Perspective
 

If perspective has nothing to do with focal length and only relates to the
distance between the subject and camera, what makes a 50mm lens normal?

Perspective
 

"N" wrote:
If perspective has nothing to do with focal length and only relates to the
distance between the subject and camera, what makes a 50mm lens normal?

Nothing.

It's a hideous focal length: it's too short for isolating the subject and
it's too long to show the space and context the subject exists in.

It became "normal" by default. In the day of fixed lens cameras. 110mm on
6x9, 75 or 80mm on 6x6, or 50mm on 35mm have the property that they are the
shortest (widest) lens that can be made with a simple lens design (although
they are retrofocus on an SLR). Anything wider would require more expensive
optics and anything longer would make a larger and less useful for snapshots
camera.

A 50mm lens on a 6x6 or 6x7 camera, on the other hand, is a lovely focal
length.

David J. Littleboy
Tokyo, Japan

Perspective
 

N wrote:
If perspective has nothing to do with focal length and only relates
to the distance between the subject and camera, what makes a 50mm
lens normal?

The fact that a lens with 50mm focal length on a regular 35mm film has
approximately the same angle of view as the normal human vision.

jue

Perspective
 

"Jürgen Exner" wrote in message
news:Hegpi.640$zJ4.435@trndny03...
N wrote:
If perspective has nothing to do with focal length and only relates
to the distance between the subject and camera, what makes a 50mm
lens normal?

The fact that a lens with 50mm focal length on a regular 35mm film has
approximately the same angle of view as the normal human vision.

jue


Does your eye have an angle of view of 46 degrees? Mine is certainly wider
than that.

Perspective
 

N wrote:
"Jürgen Exner" wrote in message
news:Hegpi.640$zJ4.435@trndny03...
N wrote:
If perspective has nothing to do with focal length and only relates
to the distance between the subject and camera, what makes a 50mm
lens normal?

The fact that a lens with 50mm focal length on a regular 35mm film
has approximately the same angle of view as the normal human vision.

Does your eye have an angle of view of 46 degrees? Mine is certainly
wider than that.

Certainly. But you don't really 'see' with your peripheral vision. The area
that you _conciously_ see and focus on is approximately equivalent to the
50mm angle of view.

jue

Perspective
 

In article
, N
writes
If perspective has nothing to do with focal length and only relates to the
distance between the subject and camera, what makes a 50mm lens normal?

Several assumptions; you use it on a 35mm full frame camera, you make a
print from the full frame, you view the print at the same distance as
its diagonal. If you do all three things then the angle between subjects
in the photograph should be the same as in the original scene. It has
noting to do with the angle of view of the human eye, which is either
much less if you only consider the fovea, or much more if you understand
how human vision works. It also has nothing to do with the ease of
manufacturing the lens, otherwise sub-miniature (small sensor) and large
format cameras would all use 50mm lenses. Although the normal for 35mm
full frame should be 43mm, which makes the 'correct' viewing distance
for a frame taken with a 50mm lens 1.15 times the diagonal. Why 50 was
adopted instead of 43 is a question for more research; perhaps marketing
and being able to describe it as a two inch lens, but this is surmise on
my part.

--
Ian G8ILZ
There are always two people in every pictu the photographer and the viewer.
~Ansel Adams

Perspective
 

Jürgen Exner wrote:
N wrote:
"Jürgen Exner" wrote in message
news:Hegpi.640$zJ4.435@trndny03...
N wrote:
If perspective has nothing to do with focal length and only relates
to the distance between the subject and camera, what makes a 50mm
lens normal?
The fact that a lens with 50mm focal length on a regular 35mm film
has approximately the same angle of view as the normal human vision.
Does your eye have an angle of view of 46 degrees? Mine is certainly
wider than that.

Certainly. But you don't really 'see' with your peripheral vision. The area
that you _conciously_ see and focus on is approximately equivalent to the
50mm angle of view.

No it's not.
The fovea centralis FOV is about 2 degrees, so what you focus on clearly
is much less than 50mm "equivalent".
As pointed out further up the thread, that FOV is boring anyway.
If you look at interesting photos in most galleries, you'll typically
find that the FOV assumed to have been used in the photos was much
longer - or much shorter than "normal" focal lengths. Wedding and other
snapshot artists won't agree, it's subjective, and YMMV.

Perspective
 

"frederick" wrote:

Certainly. But you don't really 'see' with your peripheral vision. The
area that you _conciously_ see and focus on is approximately equivalent
to the 50mm angle of view.

No it's not.
The fovea centralis FOV is about 2 degrees, so what you focus on clearly
is much less than 50mm "equivalent".

And one's peripheral vision is way wider than 50mm equivalent: it's more
like 20mm or wider. I'm finding that (with care, lots of care) even 12mm (on
FF) can feel about right.

As pointed out further up the thread, that FOV is boring anyway.
If you look at interesting photos in most galleries, you'll typically find
that the FOV assumed to have been used in the photos was much longer - or
much shorter than "normal" focal lengths. Wedding and other snapshot
artists won't agree, it's subjective, and YMMV.

Still, a lot of great photos have been taken with the 50mm FOV. Here's a
photo I'm fond of (inexplicably, you'll probably find), although it's taken
with a 75mm lens (on 6x6 with an early 1950's Rolleiflex).

http://www.pbase.com/davidjl/image/37431099/large

David J. Littleboy
Tokyo, Japan

Perspective
 

Prometheus wrote:

In article
, N
writes
If perspective has nothing to do with focal length and only relates to
the distance between the subject and camera, what makes a 50mm lens
normal?

Several assumptions; you use it on a 35mm full frame camera, you make
a print from the full frame, you view the print at the same distance
as its diagonal. If you do all three things then the angle between
subjects in the photograph should be the same as in the original
scene. It has noting to do with the angle of view of the human eye,
which is either much less if you only consider the fovea, or much more
if you understand how human vision works. It also has nothing to do
with the ease of manufacturing the lens, otherwise sub-miniature
(small sensor) and large format cameras would all use 50mm lenses.
Although the normal for 35mm full frame should be 43mm, which makes
the 'correct' viewing distance for a frame taken with a 50mm lens 1.15
times the diagonal. Why 50 was adopted instead of 43 is a question for
more research; perhaps marketing and being able to describe it as a
two inch lens, but this is surmise on my part.

50mm is "normal" for 35mm film cameras because when Oskar Barnack was
designing the original Leica, he had some spare 2" microscope lenses
lying about, and they seemed to work well enough with the new frame
format. As you say, the traditional rule of thumb of a normal lens
being of a focal length equivalent to the diagonal of the frame would
suggest 43mm as being the best choice, but I've seen anything from 40
to 60mm being used.

Personally, I find I use my 28mm more than anything else on 35mm, and
the 28mm equivalent setting most often on my digital ultrazoom bridge,
but I do tend to shoot more landscapes than anything else.

Perspective
 

Alex Monro wrote:
[]
Personally, I find I use my 28mm more than anything else on 35mm, and
the 28mm equivalent setting most often on my digital ultrazoom bridge,
but I do tend to shoot more landscapes than anything else.

I found that with my Nikon 5700, I was using the widest angle (35mm IIRC)
a lot of the time, and therefore I decided to get the 24-85mm Nikon 8400.
Trouble is that I like telephoto as well.

There's a handy little program here (free) which will show you what focal
lengths you are using in a set of images:

http://www.cpr.demon.nl/prog_plotf.html

Cheers,
David