Wide angle - how much is too much?

[TheMaggedy]

I took these shots over the weekend using the 10-22 on my T1i. There is quite a bit of distortion around the edges of some of the photos and the bottom where the people are. Is that part of using wide angle or should I have done something differently?

[neilwood32]

It is part of using a wide angle and to be expected.

[SkipD]

The perspective distortion is not due to the focal length per se. It's actually due to being far too close to the buildings and far too low relative to the building's faces to be able to make an image that looks undistorted. If you keep the camera's film plane (sensor) parallel to the building faces, a lot of the "distortion" can be reduced.

If you used a view camera and appropriately changed the position of the lens relative to the film, among other things, you could reduce the perspective distortion. A tilt-shift lens can help with an EOS camera but is nowhere near as flexible as a view camera with all the adjustment it can allow for the lens position. With a fixed lens-film (sensor) orientation there's little you can do in the camera other than relocating the entire camera.

Software can be used today to modify the appearance of the perspective in a digital image.

[EtherealZee]

Use the distortion to aid the pics. People don't look too good stretched, but I actually like jamming my 10-22 right up next to buildings and other objects. Learn where the most distortion occurs, and then take advantage of the effect.

These are HDR's, and aren't really my best examples, but they are the only ones I have online





Both those were taken at 10mm, I wouldn't have put a person in either of them, but objects where the scale is not obvious, that sort of thing works well..

Z...

[bohdank]

Everything to do with realtives angles and less to do with how wide the lens is. The 10-22 actually has very little distortion.

This is at 17mm, with the 17-40 on a FF. No real perspective induced distortion.

[PhotosGuy]

Sometimes I use the WA distortion, & sometimes I don't. If you want to minimize it, the thing you have to remember is to not tilt the camera, & to keep the back vertical to avoid keystoning.
What is Keystoning

[DStanic]

As others have said it's all about the perspective. UWA lenses IMO are the most difficult to use, because it's easy to mess up a shot and there is not much you can do about it afterwards. Try to center yourself or shoot at certain angles. Make sure you look carefully through the viewfinder what you see is what you're gonna get.

[rdenney]

The easiest way to level the camera, by the way, is by putting the horizon right in the middle of the image.

Horizon lower than image center = distortion:



Horizon closer to center of image = less distortion:



The more the camera is tilted, the more the perspective will be exaggerated. What makes the wide-angle lens do this more noticeably is that it allows you stand much closer, and tilt the camera back much farther, to include the subject within the frame. To get that church with a 200mm lens, for example, you'd have been on the other side of town, and were it not for the intervening buildings, the perspective would have been no issue.

In the second image above, the lens was even wider than in the first, 12mm versus 24mm on a full-frame camera. So, it's not the short focal length that is exaggerating the perspective, it's leaning the camera back to see the top of the church. In the second image, I just backed up so I could get the church in the image, but of course it meant I got a lot of car park, too. The alternative is a lens with movements, as Skip described.

Here's a shot where I was standing too close, again as Skip describes. I corrected for the vertical perspective by holding the camera level, but the horizontal perspective is still too exaggerated, because I'm too close. The 12mm lens is what made it possible to be that close:



Rick "Rick's article on camera movements for Canons" Denney

[TheMaggedy]

Excellent advice as always from everyone. Thank you. I'll feel better prepared next time.

[PhotosGuy]

The easiest way to level the camera, by the way, is by putting the horizon right in the middle of the image.

For images like the example, that's true. For closer shots, I try to put the center focus point at my eye level after I stupidly bought one of those little levels for my Nikon.

[chauncey]

With all due respect to those that have already responded...you don't have the op's difficulties if you take multiple images with a longer lens and photomerge them.

[rdenney]

Originally Posted by chauncey

With all due respect to those that have already responded...you don't have the op's difficulties if you take multiple images with a longer lens and photomerge them.

Sure you do. The back of the camera still has to be vertical, or you have to distort the image in software (which is what Photomerge does). You could also take the images he made and correct the perspective using something like Panotools (or even the perspective envelope transformation in Photoshop), but again there would be a lot of pixel interpolation going on.

And it isn't that easy. I have found that Photomerge basically sucks at aligning images. In this image...



...I had a single, 6x12 transparency made in one exposure using an ultra-wide lens in my view camera. My Nikon film scanner only scans up to 6x9, however, so I scanned this as two 6x7 images with plenty of overlap. The two scans were absolutely identical in scanner parameters, and since they came from the same exposure, they were identical in the overlapped areas down to the pixel. But when I tried to merge them with Photomerge, I found that it missed by a very large margin in aligning the images, and I had to do it manually (not easy with a file that ended up with about 57 megapixels).

And I had to manually go in and set merge points when putting these nine images together. It was worth the trouble, but it took many hours to get it right. With these, the trees still needed to be vertical, so I carefully leveled the camera to eliminate vertical perspective convergence. But horizontal perspective was handled by the cylindrical panoramic projection, though that required LOTS of pixel interpolation.



These tools seem to have been designed for images for web display--at web resolutions the automatic merges were acceptable. But for large prints, a miss is as good as a mile, and they missed (or I didn't know how to use them, despite following instructions from experts carefully).

Rick "not to mention the problem of blending clouds that moved between exposures" Denney

[chauncey]

Denney, I'm sorry, but I don't understand why you have those difficulties. This was done in CS4 from about 10 handheld images, 1Ds MkIII with a 300 f/2.8 lens.



Was done automatically in CS4's photomerge.

On this one, 4 images with the aforementioned body and lens, I did apply manual alignment.


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