Wide Angle Focal lengths and Perspective

At what focal length/angle does a wide angle really start to show the perspective distortion?

I want to get a wide angle but I want to keep it not so extreme.

In a DX lens I am thinking around 18-35mm in a tele zoom or a 17-55mm tele zoom.

Every lens can show perspective distortion. Just aim a 1000mm lens down the center of a set of railroad tracks.

I'd say anything below 35 begins to pick up that wide angle bend, to one degree or another. I wouldn't worry too much about it, today's software is very good at straightening up lines. Moreover, you can avoid it altogether by making a panorama instead of using a WA and avoid nearly all of the distortion effects.

Lightroom does a really good job of correcting lens distortion, and they're updating the lenses all the time.

With a wide angle lens, the closer you are to your subject the more you will notice perspective distortion. Think of the photos you've seen of pets where their noses are really exaggerated. Those tend to be shot really close. And as for angle, the wider it is, perspective distortion will be more noticeable. Think about really tall skyscrapers and how the lines of a building will converge when you point the lens upwards (referencing angle that you mentioned) plus the buildings look overly tall compared to reality. Plus the wider a lens, the further back you push the farthest part of your subject. That's why pet noses look so close and huge while their heads look smaller than they really are and why the height of buildings is exaggerated when shot with a wide angle lens.

Since you've picked two lenses that are so close at their widest (17mm vs 18mm), there won't be a huge amount of difference between them when shooting wide. You will be able to see the perspective distortion through the viewfinder. I'd suggest reading up on some lens tests to see which one is better as I am not familiar with how well either one is rated, but functionality wise, the 17-55mm covers a lot more than the 18-35mm.

If you are referring to the 18-35mm G lens which is full frame, it is rated very well. I believe the other lens you listed is a DX lens. My interest was always with FX lenses, and I'm glad to have picked all but one of my lenses as FX simply because of finally switching from DX to FX. Please be aware there is also an 18-35mm D lens (not a G lens) which isn't rated nearly as well as the newer G version.

First off, not all of the lenses with the same focal length have the same level of distortion(s) - for example, Nikon 15mm f3.5 distorts less than Nikon 16-85 VR, at, say 18mm.. Secondly, most of the modern DSLRs are capable of doing the "in-camera correction" of the lens's distortion(s). Since you already own a 24-120mm (just like I do), I suggest a good prime of about 15mm. Very wide on DX, ultra wide on FX, still with very acceptable and software-correctable perspective distortions...

DraganDL said:

First off, not all of the lenses with the same focal length have the same level of distortion(s) - for example, Nikon 15mm f3.5 distorts less than Nikon 16-85 VR, at, say 18mm.. Secondly, most of the modern DSLRs are capable of doing the "in-camera correction" of the lens's distortion(s). Since you already own a 24-120mm (just like I do), I suggest a good prime of about 15mm. Very wide on DX, ultra wide on FX, still with very acceptable and software-correctable perspective distortions...

Click to expand...

Perspective distortion is not the same as optical distortion.

Perspective distortion is the natural result of trying to impose a 3-dimensional world onto a 2-dimensional image. Optical distortion is a result of the optical design of the lens.... barrelling, pincushioning, and compound( mustache).

DraganDL said:

"Perspective distortion is the natural result of trying to impose a 3-dimensional world onto a 2-dimensional image"

Yes, but the intensity with which it is going to occur within the photo is depending on the focal length and the distance between the camera and the object, too. Try to make a photo of a tall tower, using the 500mm telephoto, for example, and do it from a distance which is just enough for the frame to be filled. Let's say it's a 1 mile. You'll get alomost perfect perspective. Now try to fill up the frame with the photo of the same object, using the 28mm lens. You will have to come closer, and you will inevitably end up with the distorted perspective, right?.....

Click to expand...

Shoot the same building from the same 1 mile distance with a 20mm and the perspective distortion will be exactly the same.

Didn't I state "...and the distance between the camera and the object..."? So, the point is, from 1 mile with the 20mm you would not be able to spot the difference between the tower and the Brigitte Bardot, not to mention fulfilling the frame. The wide angle lens, in this case is FORCING you to come closer. And when you do that, voila: you've got distorted object's lines all over the frame...[h=1][/h]