I have just received images from 3D World of
their more recent prototype (and received
explicit permission to share them). The most
significant difference between this and the
camera I have in-hand is the larger handgrip.

I have updated my pages to incorporate some of
the 3D World images. http://stereo.thurstons.us
________________________________________
John Thurston
Juneau, Alaska
http://stereo.thurstons.us

Hi John,

>I have just received images from 3D World of
> their more recent prototype

I wonder why you call this "prototype". Isn't being sold in China
right now? In that respect it is a production camera, not a prototype.

Also, I wonder why you are breaking your pages in very small segments,
instead of putting all the information in one or two pages maybe. Having
everything in one page would make the information easier to load
and read, IMO.

George

DrT (George Themelis) wrote:

>> I have just received images from 3D World of
>> their more recent prototype
>

> I wonder why you call this "prototype". Isn't
> being sold in China right now? In that respect
> it is a production camera, not a prototype.

I'm currently calling it a "prototype" because
that is the description I recall reading in an
e-mail from 3D World. The feeling I have is
that they are still making small changes and
improvements.

I, for one, hope they plan tweaks to the
film-advance/shutter-speed controls.

--
John Thurston
Juneau Alaska
http://stereo.thurstons.us

> DrT (George Themelis) wrote:

> > I wonder why you call this "prototype". Isn't
> > being sold in China right now? In that respect
> > it is a production camera, not a prototype.

The current versions in limited circulation are not the final
production model, hence the "prototype" label. There are several other
mods required, as well as assuring product support is available for
international distribution. I am perhaps partly to blame for the
delay, as there were several aspects I relayed as a Beta tester and
NSA rep that were taken quite seriously. 3DWorld is a quality-driven
company. Retailers will simply have to wait until the company is ready
for a production release of their product.

Sam

When I bought my camera from them they said it was for tryout.
In other word, no oversea warranty, but if any problems I could send
it back for repair. I also got some extra stuff.

MR

--- In MF3D-group@yahoogroups.com, John Thurston
wrote:

>
> DrT (George Themelis) wrote:
> >> I have just received images from 3D World of
> >> their more recent prototype
> >
>
> > I wonder why you call this "prototype". Isn't
> > being sold in China right now? In that respect
> > it is a production camera, not a prototype.
>
> I'm currently calling it a "prototype" because
> that is the description I recall reading in an
> e-mail from 3D World. The feeling I have is
> that they are still making small changes and
> improvements.
>
> I, for one, hope they plan tweaks to the
> film-advance/shutter-speed controls.
>
> --
> John Thurston
> Juneau Alaska
> http://stereo.thurstons.us
>

Sam wrote:

> The current versions in limited circulation are not
> the final
> production model, hence the "prototype" label.

In all this talk about the new camera and what it will become
I have only noticed one complaint about the lenses on a
prototype, and that was mostly that they add a lot of weight,
being F/2.8, making the camera about 4.4 lbs. It just may be
that there are no other lenses that can be used on the camera
at an affordable price. I agree that the lenses do not need
any F stop wider than F/5.6 ( or even F/8 for me) but would
also like to see the FL to be 75mm or a little less (maybe as
short as 60mm) and would really like an F stop of F/32 that
could be used. Both would give extended DOF allowing more in
focus depth in the views. Maybe it is too costly or too late
for such a change to be made.

Chuck Holzner

Hi Chuck!

On Mon, 18 Sep 2006, Chuck Holzner wrote:

> I agree that the lenses do not need
> any F stop wider than F/5.6 ( or even F/8 for me) but would
> also like to see the FL to be 75mm or a little less (maybe as
> short as 60mm) and would really like an F stop of F/32 that
> could be used. Both would give extended DOF allowing more in
> focus depth in the views. Maybe it is too costly or too late
> for such a change to be made.

I'm with you and John regarding their choice to mount 80mm f/2.8 lenses.
Like you, I'd be content with f/8, except for the viewing lens, where
f/5.6 is about as dim as I'd be willing to go. Actually, in the interest
of saving weight and expense, I'd be content with a shoe-attached optical
finder or even a wire-frame finder. Seriously. I always use the distance
scales to set my focus, so I'd be happy with only only two lenses and no
prism finder.

Many experienced shooters have written on this forum and elsewhere that
they prefer to shoot subject spaces that require a lot of DoF. Any
subject space that's shallow enough to use an aperture wider than f/16
(with 80mm lenses) for sufficient DoF will make a boring 3D image, in my
opinion.

