Olympus M.ZUIKO 60mm 1:2.8 macro - minimum field size?

On Sun, 07 Aug 2016 15:52:02 -0800, (Floyd L.
Davidson) wrote:

Eric Stevens wrote:
On Sun, 07 Aug 2016 02:02:36 -0800, (Floyd L.
Davidson) wrote:

Eric Stevens wrote:
On Sat, 06 Aug 2016 23:06:37 -0800, (Floyd L.
Davidson) wrote:

Eric Stevens wrote:
On Sat, 06 Aug 2016 03:07:47 -0800, (Floyd L.
Davidson) wrote:

David Taylor wrote:
Could anyone please confirm what the field seen is for
the Olympus M.ZUIKO 60mm 1:2.8 macro lens at maximum
macro setting (closest focus):

https://www.amazon.co.uk/gp/product/B009C742Y2

Is it the MFT frame size (17.3 mm Ã--- 13.0 mm) or twice
that (i.e. 34.6 x 26 mm)?

At 1:1 the field of view is exactly the same as the sensor size.
So if you put it on a 17.3x13.0mm sensor, that is what the
field of view will be.

That will occur only when the lens is racked (screwed?) out to twice
its nominal focal length. Before the size of the seen field can be
determined it is necessary to now how far the lense can extended.

Nonsense Eric.

One thing, see that last paragraph below, that has not
been stated at all is important to your comment, but
really the only thing that counts is the "At 1:1"
factoid.

With a lens designed specifically for a minimum focus
distance that produces 1:1 magnification ...

Nobody has stated what minimum focus distance or its accompanying
magnification actually is.

Because it clearly does not make any difference what is actually is.

That's a silly remark. The magnification is at the heart of the
question.

Your question was the silly remark! We know what the
magnification is, that was specified. We don't care
what the MFD actuall is because, for this discussion, it
does not make any difference. That's not silly, that's
a fact.

Regardless of all of your obfuscation, at 1:1
magnification the size of the field of view will be
*exactly* the size of the sensor.

There can be no argument with that. My original response arose from
the fact that (1) I did not know the near limit of the focussing range
for the lens and (2) whether or not its focussing enabled it to give a
1:1 image/object ratio. None of this would have arisen if I had
written 'focussed' rather than 'extended'.

By definition. If
the lens is specified to have 1:1 magnification at the
MFD, we don't need to know the mfd we jus need to set
focus the the minimum distance.

The question was not what the MFD is, it was what is the field
of view at MFD for that one specific lens. It turns out that
lens is specified to have 1:1 magnification at MFD.

... the entirety of your comment is meaningless.

Go back to basic optics.

Good idea Eric. Do that!

Just set the lens at
minimum focus distance, and 1) it is at 1:1
magnification which brings about 2) the sensor size is
exactly the field of view.

But is that correct? Where do you get the information about minimum
focus distance from?

Try using Google to check the specifications for
that specific lens, and then actually *read* what it
says...

Did you check this information before you first replied? If you did,
why didn't you state the fact and give a source? Or did you just
assume that the lens had 1:1 capability?

Of course I looked at the URL that David provided. I
also read it, and I even understood what it said!:-)

You should have done the same...

What I stated is correct. A simple lens will give 1:1 reproduction
when both the object distance and the image distance = twice the focal

You didn't say "A simple lens will", you said that *this* lens will.
*t won't.*

length. This is measured from the centre of the lens plane. With a
complex compound lens such as the lens under discussion there is no
single physical lens plane but there is a virtual lens plane.

Eh? Making things up again huh. That has nothing to do
with anything. What does make a difference, for this
part of your error, is that this lens uses what is
called an "Internal Focus" design. It doesn't move the
lens as a unit away from the sensor to focus closer.
Instead the sensor to lens distance is fixed, and
internal element groups are moved in relation to each
other. (Yes I know what wanted to say, and why. It makes
not difference though. Even if you'd said it correctly.)

Unfortunately this moves around and can even lie outside either end of
the lens assembly. And then with built in telephoto lens units the
image distance in particular can be telescoped. Nevertheless, my point
stands: at 1:1 the object is 12cm from the virtual lens.

You are talking about what is called the "principal
focal plane". Obviously we don't really need to be
concerned with that for this discussion.

The principal focal plane is a different thing altogether.

David gave us the needed information:

"the Olympus M.ZUIKO 60mm 1:2.8 macro lens at maximum
macro setting (closest focus):

https://www.amazon.co.uk/gp/product/B009C742Y2"

Otherwise, what your comment above missed entirely is
that the lens in question uses an "Internal Focus"
design. The sensor to lens distance does not change as
it is focused.

