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Macro --what happens in camera?

Last response: in Digital Camera
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January 27, 2005 11:28:47 AM

Archived from groups: rec.photo.digital (More info?)

I have a few digicams--Nikon,Canon all with their macro mode. I could
not figure out what this mode does to the camera. I cannot hear any
lens being moved inside to change the focusing ability.

A search on Google discovered no answer but only a few similar
questions.

anyone,please?

ABC
Do not reply by email. Replay to NG

More about : macro camera

Anonymous
January 27, 2005 11:28:48 AM

Archived from groups: rec.photo.digital (More info?)

To focus closely (what is referred to as macro mode) The lens system moves
out away from the sensor. On compact cameras, this may be slight and not
very apparent.

If you ever get your hands on a film or digital SLR, focus the lens on
something close. You should note how the lens extends more from the main
barrel (unless it is internal focusing type which could also be the case on
some digital compacts.)

John


"ABC" <ABC@nospam.net> wrote in message
news:p 7dgv092j1oobitogvgfhh7v1415ih46oh@4ax.com...
>I have a few digicams--Nikon,Canon all with their macro mode. I could
> not figure out what this mode does to the camera. I cannot hear any
> lens being moved inside to change the focusing ability.
>
> A search on Google discovered no answer but only a few similar
> questions.
>
> anyone,please?
>
> ABC
> Do not reply by email. Replay to NG
Anonymous
January 27, 2005 4:00:02 PM

Archived from groups: rec.photo.digital (More info?)

Optics is an unforgiving science. It turns out that for any (typical)
optical system, one can only optimize for one particular
camera-to-object relationship. Given an object distance, the lens
lements can be subtly bent to optimize spherical aberations, comatic
aberations, astigmetic aberations, field flatness, distortion, and last
but not least Chromatic aberations. Once bent, the lens as a whole has
been optimized for this lens-to-object relationship, and the lens will
be less sharp anywhere else. Notice that the changes are occuring to
the glass elements themselves, to to their spacing.

A 'regular' camera lens is optimized for a focus point close to
infinity. Optimized means that the aberations are made as well as the
lens designer can do for that focal length (almost infinity).

A 'macro' lens is optimized for lens to object distances close to the
focal length of the lens, adjusting the shapes of the lens surfaces to
optimize this different goal--sharp focus at very small distances.

When a regular lens is used at very close focal distances (as a
'macro'), the shperical aberation can become unusefully larger than the
'regular' case. With a small sacrifice to coma and astigmatism, an
interior lens (or lens group) can be moved a small amount to optimize
the lens for a focal distance only a few focal lengths away from the
front element of the lens itself. Done thusly, the combination lens is
passable as a macro.
Related resources
Anonymous
January 27, 2005 4:10:14 PM

Archived from groups: rec.photo.digital (More info?)

MitchAlsup@aol.com wrote:
> Optics is an unforgiving science. It turns out that for any (typical)
> optical system, one can only optimize for one particular
> camera-to-object relationship. Given an object distance, the lens
> lements can be subtly bent to optimize spherical aberations, comatic
> aberations, astigmetic aberations, field flatness, distortion, and
> last but not least Chromatic aberations. Once bent, the lens as a
> whole has been optimized for this lens-to-object relationship, and
> the lens will be less sharp anywhere else. Notice that the changes
> are occuring to the glass elements themselves, to to their spacing.
>
> A 'regular' camera lens is optimized for a focus point close to
> infinity. Optimized means that the aberations are made as well as the
> lens designer can do for that focal length (almost infinity).
>
> A 'macro' lens is optimized for lens to object distances close to the
> focal length of the lens, adjusting the shapes of the lens surfaces to
> optimize this different goal--sharp focus at very small distances.
>
> When a regular lens is used at very close focal distances (as a
> 'macro'), the shperical aberation can become unusefully larger than
> the 'regular' case. With a small sacrifice to coma and astigmatism, an
> interior lens (or lens group) can be moved a small amount to optimize
> the lens for a focal distance only a few focal lengths away from the
> front element of the lens itself. Done thusly, the combination lens is
> passable as a macro.

