Go Back   Steve's Digicams Forums > Digicam Help > Newbie Help

Reply
 
Thread Tools Search this Thread
Old Sep 16, 2008, 3:59 PM   #1
Junior Member
 
Join Date: Mar 2007
Posts: 21
Default

This is probably a dumb question, but how do you stop tall buildings looking like they're leaning away from you, if you're near the base of the building?

I get that if you're tilting your head back to take a photo, the lens is positioned in such a way that the top of the building will seem as if it's learning back from you. In addition I get that you can counteract that lean by standing further away from the base, flattening the angle between the camera and the top of the building (and zooming in from there), but is there another way of doing this?

I ask because we visited New York over the summer want wanted to take pictures of skyscrapers (what can I say we're easily impressed where we're from), but when we looked at them we were a little underwhelmed at some because of this problem.
JimBowen1 is offline   Reply With Quote
Sponsored Links
Old Sep 16, 2008, 4:50 PM   #2
Senior Member
 
rjseeney's Avatar
 
Join Date: Dec 2004
Location: Taylor Mill, Kentucky
Posts: 2,398
Default

Perspective distortion is a common problem in many lenses, especially wider angle lenses. It's handled pretty easily with editing software. I use PTLens. It will crop some of the image...the more distortion, the more cropping you will have to do.
rjseeney is offline   Reply With Quote
Old Sep 16, 2008, 5:14 PM   #3
Senior Member
 
TCav's Avatar
 
Join Date: Sep 2005
Location: Washington, DC, Metro Area, Maryland
Posts: 13,543
Default

If you do ita lot, Canon has its Tilt-Shift Lenses, and Nikon has its Perspective Control Lenses.

For ocassional use, software is a good solution, but the effect is acheived by playing with the pixels and the result can often be a softer image.
TCav is offline   Reply With Quote
Old Sep 17, 2008, 8:16 AM   #4
Senior Member
 
BillDrew's Avatar
 
Join Date: Jun 2002
Location: Hay River Township, WI
Posts: 2,512
Default

JimBowen1 wrote:
Quote:
This is probably a dumb question, but how do you stop tall buildings looking like they're leaning away from you, if you're near the base of the building? ...
Not dumb, but often asked. As noted by rjseeney & TCav noted, the issue is perspective distortion. You will find lots of info on the subject once you know what it is called.
JimBowen1 wrote:
Quote:
... I get that if you're tilting your head back to take a photo, the lens is positioned in such a way that the top of the building will seem as if it's learning back from you. ...
Exactly correct. To get rid of that kind of distortion the film/sensor should be parallel to the surface you want in undistorted form. The tilt/shift movements of view cameras allow that. The thing to keep in mind is that a tilt will also change the plane of focus so for architectural purposes you will almost always want to only use the shift.
JimBowen1 wrote:
Quote:
... In addition I get that you can counteract that lean by standing further away from the base, flattening the angle between the camera and the top of the building (and zooming in from there), but is there another way of doing this? ...
Yes - simply keep the camera's sensor vertical (no tilt) and crop away the bottom latter. If you also want to avoid perspective distortion in the horizontal direction, you must stand in a place such that the sensor is parallel in both the horizontal and vertical direction.

As sjreeney noted, software is another way to deal with the issue. Since only moderate perspective correction can be done without other odd effects becoming obvious, software is adequate unless you are going to make very large prints - in which case you should get a camera designed to deal with the issue like a large format view or field camera. Those, with a lens having enough coverage to deal with a large amount of shift, get very expensive very fast.

The focal length of the lens has nothing whatsoever to do with the problem. It does seem that wide lenses cause more problem, but that is only because the camera is closer to cover the same vertical height so requires more tilt to keep the whole building in the frame. That can easily be tested by putting your camera on a tripod tilted back. Shoot once at the wide angle of your zoom and another at the longest. Compare the distortion in a detail captured with the long end, e.g., a window. You will find that the distortion is exactly the same.

BillDrew is offline   Reply With Quote
Old Sep 17, 2008, 12:56 PM   #5
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

Here is a tutorial on perspective correction using Hugin (a GUI front end for Panorama Tools):

http://hugin.sourceforge.net/tutoria...ctive/en.shtml

See more about it here:

http://wiki.panotools.org/Hugin

Download the latest betas from here:

WindowsOSXLinux
JimC is offline   Reply With Quote
Old Sep 17, 2008, 7:41 PM   #6
Senior Member
 
BillDrew's Avatar
 
Join Date: Jun 2002
Location: Hay River Township, WI
Posts: 2,512
Default

I agree with JimC's suggestion of Hugin for perspective correction. If you want more hand-holding and don't mind paying a bit of money there are some shareware front-ends for Panorama Tools (PTGui, PTAssmber, PTMac).

Panorama Tools (with any of the front-ends) will do a great deal more than that and thus is not easy to figure out. Well worth the effort.
BillDrew is offline   Reply With Quote
Old Sep 17, 2008, 8:26 PM   #7
Senior Member
 
VTphotog's Avatar
 
Join Date: Mar 2005
Location: Extreme Northeastern Vermont, USA
Posts: 4,214
Default

Shoot, I guess I have got to get with it. I just use a big jackon the backside of the building.:lol:



brian
VTphotog is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 4:35 AM.