But what does the magnification do? You don't actually know.

Maybe you don't know, but I do! At the MFD the
magnification is specified as 1:1. I guarantee the
focal length has changed, the effective aperture has
changed, but the sensor to lens distance is exactly the
same.

But with focussing relying on three sets of independently driven
moving elements, the sensor to virtual lens distance *will* have
changed.

Who cares? That still has nothing to do with this
discussion. We can't see where the principal focal
plane is, and never need to know while using a lens. We
need to know where the sensor plane is, where the front
of the lens is, and how those two relate to the object.

http://www.bhphotovideo.com/c/produc...0mm_f_2_8.html
or http://tinyurl.com/bm5l28o says:

"You can focus as close as 7.4" (18.8 cm) with the maximum
reproduction ratio of 1:1. Other minimum focusing distances

Ha ha, that is funny! "Other minimum focusing distances"???
They aren't. Only the minimum focusing distance is a
minimum focusing distance. For that lens it is 18.8cm.

Measured from where?

It is measured from the sensor. There is only one
minimum focusing distance. Any other distance at which
the lens can focus is not the minimum. Note that there
is also a "minimum working distance", measured from the
front element of the lens to the subject when focused at
the MFD.

available include 7.9" (20 cm) at a reproduction ratio of 1:1.3,
9.1" (23 cm) at 1:2, and 13.4" (34 cm) at 1:4."

... so 1:1 does seem to be the limit.

And that is all we need to know! That is what the
question was about. That is what the discussion was
initially about. And note that it says nothing at all
about changing the lens extension (because it doesn't
change).

But it changes the effective optical centre.

So what? You can't see it and you can't use it for any
purpose while making pictures with the lens.
--

Regards,

Eric Stevens

Eric Stevens wrote:
On Sun, 07 Aug 2016 15:52:02 -0800, (Floyd L.
Davidson) wrote:

Eric Stevens wrote:
On Sun, 07 Aug 2016 02:02:36 -0800, (Floyd L.
Davidson) wrote:

Eric Stevens wrote:
On Sat, 06 Aug 2016 23:06:37 -0800, (Floyd L.
Davidson) wrote:

Eric Stevens wrote:
On Sat, 06 Aug 2016 03:07:47 -0800, (Floyd L.
Davidson) wrote:

David Taylor wrote:
Could anyone please confirm what the field seen is for
the Olympus M.ZUIKO 60mm 1:2.8 macro lens at maximum
macro setting (closest focus):

https://www.amazon.co.uk/gp/product/B009C742Y2

Is it the MFT frame size (17.3 mm Ã--- 13.0 mm) or twice
that (i.e. 34.6 x 26 mm)?

At 1:1 the field of view is exactly the same as the sensor size.
So if you put it on a 17.3x13.0mm sensor, that is what the
field of view will be.

That will occur only when the lens is racked (screwed?) out to twice
its nominal focal length. Before the size of the seen field can be
determined it is necessary to now how far the lense can extended.

Nonsense Eric.

One thing, see that last paragraph below, that has not
been stated at all is important to your comment, but
really the only thing that counts is the "At 1:1"
factoid.

With a lens designed specifically for a minimum focus
distance that produces 1:1 magnification ...

Nobody has stated what minimum focus distance or its accompanying
magnification actually is.

Because it clearly does not make any difference what is actually is.

That's a silly remark. The magnification is at the heart of the
question.

Your question was the silly remark! We know what the
magnification is, that was specified. We don't care
what the MFD actuall is because, for this discussion, it
does not make any difference. That's not silly, that's
a fact.

Regardless of all of your obfuscation, at 1:1
magnification the size of the field of view will be
*exactly* the size of the sensor.

There can be no argument with that. My original response arose from
the fact that (1) I did not know the near limit of the focussing range
for the lens and (2) whether or not its focussing enabled it to give a
1:1 image/object ratio. None of this would have arisen if I had
written 'focussed' rather than 'extended'.

By definition. If
the lens is specified to have 1:1 magnification at the
MFD, we don't need to know the mfd we jus need to set
focus the the minimum distance.

The question was not what the MFD is, it was what is the field
of view at MFD for that one specific lens. It turns out that
lens is specified to have 1:1 magnification at MFD.

... the entirety of your comment is meaningless.

Go back to basic optics.

Good idea Eric. Do that!

Just set the lens at
minimum focus distance, and 1) it is at 1:1
magnification which brings about 2) the sensor size is
exactly the field of view.

But is that correct? Where do you get the information about minimum
focus distance from?

Try using Google to check the specifications for
that specific lens, and then actually *read* what it
says...

