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Author Topic: Is 50mm normal lens on 5d?  (Read 4852 times)

ssrdd

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Is 50mm normal lens on 5d?
« on: May 06, 2011, 03:32:24 AM »
On 5D, 50mm images are magnifying than normal view( eye view).
since 50mm considered as normal lens.....what is this phenomenon?

thank u all.

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Is 50mm normal lens on 5d?
« on: May 06, 2011, 03:32:24 AM »

Edwin Herdman

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Re: Is 50mm normal lens on 5d?
« Reply #1 on: May 06, 2011, 03:47:19 AM »
On any "full frame" sensor camera, the 50mm lens will have more or less the same perspective as it would on 35mm film.  On a smaller sensor camera (i.e. APS-C seen on the T1i, T2i, T3i, 50D and 60D, 7D, etc) it will appear as if your lens is roughly 1.6 times longer in focal length (i.e. the 50mm acts like a portrait lens, i.e. 80mm).  From what I understand, the depth of field and most other essential characteristics do not change, but since the sensor is smaller it's as if you've cut away the outer portion of a picture taken with a 35mm film perspective - thus it appears to be "zoomed in" because, well, it is.  The rest of the flat image plane focused by the 35mm camera lens falls outside the sensor plane and is simply not recorded.

kirillica

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Re: Is 50mm normal lens on 5d?
« Reply #2 on: May 06, 2011, 05:03:13 AM »
I like the question "is normal"? I think the answer should be: yes, it's quite normal... :D

NormanBates

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Re: Is 50mm normal lens on 5d?
« Reply #3 on: May 06, 2011, 06:21:40 AM »
if you have some spare time, head over here to read about human eyes and "normal" FoV:
http://www.lensrentals.com/blog/2009/03/the-camera-vs-the-eye

Viggo

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Re: Is 50mm normal lens on 5d?
« Reply #4 on: May 06, 2011, 07:12:43 AM »
I always heard that 50mm is the same as looking with your eyes, aka, moving the eye in and out of the VF makes for the same mag ratio, but it isn't, it's much closer to 75-85mm, I've never heard anyone explain why this is. Also read somewhere that the ACTUAL focal is closer to 43mm, which makes no sense to me.

SO instead of telling the op that this is normal, and the 50 IS the same, when it clearly isn't, maybe explain why it appears to be a longer focal that gives the same mag ratio as the eye. I would also love to get it explained.

A FOV of the eye is 180 degrees, no? At least I can see 180, so it can't be that a fov of a 50 is equal to the human eye, it must be the mag ratio. And doesn't this have something to do with how the VF itself is constructed? how great coverage etc?
« Last Edit: May 06, 2011, 07:16:09 AM by Viggo »
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ssrdd

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Re: Is 50mm normal lens on 5d?
« Reply #5 on: May 06, 2011, 07:56:02 AM »
I knew in theory 50mm on 35mm film will project an image which is equal as eye.
also 35mm film is being cropped from all sides, which is similar to APS-C sensor, unlike 7d etc...(24x14mm)

but here 5d(36x24mm), which is 43mm diagonal width. On film it was like 30mm diagonal width.
On 5d with the same 5omm lens, difference between 5d and film is around 13mm(diagonal),
so will i achieve the same effect which is normal to some of u?

now i don't understand the word normal anymore

thanks for the response guys..
bests.

Lawliet

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Re: Is 50mm normal lens on 5d?
« Reply #6 on: May 06, 2011, 08:00:49 AM »
I always heard that 50mm is the same as looking with your eyes, aka, moving the eye in and out of the VF makes for the same mag ratio, but it isn't, it's much closer to 75-85mm, I've never heard anyone explain why this is. Also read somewhere that the ACTUAL focal is closer to 43mm, which makes no sense to me.

"Normal lens" only means that the fl is close to the sensor diagonal. That comes from a time where photographers used all kinds of formats from the puny 135 ;) to 8x10, so just stating the fl didn't say much, they needed some reference.

The whole natural thing was made up later to avoid questions from people who would use only one film size, and not for artistic reasons but because its the cheapest. Good luck finding an explanation that doesn't fall apart at closer inspection.

