Being pretty bad at maths I am looking for some software that does to
the calculation of near and far points what the DOF calculator does to
Depths of Field calculation. Can anyone help me.
I should be most grateful for hints!
Regards,
Andreas

Mike Davis is the wiz at this. Have a look in the FILES section of
this group. He has two handy calculators that will give you just what
you need. The link is:

http://tech.groups.yahoo.com/group/MF3D-group/files/


Sam

--- In MF3D-group@yahoogroups.com, "autre_valse" wrote:
>
> Being pretty bad at maths I am looking for some software that does to
> the calculation of near and far points what the DOF calculator does to
> Depths of Field calculation. Can anyone help me.
> I should be most grateful for hints!
> Regards,
> Andreas
>

autre_valse wrote:

>
> Being pretty bad at maths I am looking for some software
> that does to the calculation of near and far points what
> the DOF calculator does to Depths of Field calculation.
> Can anyone help me. I should be most grateful for hints!

I highly recommend DOF Master
http://www.dofmaster.com/

Where one can do online DOF calculations, create DOF charts,
or download software which will let you make circular DOF
calculators on your computer.
________________________________________
John Thurston
Juneau, Alaska
http://stereo.thurstons.us

Hi Andreas,

At 09:37 AM 1/13/2008, you wrote:

>Being pretty bad at maths I am looking for some software that does to
>the calculation of near and far points what the DOF calculator does to
>Depths of Field calculation. Can anyone help me.
>I should be most grateful for hints!
>Regards,
>Andreas

What kind of camera setup are you using (a stereo camera or a twin
camera rig)? If you're using a twin-camera rig, how close together
can you position the lens axes?

Also: What are the focal lengths of your taking lenses and viewer lenses?

Thanks,

Mike Davis

Hi Mike,
I will hopefully receive the Chinese 120 camera later this week, and
that is what I would like to use the calculation for.
Andreas

--- In MF3D-group@yahoogroups.com, "Michael K. Davis" wrote:
>
>
> Hi Andreas,
>
> At 09:37 AM 1/13/2008, you wrote:
>
> >Being pretty bad at maths I am looking for some software that does to
> >the calculation of near and far points what the DOF calculator does to
> >Depths of Field calculation. Can anyone help me.
> >I should be most grateful for hints!
> >Regards,
> >Andreas
>
> What kind of camera setup are you using (a stereo camera or a twin
> camera rig)? If you're using a twin-camera rig, how close together
> can you position the lens axes?
>
> Also: What are the focal lengths of your taking lenses and viewer
lenses?
>
> Thanks,
>
> Mike Davis
>

Andreas,

On Mon, 14 Jan 2008, autre_valse wrote:

> Hi Mike,
> I will hopefully receive the Chinese 120 camera later this week, and
> that is what I would like to use the calculation for.
> Andreas

I'll assume that you also want to optimize your shooting for the 75mm
lenses 3DWorld has been using in their rotary and STL viewers.

You can use your choice of the 5 lp/mm or 8 lp/mm Sputnik Depth of Field
and % MAOFD spinning disk calculators that Sam Smith referenced - the two
GIF files at: http://tech.groups.yahoo.com/group/MF3D-group/files/

They were made using Don Fleming's software that John Thurston
recommended, which can be downloaded from the link he provided:
http://www.dofmaster.com/

That would allow you to customize your own spinning disk DoF calculator
for the 80mm focal length of the TL-120 lenses, but the Sputnik
calculators that are optimized for a camera focal length of 75mm, should
be close enough if you don't want to go to the trouble of creating your
own. (Calculating for 75mm vs. 80mm is a DoF error of only 1/8th of a stop
- no big deal.)

