How Wide Without Distortion?

banpreso wrote in post #12672364
YES THEY WILL LOOK DIFFERENT! the subjects on the background will be smaller on the 30mm crop shot compared to the 50mm full frame shot.

this is how crop sensor works. if you put 50mm on both crop and full frame, take a shot at the same subject from the same distance, now you take the image from the full frame shot, crop away the edges and leaving only the middle, you get the same picture as the crop sensor shot.

There is some confusion here. What I described (50mm on FF vs. 30mm on a crop) is one situation, and in this situation the shots will be identical. But what you are describing ("if you put 50mm on both crop and full frame") is a completely different situation - and different from what you described in your first post.

If you are talking about the natural perspective distortion, this is controlled by the camera/subject distance not the focal length...

A 400mm lens and a 12mm lens have the same perspective if they are shot from the same distances. Crop the image provided by the 400mm lens out of the 12mm frame and you will have the same perspective. It will be a terrible image, a bit fuzzy and a lot of noise, but the perspective will be identical...

Of course, your camera/subject distance often controls the focal length you will use or your focal length will determine the camera/subject distance. So, focal length will have an impact on perspective distortion...

Higgs Boson wrote in post #12672241
The arms were equidistant from the camera. One was closer to the side of the frame though....

So the question becomes then not what FL, but HOW do most of you successfully acheive a wide environmental portrait? I want the owner to be close enough to the camera to be recognizable but still show his business (which is consumes a fairly wide space).....I'd like to get his whole body, not just a headshot....

I'm going to assume I should move myself (camera) and the subject both farther from the background subject and use a longer lens to contain the background rather than a short lens to try and capture it from a closer distance. Fortunately, we have more room to move....

Based on this post, and without seeing the image, I don't think you're talking about perspective. You're talking about the fact that the wide angle lens, in mapping the scene's curved plane of focus onto the flat camera sensor, must distort the outer track of the imaging circle to make the image rectilinear.

To avoid this, my suggestion is to use a lens with as long a focal length as is possible for the given space. The smaller the angle of view, the less distortion to the outer track is required to make the image rectilinear. Or if you really do want to have a wide angle of view to get lots of background in your shot, then keep your subject in the center of the frame and make sure that whatever is at the edges of the scene will not be noticeably affected by this distortion.

Now when it comes to understanding perspective, I think it's best to think of it in terms of the ratio between different distances. For example, when someone's head is a foot in front of your lens, then their nose may be twice as close as the back of their head, or 2:1. Move them back another foot, and that ratio grows smaller, at about 1.5:1. Move them back 10 feet away, and the ratio is almost 1:1.

Let's see if I can untangle this a bit with a couple of simple rules.

1) Choose where you stand in order to achieve the perspective you want (and so deal with any "distortion" issues).
2) Choose the focal length you need to achieve the framing you want on the format you are using.

That solves your issues.

Example:
For the couple posed by the lake, to resolve the "distortion", you need to stand further away.
To get the same effective framing you will need a longer lens.

frugivore wrote in post #12673372
Based on this post, and without seeing the image, I don't think you're talking about perspective. You're talking about the fact that the wide angle lens, in mapping the scene's curved plane of focus onto the flat camera sensor, must distort the outer track of the imaging circle to make the image rectilinear.

To avoid this, my suggestion is to use a lens with as long a focal length as is possible for the given space. The smaller the angle of view, the less distortion to the outer track is required to make the image rectilinear.

This IS what I am talking about. And the thread title is even called Distortion, not Perspective! Bingo, thank you.

It kind of sucks being a noob. Anyone want to talk about cars?

Higgs Boson wrote in post #12673457
This IS what I am talking about. And the thread title is even called Distortion, not Perspective! Bingo, thank you.

hence the saying 'a picture's worth a thousand words'...post a picture in the first post, and everyone knows exactly what you're talking about...

i think around here though the saying should be "A picture is worth a thousand words...and one with EXIF intact is priceless..."

Most good software can correct for barrel distortion when using a wide angle lens.. This helps keep people looking normal (upright objects, including people, tend to curve inward as is seen in your second photo) while maintaining almost the same FOV. It straightens out a curved horizon too, if you have one..

Using the perspective tool you can "pull" the top edges out, straightening everyone up..

this was taken with a 17mm on a 5d (which shows more distortion than a crop camera since it uses the lens edge-to-edge) from about the same distance away as you were....

The tops were pulled out to straighten the trees and look "normal", but still give them height.

SkipD wrote in post #12672058
The real fact that you must understand if you're going to make well-composed photographs is that the perspective that folks have been referring to has NOTHING to do with focal lengths per se. Perspective is controlled purely by the position of the camera relative to the elements of the scene in front of it.

While it's true that many old-time photographers (including me a couple of decades ago) believe that the chosen focal length controls perspective, that's a very old myth. Several of us here decided to prove the truth and write an article that's been viewed almost 58,000 times so far and received lots of kudos.

For more information on perspective and how to control it, please read our "sticky" (now found in the General Photography Talk forum) tutorial titled Perspective Control in Images - Focal Length or Distance?.

before i even opened this thread i knew skip would chime in here
i'm amazed at your persistence, and also thankful as it corrected my misunderstandings when starting out.

Higgs Boson wrote in post #12672138
Perspective distortion. I have CS5 and LR3. I took a photo of a guy standing in front of his business with a wide lens and his left arm is twice the size of his right arm. I could not correct this in post. I am trying to figure out how wide I can go and avoid this type of problem. Yes, he was standing a lot closer than the rest of the subject matter but that's how I want it.

Can you show us this image so we can help determine what the actual issue(s) is/are?

SkipD wrote in post #12675805
Can you show us this image so we can help determine what the actual issue(s) is/are?

Ok here is a rough draft of the image, after I saw his arm, I moved on, lol.

I want to reshoot this photo with his whole body and no goofy arms. (and I think I will have him tuck in his shirt, lol.

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Higgs Boson wrote in post #12676573
Ok here is a rough draft of the image, after I saw his arm, I moved on, lol.

I want to reshoot this photo with his whole body and no goofy arms. (and I think I will have him tuck in his shirt, lol.

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Move back.
Use a longer lens.

Assuming from your signature that you shot this with the 24-105 - you may want to get it checked. Of course, this close to the subject - you will get distortion, but not nearly as severe as this guy's arm @24mm!

this thread was exactly what i was looking for a few days ago. made me realize i still have a long way to go and expensive gear really doesn't make you a better photographer