plugs" go, they are "controls" and if
you want to build your own...i believe you can. Plugs are just
that...someone farmed the runtime or api for functionality, or added
to it via it's interface/component extensiblity..that's cool.

I don't know paint shop at all...wish i had a copy cause i've seen
some neat stuff done in it; but how much do you want to learn.
It becomes daunting...

I enjoyed the question because it made me think about what native
filter did what a debarrelize plug i have did...and now i can fool
with that.
I
f you want to draw a rectangle and hit the button (taylors post) and
you like the result. ...it's all good. Often, i think that would be
appealing. If you want more control...welcome to the complexity.

That's alot of verbage for me and it was easier to just list the
controls; and let someone else say RTHF.

Best to ya's all
Ken
Anonymous
February 14, 2005 4:01:56 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

"Rudy Benner" <bennerREMOVE@personainternet.com> wrote in message
news:110vl418ts7mo0b@corp.supernews.com...
>
> "Alan Browne" <alan.browne@freelunchVideotron.ca> wrote in message
> news:cuofjl$3ma$2@inews.gazeta.pl...
>> Image -> Transform -> Perspective. (Not a plugin). Easy to
>> use.
>>
> .
>
> There is no such function on my copy of Photoshop 8 CS.

Alan just made a small typo.
First "Select-> All, and then EDIT -> Transform -> Perspective.

Bart
Anonymous
February 14, 2005 4:01:57 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

"Bart van der Wolf" <bvdwolf@no.spam> wrote in message
news:420fea76$0$28985$e4fe514c@news.xs4all.nl...
>
> "Rudy Benner" <bennerREMOVE@personainternet.com> wrote in message
> news:110vl418ts7mo0b@corp.supernews.com...
>>
>> "Alan Browne" <alan.browne@freelunchVideotron.ca> wrote in message
>> news:cuofjl$3ma$2@inews.gazeta.pl...
>>> Image -> Transform -> Perspective. (Not a plugin). Easy to use.
>>>
>> .
>>
>> There is no such function on my copy of Photoshop 8 CS.
>
> Alan just made a small typo.
> First "Select-> All, and then EDIT -> Transform -> Perspective.
>
> Bart

Got it. Thanks.
Anonymous
February 14, 2005 2:51:23 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Ken Ellis wrote:
> So anyway.... There's alot of tools in potoshop. I'm no expert..but i
> suspect you might be able to create an action that would give
> you a vanilla correction.
>
> Fundamentally, it's a loaded question, because imo you are paying for
> that "distortion" by going wide angle - it's what it does. The best
> correction might be using a longer lens - or factor, and making a pan.
[]
> Ken

Ken, some of the confusion here is because there are typically two image
"defects" to correct:

A - lens faults, typically barrel distortion in wide-angle lenses - a
failure to photograph a brick wall without some curved lines

B - perspective "distortion" (I don't like that word), because of the
viewpoint being used (e.g. tipping the camera upwards to get all of a
building in).

It seems that whilst both Paint Shop Pro and Photoshop have native tools
for (B), only Paint Shop Pro can do (A) natively, although they both have
plug-ins which can do the job.

I hope I've read that correctly.

Cheers,
David
Anonymous
February 14, 2005 3:07:51 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Bart van der Wolf wrote:

>
> "Rudy Benner" <bennerREMOVE@personainternet.com> wrote in message

>>> Image -> Transform -> Perspective. (Not a plugin). Easy to use.
>>>
>> .
>>
>> There is no such function on my copy of Photoshop 8 CS.
>
>
> Alan just made a small typo.
> First "Select-> All, and then EDIT -> Transform -> Perspective.

I don't know about PS CS 8. In Photoshop Elements 2.0, the sequence is:
From the very top menu (File Edit Image Enhance Layer Select ...)

DO: Image -> Transform -> Perspective

I haven't had the need to get CS 8, but I do kick myself for passing up an
electronic coupon offer for $299.

Cheers,
Alan

--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.
Anonymous
February 14, 2005 3:10:21 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

David J Taylor wrote:

> B - perspective "distortion" (I don't like that word), because of the
> viewpoint being used (e.g. tipping the camera upwards to get all of a
> building in).

I agree it's a 'difficult' word for the context, but it is appropriate esp. for
shots like the one you mention. Oddly, and I make this mistake myself, the
distortion can look manageable when you take the shot and a disaster when you
make the print...

Cheers,
Alan

--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.
Anonymous
February 14, 2005 9:09:57 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Alan Browne wrote:
> David J Taylor wrote:
>
>> B - perspective "distortion" (I don't like that word), because of the
>> viewpoint being used (e.g. tipping the camera upwards to get all of a
>> building in).
>
> I agree it's a 'difficult' word for the context, but it is
> appropriate esp. for shots like the one you mention. Oddly, and I
> make this mistake myself, the distortion can look manageable when you
> take the shot and a disaster when you make the print...

I've taken some vertical panoramas and joined then together successfully
when I needed a huge vertical FOV. Of course, a really wide-angle PC lens
would have been a better solution.

