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I'm interested in using my 10D for some macro pictures but I am confused
about which lens to get. I admit I don't understand much about macro - never
having tried it before. I'd like to get a decent lens for this because I can
use it for portrait work.

Basically, I'd like to know about the ratios that are often quoted alongside
these lenses. What does 0.5x or 1:1 actually mean? I'm considering the Canon
100mm 2.8 USM because everything I've read is good. I'm not sure how useful
it would be as a portrait lens though because it's quite long and there's
the multiplier factor to consider as well. The 50mm macros I've seen seem to
quote a 0.5x - does that mean it's inferior for macro work (but more useful
for portrait)?

Thanks for any help - macro really us uncharted territory for me, although I
consider myself fairly clued up in other areas

Mike wrote:
> I'm interested in using my 10D for some macro pictures but I am confused
> about which lens to get. I admit I don't understand much about macro -
> never
> having tried it before. I'd like to get a decent lens for this because I
> can
> use it for portrait work.
>
> Basically, I'd like to know about the ratios that are often quoted
> alongside
> these lenses. What does 0.5x or 1:1 actually mean? I'm considering the
> Canon
> 100mm 2.8 USM because everything I've read is good. I'm not sure how
> useful
> it would be as a portrait lens though because it's quite long and there's
> the multiplier factor to consider as well. The 50mm macros I've seen seem
> to
> quote a 0.5x - does that mean it's inferior for macro work (but more
> useful
> for portrait)?
>
> Thanks for any help - macro really us uncharted territory for me, although
> I
> consider myself fairly clued up in other areas

A "true" macro will reproduce a life size image on the recording media.
On film that means a one inch bug will appear to be exactly one inch long on
the negative. That is 1:1 ratio At a 1:2 or 0.5X, the bug would be ½ inch
long on the negative. Many "macro" lenses need a extension which may or may
not come with the lens to active the full 1:1.

Digital does not come into play here as they are taking about the size
of the image on the media so a 1:1 image on a 8X10 negative will be the same
size, but include a subject area of 8X10 inches as a 35 mm camera image buy
the 35mm image will not cover as much area and you digital may cover even
less.

Next thing to think about is the fact that there appears to be no legal
definition of "macro" so you will find some manufacturers using the term
loosely to refer to anything that may take a close up. Zoom lenses with the
ability to focus reasonably close are often called macro, especially if they
have a special setting to allow them to focus close. They may not focus
close enough to get anywhere near life size 1:1.

Also worth noting is that most true macro lenses are very sharp at
normal distances and have been optimized for close work so they are
outstanding at those distances. They also are usually corrected for a very
flat field so when you are copying something flat like a stamp it will be
sharp from the center to the edge, most lenses will not do that if you add
extension tubes or close up lenses to focus that close.

Good Luck
--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math

On Wed, 20 Oct 2004 16:42:48 +0100, "Mike" <>
wrote:

>I'm interested in using my 10D for some macro pictures but I am confused
>about which lens to get. I admit I don't understand much about macro - never
>having tried it before. I'd like to get a decent lens for this because I can
>use it for portrait work.
>
>Basically, I'd like to know about the ratios that are often quoted alongside
>these lenses. What does 0.5x or 1:1 actually mean? I'm considering the Canon
>100mm 2.8 USM because everything I've read is good. I'm not sure how useful
>it would be as a portrait lens though because it's quite long and there's
>the multiplier factor to consider as well. The 50mm macros I've seen seem to
>quote a 0.5x - does that mean it's inferior for macro work (but more useful
>for portrait)?
>
>Thanks for any help - macro really us uncharted territory for me, although I
>consider myself fairly clued up in other areas

The 100mm macro is the way to go for you. The 1:1 means that an
object is the same size on the image as it is in real life, 1:0.5 (or
0.5x) means that the object is 1/2 of life size. A true macro lens is
1:1 or better, Canon makes another macro lens that 1:1: - 1:5

Mike wrote:


>
> Basically, I'd like to know about the ratios that are often quoted alongside
> these lenses. What does 0.5x or 1:1 actually mean? I'm considering the Canon
> 100mm 2.8 USM because everything I've read is good. I'm not sure how useful
> it would be as a portrait lens though because it's quite long and there's
> the multiplier factor to consider as well. The 50mm macros I've seen seem to
> quote a 0.5x - does that mean it's inferior for macro work (but more useful
> for portrait)?


Go for the 100mm for macro. It is a very good macro and pretty good portrait
lens (on film).

The crop makes it a bit severe for portrait, and you'll need a lot of room ...
the result will be a bit flat looking for a head and shoulders shot.

In macro, it is generally accepted that 1:2 (0.5x) or better is a 'macro' lens,
but most claim 1:1 or better is the real deal.

On film 1:1 means a 1/2 inch long feature (shot at 1:1) will be 1/2 inch long on
the film itself (same for digtital wrt the sensor of course, but meaningless
once stored). This means a lot of detail is captured.

Even if the 50mm were 1:1, 100mm is better as it gives you more working room in
front of the lens to get light in there.

Pick up a basic (low cost) 50mm f/1.8 and you will have a very decent 1.5x
portrait lens, or even an f/1.4 if that little bit more light and shallower DOF
is important to you.

Cheers,
Alan

--
-- rec.photo.equipment.35mm user resource:
-- http://www.aliasimages.com/rpe35mmur.htm
-- e-meil: there's no such thing as a FreeLunch.--

"Mike" <> wrote in message news:cl611p$o8a$...
> I'm interested in using my 10D for some macro pictures but I am confused
> about which lens to get. I admit I don't understand much about macro - never
> having tried it before. I'd like to get a decent lens for this because I can
> use it for portrait work.
....

I'll comment only on the portrait part of your question.

A slight telephoto is good for portraits for a number of
reasons.

1. It lowers the depth of field at close ranges so you
can isolate your subject from the background more
easily.

2. It prevents the lens distortion that one gets with
wide angle lenses where, for example, a person's
nose may show up bigger because it's closer to the
lens than, say, the ears. It does this because of point 3.
If you stand too close to the subject, you get that
lens distortion.

3. It allows you to stand back a bit from the subject
and fill the frame with head or head and shoulders
without being in the subject's face.

I think that in the 35mm world, 75-100 mm lenses
are commonly used for portraits.

Alan

>1:0.5 (or
> 0.5x) means that the object is 1/2 of life size.

1:0.5 means the image is twice life size. 1:2 means the image is 1/2 life
size.

The prior posts address most of your questions. I'll add that the Sigma 105
mm f/2.8 macro lens is worth taking a look at. I like mine.

I've only got Sigma lenses so far - three EX lenses covering all options
from 16mm up to 500mm and yes, I'm satisfied with the results. I'm looking
at Canon options after reading that their lenses are far superior (I want to
see the results for myself!) I'll obviously give the lenses a test drive at
the store first and I will add the Sigma to my list. It now consists of the
Canon 100mm, the Tamron 90mm and the Sigma you mention. By the way, I am the
OP - using my home computer instead of work!
Thanks.

"Charles Schuler" <> wrote in message
news:v4adnZDYG9aPS-vcRVn-...
> The prior posts address most of your questions. I'll add that the Sigma
105
> mm f/2.8 macro lens is worth taking a look at. I like mine.
>
>