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50mm "normal" lens with digital SLR?



 
 
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  #1  
Old June 24th 04, 09:52 AM
Chris Brown
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Posts: n/a
Default 50mm "normal" lens with digital SLR?

In article ,
G.T. wrote:
Chris Brown wrote:

It's very, very simple.


The more I read this thread the more confused I get.

35mm is the "standard" focal length for that camera.


I thought I read someone's calculation that 28mm is.


Well, the actual "normal" focal length is bewteen the two, and there's not a
lot of difference between them, so either will do the job.

Shorter is wide-angle. Longer is telephoto.


Got it.

It's not a 35mm camera, and
trying to use some sort of hybrid system where some lenses are marked with
their real focal lengths, and some marked with "equivalent" focal lengths is
a sure-fire way to maximise confusion, not minimise it.


So if one has never used a 35mm SLR then one wouldn't need to know about
1.6 (or whatever) conversion factors, right? One would just use lenses
at focal lengths shorter than 35mm (or 28mm, whichever is correct for
the particular sensor) for wide-angle, and longer for telephoto. I'm
starting to get it now.


Indeed, that's exactly it.

The argument over whether it's a "crop", a "magnification", or whatever else
is an irrelevant distraction over nomenclature, and just overcomplicates the
issue AFAICS. If someone is used to thinking in a 35mm mindset, then the
"conversion factor" may help them decide what lens to use in a given
situation. What they actually call it doesn't matter.

Also, anyone saying that you don't get the "perspective" of a normal lens
when using a 35/28 on one of these cameras is confused. Lenses don't have
any effect on perspective, which is a function of where you stand to take
the photo. The real reason the phenomenon of "telephoto flattening" occurs
is simply that to frame the same object with a telephoto lens, you have to
stand further away from it than you would with a shorter focal length.
  #2  
Old June 24th 04, 01:12 PM
Adam
external usenet poster
 
Posts: n/a
Default 50mm "normal" lens with digital SLR?

Chris Brown explained :
In article ,
G.T. wrote:
Chris Brown wrote:

It's very, very simple.


The more I read this thread the more confused I get.

35mm is the "standard" focal length for that camera.


I thought I read someone's calculation that 28mm is.


Well, the actual "normal" focal length is bewteen the two, and there's not a
lot of difference between them, so either will do the job.

Shorter is wide-angle. Longer is telephoto.


Got it.

It's not a 35mm camera, and
trying to use some sort of hybrid system where some lenses are marked with
their real focal lengths, and some marked with "equivalent" focal lengths
is a sure-fire way to maximise confusion, not minimise it.


So if one has never used a 35mm SLR then one wouldn't need to know about
1.6 (or whatever) conversion factors, right? One would just use lenses
at focal lengths shorter than 35mm (or 28mm, whichever is correct for
the particular sensor) for wide-angle, and longer for telephoto. I'm
starting to get it now.


Indeed, that's exactly it.

The argument over whether it's a "crop", a "magnification", or whatever else
is an irrelevant distraction over nomenclature, and just overcomplicates the
issue AFAICS. If someone is used to thinking in a 35mm mindset, then the
"conversion factor" may help them decide what lens to use in a given
situation. What they actually call it doesn't matter.

Also, anyone saying that you don't get the "perspective" of a normal lens
when using a 35/28 on one of these cameras is confused. Lenses don't have
any effect on perspective, which is a function of where you stand to take
the photo. The real reason the phenomenon of "telephoto flattening" occurs
is simply that to frame the same object with a telephoto lens, you have to
stand further away from it than you would with a shorter focal length.


I have the 50mm 1.8 for my new Nikon D70. It works great as a low
light/portrait lense.

--
ME!

  #3  
Old June 25th 04, 01:57 AM
Dave Martindale
external usenet poster
 
Posts: n/a
Default 50mm "normal" lens with digital SLR?

