Prime lenses for x1.6 focal length cameras

In my (many) years of 35mm film photography, prime lense selection
always seemed raher simple:

50mm gave a perspective that seemed natural to the human eye and could
be considered "standard"; 35mm was moderately wide angle; 28mm rather
wide angle and 80mm good for reducing depth of field in portraits.

Now that I have been seduced to the EOS400 world, with its accompanying
1.6 focal length multiplier, it all seem rather more awkward.

In an attempt to get a "standard" lens I have bought an EF 28mm f2.8.
This works out as quite visibly more wide angle than a 50mm on a film
camera. I did try an EF 35mm but its equivalent 56mm was markedly
narrower in field of view than a 50mm on a film camera.

The only easy one was the 50mm which gives me the 80mm portrait lens I
am used to.

So do I just have to get used to this or will some "standard" small
sensor lenses eventually appear? Or is this why there are so many zooms
about?


Peter

 

For many years I owned a plastic 127 Kodak Brownie camera
of no particular focal length, no diaphragm and a fixed, unknown
shutter speed. Then all of a sudden I was given a Kodak 35mm
rangefinder camera with 50mm lens, shutter speeds from B to 1/200 and
an f3.5 to f22 lens. I am still stunned and perplexed by the changes
that were thrust upon me and still suffer from missing the joys of
that 127 Brownie. Why does the world frustrate me so?!

 

It really answers the recent crop of wider "standard kit zooms" that are
about. Fixed focal length lenses are just not highly popular.

OTOH, if you simply crop the 28mm result a little bit, you will get a
look very similar to the original 50mm result ... in fact center-to-edge
sharpness will be a little better for anything up to about an 8x12
print. So just frame a little loosely and crop it a little in the
computer later on.

Cheers,
Alan.

 

Sigma has a nice, fast 30mm lens (f/1.4) which is equivalent to
48mm on your EOS400. I've used 50mm, 55mm, 58mm and 60mm fixed
focal length lenses on my old SLRs, and didn't consider the
differences in focal lengths so be substantial. A zoom lens would
certainly solve your problem getting precisely the 50mm focal length
that you want, but I suspect that if you checked the photos you'd
take with it, you'd have nearly as many taken using 45mm and 55mm as
50mm. In any case, if you think that the Sigma's equivalent 48mm fl
would be too short, you must have loved reading H. C. Andersens "The
Princess And The Pea" when you were but a mere tadpole.

 

On a Canon 1.6 cropped body:

24mm
50mm

 

: In my (many) years of 35mm film photography, prime lense selection
: always seemed raher simple:
:
: 50mm gave a perspective that seemed natural to the human eye and could
: be considered "standard"; 35mm was moderately wide angle; 28mm rather
: wide angle and 80mm good for reducing depth of field in portraits.
:
: Now that I have been seduced to the EOS400 world, with its accompanying
: 1.6 focal length multiplier, it all seem rather more awkward.
:
: In an attempt to get a "standard" lens I have bought an EF 28mm f2.8.
: This works out as quite visibly more wide angle than a 50mm on a film
: camera. I did try an EF 35mm but its equivalent 56mm was markedly
: narrower in field of view than a 50mm on a film camera.
:
: The only easy one was the 50mm which gives me the 80mm portrait lens I
: am used to.
:
: So do I just have to get used to this or will some "standard" small
: sensor lenses eventually appear? Or is this why there are so many zooms
: about?

Try the Sigma 30mm f/1.4. I bought one after a very long discussion of its
good and bad points in either this newsgroup or its parent.

IMO, a compelling argument for an f/1.4 lens is that there are quite good
normal zoom lenses down to f/2.8. So there's little point in buying a non-zoom
if you don't get that extra couple of stops.

Bob

 

I do believe that is why there are so many zooms about. I've settled
on the 17-85 EF IS as my walkaround lens on my 400D, after trying the
28-135 IS for a while.

I also miss my official Cub Scout 127 box camera, and the smell of the
fired flash bulbs, from 1958!

Paul B.
www.scienceteacher.biz

 

: On a Canon 1.6 cropped body:
:
: 24mm
: 50mm

I guess I can't be certain what you're saying, but I'm pretty sure it's wrong.

Bob

 

: I also miss my official Cub Scout 127 box camera, and the smell of the
: fired flash bulbs, from 1958!

Ah, yes, the characteristic aroma (smoky with a hint of toasted vinyl) of a
burned-out speed midget. ;^)

But who made a 127 box camera? All the box cameras (i.e., cameras in the shape
of an equiangular hexahedron) I ever saw took either 620 or 616 film. The 127
Brownies had rounded corners and/or beveled edges and weren't true box cameras
by my definition.

Bob

 

The focal length IS NOT MULTIPLIED!!!!!!!! This is the most constant
digital camera myth. The image is cropped. Print an 8x12 from a film SLR
and chop the center 5x8 from that image.

You observations go counter to what has been said on the Net, and by
misinformed camera sales people.