The larger issue is just how aggressive you want to be in the first place,
in regards to eliminating defocus. If you shoot with the 8 lp/mm DoF
calculator, you'll find yourself having to work farther away from the
nearest subjects - you'll have less DoF, but adherance to that calculator
will support a resolution that's right at the limit of what most people
can appreciate at the 3.39x magnification suffered with an
Infinity-focused 75mm stereo viewer. The neat thing bout the TL-120 is
that unlike most Sputniks, its lenses are actually sharp enough to take
advantage of the smaller Circles of Confusion you'be be recording with
that calculator. Only a handful of Sputniks even come close.

If you choose to shoot with the more generous 5 lp/mm calculator, you'll
be able to record subject spaces that have greater depth (instead of not
shooting at all), but your images will appear softer at the Near and Far
sharps. 5 lp/mm would still be considered "sharp" by most people, but
it's not going to be extracting all the resolution those TL-120 lenses are
capable of delivering.

Another thing to consider is that if your views are ever displayed in a
focusable viewer, the enlargement factor will increase as the user focuses
more closely than Infinity - as much as 125% (when the image distance is
at 10 inches, instead of Infinity - 4.24x magnification instead of 3.39x).
Not everyone can focus their eyes at 10 inches in a viewer that permits
it, but the probability that your views might be used in any focusable
viewer is a good reason to shoot for a CoC diameter that supports a goal
of 8 lp/mm for an Infinity-focused viewer, rather than using a less
aggressive resolution goal.

Now for an explanation of the % MAOFD tables I incorporated into each of
those GIF files...

Here's the short version:

When using a fixed-base stereo camera like the 3DWorld TL-120, the amount
of depth you record for a given scene is determined by the intrinsic depth
of the subject space, not by anything you can do at the camera - because
the lens spacing is fixed. This doesn't mean that you can ignore subject
distances altogether, however. It is generally agreed (but vigorously
disputed by some) that the average person will find on-film deviations
exceeding a value of viewer focal length divided by 30 to be uncomfortable
or fatiguing to the eyes over time. There's certainly no hard line here,
as some people can enjoy so-called "double-depth" views (200% of MAOFD)
without discomfort, but I like to limit the deviation recorded in my views
to something less than or equal to 100% of the theoretical Maximum
Acceptable On-Film Deviation (where MAOFD = Viewer FL/30).

If you choose to deploy the 5 lp/mm Sputnik DoF calculator available at
the aforementioned link, you'll find that all the subject distances that
calculator will permit you to shoot will record on-film deviations less
than 100% of MAOFD. For example, even for those scenes that require f/22,
you'll be recording an OFD equal to 92.1% of MAOFD. Subject spaces
requiring even less DoF (wider apertures) will record even smaller on-film
deviations (65.1% of MAOFD with f/16, for example).

If you choose to use the 8 lp/mm Sputnik DoF calculator that produces
smaller CoC diameters and thus accomodates shorter DoF ranges at any given
f-stop, you'll again find that no subject space permitted by the DoF
calculator will record OFDs greater than 100% of MAOFD. In fact, even
those subject spaces requiring f/22 will only record an OFD equal to 56.8%
of MAOFD.

So how do you make practical use of this information while shooting with
the TL-120? With the small CoC's produced using either of these DoF
calculators, there's no need for concern about recording too much
deviation in your stereo views. Neither DoF calculator will permit you to
shoot a subject space that could record an OFD equal to even 100% of
MAOFD. The only way you could record an OFD exceeding MAOFD is
to shoot a subject space that's far deeper than what the DoF calculator is
telling you is possible to shoot at f/22.

Instead, you should be concerned about how SHALLOW your subject spaces
are. Any subject space that records an OFD of less than 33% of MAOFD
will, in my opinion, appear unsatisfyingly "flat" in the 3D viewer.

So, if you're shooting with the 8 lp/mm DoF calculator, don't bother
shooting a subject space that does not require f/13.5 (f/11 and 1/2 stop)
or larger f-Numbers for sufficient DoF. If you're shooting with the 5
lp/mm DoF calculator, don't bother shooting a subject space that does not
require f/8 or larger f-Numbers for sufficient DoF. Those subject spaces
are simply too shallow to be worthy of shooting in 3D (again, in my
opinion).