Entering the appropriate values into the spreadsheet at this link...

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

... shows that a fixed-base (65mm)_stereo camera with 80mm lenses will
produce the following amounts of stereo depth (expressed as a percentage
of MAOFD) at the f-stops given (where these f-stops are sufficient to
limit circles of confusion to a diameter of 0.06mm on-film, supporting a
desired resolution 5 lp/mm after 3.33x magnification in an
infinity-focused 3DWorld viewer equipped with 75mm lenses):

f/2.8 11.0 % of MAOFD
f/4.0 15.6 % of MAOFD
f/5.6 22.1 % of MAOFD
f/8.0 31.2 % of MAOFD
f/11.3 44.1 % of MAOFD
f/16.0 62.4 % of MAOFD
f/22.6 88.3 % of MAOFD
f/32.0 124.8 % of MAOFD

Subject spaces requiring anything less than f/8 for sufficient DoF are
simply not very entertaining in the Z-axis. Even f/8, at 31.2 % of MAOFD,
is somewhat flat.

Subject spaces requring f/32 for sufficient DoF will yield an excessive
OFD, exceeding MAOFD by 25%, making it difficult, if not impossible, to
mount without forcing the eyes to diverge.

I was also concerned that f/32 might induce Airy disks large enough to
interfere with a goal of supporting 5 lp/mm after magnification in the
3.33x infinity-focused 3DWorld viewers, but I've calculated that we could
actually stop down to f/44.3 before diffraction would inhibit 5 lp/mm at
that magnification.

The bigger issue with using stop smaller than f/22 is that if such a stop
is actually necessary to obtain sufficient DoF for a given subject space,
that subject space will yield an OFD that's greater than MAOFD.

I, too, would much prefer a shorter focal length. The 80mm focal length
alone is enough to make the camera undersirable, in my opinion. The
3DWorld viewers have 75mm lenses, but no harm would have come from using
lenses as short as 43mm - my favorite length for shooting MF3D landscapes.

All that said, just imagine how much lighter, smaller, and less expensive
the camera would be had it been equipped with a wire frame or shoe-mount
optical finder and two f/8-to-f/22 lenses instead of three f/2.8 lenses.

As is, the 3DWorld camera's design evidences a lack of knowledge of
stereography. They may know how to make lenses and how to bolt together a
functioning camera, but their choice of lenses is proof that they didn't
do their homework.

Still, the unnecessary weight and expense of lenses that are too fast and
too long isn't likely to have a negative impact on image quality. If the
camera can produce sharp chromes with good sync at all shutter speeds, it
could still be a viable solution for many 3D subjects.

Mike Davis

Chuck, in most cases, the maker uses wider lenses to "see" through the
viewfinder. If the lens was f8, its tough to compose a view in such
darkness..... considering 80mm lenses are still small at f2.8, I
imagine this is the compromise they considered. I think a rangefinder
viewfinder would have been nicer....

> In all this talk about the new camera and what it will become
> I have only noticed one complaint about the lenses on a
> prototype, and that was mostly that they add a lot of weight,
> being F/2.8, making the camera about 4.4 lbs. It just may be
> that there are no other lenses that can be used on the camera
> at an affordable price. I agree that the lenses do not need
> any F stop wider than F/5.6 ( or even F/8 for me) but would
> also like to see the FL to be 75mm or a little less (maybe as
> short as 60mm) and would really like an F stop of F/32 that
> could be used. Both would give extended DOF allowing more in
> focus depth in the views. Maybe it is too costly or too late
> for such a change to be made.
>
> Chuck Holzner
>
>
>

The 2.8 lenses are actually a real benefit in many situations. Being
able to shoot at 1/500th with a limited depth subject may only be
obtainable with a faster lens. Also don't forget those "hyper" guys,
who don't need DOF. The viewfinder is significantly brighter and
easier to focus than a Scope or a Spud. f:32 is on the drawing board.

As for different lenses, the front lensboard is secured with 4 screws.
I'm hoping to be able to fit my 55mm lenses on at some point by simply
switching fronts. If I fix them at 12 feet, no focus would be needed.