Thank you.


--
Frank ess

PS: I'll appreciate it when you leave enough of the post you are
responding to so I can understand your motives and references.
Anonymous
January 27, 2005 11:36:51 PM

Archived from groups: rec.photo.digital (More info?)

"JohnR66" <nospam@att.net> wrote in
news:SyYJd.95455$w62.8952@bgtnsc05-news.ops.worldnet.att.net:

> To focus closely (what is referred to as macro mode) The lens system
> moves out away from the sensor. On compact cameras, this may be slight
> and not very apparent.

On my Canon G2 nothing happens.

It is my guess that the macro setting is just a software thing.
It makes it more easy for the camera to focus by limiting the
search to two different areas. Or - it might (ouch!) be just
a marketing ploy. A camera must have a macro mode - otherwise it
is not possible to sell.


/Roland
Anonymous
January 28, 2005 12:47:05 PM

Archived from groups: rec.photo.digital (More info?)

On 27 Jan 2005 20:36:51 GMT, Roland Karlsson
<roland_dot_karlsson@bonetmail.com> wrote:

>"JohnR66" <nospam@att.net> wrote in
>news:SyYJd.95455$w62.8952@bgtnsc05-news.ops.worldnet.att.net:
>
>> To focus closely (what is referred to as macro mode) The lens system
>> moves out away from the sensor. On compact cameras, this may be slight
>> and not very apparent.
>
>On my Canon G2 nothing happens.
>
>It is my guess that the macro setting is just a software thing.
>It makes it more easy for the camera to focus by limiting the
>search to two different areas. Or - it might (ouch!) be just
>a marketing ploy. A camera must have a macro mode - otherwise it
>is not possible to sell.

on the G6 the lens systems moves and the cam refocusses when switching
to macro .. so what is the take on that ? same on supermacro ..
curious to read .. (similar thread on dpreview almost ad infinitum ..
:-))
Anonymous
January 28, 2005 11:40:12 PM

Archived from groups: rec.photo.digital (More info?)

Roland Karlsson <roland_dot_karlsson@bonetmail.com> writes:

>On my Canon G2 nothing happens.

You mean nothing happens when you press the button to engage macro mode.
But the camera now searches a larger range of distances to look for
correct focus. Now it will focus on closer things - but it takes longer
to fail to focus if it's going to.

>It is my guess that the macro setting is just a software thing.
>It makes it more easy for the camera to focus by limiting the
>search to two different areas.

That's right. Or it might still be able to focus at infinity in macro
mode; I don't remember. In other words, it either shifts the focus
range, or just extends it.

>Or - it might (ouch!) be just
>a marketing ploy.

No, there's a real difference in the distance range that the focus will
lock.

Dave
Anonymous
January 28, 2005 11:43:10 PM

Archived from groups: rec.photo.digital (More info?)

"Frank ess" <frank@fshe2fs.com> writes:

>PS: I'll appreciate it when you leave enough of the post you are
>responding to so I can understand your motives and references.

That might be nice, but that's also what threaded newsreaders provide.
It's usually a single keystroke or mouse click to read the preceding
article that any given article is a reply to.

If your newsreader doesn't provide threading at all, you really should
look for something better. You're missing an important tool without
it.

Dave
Anonymous
January 28, 2005 11:43:11 PM

Archived from groups: rec.photo.digital (More info?)

Dave Martindale wrote:
> "Frank ess" <frank@fshe2fs.com> writes:
>
>> PS: I'll appreciate it when you leave enough of the post you are
>> responding to so I can understand your motives and references.
>
> That might be nice, but that's also what threaded newsreaders provide.
> It's usually a single keystroke or mouse click to read the preceding
> article that any given article is a reply to.
>
> If your newsreader doesn't provide threading at all, you really should
> look for something better. You're missing an important tool without
> it.
>

You are so generous with your advice.

--
Frank ess
!