"Dag Korsnes" writes:

I thought a "normal" lens giving the same field of view or magnification as
the eye on 35 mm SLR was about 57 mm, not 50 mm. For some reason 50 mm has
become the standard "normal" lense (except on some old Praktica).


The usual definition of a normal lens is one with a focal length equal
to the format diagonal. By that measure, the normal lens for a 35 mm
camera is 43 mm FL. There have been some 45 mm normal lenses included
with cameras, but 50 mm is most common.

Minolta used to have 57 and 58 mm "normal" lenses. I think the
rationale for these was that, when used with the viewfinder
magnification of their cameras, they gave nearly 1X angular
magnification (i.e. "life size" viewing in the finder).

Dave


  #4  
Old June 27th 04, 04:45 PM
Richard Ballard
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Posts: n/a
Default 50mm "normal" lens with digital SLR?

In article ,
Chris Brown writes:

In article ,
G.T. wrote:

Chris Brown wrote:

It's very, very simple.


The more I read this thread the more confused I get.

35mm is the "standard" focal length for that camera.


I thought I read someone's calculation that 28mm is.


Well, the actual "normal" focal length is bewteen the two,
and there's not a
lot of difference between them, so either will do the job.


In 35mm film photography there is sufficient difference
between the coverage (and fisheye distortion) of 35mm
and 28mm lenses to justify offering both these lenses --
they are not identical.

As focal length decreases, each millimeter focal length
reduction becomes (percentagewise) increasingly significant.
In some ways, longer focal length lenses are more forgiving
of (a given amount of) imprecision.

I have read this thread with some amusement because
I believe you are arguing the wrong issue.

"Normal" relates imaged scene coverage to human vision coverage
(i.e., what a human views normally using their eyes), while the
imaged scene coverage of a given focal length lens depends upon
the digital SLR's sensor chip area. A smaller focal length lens
coupled with a smaller sensor chip (and appropriate camera
dimensions) gives the same imaged coverage as a larger focal
length lens coupled with a larger sensor chip (and appropriate
camera dimensions). Using a film analogy, the normal (nominal)
50 mm lens used with 35mm SLRs would _not_ provide normal
coverage were they used with a 2"x2" format (type 120 film --
e.g., Hasselblad) SLR. 35mm film is one sensor standard and
2"x2" film is a different sensor standard -- different "normal"
lenses for different sensor areas.

Digital photography is not yet fully mature. The different dSLR
manufacturers have not yet agreed on a common sensor size(s).
(The analogous situation is different SLR manufacturers having
different definitions for 35mm film coverage area -- some mask
portions of the 35mm frame to hide lens flaws.) IMO digital
photography will _not_ be fully mature until manufacturers agree
on sensor size. Then industrywide standards will develop,
component commonality will occur, and economies of scale will
drive down digital photography equipment costs. dSLR
manufacturers will compete in the areas of optics quality,
man-machine interface (ease and flexibility of use -- think of the
VCRs you never learned to program), provided features, and
dSLR durability/maintainability.

Sensor quality will become less of an issue because most
manufacturers will utilize the same sensor chip -- a high quality
product made affordable by manufacturing economies of scale
(just like photographic film).

An analogous situation already exists in the computer industry,
and (IMO with some justification) a person can view a dSLR
as a special purpose computer.

'Hope that helps.

Richard Ballard MSEE CNA4 KD0AZ
--
Consultant specializing in computer networks, imaging & security
Listed as rjballard in "Friends & Favorites" at www.amazon.com
Last book review: "Guerrilla Television" by Michael Shamberg

  #5  
Old June 27th 04, 04:56 PM
Richard Ballard
external usenet poster
 
Posts: n/a
Default 50mm "normal" lens with digital SLR?

In article ,
(Richard Ballard) writes:

In article ,
Chris Brown writes:

In article ,
G.T. wrote:

Chris Brown wrote:

It's very, very simple.

The more I read this thread the more confused I get.

35mm is the "standard" focal length for that camera.

I thought I read someone's calculation that 28mm is.


