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What do they mean when they refer to 1:1 magnification on a Canon 100mm
macro f2.8?

It seems like a 1:1 ration wouldn't give any magnification so what's the
deal?

Jimmy

Hint: Do you print your images in post stamp format? And, if you are using a
computer monitor, how large is your screen? Is it just the size of your
camera's image sensor? A super tiny screen perhaps?

"Jimmy Smith" <> wrote in message
news:E%EFd.25147$. ..
> What do they mean when they refer to 1:1 magnification on a Canon 100mm
> macro f2.8?
>
> It seems like a 1:1 ration wouldn't give any magnification so what's the
> deal?
>
> Jimmy
>
>

"Jimmy Smith" <> wrote in message
news:E%EFd.25147$. ..
> What do they mean when they refer to 1:1 magnification on a Canon 100mm
> macro f2.8?
>
> It seems like a 1:1 ration wouldn't give any magnification so what's the
> deal?
>
> Jimmy

The ratio of 1:1 is the comparison of how big the subject you're shooting
will be compared with it's actual size on the negative (or sensor).

In other words... A lens that is mounted on a film camera, shooting at a
range giving 1:1 macro enlargement...that takes a close-up of a grape that
is one centimeter accross...will produce an image of that grape that takes
up one centimeter of the actual film's surface.

How this translates to tiny sensors in little digicams, or to larger sensors
with DSLRs is a bit more confusing, but the idea is similar. It's not about
magnification via the optics, so much as it is the len's ability to focus
CLOSE enough to the subject to produce this ratio.

If you have a 50mm lens (assuming a 35mm system) that does 1:1, you can be
sure that to acheive this, you must be only a few **inches** away from your
subject. With a 180mm 1:1 macro lens, you'll have the luxery of nearly
quadrupling the distance from your subject, while still acheiving 1:1 images
on the film/sensor plane.
-Mark

GTO wrote:
> Hint: Do you print your images in post stamp format? And, if you are
> using a computer monitor, how large is your screen? Is it just the
> size of your camera's image sensor? A super tiny screen perhaps?
>
> "Jimmy Smith" <> wrote in message
> news:E%EFd.25147$. ..
>> What do they mean when they refer to 1:1 magnification on a Canon
>> 100mm macro f2.8?
>>
>> It seems like a 1:1 ration wouldn't give any magnification so what's
>> the deal?
>>
>> Jimmy

This would mean that the image of your subject would appear on your sensor
the same size.
A 1/2 inch object would be 1/2 inch (on the sensor).

Ken.


--
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Jimmy Smith wrote:
> What do they mean when they refer to 1:1 magnification on a Canon 100mm
> macro f2.8?
>
> It seems like a 1:1 ration wouldn't give any magnification so what's the
> deal?
>
> Jimmy
>
>
Any lens that can focus at a distance equal to its focal length will
give a 1:1 ratio.
That means, Image Size (on the sensor) = Subject Size.
The problem with most regular lenses in regular mounts is that they
cannot focus at distances as short as their focal lengths. But 1:1 Macro
lenses are designed to focus as close as their focal length. e.g. a 50
mm Macro wil give a 1:1 image size when focused at 50 mm or ~2 inches
from the subject.
Bob Williams

On Thu, 13 Jan 2005 20:14:30 -0500, "Jimmy Smith"
<> wrote:

>What do they mean when they refer to 1:1 magnification on a Canon 100mm
>macro f2.8?
>
>It seems like a 1:1 ration wouldn't give any magnification so what's the
>deal?
>
>Jimmy
>

In the film world, 1:1 means that the subject will be the same size on
the negative as in real life. ie. If you took a 1:1 image of a
penny, you could lay a real penny on the negative and it would
precisely match the image,

I don't know how this relates to a CCD environment. I would assume
the same. ie. The same size on the CCD as in real life.

Close ... but I think your "math" is a little off.

Your statement "... Any lens that can focus at a distance equal to its
focal length will
give a 1:1 ratio. ..." is incorrect.

If you use the proper formula, you will find that the image will be the
exact size as the subject when

The distance from the subject image to the lens nodal point is equal to the
distance from the lens' nodal point to the film plane ... which is equal to
*twice* the focal length.

See ... for example ...:
http://www.graflex.org/lenses/lens-faq.html
http://www.photo.net/learn/optics/lensTutorial
http://www.zeiss.de/C12567A8003B58B9...2E5C1C1256CED0
054968D

and several hundred other sites that present the basic lens equation(s).

>>What do they mean when they refer to 1:1 magnification on a Canon 100mm
>>macro f2.8? It seems like a 1:1 ration wouldn't give any magnification so
what's the deal?
>>Jimmy

>In the film world, 1:1 means that the subject will be the same size on
>the negative as in real life. ie. If you took a 1:1 image of a
>penny, you could lay a real penny on the negative and it would
>precisely match the image,
To add to the last reply, I used to have a macro lens that only had a 0.5
magnification. The 1.0 mag. was the best at that time. The only way to best
that was to use a bellows and assemble the lens backwards. Possinly, the 1.0
mag. is still the best macro lens you can get.
Lynn

RSD99 wrote:
> Close ... but I think your "math" is a little off.
>
> Your statement "... Any lens that can focus at a distance equal to its
> focal length will
> give a 1:1 ratio. ..." is incorrect.
>
> If you use the proper formula, you will find that the image will be the
> exact size as the subject when
>
> The distance from the subject image to the lens nodal point is equal to the
> distance from the lens' nodal point to the film plane ... which is equal to
> *twice* the focal length.
>
> See ... for example ...:
> http://www.graflex.org/lenses/lens-faq.html
> http://www.photo.net/learn/optics/lensTutorial
> http://www.zeiss.de/C12567A8003B58B9...2E5C1C1256CED0
> 054968D
>
> and several hundred other sites that present the basic lens equations



Mea Culpa!
You are absolutely correct.
I should have said that, "any lens that can focus at TWICE its focal
length will give a 1:1 magnification."
Thanks for the heads up.
Bob Williams

RSD99 wrote:
> Close ... but I think your "math" is a little off.
>
> Your statement "... Any lens that can focus at a distance equal to its
> focal length will
> give a 1:1 ratio. ..." is incorrect.
>
> If you use the proper formula, you will find that the image will be the
> exact size as the subject when
>
> The distance from the subject image to the lens nodal point is equal to the
> distance from the lens' nodal point to the film plane ... which is equal to
> *twice* the focal length.
>
> See ... for example ...:
> http://www.graflex.org/lenses/lens-faq.html
> http://www.photo.net/learn/optics/lensTutorial
> http://www.zeiss.de/C12567A8003B58B9...2E5C1C1256CED0
> 054968D
>
> and several hundred other sites that present the basic lens equation(s).
>
>
>

Ha! Finally somebody that knows the standard definition.

Also what is it about 1:1 that do people not understand?
It's a ratio. $1 for 1 orange, 1 foot high for each 1 foot
forward, etc. With a lens what else can it mean but the
image is the same size as the object?

Why do people speculate about definitions instead of just
reading about them in an authoritative publication.