A 50mm will always be a 50mm lens, the DoF and perspective doesn't
change when the lens is then mounted on an APS-C dSLR.

 

Might I suggest a Nikon D40 with a 25mm lens?
Set on "P" or better yet, some "Scene" setting designed to freeze
action.

 

Just make sure you can return it for a new one (a reputable dealer and
not someone on Ebay) if it has backfocus issues.

 

My first camera, a real P&S if there ever was one :

http://mattdentonphoto.com/cameras/kodak_hawkeye.html

and the Sylvania Blue Dots that warmed my pockets :


http://www.cedu.niu.edu/blackwell/multimedia/images/JPEGS/SLIDE213.JPG

 

That's not what you find when you actually do photography. You assume DoF is
observed at the sensor; it's not, it's observed in the print. (Also,
perspective is determined by the distance of the camera from the subject,
not focal length.)

Stand at the same place. Use a 30mm on your 12MP APS-C, 50mm on your 5D.
Take the same picture (same composition), same f stop, same ISO, same
shutter speed.

Make prints that are the same size, e.g. 8x12.

The APS-C image will have 1.6x the DOF.

It will also have slightly more than a stop worse noise, and if the f stop
is f/4 (maybe even f/5.6) or wider, of f/16 or narrower, the APS-C camera
image will be softer due to the finer pixel pitch and greater enlargement
used.

David J. Littleboy
Tokyo, Japan

 

Yes, a 30mm lens has more DoF than a 50mm, which is what I said!

 

However, a 30mm lens on a sensor with the size of 135mm film will have
1.5^2 times more DOF than the same lens on a (say) Nikon sensor (one
with 1.5 times smaller linear dimensions). If you change the sensor
size and, simultaneously, the focal length so as to keep the field of
view constant, the end result is that you get A times more DOF, where
A is the factor by which your sensor is smaller (linearly). So 1.5 (or
1.6), as DJL said.

DOF is usually defined on the print, not on the sensor (it's ok if you
don't like that, though); a smaller sensor means more magnification to
get the same print size, which brings in a factor 1/A (multiplied by
A^2 due to the shorter focal length, this results in a DOF larger by
A).

If you put the same lens on two cameras with two sensors differing in
linear size by A, and print to the same size (and focus at the same
distance, same f/stop etc), the smaller sensor will display less DOF.
This is because you enlarge the image more, so the circle to which a
point is mapped is enlarged more.

 

: On Sat, 04 Aug 2007 20:11:18 -0400, Robert Coe wrote:
: > Ah, yes, the characteristic aroma (smoky with a hint of toasted vinyl) of a
: > burned-out speed midget. ;^)
:
: My first camera, a real P&S if there ever was one :
:
: http://mattdentonphoto.com/cameras/kodak_hawkeye.html
:
: and the Sylvania Blue Dots that warmed my pockets :
:
:
: http://www.cedu.niu.edu/blackwell/multimedia/images/JPEGS/SLIDE213.JPG

!!! ;^)

My first camera was a "Brownie Reflex - Synchro Model" (which meant it could
take a flash unit, which I eventually bought). My brother - three years
younger - got a "Baby Brownie Special" (no flash) that same Christmas.

My Brownie Reflex had X-synchronization between the shutter and the flash,
which meant that your 25-millisecond foil-filled bulbs would have been too
slow. I had to buy the gas-filled "speed midgets".

The Brownie lasted me until I was fifteen, when my parents gave me an Argus
C-3, WHICH I STILL HAVE along with my Nikon F-2. Of course I never use either
one in this Digital Age. :^|

Bob


"Brownie, you're doin' a heck of a job." - The Moron Bush

 

Err... Let's try again: a 30mm on a 135mm film-sized sensor will have
around 1.5^2 more DOF than a 50mm lens on the same sensor. But if you
have a smaller sensor (1.5 times smaller) and a 30mm lens, it will
have only 1.5 times more DOF than a 50mm lens on a 135mm film-sized
sensor.

 

: > On Sat, 04 Aug 2007 20:58:02 +0100, Peter Amey wrote:
: > > In an attempt to get a "standard" lens I have bought an EF 28mm f2.8.
: > > This works out as quite visibly more wide angle than a 50mm on a film
: > > camera. I did try an EF 35mm but its equivalent 56mm was markedly
: > > narrower in field of view than a 50mm on a film camera.
: > > . . .
: > > So do I just have to get used to this or will some "standard" small
: > > sensor lenses eventually appear? Or is this why there are so many
: > > zooms about?
: >
: > Sigma has a nice, fast 30mm lens (f/1.4) which is equivalent to
: > 48mm on your EOS400.
:
: Just make sure you can return it for a new one (a reputable dealer and
: not someone on Ebay) if it has backfocus issues.

Rich, are you sure you're playing this game with all 52 cards? The 30mm Sigma
is a NEW lens specifically DESIGNED FOR 1.6-crop digitals. I bought one for my
EOS 400D, and it works just fine.

Bob