What I do find is that if you correct 100% for the "perspective
distortion" so that straight lines are 100% straight, it looks as is
you've overdone it and the building is tilted towards you. It seems
better if you leave just a little skew in the image. I expect the Greeks
would have understood about making the building appear "correct"!

Cheers,
David
Anonymous
February 14, 2005 9:09:58 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

David J Taylor wrote:


> I've taken some vertical panoramas and joined then together successfully
> when I needed a huge vertical FOV. Of course, a really wide-angle PC lens
> would have been a better solution.
>
> What I do find is that if you correct 100% for the "perspective
> distortion" so that straight lines are 100% straight, it looks as is
> you've overdone it and the building is tilted towards you. It seems
> better if you leave just a little skew in the image. I expect the Greeks
> would have understood about making the building appear "correct"!

A good point and in the image I linked I get that impression. At Chichen Itza I
was shown something odd: The steps up the pyramids widen slightly to the top
such that they appear rectangular (eg: "correct") to the eye at a distace away!
http://www.aliasimages.com/images/Mexico/Chichen_Itza_0...

Cheers,
Alan


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-- e-meil: there's no such thing as a FreeLunch.
Anonymous
February 14, 2005 9:09:59 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Alan Browne wrote:

> David J Taylor wrote:
>
>
>> I've taken some vertical panoramas and joined then together
>> successfully when I needed a huge vertical FOV. Of course, a really
>> wide-angle PC lens would have been a better solution.
>>
>> What I do find is that if you correct 100% for the "perspective
>> distortion" so that straight lines are 100% straight, it looks as is
>> you've overdone it and the building is tilted towards you. It seems
>> better if you leave just a little skew in the image. I expect the
>> Greeks would have understood about making the building appear "correct"!
>
>
> A good point and in the image I linked I get that impression. At
> Chichen Itza I was shown something odd: The steps up the pyramids widen
> slightly to the top such that they appear rectangular (eg: "correct") to
> the eye at a distace away!
> http://www.aliasimages.com/images/Mexico/Chichen_Itza_0...

Ooops ... re-looking at that image, there is in fact perspective distortion on
the steps as they go up, so to hell with that! Deleted the file above.

(But I was 'told' the fact that I mentioned above).

Cheers,
Alan


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-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.
Anonymous
February 14, 2005 10:23:25 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

"Tumbleweed" <Shovels@five.paces> wrote:

> It's all there in "Help"
> I tried it after seeing this post and it's just great for getting rid of
> converging verticals.
>
>
>

Converging verticals aren't distortion. I believe the OP was asking about
barrel and/or pincushion distortion.
Anonymous
February 14, 2005 10:53:52 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

On Mon, 14 Feb 2005 18:09:57 -0000, "David J Taylor"
<david-taylor@invalid.com> wrote:

>Alan Browne wrote:
>> David J Taylor wrote:
>>
>>> B - perspective "distortion" (I don't like that word), because of the
>>> viewpoint being used (e.g. tipping the camera upwards to get all of a
>>> building in).
>>
>> I agree it's a 'difficult' word for the context, but it is
>> appropriate esp. for shots like the one you mention. Oddly, and I
>> make this mistake myself, the distortion can look manageable when you
>> take the shot and a disaster when you make the print...
>
>I've taken some vertical panoramas and joined then together successfully
>when I needed a huge vertical FOV. Of course, a really wide-angle PC lens
>would have been a better solution.
>
>What I do find is that if you correct 100% for the "perspective
>distortion" so that straight lines are 100% straight, it looks as is
>you've overdone it and the building is tilted towards you. It seems
>better if you leave just a little skew in the image. I expect the Greeks
>would have understood about making the building appear "correct"!
>
>Cheers,
>David
>

Indeed they would David <g>, and i must say initially i had perhaps
misunderstood the post's request. But it's been informative and i
think we're all on the same page; and now i'm intrigued to see what
'all "native" effects of photoS will do the job..or what i need in it
to accomplish that. The paintS thing sounds really usefull. It would
be interesting to compare/contrast - though i think the photoS
case would be better served by someone more knowledgeable than
I.

In any event..I have to come to grips with this as i have an cannon
10-22 ef-s that i love and have been podering the problem of course.
All my current corrections have used the transform tools.

Interestingly, this discussion really belongs in a photoshop group...
but as long as no-ones complaining.

Ta
Ken
Anonymous
February 14, 2005 10:53:53 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Ken Ellis wrote:

> Interestingly, this discussion really belongs in a photoshop group...
> but as long as no-ones complaining.

.... since we're in the realm of what the photographer did with what lens on what
subject, the line is a bit blurry...


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-- e-meil: there's no such thing as a FreeLunch.
Anonymous
February 14, 2005 11:01:49 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

In article <hgv111dn66rfkk2v2mf3ogi47fu2se579m@4ax.com>,
Ken Ellis <kenellis@nycap.rr.com> wrote:
>
>Interestingly, this discussion really belongs in a photoshop group...