If you really want your portofolio to be consistently entertaining from
one view to the next, in terms of 3D "wow factor", you should limit
yourself to shooting subject spaces that will record OFDs greater than 50%
of MAOFD.

Here's the long version, if you're interested in how those percentages
were derived:

Now deceased, Frank Di Marzio, an Australian physics lecturer at Trinity
College, University of Melbourne, worked out the relationship between
stereo base and the smallest f/Number capable of providing sufficient DoF
for a given subject space. His goal was to come up with an equation that
would translate the f-stop necessary for suffient DoF into the stereo base
required for a twin-camera rig to achieve MAOFD (maxium acceptable on-film
deviation) in a stereo view.

Unfortunately, the "Di Marzio Equation" for stereo base...

Base = ( 100 * Fc ) / ( 3 * N )

where Fc is the camera focal length and N is the "the smallest f/number
(largest aperture) capable of providing a depth of field ranging from the
near point Dn to the far point Df."

... as published in his white paper on the subject
(http://nzphoto.tripod.com/stereo/3dtake/Di_Marzio_Equation_Technical_Web.pdf),
is only accurate when the CoC diameter used to calculate the f-Number for
nominal DoF equals:

Di * Fv / (2000 * (Fv + Di))

where Di is the virtual image distance at which the viewer is focused and
Fv is the viewer focal length.

Frank's white paper evidences awareness of the limitations of his Di
Marzio Equation for Stereo Base - he provided information on how to
customize the equation for use with CoC diameters other than those that
satisfy the ratio given above. He was so fluent at mathematics that I
think he just underestimated the algebra skills of the typical reader. I
think, too, that his published equation better illustrates the core
relationship between f-Number and stereo base than would a more
complicated but practical derrivative of his equation.

My algebra skills are so rusty it took many hours for me to flesh out his
recommendations to produce a more practical equation that will work with
any CoC diameter - "The Davis-Di Marzio Equation" for stereo base:

Base = M * Fc * Di * Fv / (6000 * Ca * N * (Fv + Di))

Where M is the % of MAOFD desired, Fc is the camera focal length, Di is
the virtual image distance at which the viewer is focused (not the
physical lens-to-film distance), Fv is the viewer focal length, N is the
f/number indicated on your Depth of Field scale or table, and Ca is the
permissible Circle of Confusion diameter that was used to calculate DoF.

The Davis-Di Marzio Equation is nowhere near as elegant (to look at) as
the Di Marzio Equation, but it's accurate for use with any CoC diameter
and it accomodates desired OFDs less than 100% of MAOFD as well as any
mismatch bewteen camera and viewer focal lengths.

When Di is set to Infinity (viewer focused at Ininity) and M is set to 100
(desired OFD is equal to 100% of MAOFD), the Davis-Di Marzio Equation will
produce the same stereo base figures generated by the long-trusted
Bercovitz equation, Eqn 1, "The General Solution", as seen on this page:
http://home.vicnet.net.au/~vic3d/bases.html

So... the Davis-Di Marzio equation allows you to calculate the appropriate
stereo base against an f-Number indicated by a DoF calculator that was
optimized to produce a given CoC diameter when the desired % of MAOFD is
communicated along with the focal length of both the camera and viewer
lenses and the image distance at which the view will be focused in the
viewer.

Having augmented the Di Marzio equation to make it more practical, I then
set out to invert the Davis-Di Marzio Equation so that it could be used to
calculate the OFD that would be recorded in a stereo view (expressed as %
of MAOFD) for a given subject space, when shooting with fixed-base stereo
cameras like the Sputnik and 3DWorld TL-120.