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Re: Is 50mm normal lens on 5d?
« Reply #6 on: May 06, 2011, 08:00:49 AM »

Viggo

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Re: Is 50mm normal lens on 5d?
« Reply #7 on: May 06, 2011, 08:05:33 AM »
Lawliet: Thanks!! That explained A LOT for me, I had no idea that was te issue! But it makes perfect sense! I'll bring the word along to some friends who had been wondering the same thing...
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jeremymerriam

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Re: Is 50mm normal lens on 5d?
« Reply #8 on: May 06, 2011, 09:05:10 AM »
Some say it is the normal lens but in essence, i don't think any lens is really normal compared to our eyes.  Our eyes are amazing bio machinery.  A 50mm feels normal at a relative distance but once you get close in to a subject (such as headshots or half body portraits), there is a decent amount of distortion.  I remember reading that the 100mm is the best distortion free portrait lense but then you lose some of the relationship with your subject due to your distance. 

neuroanatomist

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Re: Is 50mm normal lens on 5d?
« Reply #9 on: May 06, 2011, 11:05:49 AM »
I always heard that 50mm is the same as looking with your eyes, aka, moving the eye in and out of the VF makes for the same mag ratio, but it isn't, it's much closer to 75-85mm, I've never heard anyone explain why this is. Also read somewhere that the ACTUAL focal is closer to 43mm, which makes no sense to me.

As Lawliet stated, 'normal' is when the focal length is approximately equal to the diagonal of the film/sensor format.  50mm was 'close enough' to the 43mm diagonal of film/FF, and was easy to produce (although I don't think 43mm would have been siginificantly more expensive...).  Calling it 'normal' wasn't just made up, however - when the lens focal length equals the image sensor diagonal, the final image tends to approximate the field of normal human attention.

Note that I stated final image.  When comparing it to what you see in the viewfinder, there's another factor - viewfinder magnification.  For example, the 5DII has a viewfinder magnification of 0.71x - so in terms of magnification, looking through a 70mm lens on a 5DII would give equivalent magnification to your eye,. explaining why, "...moving the eye in and out of the VF makes for the same mag ratio, but it isn't, it's much closer to 75-85mm."

A FOV of the eye is 180 degrees, no? At least I can see 180, so it can't be that a fov of a 50 is equal to the human eye, it must be the mag ratio. And doesn't this have something to do with how the VF itself is constructed? how great coverage etc?

A little more - the total human visual field (both eyes) is about 200°, with about 120° of overlap (binocular vision).  But even though you can see a 200° visual field, I'm sure you notice that objects away from the center are not sharp.  In reality, you don't pay attention to the whole visual field - you really only use the very center of each eye's visual field, and when you look at a scene, your eyes rapidly move around the scene (called saccades), and your brain builds a cohesive picture from the individual, small parts of the scene.  Probably the idea of a 'normal' lens comes from the fact that the FoV of a 45-50mm lens on a 35mm/FF camera approximates the area of the total human visual field that is usually scanned to build up that mental picture.  If there's something of interest at the periphery, you'll turn your head to look at that area and build another mental scene.

So, jeremymerriam hit the nail on the head - a camera functions in a complately different manner than the human visual system.  That fact is part of the challenge of photography - it's pretty common to see an amazing vista with your eyes, but when you snap a wide angle shot of that scene, it looks flat and boring, capturing nothing of the feel of the real scene.  That's why composition is so important!
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nico

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Re: Is 50mm normal lens on 5d?
« Reply #10 on: May 06, 2011, 11:21:38 AM »
Hi,

Quote
I always heard that 50mm is the same as looking with your eyes

You are totally right, and it's true on a FF.

Quote
aka, moving the eye in and out of the VF makes for the same mag ratio, but it isn't, it's much closer to 75-85mm, I've never heard anyone explain why this is.

You all miss another parameter you have to consider which you can find in the technical specifications of your camera. The viewfinder has a magnification factor, which is 0.71x in your 5d.
That's why with a 50mm on a 5d you see a smaller image in your VF than with your eyes, but the vision angle is really the same!
Hope it's clear, I'm french.. :)

neuroanatomist

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Re: Is 50mm normal lens on 5d?
« Reply #11 on: May 06, 2011, 11:34:35 AM »
You all miss another parameter you have to consider which you can find in the technical specifications of your camera. The viewfinder has a magnification factor, which is 0.71x in your 5d.

I didn't miss that...   :P
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nico

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Re: Is 50mm normal lens on 5d?
« Reply #12 on: May 06, 2011, 12:07:05 PM »
You all miss another parameter you have to consider which you can find in the technical specifications of your camera. The viewfinder has a magnification factor, which is 0.71x in your 5d.

I didn't miss that...   :P

Yes, I wrote my post before seeing yours! sorry :P And your explanation was much complete and very interesting  ;) what is important is the angle of view, not the image size

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Re: Is 50mm normal lens on 5d?
« Reply #12 on: May 06, 2011, 12:07:05 PM »