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Wide angle vs telephoto
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Oct 8, 2023 15:19:03   #
larryepage Loc: North Texas area
 
Architect1776 wrote:
So for a 4x5 format the same happens at 50mm?


No...for a 4x5 camera, a "normal" lens is about 6" which is somewhere around 150mm. When I shot 120 film in 645 format (45mm x 60mm) a normal lens was 80 or 85mm.

There doesn't seem to be a lot of arithmetical rigor around what is a "normal" lens, but it's always close to the diagonal measurement of the exposure area. That's what has led me to conclude that it grew from lens design somehow rather than being strictly related to field of view.

There is also a chance that it is just one of those mysterious photographic rules of thumb whose real origin has been lost or may have never existed. I have not found anything more definitive or provable beyond what I've pieced together and deduced so far. Any comparison to "what the eye sees" seems the least objectively accurate option. For one thing, our field of view is very different vertically from what it is horozontally.

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Oct 8, 2023 15:32:22   #
wdross Loc: Castle Rock, Colorado
 
Architect1776 wrote:
Why is 50mm generally considered the transition point between what is considered wide angle and telephoto?
It seems that this would vary depending upon format and even to a greater extent the subjective opinion of someone.


It is what the eye covers with general or normal vision. That is why eyeglasses cover the same basic angle of view. That angle is what the eye covers the easiest with it's movement and focus. Detail is only provide by the fovea of the eye. Per Gray's Anatomy, that is only 3.8° for very fine detail. Some detail resolution goes out to 5°. After that, the eye resolves
less detail and more general area information. Since we are talking 48° for 50mm, the eye tracks everything within that 48° with very fast movement and refocus. This varies for people to a small degree which is the reason that often the term "normal lens" is used to refer to any lens from 40mm to 60mm with 50mm or 55mm sort of in the middle.

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Oct 8, 2023 15:38:59   #
fetzler Loc: North West PA
 
Architect1776 wrote:
Why is 50mm generally considered the transition point between what is considered wide angle and telephoto?
It seems that this would vary depending upon format and even to a greater extent the subjective opinion of someone.


A normal lens has a focal length equal to the diagonal dimension of the film or a sensor. Such a lens gives a perspective that is similar to that of human vision as reflected in paintings of the past.

For 35mm film this dimension is about 43mm and is generally rounded to 50mm. If one has a micro 4/3 camera a normal lens is 25mm and for a 6 x4.5 cm 75mm and for an 8x10in camera a normal lens is about 300mm. These various focal lengths give what is considered to be the perspective of human vision and all have a similar FOV when used on their respective format cameras.

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Oct 8, 2023 15:50:20   #
fetzler Loc: North West PA
 
larryepage wrote:
No...for a 4x5 camera, a "normal" lens is about 6" which is somewhere around 150mm. When I shot 120 film in 645 format (45mm x 60mm) a normal lens was 80 or 85mm.

There doesn't seem to be a lot of arithmetical rigor around what is a "normal" lens, but it's always close to the diagonal measurement of the exposure area. That's what has led me to comclude that it grew from lens design somehow rather than being strictly related to field of view.

There is also a chance that it is just one of those mysterious photographic rules of thumb whose real origin has been lost or may have never existed. I have not found anything more definitive or provable beyond what I've pieced together and deduced so far. Any comparison to "what the eye sees" seems the least objectively accurate option. For one thing, our field of view is very different vertically from what it is horozontally.
No...for a 4x5 camera, a "normal" lens i... (show quote)



There is a bit of science in this. See the following article for more details.

https://en.wikipedia.org/wiki/Normal_lens

It seems that the idea goes back to Leonardo's studies on perspective.

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Oct 8, 2023 15:54:33   #
fetzler Loc: North West PA
 
imagemeister wrote:
Way back at the dawn of 35mm ( rangefinder Leicas ) film photography, 50mm was the simpleist/cheapest and best performing lens to make to cover 35mm (actually 42.5mm diagonal). Later, when SLR's came into vogue and cheaper wides and teles became available, 50mm was still the cheapest lens to build to accomodate the mirror box. So, because it was always the cheapest, it became the "normal" kit lens to be sold with cameras and was "normal" because it was plentiful and cheap ! - and shorter lengths became wide angle and longer ones became telephoto's.
P.S. Human "sight" has never had anything to do with it ...... 8-) except as an argument starter 8-(
Way back at the dawn of 35mm ( rangefinder Leicas ... (show quote)


While 50mm lenses easily cover 35mm film and are easy to design. Your thesis that human sight has "nothing to do with it" is flawed and indeed incorrect.

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Oct 8, 2023 15:58:17   #
imagemeister Loc: mid east Florida
 
fetzler wrote:
While 50mm lenses easily cover 35mm film and are easy to design. Your thesis that human sight has "nothing to do with it" is flawed and indeed incorrect.


