50mm prime lens


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Nikonnew

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May 31, 2005
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Hi,
I understand that 50 mm lens is equivalent to the human eye perspective for 35mm film, so for DSLR with a magnification factor of 1.5 , is this still true?, or should we be looking at 35 or 38mm lens (or something close, as I do not know if such lens is available) in such cases?
 

Feb 14, 2004
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#2
u can look for 35mm F2.. there is dis lens inde market.. aft 1.5 crop factor..it will bcome 52.5mm..very close to 50mm.. or u can jus get de 50mm F1.8..as its a gd prime lens for people shots too..

Cheers!
 

n0d3

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Feb 3, 2003
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Nikonnew said:
Hi,
I understand that 50 mm lens is equivalent to the human eye perspective for 35mm film, so for DSLR with a magnification factor of 1.5 , is this still true?, or should we be looking at 35 or 38mm lens (or something close, as I do not know if such lens is available) in such cases?
Actually, no. 50mm doesn't give you an equivalent to the human eye's perspective.

http://www.mhohner.de/essays/myths.php#50mm
 

LittleWolf

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Jan 23, 2005
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n0d3 said:
Actually, no. 50mm doesn't give you an equivalent to the human eye's perspective.
In the first place, focal length has nothing to do with perspective.
 

Nikonnew

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LittleWolf said:
In the first place, focal length has nothing to do with perspective.

My apology Littlewolf ,for my lacking in photography vocab......what do you call it?.....human view perhaps?? I really not very sure .......but i think the link explains it well
 

Nikonnew

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Nikonnew said:
My apology Littlewolf ,for my lacking in photography vocab......what do you call it?.....human view perhaps?? I really not very sure .......but i think the link explains it well
Woops ....i think the right word is photography terminology
 

#12
Extract from book, hope it help. ;)

In photography, lens focal length is the distance
between the optical center of a lens and the focal plane
(film plane) of the camera when the lens is focused at
infinity.
 

LittleWolf

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Jan 23, 2005
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#13
Nikonnew said:
My apology Littlewolf ,for my lacking in photography vocab......what do you call it?.....human view perhaps?? I really not very sure .......but i think the link explains it well
No need for apologies... I'm just trying to fight the urban legend that focal length affects perspective, and my comment wasn't really aimed at you. (And even if it was, you wouldn't owe me an apology ...) :)
 

Nikonnew

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#14
LittleWolf said:
No need for apologies... I'm just trying to fight the urban legend that focal length affects perspective, and my comment wasn't really aimed at you. (And even if it was, you wouldn't owe me an apology ...) :)
I don't think it's an urban legend, probably just a case of using words loosely........
 

#15
From what I can remember, the human eye's perspective is more similar to the angle of view u get using a 45mm lens, which is about 50 degrees. The anglel of view you get using a 50mm lens is 46 degrees. I'm not sure why they end up making standard lenses 50mm though.

Nikon makes a 45mm 2.8 lens but it's awfully expensive... it cost more than the 50mm 1.4!
 

Jan 23, 2005
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#16
Nikonnew said:
I don't think it's an urban legend, probably just a case of using words loosely........
Try it out: take a photo using a tele lens, and - from the same position, so as to not change the perspective - witha wide angle lens. Then crop the wide angle photo so that the field of view is the same as that of the tele lens. Compare. You'll find that apart from depth of field and maybe lens flaws/resolution limitations, the images are identical.
 

Jan 23, 2005
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#17
Seeto said:
I'm not sure why they end up making standard lenses 50mm though.
"Standard" lenses for 24mm x 36 mm format have historically changed over a wide range, and even "strange" numbers like 58 mm are/were common.

For SLR cameras, the region around 50 mm is a good technical compromise. It is more complex (= expensive) to build wide angles, as the mirror box limits how close the lens can be to the film. On the other hand, tele lenses require vastly more optical glass (and more solid mechanics) to achieve the same relative opening. That's why 50mm/1.8 lenses are relatively cheap to make, whereas 100mm/1.8 or 28mm/1.8 lenses cost a bomb. In the days when 50mm was the "kit lens", large production volumes also helped.

There's no technical reason why a 40mm/2.8 lens has to be more expensive. This is probably more a result of small production volume and also marketing (you pay for the exclusivity of a "pancake" lens).
 

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