Here is the inverted formula, the Davis-Di Marzio Equation for Percent of
MAOFD, that was used to produce the % MAOFD tables seen on the two
spinning disk calculators at the aforementioned link:

% of MAOFD = B / (Fc * Di * Fv / (6000 * Ca * N * (Fv + Di)))

Where M is the % of MAOFD desired, Fc is the camera focal length, Di is
the virtual image distance at which the viewer is focused (not the
physical lens-to-film distance), Fv is the viewer focal length, N is the
f/number indicated on your Depth of Field scale or table, and Ca is the
permissible Circle of Confusion diameter that was used to calculate DoF.

Spreadhseets that exploit both formulas can be downloaded from these
links:

http://home.globalcrossing.net/~zilch0/tools/DiMarzio-Davis.xls
http://home.globalcrossing.net/~zilch0/tools/DiMarzio-Davis_for_OFD.xls

Other stereo base spreadsheets (based on the Bercovitz equation) can be
found here: http://home.globalcrossing.net/~zilch0/tools.htm

Mike Davis

Thanks a lot.
You have been given me something to think about.
I will have to read this very very carefully.
Once again thanks,
Andreas

--- In MF3D-group@yahoogroups.com, "Michael K. Davis" wrote:
>
>
> Andreas,
>
> On Mon, 14 Jan 2008, autre_valse wrote:
>
> > Hi Mike,
> > I will hopefully receive the Chinese 120 camera later this week, and
> > that is what I would like to use the calculation for.
> > Andreas
>
> I'll assume that you also want to optimize your shooting for the 75mm
> lenses 3DWorld has been using in their rotary and STL viewers.
>
> You can use your choice of the 5 lp/mm or 8 lp/mm Sputnik Depth of Field
> and % MAOFD spinning disk calculators that Sam Smith referenced -
the two
> GIF files at: http://tech.groups.yahoo.com/group/MF3D-group/files/
>
> They were made using Don Fleming's software that John Thurston
> recommended, which can be downloaded from the link he provided:
> http://www.dofmaster.com/
>
> That would allow you to customize your own spinning disk DoF calculator
> for the 80mm focal length of the TL-120 lenses, but the Sputnik
> calculators that are optimized for a camera focal length of 75mm, should
> be close enough if you don't want to go to the trouble of creating your
> own. (Calculating for 75mm vs. 80mm is a DoF error of only 1/8th of
a stop
> - no big deal.)
>
> The larger issue is just how aggressive you want to be in the first
place,
> in regards to eliminating defocus. If you shoot with the 8 lp/mm DoF
> calculator, you'll find yourself having to work farther away from the
> nearest subjects - you'll have less DoF, but adherance to that
calculator
> will support a resolution that's right at the limit of what most people
> can appreciate at the 3.39x magnification suffered with an
> Infinity-focused 75mm stereo viewer. The neat thing bout the TL-120 is
> that unlike most Sputniks, its lenses are actually sharp enough to take
> advantage of the smaller Circles of Confusion you'be be recording with
> that calculator. Only a handful of Sputniks even come close.
>
> If you choose to shoot with the more generous 5 lp/mm calculator, you'll
> be able to record subject spaces that have greater depth (instead of not
> shooting at all), but your images will appear softer at the Near and Far
> sharps. 5 lp/mm would still be considered "sharp" by most people, but
> it's not going to be extracting all the resolution those TL-120
lenses are
> capable of delivering.
>
> Another thing to consider is that if your views are ever displayed in a
> focusable viewer, the enlargement factor will increase as the user
focuses
> more closely than Infinity - as much as 125% (when the image distance is
> at 10 inches, instead of Infinity - 4.24x magnification instead of
3.39x).
> Not everyone can focus their eyes at 10 inches in a viewer that permits
> it, but the probability that your views might be used in any focusable
> viewer is a good reason to shoot for a CoC diameter that supports a goal
> of 8 lp/mm for an Infinity-focused viewer, rather than using a less
> aggressive resolution goal.
>
