Architecture, Weekly Assignment Topic for 12 - 19 July 2010

[keithsnell]

For something a bit different than our recent assignments, this week's assignment is "Architecture."  Your images can be of a building or structure, or an architectural feature that you find interesting. 

Please post your images to the "Architecture" album in the weekly assignment category of the gallery no-later-than midnight Mountain Time (GMT - 07:00) on Sunday, 18 July 2010.

I'll look forward to seeing your images.

Keith

[prairiedust]

This assignment pushed me into areas that don't usually interest me that much, but I did enjoy the exercise.  I lost all my excuses at sitting this one out when Marilyn did hers in 115 degree heat.  I was heading toward the classic limestone construction of Eskridge and Alma, but some lovely clouds drifting overhead spoke of huge expanses of glass and color, so off to Kansas City I went. Thanks for another great assignment.  Still, I'd rather be in Colorado attending your wildflower class.

[keithsnell]

This assignment pushed me into areas that don't usually interest me that much, but I did enjoy the exercise.  I lost all my excuses at sitting this one out when Marilyn did hers in 115 degree heat.  I was heading toward the classic limestone construction of Eskridge and Alma, but some lovely clouds drifting overhead spoke of huge expanses of glass and color, so off to Kansas City I went. Thanks for another great assignment.  Still, I'd rather be in Colorado attending your wildflower class.

I absolutely loved the etherial image of Corporate Woods.  I'm glad you didn't sit this one out.  It's a beautiful image.

Colorado has been going through a heat wave as well, so I'm a bit concerned that the wildflowers might have been scorched already.  We've definitely missed the peak at the lower elevations, which of course will lead to more adventurous off-road driving at the higher elevations.  I think next year we'll plan the workshop for at least a week earlier.  Still, it should be a wonderful time.  I'm looking forward to discovering something new about the wildflowers this year.

We head up to Crested Butte tomorrow.

Keith

P.S.
Next year for something even more adventurous (more in the vein of "wildly exploring") we should head up to the Ouray area, and Yankee Boy Basin and American Basin.  I've been hearing that the wildflowers in American Basin this year are "the best we've ever seen."

[keithsnell]

This assignment pushed me into areas that don't usually interest me that much, but I did enjoy the exercise.  I lost all my excuses at sitting this one out when Marilyn did hers in 115 degree heat.  I was heading toward the classic limestone construction of Eskridge and Alma, but some lovely clouds drifting overhead spoke of huge expanses of glass and color, so off to Kansas City I went. Thanks for another great assignment.  Still, I'd rather be in Colorado attending your wildflower class.

I just looked through your personal album from your day in Kansas City.  It looks like you had a great day photographing the sites.  I enjoyed seeing some of the great architecture through your eyes.

Keith

[prairiedust]

Keith (or anyone else with advice) - I know you're knee-deep in wildflowers at the moment (lucky) - but when you have time do you have any tips for keeping perspective or angles correct when photographing architecture.  No matter how hard I try, grid lines or none, my buildings always have weird tilts when I edit them.  Old Abilene used to have a crazy place where all the walls are tilted and you walk through and things get really weird.  Architecture photography gets like that for me.  Sometimes it's fun to have wild angles, but often as not it just looks wrong.

[keithsnell]

Hi Dave,

The weird tilts in architectural photography can be caused by a number of things, but usually the primary culprit is keystoning.  Keystoning is caused when your sensor plane is not kept parallel to the plane of the object you are photographing.  There's a decent graphic that describes this effect at this link:  http://www.cambridgeincolour.com/tutorials/tilt-shift-lenses1.htm  The only way to avoid the effect of keystoning is to keep the lens parallel to the plane of the object, or to us a perspective control lens as described in the article.  

Here's another link that talks about perspective control, with a few more illustrations, and a short tutorial on how to correct the perspective using software.  http://www.flickr.com/groups/afterclass/discuss/72157621501336010/

You can correct perspective in Photoshop by using the crop tool, checking the "perspective" box and then dragging in the corners of the cropped area so that the borders of the crop are parallel to the converging lines in the image.  An even more powerful way of correcting the perspective in Photoshop is through the Filter>Distort>Lens Correction dialog, and using the transforms for vertical and horizontal perspective.  Be careful about "over correcting."   As the article referenced above cautions, overcorrecting even slightly can often look worse than no correction at all.

In the following example, I photographed the architectural detail at Glen Eyrie from ground level, and had to tilt the camera up in order to include everything in the scene.  When I reviewed the image on the computer, the vertical tilts (keystoning) bothered me, so I went back the next day and photographed a similar scene from a nearby stairway, trying to keep the sensor/focus plane parallel to the vertical lines of the building:

First shot with lens tilted up


Reshoot with the lens/sensor plane more parallel to the vertical plane of the building.  (There's still a bit of a tilt in order to get the framing I wanted, but not nearly as severe as the first try.)

Note that the horizontal lines are still converging towards a vanishing point (in the bay window for example); however, our minds are able to translate that perspective cue much better than the tilted verticals.

In the next scene, I walked up a nearby path in order to minimize the amount that I had to tilt up the lens, however I still had to tilt the lens some in order to frame the scene the way I wanted to.  The inward lean of the portion of the building on the left bothered me, so I corrected most of the lean using the Filter>Distort>Lens Correction>Vertical Perspective transform in Photoshop.  I under-corrected the lean just a bit because when I corrected the lines to be exactly vertical it made the building look oddly out of whack.  

As shot, with disturbing "keystoning" on the portion of the castle on the left."


Corrected with Vertical Perspective Transform in Photoshop (but slightly under corrected to keep the scene looking more natural).
(I suspect this lens has a bit of barrel distortion, which makes fully correcting the vertical tilt a bit more complex.)

Does this help any?

Keith

[prairiedust]

Yes, thanks.  Those are the problems I run into, and the more interplay of surfaces, verticals and horizontals the more complicated it gets to try to correct - especially if I'm not thoughtful about it when I'm taking the photograph.  Those are great examples you posted. Bringing up the issue of keystoning helps, and the exploring to find a view that works better.  Sounds like some of the stickier issues are caused by where I am relative to the scene, not just the orientation of the camera.  Challenging isn't it?

[keithsnell]

Sounds like some of the stickier issues are caused by where I am relative to the scene, not just the orientation of the camera.  Challenging isn't it?

Yup, that's why most architectural photographers bring step ladders along or use perspective control (shift) lenses.  Sometimes I shoot with a wider angle lens in order to get the entire scene in the viewfinder without tilting up the camera, then I crop out the portions I don't need for the image.  This prevents keystoning, but reduces the resolution available for the final image (OK if your client only needs images for the web).

I guess the fact that it is very challenging is why photographers that have made a niche for themselves in architectural photography can make a decent living.