Sam

> In all this talk about the new camera and what it will become
> I have only noticed one complaint about the lenses on a
> prototype, and that was mostly that they add a lot of weight,
> being F/2.8, making the camera about 4.4 lbs. It just may be
> that there are no other lenses that can be used on the camera
> at an affordable price. I agree that the lenses do not need
> any F stop wider than F/5.6 ( or even F/8 for me) but would
> also like to see the FL to be 75mm or a little less (maybe as
> short as 60mm) and would really like an F stop of F/32 that
> could be used. Both would give extended DOF allowing more in
> focus depth in the views. Maybe it is too costly or too late
> for such a change to be made.
>
> Chuck Holzner
>

Chuck Holzner wrote:

> ...It just may be that there are no other
> lenses that can be used on the camera
> at an affordable price.

That was the indication I had when I mentioned
this topic to them. Lens and shutter choices
were limited to what was available.

Yeah, I'd rather f/4.5 lenses. But I'd rather
have working shutters and f/2.8 lenses than an
unreliable shutter and f/4.5 lenses (such as I
already have in my Sputnik)
________________________________________
John Thurston
Juneau, Alaska
http://stereo.thurstons.us

Mike Davis wrote:

> Like you, I'd be content with f/8, except for the
> viewing lens, where
> f/5.6 is about as dim as I'd be willing to go.

Of course I was talking about the taking lenses. Even the
Sputnik has a lens different for viewing from the ones used
for taking.

> Actually, in the interest
> of saving weight and expense, I'd be content with a
> shoe-attached optical
> finder or even a wire-frame finder.

A optical finder similar to those on 35mm stereo cameras would
be fine with me as long as it is somewhat accurate. I thought
I saw a picture of a prototype of this camera that had such a
viewfinder.

> f/16.0 62.4 % of MAOFD
> f/22.6 88.3 % of MAOFD
> f/32.0 124.8 % of MAOFD

As you show, You can't get full DOF even at F/22 and so a
tighter F stop is desirable. Having extra DOF is not a
problem as it is still far enough away from diffraction
limiting and will allow DOF all the way from the 2 meter
window to infinity with some extra in case you didn't get the
focus dead on.

> Subject spaces requiring f/32 for sufficient DoF
> will yield an excessive
> OFD, exceeding MAOFD by 25%, making it difficult,
> if not impossible, to
> mount without forcing the eyes to diverge.

Not a problem. There is no requirement that you use all the
available DOF in every picture, I know I don't, but it is nice
to have it available. Should you want to use the absolute
maximum according to your chart, you can make your own mount
or modify a standard mount and mount them without eye
divergence. That is not so hard to do.

>
> I was also concerned that f/32 might induce Airy
> disks large enough to
> interfere with a goal of supporting 5 lp/mm after
> magnification in the
> 3.33x infinity-focused 3DWorld viewers, but I've
> calculated that we could
> actually stop down to f/44.3 before diffraction
> would inhibit 5 lp/mm at
> that magnification.

So F/32 is a good useable aperture for MF stereo.

>
> The bigger issue with using stop smaller than f/22
> is that if such a stop
> is actually necessary to obtain sufficient DoF for
> a given subject space,
> that subject space will yield an OFD that's greater
> than MAOFD.

Again, not so. If you want to have in focus depth from the
standard window of 2 meters to infinity, According to your
chart, you can't get it at F/22, but you can at F/32 and have
some wiggle room on the focus dial.

>
> I, too, would much prefer a shorter focal length.
> The 80mm focal length
> alone is enough to make the camera undesirable, in
> my opinion. The
> 3DWorld viewers have 75mm lenses,

You would think that they would have matched the FL on the
viewer and camera. 75mm is Sputnik's standard and most MF
shooters are using a Sputnik. It would have been a good place
to start. If they had to deviate from the 75mm FL, I would
prefer shorter. Perhaps with 60mm taking lenses F/22 would
give a DOF from 2 meters to infinity at F/16. I would still
like to have the F/32 option. Even be able to set it between
stops. It would be nice if this new (expensive) camera could
do everything I can do and things I can't do with my Sputnik.

> All that said, just imagine how much lighter,
> smaller, and less expensive
> the camera would be had it been equipped with a
> wire frame or shoe-mount
> optical finder and two f/8-to-f/22 lenses instead
> of three f/2.8 lenses.

I would like F/8 to F/32 lenses but not a wire finder. My
eyes will not focus that close.

>
> As is, the 3DWorld camera's design evidences a lack
> of knowledge of
> stereography. They may know how to make lenses and
> how to bolt together a
> functioning camera, but their choice of lenses is
> proof that they didn't
> do their homework.

