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Old Jul 23, 2009, 10:10 PM   #1
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Default Perspective and DA 12-24

Recently someone noted how this lens had quite a bit of "falling lines" or perspective distortion. You can see that under certain conditions with just about any lens, but it's significantly more with something that's really wide angle. To give you an example that distance matters and show some rather extreme examples:

#1. A wide angle makes things look smaller and further away than they actually are. This is not a reflecting pool, it's a small fountain in the foreground, and the building looks much smaller (so further away) than it should be in relationship to the fountain.

Here's some not so extreme falling lines - I'm standing a little away from the steps and looking up at the front of the library. It's what I think of when I look up at a building. Yes, there's perspective, but to my mind, it's expected and so looks fairly "normal".

Here I'm closer to the building - the perspective distortion looks very extreme and the building almost looks like it's lying back. All I want to do when I look at this picture is rotate it back to where it doesn't look so strange. You can actually use this effect artistically in other situations, but here its disturbing.

Rather than leave you with such a strange picture as my last one, I'll throw this one in. It's also taken at 12mm, but I'm only a foot or two away from the tiles. There's a certain amount of barreling, but I've seen lots worse, especially from such a wide angle lens (my DA 55-300 has some, I noticed it when shooting brick walls). This barreling can be easily corrected in Photoshop's lens correction feature.

All pictures taken just after the sun came up with the DA 12-24 and K-7.

Last edited by mtngal; Jul 23, 2009 at 10:13 PM.
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Old Jul 23, 2009, 10:21 PM   #2
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That is a great series of photos that does a great job of explaining the characteristics of the Pentax 12-24 lens. Congratulations! Well done!

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Old Jul 23, 2009, 10:56 PM   #3
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Very interesting and I love that first shot, I don't mind the 'falling' it makes that building look HUGE.


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Old Jul 23, 2009, 11:56 PM   #4
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Since perspective is essentially an expression of things getting smaller as they get farther away, it is a familiar naturally observed phenomenon and is expected, so we do not find it disturbing. The first image, which is excellent, illustrates this very well. It has nothing to do with the design of the lens, except that its effect is increased as the angle of view of lenses get wider. The same object in two pictures taken by lenses with different angles of view would be smaller and look farther away in the picture taken with the wider lens.

Distortions (like barrel and pincushion) on the other hand are disruptions of the expected image resulting from the failure of a lens to to produce a rectilinear image, and are not expected or familiar from being experienced with the naked eye, so are disturbing to us. What I find interesting is the way the building seems to get shorter as you get closer to it in the second of the next two images - the base gets wider and the top narrower, even though the top is actually closer to you - an excellent example of foreshortening. Think of it as a right triangle - the building is at 90 degrees from the ground, and the third side (the hypotenuse) gets shorter as you near the building (as does the leg along the ground). Even though the height of the building has not changed, it looks shorter. This could be perceived as a distortion, even though, as a natural phenomenon and not a fault in the lens, it is not.

(take your choice)
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Old Jul 24, 2009, 7:51 AM   #5
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Ultimately what matters is not what the lens does or does not do as suggested by Sarah Joyce, it matters hoe you as the photographer/artist perceives the image in your mind. After all us photographers are in more wars than one artists without brushes. FOr me I do like the perspectives in this series: - a sense of grandeur and what one would expect from older buildings of learning.

You can certainly correct some of the distortion...but then that would take awey from your artistic license and lean towards the more accurate. If thats what you like then more power to you. As for me I do enjoy the unique perspectives...they speak to me....eg: Jelpees pictures with the FE lens.

All that being said...lovely pictures Harriet!

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Old Jul 24, 2009, 9:59 AM   #6
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Great series Harriet,
I don't know if its the K7 or if you have a better copy than my 12-24 but, you seem to get a little sharper image than I do.

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Old Jul 24, 2009, 4:55 PM   #7
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Hi Harriet,

Some very nice illustrative "golden hour" shots. The lighting really works well with the older building, IMO.

OT, but on the subject of ultra wide angle shooting, I ran across this article by Ken Rockwell -- I know, I know, KR isn't my favorite photography blogger, and generally consider most of his opinions as inconsequential, but as one who really concentrates on extreme teles, I thought this perspective was very interesting.


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Old Jul 24, 2009, 8:26 PM   #8
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His article is very good. When I got my first SLR camera back in 1980, I read that one should have a normal, telephoto and wide angle lens. My camera came with a 50mm and 135mm lens, but no wide angle. So I bought a 24mm lens. Tried it a couple of times and hated it - everything was very small. I stuck that lens away and never used it - figured I had no use for a wide angle.

Then I got a digital camera and started to play around with that same 24mm f2.8 lens. It's wide angle viewpoint wasn't as broad, so I used it somewhat as a fast normal lens. Then I read a book about landscape shooting and discovered how to use a wide angle more effectively. Ken Rockwell's article covers part of how to use one effectively - get close - but you can add a bit more to that. If you are doing landscape with a wide angle - make very sure you have something interesting in the foreground - that's why my first one works so well, the reflection in the small fountain. All of a sudden the wide angle became so much fun to use.

GW - I found my lens is soft when using apertures smaller than about f11. The lens is very sharp wide open at f4, so I usually use f4 and f5.6, perhaps f8. Because the lens has such a deep DOF, you can focus about 7-10 feet away and have everything from about 3-5 feet to infinity in focus. If you've been using smaller apertures, try using something bigger and see if it makes a difference. The K20 would hunt more with this lens than any other I own, for some reason. The K-7 seems to get a focus more often, though in one case it said it had a focus, but it really didn't (or else I moved the camera but the shutter speed was fast enough that camera shake shouldn't have been a problem). I did add a little USM/Smart sharpen to these, but then I usually do when I'm resizing for the internet.

If using larger apertures doesn't make enough difference, PM me and we can shoot some brick walls for comparison. It's possible your lens could have a problem (like my 55-300 did) and will need to be repaired/replaced. After having such a good experience with that, I'm now far more open to the idea that a lens could be faulty, and have faith in Pentax repair service.
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Old Jul 24, 2009, 8:44 PM   #9
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Thanks for the post, it makes me think more about getting a shorter rather than longer lens when I see lovely shots like yours.

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Old Jul 27, 2009, 6:55 AM   #10
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This one must have gotten buried as I never saw it. These are amazing, Harriet. I really like that first one. Even if it doesn't look what the view really is. It's beautiful as shot.

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