Well, the actual "normal" focal length is bewteen the two,
and there's not a
lot of difference between them, so either will do the job.


In 35mm film photography there is sufficient difference
between the coverage (and fisheye distortion) of 35mm
and 28mm lenses to justify offering both these lenses --
they are not identical.

As focal length decreases, each millimeter focal length
reduction becomes (percentagewise) increasingly significant.
In some ways, longer focal length lenses are more forgiving
of (a given amount of) imprecision.

I have read this thread with some amusement because
I believe you are arguing the wrong issue.

"Normal" relates imaged scene coverage to human vision coverage
(i.e., what a human views normally using their eyes), while the
imaged scene coverage of a given focal length lens depends upon
the digital SLR's sensor chip area. A smaller focal length lens
coupled with a smaller sensor chip (and appropriate camera
dimensions) gives the same imaged coverage as a larger focal
length lens coupled with a larger sensor chip (and appropriate
camera dimensions). Using a film analogy, the normal (nominal)
50 mm lens used with 35mm SLRs would _not_ provide normal
coverage were they used with a 2"x2" format (type 120 film --


Before somebody jumps down my throat, I know that type 120
film has a (nominal) 2.25" by 2.25" coverage area. Obviously
I never owned a Hasselblad.

e.g., Hasselblad) SLR. 35mm film is one sensor standard and
2"x2" film is a different sensor standard -- different "normal"
lenses for different sensor areas.

Digital photography is not yet fully mature. The different dSLR
manufacturers have not yet agreed on a common sensor size(s).
(The analogous situation is different SLR manufacturers having
different definitions for 35mm film coverage area -- some mask
portions of the 35mm frame to hide lens flaws.) IMO digital
photography will _not_ be fully mature until manufacturers agree
on sensor size. Then industrywide standards will develop,
component commonality will occur, and economies of scale will
drive down digital photography equipment costs. dSLR
manufacturers will compete in the areas of optics quality,
man-machine interface (ease and flexibility of use -- think of the
VCRs you never learned to program), provided features, and
dSLR durability/maintainability.

Sensor quality will become less of an issue because most
manufacturers will utilize the same sensor chip -- a high quality
product made affordable by manufacturing economies of scale
(just like photographic film).

An analogous situation already exists in the computer industry,
and (IMO with some justification) a person can view a dSLR
as a special purpose computer.


'Hope that helps.

Richard Ballard MSEE CNA4 KD0AZ
--
Consultant specializing in computer networks, imaging & security
Listed as rjballard in "Friends & Favorites" at
www.amazon.com
Last book review: "Guerrilla Television" by Michael Shamberg

  #6  
Old June 27th 04, 06:58 PM
john
external usenet poster
 
Posts: n/a
Default 50mm "normal" lens with digital SLR?

Uh... anyway, as the guy who started this thread...

I bought the lens (Nikon 50mm f/1.8). Even if it's not "normal" for me, I
like the f/1.8-ness of it.






"Big Bill" wrote in message
...
On Tue, 22 Jun 2004 15:42:11 GMT, "Frank ess"
wrote:

Big Bill wrote:
On Tue, 22 Jun 2004 00:37:25 +0100, Chris Brown
wrote:

So once again, with these cameras, the 50mm lens is telephoto, the
35mm is "normal". It really is that simple.

Yep.
And you wrote a lot to indicate just how simle you think it is.

OTOH, a lot of people like to understad the tools they are using, and
how they work.
They think this understanding lets them use the tools better.


Well, I dunno...

I have the barest understanding of how a refrigerator works (some kind
of siphoning of energy from the full moon, I think) but the shortcoming
doesn't keep me from grabbing a cool beer now and then. Of course my
needs are relatively simple. If I needed to keep strawberry icecream
cold, it might be too big a challenge. Some day I'll have to look behind
that top door...


Frank ess

Do you use the fridge to make the beer? :-)

Bill Funk
Change "g" to "a"



 




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