It would have been nice if they had asked what we would want
but it is also possible that we could not agree on what we
want.

>
> Still, the unnecessary weight and expense of lenses
> that are too fast and
> too long isn't likely to have a negative impact on
> image quality. If the
> camera can produce sharp chromes with good sync at
> all shutter speeds, it
> could still be a viable solution for many 3D subjects.

Some MF shooters are using 80mm lenses now and are happy doing
so. I am a depth "junky" and like them shorter with a tighter
F stop.

Chuck Holzner

Hi Chuck!

At 04:46 PM 9/18/2006, you wrote:

> > f/16.0 62.4 % of MAOFD
> > f/22.6 88.3 % of MAOFD
> > f/32.0 124.8 % of MAOFD
>
>As you show, You can't get full DOF even at F/22

Actually, the data shown above for f/22 tells us that we can't get an OFD
equal to 100% of MAOFD when shooting a scene where the depth of that scene
requires f/22 for depth of field sufficient to deliver Circles of Confusion
no larger than 0.06mm at the Near and Far sharps on-film, before
magnification.

Here's the entire table again:

f/2.8 ----- 11.0 % of MAOFD
f/4.0 ----- 15.6 % of MAOFD
f/5.6 ----- 22.1 % of MAOFD
f/8.0 ----- 31.2 % of MAOFD
f/11.3 --- 44.1 % of MAOFD
f/16.0 --- 62.4 % of MAOFD
f/22.6 --- 88.3 % of MAOFD
f/32.0 --- 124.8 % of MAOFD

Looking at the first entry in the table: This shows that when f/2.8 is
sufficient to render the Near and Far sharps of the subject space with
Circles of Confusion that will not exceed 0.06mm, that subject space, when
rendered as a stereo pair, using 80mm taking lenses that have a fixed 65mm
base and a 75mm stereo viewer that's focused at Infinity, will deliver an
On-Film Deviation (OFD) equal to only 11.0% of the Maximum Acceptable
On-Film Deviation (MAOFD). For a 75mm viewer, MAOFD is equal to 75/30 =
2.5mm.

So... when shooting a scene that's so shallow it only requires f/2.8 for
sufficient DoF (per the specificatons given above), the resulting stereo
pair will have an OFD equal to 11.0% of 2.5mm, which is only 0.275mm, or
less than 1/3 of a millimeter. For a stereo pair with an OFD of 0.275mm,
if the Near homologs are mounted to the window in a mount with a window
separation of 62.0mm, the Far homologs will fall at a separation of only
62.275mm. This is a very flat scene - hardly worth shooting in 3D.

Looking at the entry for f/22.6 : This shows that when f/22 is sufficient
to render the Near and Far sharps of the subject space with Circles of
Confusion that will not exceed 0.06mm, that subject space, when rendered as
a stereo pair, using 80mm taking lenses that have a fixed 65mm base and a
75mm stereo viewer that's focused at Infinity, will deliver an On-Film
Deviation (OFD) equal to 88.3% of the Maximum Acceptable On-Film Deviation
(MAOFD). Again, for a 75mm viewer, MAOFD is equal to 75/30 = 2.5mm.

So... when shooting a scene that's deep enough to require f/22.6 for
sufficient DoF (per the specifications given above), the resulting stereo
pair will have an OFD equal to 88.3% of 2.5mm, which is 2.21mm. For a
stereo pair with an OFD of 2.21mm, if the Near homologs are mounted to the
window in a mount with a window separation of 62.0mm, the Far homologs
will fall at a separation of 64.21mm. This is nearly as deep a scene as can
be rendered with the viewer and fixed-base camera described.

Thus, it's a given that at each of the f-stops shown in the table there is
sufficient DoF. The table is actually using the f-stops to describe just
how deep the scenes are that will be rendered at the calculated OFD's,
expressed as percentages of MAOFD.

You might certainly come across a scene that requires f/32 to yield Near
and Far sharps with Circles of Confusion that do not exceed the goal of
0.06mm on-film (which, after 3.33x magnification in the 75mm
Infinity-focused 3D World viewer, would support a desired resolution of 5
lp/mm), but any scene THAT deep, would end up having an OFD exceeding MAOFD
by 24.8%. Therefore, if the scene actually requires f/32 for sufficient
depth of field, you won't be able to mount it in the system I've described
without forcing some window violations (mounting the Near homologs closer
than the window separation), some divergence of the eyes (mounting the Far
homologs farther apart than the viewer lens spacing, or a little bit of both.