> Now for an explanation of the % MAOFD tables I incorporated into each of
> those GIF files...
>
> Here's the short version:
>
> When using a fixed-base stereo camera like the 3DWorld TL-120, the
amount
> of depth you record for a given scene is determined by the intrinsic
depth
> of the subject space, not by anything you can do at the camera - because
> the lens spacing is fixed. This doesn't mean that you can ignore
subject
> distances altogether, however. It is generally agreed (but vigorously
> disputed by some) that the average person will find on-film deviations
> exceeding a value of viewer focal length divided by 30 to be
uncomfortable
> or fatiguing to the eyes over time. There's certainly no hard line
here,
> as some people can enjoy so-called "double-depth" views (200% of MAOFD)
> without discomfort, but I like to limit the deviation recorded in my
views
> to something less than or equal to 100% of the theoretical Maximum
> Acceptable On-Film Deviation (where MAOFD = Viewer FL/30).
>
> If you choose to deploy the 5 lp/mm Sputnik DoF calculator available at
> the aforementioned link, you'll find that all the subject distances that
> calculator will permit you to shoot will record on-film deviations less
> than 100% of MAOFD. For example, even for those scenes that require
f/22,
> you'll be recording an OFD equal to 92.1% of MAOFD. Subject spaces
> requiring even less DoF (wider apertures) will record even smaller
on-film
> deviations (65.1% of MAOFD with f/16, for example).
>
> If you choose to use the 8 lp/mm Sputnik DoF calculator that produces
> smaller CoC diameters and thus accomodates shorter DoF ranges at any
given
> f-stop, you'll again find that no subject space permitted by the DoF
> calculator will record OFDs greater than 100% of MAOFD. In fact, even
> those subject spaces requiring f/22 will only record an OFD equal to
56.8%
> of MAOFD.
>
> So how do you make practical use of this information while shooting with
> the TL-120? With the small CoC's produced using either of these DoF
> calculators, there's no need for concern about recording too much
> deviation in your stereo views. Neither DoF calculator will permit
you to
> shoot a subject space that could record an OFD equal to even 100% of
> MAOFD. The only way you could record an OFD exceeding MAOFD is
> to shoot a subject space that's far deeper than what the DoF
calculator is
> telling you is possible to shoot at f/22.
>
> Instead, you should be concerned about how SHALLOW your subject spaces
> are. Any subject space that records an OFD of less than 33% of MAOFD
> will, in my opinion, appear unsatisfyingly "flat" in the 3D viewer.
>
> So, if you're shooting with the 8 lp/mm DoF calculator, don't bother
> shooting a subject space that does not require f/13.5 (f/11 and 1/2
stop)
> or larger f-Numbers for sufficient DoF. If you're shooting with the 5
> lp/mm DoF calculator, don't bother shooting a subject space that
does not
> require f/8 or larger f-Numbers for sufficient DoF. Those subject
spaces
> are simply too shallow to be worthy of shooting in 3D (again, in my
> opinion).
>
> If you really want your portofolio to be consistently entertaining from
> one view to the next, in terms of 3D "wow factor", you should limit
> yourself to shooting subject spaces that will record OFDs greater
than 50%
> of MAOFD.
>
> Here's the long version, if you're interested in how those percentages
> were derived:
>
> Now deceased, Frank Di Marzio, an Australian physics lecturer at Trinity
> College, University of Melbourne, worked out the relationship between
> stereo base and the smallest f/Number capable of providing
sufficient DoF
> for a given subject space. His goal was to come up with an equation
that
> would translate the f-stop necessary for suffient DoF into the
stereo base
> required for a twin-camera rig to achieve MAOFD (maxium acceptable
on-film
> deviation) in a stereo view.
>
> Unfortunately, the "Di Marzio Equation" for stereo base...
>
> Base = ( 100 * Fc ) / ( 3 * N )
>
> where Fc is the camera focal length and N is the "the smallest f/number
