But I thought 50mm was 80mm on my 1.6x crop...!

Noob question...hopefully in the correct thread:

So, from people much wiser than I I'm told that approx. 85-135mm is the best lens range for portraiture. With that in mind, I'd been assuming that my trusty 50mm 1.4, which is 80mm equivalent with the 50D's 1.6 crop in mind, was therefore a good 'portrait' lens. To be sure, I've taken some fair pix with it despite my still-quite-green status.

BUT, this evening, the wife said I needed to take a "passport" style pic for the kid's school ID. SO, I put on me trusty 50, set up the D-Lites, sneaker-zoomed waaay in to capture just the face, and took pic #1 -- which was fine except THIS WAS NOT MY KID! The features were highly distorted, particularly the nose. But, wait! I thought 85mm was a 'sweet spot' for portraiture?? Why was I getting so much distortion??? at 80?

So, I swapped the 50 for the 70-200, ratcheted down to about 135mm and re-shot, and got pic #2, which indeed was the daughter that I am accustomed to.

SOOO...Did I just learn that the crop factor IS TOTALLY IRRELEVANT when talking about distortion from being too close to the subject? In other words, a better portrait lens would *still* be 85mm or higher even on my 50D's cropped sensor?? I feel as if I've just stumbled on some fundamental law of physics but need a real scientist to confirm my findings. Help, please.

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You're obviously confusing Field of View with focal length. A 50mm lens on a 1.6 crop camera gives you the same field of view as a 80mm lens on a full frame camera if both cameras are in the same position but the characteristics determined by focal length will still differ.

A 50mm on a camera with APC sensor is just about the same as 80mm in full format. However 80mm can very easy become to little when it comes to head shots, especially of kids (smaller subject). I am using a 150mm in full format and have never felt that it's to much. If i need shoulder shoots i just go a little further away. If you have limited space that can be a different factor.

Yep. Crop factor won't change the characterstics of the lens like distortion and compression for example.

PixelMagic wrote in post #9969222
You're obviously confusing Field of View with focal length.

That is absolutely what I've been doing, and the realization came as something of a shock. As Blue9 says, I can easily see using 135+ but with my 50D I'd be hanging out my window...I just don't have the real estate. Yikes.

First - cute girl!

Now, to the Q at hand. You've stumbled on the common mis-conception that it is the lens that makes the good portrait shot, when, in fact it is the DISTANCE that is the real controlling factor.

The distance from the camera to the scene controls the perspective. The closer you are, the bigger things are. Something twice as close appears twice as large. Pretty simple, ea? So here's what happened.

You were so close in the first shot that the distance to your daughter's nose was significantly less than the distance to her ears, making her nose appear significantly larger than her ears (and other parts of her face. It wasn't your lens choice it was your distance choice that created the distortion you see.

When you put the 70-200 on, you were forced to step back. From a further back, the distance to her nose is about the same as the distance to her ears so they are both rendered about the same size.

Portrait lenses were chosen because they allowed the photographer to fill the field of view appropriately from the correct distance. 50mm Is great for full-body shots. If you want tight head & shoulders shots and you're shooting from the right distance, you'll need a 135mm lens to fill the field of view with your subject.

See, first you pick the distance, then you pick the lens. I try to stay between 3 an 5 paces when I'm shooting people and don't want the distortion you see in pic 1.

nicksan wrote in post #9969241
Yep. Crop factor won't change the characterstics of the lens like distortion and compression for example.

Well as they are related to perspective, yes it will. Perspective is distance related - period. You will be as far away from the subject with a 50mm on 1.6x as an 80mm on FF.

The problem is that using 50 on a crop or 85mm on a FF is still probably too short for the ideal headshot length. You'd want a lens that lets you get about 8 feet away with the same framing. 80mm equivalent puts you at about 3-4 feet.

Freddie Alessio wrote in post #9969205
SOOO...Did I just learn that the crop factor IS TOTALLY IRRELEVANT when talking about distortion from being too close to the subject? In other words, a better portrait lens would *still* be 85mm or higher even on my 50D's cropped sensor?? I feel as if I've just stumbled on some fundamental law of physics but need a real scientist to confirm my findings. Help, please.

Yes crop factor is irrelevent to the optical properties of the lens. Optical physics remain optical physics no matter which body is used. It does not turn a 50mm lens into a 80mm lens. 50mm = 50mm no matter what body it's on. It does however crop out the center section of the image giving the same field of view as if you had a 80mm lens. But that is an editing property, not an optical property. You can achieve the identical image if you placed the 50mm lens on a full framed body, then cropped the center section from it.

But optics has nothing to do with perspective distortion as the OP is showing here. that is 100% distance from subject to camera. You will be the exact same distance from the camera using a 50mm on 1.6x or 80mm on FF, so perspective distortion will also be the same. The issue here is that while 80mm equiv is nice for SOME portraits, it is not the best for headshot portraits. 50mm on a crop is great for like half body or sitting portraits. For a headshot, you probably want 85-100mm or more.

85mm is considered a 'classic; portait lens on 35mm cameras for people shot anywhere from full length to waist up.

Your passport photo above is a very tight portrait. This would classically be shot using a 200mm lens on 35mm, about 135mm for you. The error in your thinking was that your tight headshot is not what people are talking about when they state that 85mm (on 35mm cameras) is good for portraits.

Passport photos are not to have dramatic lighting by the way. You should shoot a passport photo with on-camera direct flash. Skip the fancy softboxes and ratios or risk having the photos rejected. I realize this is for a school ID, but I bet they want the same thing.

JeffreyG wrote in post #9969325
Skip the fancy softboxes and ratios or risk having the photos rejected.

He said it was for a school ID, so I bet they will be OK

As stated above, you must maintain a certain distance for a flattering perspective, which is something like 6ft or more (for adults...you can probably get closer for children). That means 50mm on APS-C is fine for head-&-shoulders, but filling the frame for a headshot moves you too close. In order to avoid large noises and such, you can either not fill the frame and crop, or you use a longer focal length.

As it happens, on 35mm, 135-200mm is what is usually used for headshots, which corresponds to 85-135mm on APS-C.

JeffreyG wrote in post #9969325
85mm is considered a 'classic; portait lens on 35mm cameras for people shot anywhere from full length to waist up.

Your passport photo above is a very tight portrait. This would classically be shot using a 200mm lens on 35mm, about 135mm for you. The error in your thinking was that your tight headshot is not what people are talking about when they state that 85mm (on 35mm cameras) is good for portraits.

Passport photos are not to have dramatic lighting by the way. You should shoot a passport photo with on-camera direct flash. Skip the fancy softboxes and ratios or risk having the photos rejected.

Lots of good tidbits...thank you. 135 would make my living room pretty much unliveable....but worth keeping in mind. And, yes, seems like I was assuming the 85mm-to-'good portrait' link was applicable to anything torso and up, including just the head. Excellent point!

I say 'passport' photo quite loosely...they're really just for kids school ID.

Good answers here!
One small point - for the intended purpose, you could shoot with the 50 from the distance required to give a pleasing perspective, and then crop for composition.

nicksan wrote in post #9969241
Yep. Crop factor won't change the characterstics of the lens like distortion and compression for example.

As said a few times above, the perspective distortion has absolutely nothing to do with the focal length of the lens being used. It has everything to do with the camera-to-subject distance. The common blaming of so-called "wide-angle distortion" and "telephoto compression" on the focal lengths are totally false.

Several of us have created a very comprehensive illustrated tutorial on the subject of image 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?.