Not really - not everybody uses photoshop as their image editor of choice.

Personally, for perspective correction, removal of barrel distortion,
etc. I use the Panorama Tools another poster has mentioned.
I use the hugin front end, which works quite well for me.

Work-in-progress examples (and links to the tools used) can be found at

<http://jfwaf.com/Panoramas/&gt;
Anonymous
February 14, 2005 11:54:32 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

johnf@panix.com (John Francis) wrote in news:cur03d$ikb$1
@reader2.panix.com:

> Work-in-progress examples (and links to the tools used) can be found at
>
> <http://jfwaf.com/Panoramas/&gt;
>

Nice. It is always hard to get seamless stitching in water.
When it is ice on the lakes here in Sweden it is much easier :) 


/Roland
Anonymous
February 15, 2005 3:04:10 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Alan Browne wrote:
> Alan Browne wrote:
>
>> David J Taylor wrote:
>>
>>
>>> I've taken some vertical panoramas and joined then together
>>> successfully when I needed a huge vertical FOV. Of course, a really
>>> wide-angle PC lens would have been a better solution.
>>>
>>> What I do find is that if you correct 100% for the "perspective
>>> distortion" so that straight lines are 100% straight, it looks as is
>>> you've overdone it and the building is tilted towards you. It seems
>>> better if you leave just a little skew in the image. I expect the
>>> Greeks would have understood about making the building appear
>>> "correct"!
>>
>>
>> A good point and in the image I linked I get that impression. At
>> Chichen Itza I was shown something odd: The steps up the pyramids
>> widen slightly to the top such that they appear rectangular (eg:
>> "correct") to the eye at a distace away!
>> http://www.aliasimages.com/images/Mexico/Chichen_Itza_0...
>
> Ooops ... re-looking at that image, there is in fact perspective
> distortion on the steps as they go up, so to hell with that! Deleted
> the file above.
> (But I was 'told' the fact that I mentioned above).

That's why I mentioned the Greeks - they applied "perspective correction"
as they were building their buildings!

Cheers,
David
Anonymous
February 15, 2005 3:04:11 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

David J Taylor wrote:

>>Ooops ... re-looking at that image, there is in fact perspective
>>distortion on the steps as they go up, so to hell with that! Deleted
>>the file above.
>>(But I was 'told' the fact that I mentioned above).
>
>
> That's why I mentioned the Greeks - they applied "perspective correction"
> as they were building their buildings!

No, I didn't get you in the prior post. Are you sure about that? I thought the
Greeks liked to stick to the Golden Mean (whatever you want to call it)?

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-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.
Anonymous
February 15, 2005 7:47:45 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Alan Browne wrote:
> David J Taylor wrote:
>
>>> Ooops ... re-looking at that image, there is in fact perspective
>>> distortion on the steps as they go up, so to hell with that! Deleted
>>> the file above.
>>> (But I was 'told' the fact that I mentioned above).
>>
>>
>> That's why I mentioned the Greeks - they applied "perspective
>> correction" as they were building their buildings!
>
> No, I didn't get you in the prior post. Are you sure about that? I
> thought the Greeks liked to stick to the Golden Mean (whatever you
> want to call it)?

I was thinking of how temple columns were tapered, but you are now at the
limit of my knowledge.

Cheers,
David
Anonymous
February 15, 2005 7:47:46 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

David J Taylor wrote:

> I was thinking of how temple columns were tapered, but you are now at the
> limit of my knowledge.

And at the limit of my interest! (eg: I won't Google on this one).

Cheers,
Alan

--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.
Anonymous
February 16, 2005 1:23:08 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Alan Browne <alan.browne@freelunchVideotron.ca> wrote in
news:cutabf$sjg$3@inews.gazeta.pl:

>> I was thinking of how temple columns were tapered, but you are now at
>> the limit of my knowledge.
>
> And at the limit of my interest! (eg: I won't Google on this one).
>
>

The greeks did two things I know of.

1. The tapered the columns. Simple even width columns does not look
as good as tapered. Modern architecture has them - but we are used
to it. So we don't mind :) 

2. Beams shall be slightly bent - highest at the middle. Perfectly straight
beams look slightly bent down. Thats an illusion. But the illusion can
can be nullified by the greek trick. The same goes here. We don't care.


/Roland
Anonymous
February 16, 2005 11:58:30 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

> Alan Browne <alan.browne@freelunchVideotron.ca> wrote in
> news:cutabf$sjg$3@inews.gazeta.pl:
>
>>> I was thinking of how temple columns were tapered, but you are now at
>>> the limit of my knowledge.
>>
>> And at the limit of my interest! (eg: I won't Google on this one).
>>
A good example of this is the Taj Mahal. (No, I know it's not Greek)
where the architect was obsessed with perfection. From the Turrets to the
inlaid decorationit was designed to cateer for perspective.
It's utterly brilliantly executed and you have to reach out and touch to
convince your brain that your eyes have been deceived.
!