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09-03-2013, 07:22 AM   #31
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QuoteOriginally posted by SyncGuy Quote
Because at times i do get confused and i've come to a conclusion that 50mm is called a "normal" as the resulting image would be similar to what your eye sees in terms of the subject size in relation to the background, with regards to camera position to subject position.
You have made an interesting and true observation. Yes, a 50mm lens will provide about the same magnification as the eye and with a 1:1 viewfinder what you see through the eyepiece of the camera will look much the same as the same view with the eye alone. That being said, "normal" generally refers to field of view rather than magnification.

The frame diagonal convention is often cited on this site, particularly in regards to the FA 43 Limited being "true normal". I think its roots are in the similar convention of expressing field of view in terms of the frame diagonal. Thing get a little stickier when you move to larger formats, though the frame diagonal convention does provide some guidance.

As for the comparison photos...that may be hard. IIRC they were part of a gallery on this site that inexplicably disappeared with a site change. I may have the originals somewhere. A quick look at your signature indicates that you have a wide range of focal lengths at your disposal. You should be able to do a controlled study of your own. What I did was to place several objects on a table top in various orientations to each other. I then put the camera on tripod at a fairly low angle to the objects and shot at three different focal lengths without moving the camera and always focusing on the same object.

After downloading the images to the computer, crop each shot to the same view as that from the longest focal length and note that all three shots have the same perspective.


Steve

09-03-2013, 06:30 PM   #32
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QuoteOriginally posted by stevebrot Quote
You have made an interesting and true observation. Yes, a 50mm lens will provide about the same magnification as the eye and with a 1:1 viewfinder what you see through the eyepiece of the camera will look much the same as the same view with the eye alone. That being said, "normal" generally refers to field of view rather than magnification.

The frame diagonal convention is often cited on this site, particularly in regards to the FA 43 Limited being "true normal". I think its roots are in the similar convention of expressing field of view in terms of the frame diagonal. Thing get a little stickier when you move to larger formats, though the frame diagonal convention does provide some guidance.

As for the comparison photos...that may be hard. IIRC they were part of a gallery on this site that inexplicably disappeared with a site change. I may have the originals somewhere. A quick look at your signature indicates that you have a wide range of focal lengths at your disposal. You should be able to do a controlled study of your own. What I did was to place several objects on a table top in various orientations to each other. I then put the camera on tripod at a fairly low angle to the objects and shot at three different focal lengths without moving the camera and always focusing on the same object.

After downloading the images to the computer, crop each shot to the same view as that from the longest focal length and note that all three shots have the same perspective.


Steve
Haha! Well, i do.. But sometimes i do worry that i might be sharing wrong information with beginners (my friends).. I guess the word perspective here is also the key word that is confusing me... LoL!

Oh nvm.. I guess i'm pretty much correct on the explanation of "normal" focal length..
To each his own, encourage learning through confusion!

Sometimes i wonder this topic has been a pretty common topic for years, has any real lens designer come forward and explain?
09-03-2013, 07:39 PM   #33
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I can see how cropping an image taken with a wide angle lens will demonstrate that the perspective is exactly the same as that taken with a telephoto.

Rather than cropping, I can also blow up the same image taken with the wide angle lens to poster size, and stand close to it, and not tell the difference.

This also means that the definition of normal has meaning only in the context of the final presentation size, i.e., the printed/displayed image size, and your viewing distance.

So as we get larger monitors and large screen TVs which fill a whole wall, maybe wider angle lenses will become the new normal.
09-03-2013, 07:57 PM   #34
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QuoteOriginally posted by Tanzer Quote
I can see how cropping an image taken with a wide angle lens will demonstrate that the perspective is exactly the same as that taken with a telephoto.

Rather than cropping, I can also blow up the same image taken with the wide angle lens to poster size, and stand close to it, and not tell the difference.

This also means that the definition of normal has meaning only in the context of the final presentation size, i.e., the printed/displayed image size, and your viewing distance.

So as we get larger monitors and large screen TVs which fill a whole wall, maybe wider angle lenses will become the new normal.
Erm... I don't think that's quite true.. There then wouldn't be a point in making a f/1.4 and f/8 lenses, other than enabling faster shutter speed. Try get a similar subject isolation with a 24/2 as compared to a 50/1.4.
Oh, and then blow it up and see if you can get the same sharpness..

There's more to the use of a focal length then just taking a picture in front of the user, ya know? Hee!


Last edited by SyncGuy; 09-03-2013 at 08:09 PM.
09-03-2013, 08:04 PM   #35
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Yes, I realize there are practical limitations, not about to sell off all my lenses.

But I'm not so sure that there needs to be strict definition that 50 mm is the only normal, unless there is a defined viewing size and distance.

For example, an IMAX movie looks great on an IMAX screen. But on a conventional movie screen, everything would look like tiny, like it was shot with a wide angle lens.
09-03-2013, 08:26 PM   #36
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QuoteOriginally posted by Tanzer Quote
This also means that the definition of normal has meaning only in the context of the final presentation size, i.e., the printed/displayed image size, and your viewing distance. So as we get larger monitors and large screen TVs which fill a whole wall, maybe wider angle lenses will become the new normal.
No, you're missing something.

Although perspective is controlled solely by the position of the camera in relation to the subject, that's not the end of the story, because in practice, field of view plays an important role.

Consider you are standing on the south rim of the Grand Canyon with a tripod, a camera and three lenses: an ultra wide, a normal, and a super telephoto. You set up the tripod and mount the camera to prove to yourself once and for all that perspective is controlled by camera position. You attach the ultra wide and take a shot, then you attach the normal lens and take a shot, and finally the super telephoto and take a shot. You get all three images home, stack them up in photoshop, and sure enough, the perspective is exactly the same in all three images. But there is a problem. The normal, and particularly the tele don't really convey the expanse of the place, only the ultra wide really lets you see the canyon when you get home. So for a given subject, the focal length, and the image format will determine the practical working distance.

Now, is there a way to photograph the Grand Canyon with a normal, or a telephoto lens and still get the whole thing in the shot? Sure there is, just stand further back, I mean WAY back, 20 miles or so should do it. Oops, but now you've moved the camera, so the perspective has changed. See? There's no winning, we might as well all give up photography right now, and become writers.
09-03-2013, 08:31 PM   #37
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QuoteOriginally posted by Tanzer Quote
Yes, I realize there are practical limitations, not about to sell off all my lenses.

But I'm not so sure that there needs to be strict definition that 50 mm is the only normal, unless there is a defined viewing size and distance.

For example, an IMAX movie looks great on an IMAX screen. But on a conventional movie screen, everything would look like tiny, like it was shot with a wide angle lens.
Yep! Many debates on this, who cares? Let's go shoot some pictures, be it a distorted portrait or a miniaturize house, it's the fun that counts!

Cheers!
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