> (largest aperture) capable of providing a depth of field ranging
from the
> near point Dn to the far point Df."
>
> ... as published in his white paper on the subject
>
(http://nzphoto.tripod.com/stereo/3dtake/Di_Marzio_Equation_Technical_Web.pdf),
> is only accurate when the CoC diameter used to calculate the
f-Number for
> nominal DoF equals:
>
> Di * Fv / (2000 * (Fv + Di))
>
> where Di is the virtual image distance at which the viewer is
focused and
> Fv is the viewer focal length.
>
> Frank's white paper evidences awareness of the limitations of his Di
> Marzio Equation for Stereo Base - he provided information on how to
> customize the equation for use with CoC diameters other than those that
> satisfy the ratio given above. He was so fluent at mathematics that I
> think he just underestimated the algebra skills of the typical
reader. I
> think, too, that his published equation better illustrates the core
> relationship between f-Number and stereo base than would a more
> complicated but practical derrivative of his equation.
>
> My algebra skills are so rusty it took many hours for me to flesh
out his
> recommendations to produce a more practical equation that will work with
> any CoC diameter - "The Davis-Di Marzio Equation" for stereo base:
>
> Base = M * Fc * Di * Fv / (6000 * Ca * N * (Fv + Di))
>
> Where M is the % of MAOFD desired, Fc is the camera focal length, Di is
> the virtual image distance at which the viewer is focused (not the
> physical lens-to-film distance), Fv is the viewer focal length, N is the
> f/number indicated on your Depth of Field scale or table, and Ca is the
> permissible Circle of Confusion diameter that was used to calculate DoF.
>
> The Davis-Di Marzio Equation is nowhere near as elegant (to look at) as
> the Di Marzio Equation, but it's accurate for use with any CoC diameter
> and it accomodates desired OFDs less than 100% of MAOFD as well as any
> mismatch bewteen camera and viewer focal lengths.
>
> When Di is set to Infinity (viewer focused at Ininity) and M is set
to 100
> (desired OFD is equal to 100% of MAOFD), the Davis-Di Marzio
Equation will
> produce the same stereo base figures generated by the long-trusted
> Bercovitz equation, Eqn 1, "The General Solution", as seen on this page:
> http://home.vicnet.net.au/~vic3d/bases.html
>
> So... the Davis-Di Marzio equation allows you to calculate the
appropriate
> stereo base against an f-Number indicated by a DoF calculator that was
> optimized to produce a given CoC diameter when the desired % of MAOFD is
> communicated along with the focal length of both the camera and viewer
> lenses and the image distance at which the view will be focused in the
> viewer.
>
> Having augmented the Di Marzio equation to make it more practical, I
then
> set out to invert the Davis-Di Marzio Equation so that it could be
used to
> calculate the OFD that would be recorded in a stereo view (expressed
as %
> of MAOFD) for a given subject space, when shooting with fixed-base
stereo
> cameras like the Sputnik and 3DWorld TL-120.
>
> Here is the inverted formula, the Davis-Di Marzio Equation for
Percent of
> MAOFD, that was used to produce the % MAOFD tables seen on the two
> spinning disk calculators at the aforementioned link:
>
> % of MAOFD = B / (Fc * Di * Fv / (6000 * Ca * N * (Fv + Di)))
>
> Where M is the % of MAOFD desired, Fc is the camera focal length, Di is
> the virtual image distance at which the viewer is focused (not the
> physical lens-to-film distance), Fv is the viewer focal length, N is the
> f/number indicated on your Depth of Field scale or table, and Ca is the
> permissible Circle of Confusion diameter that was used to calculate DoF.
>
> Spreadhseets that exploit both formulas can be downloaded from these
> links:
>
> http://home.globalcrossing.net/~zilch0/tools/DiMarzio-Davis.xls
> http://home.globalcrossing.net/~zilch0/tools/DiMarzio-Davis_for_OFD.xls
>
> Other stereo base spreadsheets (based on the Bercovitz equation) can be
> found here: http://home.globalcrossing.net/~zilch0/tools.htm
>
> Mike Davis
>