Human sight has NOTHING to do with WHY 50mm was and has become "normal".......period. - And yes, my seat belt is buckled......for all the nay-sayers - tho, I must admit there is a lot of mis-construed internet hyperbole concerning human sight .....

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Oct 8, 2023 16:02:02   #
Architect1776 Loc: In my mind
 
imagemeister wrote:
Way back at the dawn of 35mm ( rangefinder Leicas ) film photography, 50mm was the simpleist/cheapest and best performing lens to make to cover 35mm (actually 42.5mm diagonal). Later, when SLR's came into vogue and cheaper wides and teles became available, 50mm was still the cheapest lens to build to accomodate the mirror box. So, because it was always the cheapest, it became the "normal" kit lens to be sold with cameras and was "normal" because it was plentiful and cheap ! - and shorter lengths became wide angle and longer ones became telephoto's.
P.S. Human "sight" has never had anything to do with it ...... 8-) except as an argument starter 8-(
Way back at the dawn of 35mm ( rangefinder Leicas ... (show quote)



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Oct 8, 2023 16:02:21   #
Architect1776 Loc: In my mind
 
imagemeister wrote:
No, it happens at or about 45-50 degrees of field coverage. (160mm for 4X5)



Thx

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Oct 8, 2023 16:02:55   #
Architect1776 Loc: In my mind
 
larryepage wrote:
No...for a 4x5 camera, a "normal" lens is about 6" which is somewhere around 150mm. When I shot 120 film in 645 format (45mm x 60mm) a normal lens was 80 or 85mm.

There doesn't seem to be a lot of arithmetical rigor around what is a "normal" lens, but it's always close to the diagonal measurement of the exposure area. That's what has led me to comclude that it grew from lens design somehow rather than being strictly related to field of view.

There is also a chance that it is just one of those mysterious photographic rules of thumb whose real origin has been lost or may have never existed. I have not found anything more definitive or provable beyond what I've pieced together and deduced so far. Any comparison to "what the eye sees" seems the least objectively accurate option. For one thing, our field of view is very different vertically from what it is horozontally.
No...for a 4x5 camera, a "normal" lens i... (show quote)



Thx

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Oct 8, 2023 16:04:42   #
Architect1776 Loc: In my mind
 
wdross wrote:
It is what the eye covers with general or normal vision. That is why eyeglasses cover the same basic angle of view. That angle is what the eye covers the easiest with it's movement and focus. Detail is only provide by the fovea of the eye. Per Gray's Anatomy, that is only 3.8° for very fine detail. Some detail resolution goes out to 5°. After that, the eye resolves
less detail and more general area information. Since we are talking 48° for 50mm, the eye tracks everything within that 48° with very fast movement and refocus. This varies for people to a small degree which is the reason that often the term "normal lens" is used to refer to any lens from 40mm to 60mm with 50mm or 55mm sort of in the middle.
It is what the eye covers with general or normal v... (show quote)


I doubt this unless you have some science.
But the eye I would doubt has anything to do with it historically unless you have something besides conjecture.

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Oct 8, 2023 16:04:53   #
Longshadow Loc: Audubon, PA, United States
 
Probably because the stuff in the image looks the same distance away as not looking through the camera.
Subjects appear no closer, no farther than viewing with the naked eye.
If the subject looks 15 feet away in reality and the picture, it's "normal".
Anything making the subject look farther away would be wide angle, conversely for telephoto.
(Would be 32mm on a 1.6 APSC body.)

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Oct 8, 2023 16:05:59   #
Longshadow Loc: Audubon, PA, United States
 
fetzler wrote:
A normal lens has a focal length equal to the diagonal dimension of the film or a sensor. Such a lens gives a perspective that is similar to that of human vision as reflected in paintings of the past.

For 35mm film this dimension is about 43mm and is generally rounded to 50mm. If one has a micro 4/3 camera a normal lens is 25mm and for a 6 x4.5 cm 75mm and for an 8x10in camera a normal lens is about 300mm. These various focal lengths give what is considered to be the perspective of human vision and all have a similar FOV when used on their respective format cameras.
A normal lens has a focal length equal to the diag... (show quote)


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Oct 8, 2023 16:13:46   #
fetzler Loc: North West PA
 
imagemeister wrote:
Human sight has NOTHING to do with WHY 50mm was and has become "normal".......period. - And yes, my seat belt is buckled......for all the nay-sayers


This is America and you can believe in the tooth fairy if you want but you are not right. 50mm is easy to make AND it closely matches 43 mm at practical level. Incidentally, my father had a 1950s rangefinder camera with a 45mm lens.

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Oct 8, 2023 16:14:29   #
Blenheim Orange Loc: Michigan
 
george19 wrote:
35 mm format is the distance between sprocket holes on the film, giving a 24 x 36 mm frame, the diagonal being 43 mm or so.




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Oct 8, 2023 16:18:55   #
imagemeister Loc: mid east Florida
 
fetzler wrote:
50mm is easy to make AND it closely matches 43 mm at practical level.


Yes, this is why and how it came to be "normal" .....

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