If we could change one or more of the parameters I defined for this system,
we could actually create a system where f/32 is useful - in other words, a
system where subject spaces requiring f/32 for sufficient DoF would not be
rendered with OFD's exceeding MAOFD.

Here are the variables that were in effect for the table I created above:

Stereo Base: 65mm
Camera FL: 80mm
Viewer FL: 75mm
Viewer Image Distance: Infinity
Maximum Permissible Circle of Confusion diameter used for DoF
Calculations: 0.06mm

If we stick with using the 3DWorld camera and the 3DWorld viewer....

We can't change the camera's base - it's fixed.
We can't change the camera's focal length - it's fixed.
We can't change the viewer focal length - it's fixed.
We can't change the viewer image distance - it's fixed.

The only variable we can change that would impact the OFD had for a subject
space that requires a particular f-stop for sufficient DoF is our choice
of maximum permissible CoC diameter used to calculate DoF.

It turns out that we would have to select a maximum permissible CoC
diameter of 0.0481mm to produce an OFD that's equal to 100% of MAOFD, no
more and no less, when shooting a subject space that requires f/32 for
sufficient DoF.

An on-film CoC diameter of 0.0481mm equates to a resolution of 6.24 lp/mm
in the Infinity-focused 75mm viewer, producing 3.33x magnification. This
is a significant increase in desired resolution over the 5.0 lp/mm I
specified when I created the table above. Some would argue that 6.24 lp/mm
is a resolution that can't be appreciated, but others say that resolutions
of 8 or even 10 lp/mm can be discerned by adults with healthy vision. So
6.24 lp/mm is not unreasonably lofty a goal, but it WILL require that you
move farther back from your nearest subjects to shoot at any given f-stop,
compared to the distances at which you could work were your resolution
requirements not so aggressive.

So, if you could get your hands on lenses that stop down to f/32 ---AND---
in all your shooting you adhered to DoF calculations done with a maximum
permissible CoC diameter of 0.0481mm, ---THEN--- a subject space deep
enough to require use of f/32 for sufficient DoF would be rendered with an
OFD equal to MAOFD (instead of an OFD that exceeds MAOFD by 24.8% - as was
the case with a CoC diameter of 0.06mm (all else being the same).

And here's some good news: Having increased your resolution requirements
from 5.0 lp/mm to 6.24 lp/mm (by making your maximum permissible CoC
diameter smaller), diffraction's Airy disks can no longer be as large as
they could with the lesser resolution requirement, BUT you can still shoot
at f/32 without fear of diffraction inhibiting your more stringent
requirements. The new diffraction limit would occur at f/35.5 instead of
at f/44.3 - leaving plenty of margin for shooting at f/32.

[snip]

> > Subject spaces requiring f/32 for sufficient DoF
> > will yield an excessive
> > OFD, exceeding MAOFD by 25%, making it difficult,
> > if not impossible, to
> > mount without forcing the eyes to diverge.
>
>Not a problem.

It is a problem for the system I originally defined. It's not a problem
for the new system I've defined above.

>So F/32 is a good useable aperture for MF stereo.

... for the 3DWorld camera and 3DWorld viewer, your statement is true if
and only if you adhere to DoF calculations made using a maximum permissible
CoC diameter equal to or less than 0.0481mm - to support an
after-magnification resolution greater than or equal to 6.24 lp/mm in the
viewer. If your DoF tables indicate you should use f/32 for a given
subject space, but they were calculated to deliver a maximum permissible
CoC diameter larger than 0.0481mm, THAT subject space will be TOO DEEP to
render a stereo pair with an On-Film Deviation that is equal to or less
than the Maximum Acceptable On-Film Deviation.

> >
> > The bigger issue with using stop smaller than f/22
> > is that if such a stop
> > is actually necessary to obtain sufficient DoF for
> > a given subject space,
> > that subject space will yield an OFD that's greater
> > than MAOFD.
>
>Again, not so. If you want to have in focus depth from the
>standard window of 2 meters to infinity, According to your
>chart, you can't get it at F/22, but you can at F/32 and have
>some wiggle room on the focus dial.

According to my chart, every f-stop shown gives precisely enough DoF for
the subject space its defining.