Did you check this information before you first replied? If you did,
why didn't you state the fact and give a source? Or did you just
assume that the lens had 1:1 capability?

Of course I looked at the URL that David provided. I
also read it, and I even understood what it said!:-)

You should have done the same...

What I stated is correct. A simple lens will give 1:1 reproduction
when both the object distance and the image distance = twice the focal

You didn't say "A simple lens will", you said that *this* lens will.
*t won't.*

length. This is measured from the centre of the lens plane. With a
complex compound lens such as the lens under discussion there is no
single physical lens plane but there is a virtual lens plane.

Eh? Making things up again huh. That has nothing to do
with anything. What does make a difference, for this
part of your error, is that this lens uses what is
called an "Internal Focus" design. It doesn't move the
lens as a unit away from the sensor to focus closer.
Instead the sensor to lens distance is fixed, and
internal element groups are moved in relation to each
other. (Yes I know what wanted to say, and why. It makes
not difference though. Even if you'd said it correctly.)

Unfortunately this moves around and can even lie outside either end of
the lens assembly. And then with built in telephoto lens units the
image distance in particular can be telescoped. Nevertheless, my point
stands: at 1:1 the object is 12cm from the virtual lens.

You are talking about what is called the "principal
focal plane". Obviously we don't really need to be
concerned with that for this discussion.

The principal focal plane is a different thing altogether.

Well that is certainly what you described. Actually there are
two "principal focal planes" and that refers to the rear principal
focal plane. Maybe you were thinking of the exit pupil, or maybe
the nodal points. Different.

David gave us the needed information:

"the Olympus M.ZUIKO 60mm 1:2.8 macro lens at maximum
macro setting (closest focus):

https://www.amazon.co.uk/gp/product/B009C742Y2"

Otherwise, what your comment above missed entirely is
that the lens in question uses an "Internal Focus"
design. The sensor to lens distance does not change as
it is focused.

But what does the magnification do? You don't actually know.

Maybe you don't know, but I do! At the MFD the
magnification is specified as 1:1. I guarantee the
focal length has changed, the effective aperture has
changed, but the sensor to lens distance is exactly the
same.

But with focussing relying on three sets of independently driven
moving elements, the sensor to virtual lens distance *will* have
changed.

Who cares? That still has nothing to do with this
discussion. We can't see where the principal focal
plane is, and never need to know while using a lens. We
need to know where the sensor plane is, where the front
of the lens is, and how those two relate to the object.

http://www.bhphotovideo.com/c/produc...0mm_f_2_8.html
or http://tinyurl.com/bm5l28o says:

"You can focus as close as 7.4" (18.8 cm) with the maximum
reproduction ratio of 1:1. Other minimum focusing distances

Ha ha, that is funny! "Other minimum focusing distances"???
They aren't. Only the minimum focusing distance is a
minimum focusing distance. For that lens it is 18.8cm.

Measured from where?

It is measured from the sensor. There is only one
minimum focusing distance. Any other distance at which
the lens can focus is not the minimum. Note that there
is also a "minimum working distance", measured from the
front element of the lens to the subject when focused at
the MFD.

available include 7.9" (20 cm) at a reproduction ratio of 1:1.3,
9.1" (23 cm) at 1:2, and 13.4" (34 cm) at 1:4."

... so 1:1 does seem to be the limit.

And that is all we need to know! That is what the
question was about. That is what the discussion was
initially about. And note that it says nothing at all
about changing the lens extension (because it doesn't
change).

But it changes the effective optical centre.

So what? You can't see it and you can't use it for any
purpose while making pictures with the lens.

--
Floyd L. Davidson http://www.apaflo.com/
Ukpeagvik (Barrow, Alaska)

On 06/08/2016 12:07, Floyd L. Davidson wrote:
David Taylor wrote:
Could anyone please confirm what the field seen is for
the Olympus M.ZUIKO 60mm 1:2.8 macro lens at maximum
macro setting (closest focus):

https://www.amazon.co.uk/gp/product/B009C742Y2

Is it the MFT frame size (17.3 mm Ã--- 13.0 mm) or twice
that (i.e. 34.6 x 26 mm)?

At 1:1 the field of view is exactly the same as the sensor size.
So if you put it on a 17.3x13.0mm sensor, that is what the
field of view will be.

Having now purchased the lens I can confirm that its minimum field of
view is indeed 17.3 x 13.0 mm (or at least, very near to that). Thanks
for all the help here.

(The confusion arises as they also quote 2:1 magnification for a "35 mm
equivalent". Yes MFT is providing a rather nice macro capability, and
the working distance isn't too bad either.
--
Cheers,
David
Web: http://www.satsignal.eu