> >
> > I, too, would much prefer a shorter focal length.
> > The 80mm focal length
> > alone is enough to make the camera undesirable, in
> > my opinion. The
> > 3DWorld viewers have 75mm lenses,
>
>You would think that they would have matched the FL on the
>viewer and camera. 75mm is Sputnik's standard and most MF
>shooters are using a Sputnik. It would have been a good place
>to start.

Yes, I'm surprised they didn't do 75 instead of 80.

>If they had to deviate from the 75mm FL, I would
>prefer shorter. Perhaps with 60mm taking lenses F/22 would
>give a DOF from 2 meters to infinity at F/16.

Leaving the CoC diameter at 0.0481mm - the CoC required to make an f/32
subject space render an OFD equal to 100% of MAOFD - changing the Camera
focal length to 60mm from 80mm would again leave you with no need for
f/32. A scene requiring f/32 to yield CoC's no larger than 0.0481mm
on-film, when using a 60mm lens, would be rendered with an OFD equal to
133.4% of MAOFD, but a scene requiring f/22 would be rendered with an OFD
equal to 94.3 % of MAOFD.

>I would still
>like to have the F/32 option. Even be able to set it between
>stops. It would be nice if this new (expensive) camera could
>do everything I can do and things I can't do with my Sputnik.

Well said. I like the way that reads. :-)

> > All that said, just imagine how much lighter,
> > smaller, and less expensive
> > the camera would be had it been equipped with a
> > wire frame or shoe-mount
> > optical finder and two f/8-to-f/22 lenses instead
> > of three f/2.8 lenses.
>
>I would like F/8 to F/32 lenses but not a wire finder. My
>eyes will not focus that close.

Yes, I'd prefer some kind of optical finder to a wire frame, but I don't
need to focus with that finder.

Mike Davis

I held the MF camera at NSA Miami and it didn't feel so heavy,
just top heavy. Most companies like to offer accessories to
customers who already bought high ticket items. I would
certainly like the option to snap on a waist level viewer
sometimes for tripod shots and just reduced weight and size for
long hauls. Since I already heard that the prism snaps off,
there may be no camera modifications needed, just designing the
finder.

Dale Yingst

--- In MF3D-group@yahoogroups.com, "Dale Yingst" wrote:

>

Since I already heard that the prism snaps off,

> there may be no camera modifications needed, just designing the
> finder.

Did I mention it took Hasselblad finders? Somebody bought a 45 degree
one and a waistlevel version (forgot who it was)to Miami. It fit
nicely, but needed a little shimming to stay secure.

Sam

I was notified that my camera would be taking an extra three weeks or so
to arrive because they were installing new shutters in this second
production run. The distributor had not been aware of any problems with
the old shutter and there may have been none. Also, I don't know if the
second run had already been assembled and they were swapping out the old
shutters or just waiting for the new shutters to arrive. I was simply
told the designer wanted the new shutters in. I have no problem with
waiting if an improvement is involved. It would be nice to have a 1/120
flash sync or indoors hand held shooting.

Dale Yingst

Dale Yingst wrote:

> It would be nice to have a 1/120
> flash sync or indoors hand held shooting.

It's worth noting that as far as I can tell,
my camera syncs just fine at 1/125 all apertures
and 1/250 at f/16 and f/22. This, despite the
fact that 1/30 is the indicated sync speed.
________________________________________
John Thurston
Juneau, Alaska
http://stereo.thurstons.us

> It's worth noting that as far as I can tell,
> my camera syncs just fine at 1/125 all apertures
> and 1/250 at f/16 and f/22. This, despite the
> fact that 1/30 is the indicated sync speed.

It appears that World3D has provided the world with the first medium
camera with a, (focal plane shutter), that offers a flash sync at a
shutter speed of 1/125. Amazing.

IMO, credit should be given to World3D and to the efforts of Sam Smith
for the availability of this breakthrough in MF stereo photpography.


Best regards,

DON

Don Lopp wrote:

> It appears that World3D has provided the world with
> the first medium camera with a, (focal plane shutter),
> that offers a flash sync at a shutter speed of 1/125.

It is also worth noting that I may be completely wrong
about the 1/125 sync. Back on Sept 13, I outlined my
flash-sync testing procedure (in message 80)
http://tech.groups.yahoo.com/group/MF3D-group/message/80
and asked if I had my methodology correct.
I haven't heard from anyone that I got it right or wrong.

Before anyone gets carried away with the 1/125 sync
figures, I'd sure like to have my methodology confirmed
as meaningful (or not).

===== BEGIN EXCERPT FROM MESSAGE #80 =====

== Setup:
TL120 with Vivitar 285 flash attached
Camera is pointed at a white wall about seven
feet away. The back of the camera is open with
my eye-balls where the film would go (the only
view of the wall is through the camera)

I would fire camera and observe the shape of
the light visible. I was able to see full,
white circles and in other cases see white circles
missing their lower sections (chopped of).

== Suggested interpretation:
When I see the full circle, I have correct
flash sync. When I see the flattened circle
the shutter is closing too soon for correct sync.

== Observation:
At 1/500 I don't see a consistent amount of light

At 1/250 I see full circles of light at f/16 and f/22

At 1/125 I see full circles of light at all apertures


== Hypotheses:
The camera can flash sync at 1/125 just fine.
They have published a sync speed of 1/30
just to be safe.

===== END EXCERPT FROM MESSAGE #80 =====

--
John Thurston
Juneau Alaska
http://stereo.thurstons.us

Your methodology seems good, but the only way to truly test it is with
film.

Arthur Payson

On Oct 23, 2006, at 3:15 PM, John Thurston wrote:

> Don Lopp wrote:
> > It appears that World3D has provided the world with
> > the first medium camera with a, (focal plane shutter),
> > that offers a flash sync at a shutter speed of 1/125.
>
> It is also worth noting that I may be completely wrong
> about the 1/125 sync. Back on Sept 13, I outlined my
> flash-sync testing procedure (in message 80)
> http://tech.groups.yahoo.com/group/MF3D-group/message/80
> and asked if I had my methodology correct.
> I haven't heard from anyone that I got it right or wrong.
>
> Before anyone gets carried away with the 1/125 sync
> figures, I'd sure like to have my methodology confirmed
> as meaningful (or not).
>
> ===== BEGIN EXCERPT FROM MESSAGE #80 =====
>
> == Setup:
> TL120 with Vivitar 285 flash attached
> Camera is pointed at a white wall about seven
> feet away. The back of the camera is open with
> my eye-balls where the film would go (the only
> view of the wall is through the camera)
>
> I would fire camera and observe the shape of
> the light visible. I was able to see full,
> white circles and in other cases see white circles
> missing their lower sections (chopped of).
>
> == Suggested interpretation:
> When I see the full circle, I have correct
> flash sync. When I see the flattened circle
> the shutter is closing too soon for correct sync.
>
> == Observation:
> At 1/500 I don't see a consistent amount of light
>
> At 1/250 I see full circles of light at f/16 and f/22
>
> At 1/125 I see full circles of light at all apertures
>
> == Hypotheses:
> The camera can flash sync at 1/125 just fine.
> They have published a sync speed of 1/30
> just to be safe.
>
> ===== END EXCERPT FROM MESSAGE #80 =====
>
> --
> John Thurston
> Juneau Alaska
> http://stereo.thurstons.us
>
>
>

> Before anyone gets carried away with the 1/125 sync
> figures, I'd sure like to have my methodology confirmed
> as meaningful (or not).
>
> ===== BEGIN EXCERPT FROM MESSAGE #80 =====
>
> == Setup:
> TL120 with Vivitar 285 flash attached
> Camera is pointed at a white wall about seven
> feet away. The back of the camera is open with
> my eye-balls where the film....

IMO,it is not necessary to use film, though it would be the surest, and
probably the most accurate way.

If I were performing the test, without film, I would aim the flash such
that the light would travel through the camera taking lenses, towards
the film apertures. Put a translucent velum or thin paper covering
the film covering the film aperture. Flash the strobe, and check
whether or not the flash illumination covers the whole film aperture,
especially the top and bottom - at 1/30th, at 1/60th, at 1/125, etc.
The test results should be readily apparent, IMO.

This test would not be a test of synchronization, as the strobe provides
the synchronization. Actually, we are attempting to determine at
which shutter speed, is the focal plane shutter slit wide open, to
enable the strobe light to reach all of the films image area in less
than 1/1000th of a second. I do not know how the test results will
turn out, but I will be surprised if the answer is a shutter speed that
is faster than 1/60th of a second.

Incidentally, my computer has only allowed me to see only a few of the
emails that were posted on the 3D web sites, during recent months,
including September, and most of October.

Maybe Maybe, I should crawl back into my cave.


Best regards,

DON