#Lenzfx
Aaron,
I am looking forward to seeing the release version of LenzFX. The flare and
glow abilities appear to be just what I want/need/lust after…. If it does
indeed compare to Alias PAv6 I will be calling to order soon, probably if it's
even just close to Alias….
BUT, regarding this discussion on Depth-Of-Field I must put in my two
cents…..
ASSUMPTIONS:
I. The human eye is our window to the human idea of PERCEPTION.
II. The CAMERA (Lens focal system) is the nearest device yet made to reproduce
the working human eye, but is really a pale imatation.
III. 3D Studio, Lightwave, and ALIAS, ect., use a CAMERA as a metaphor for
simulating a lens-focal-system, which in turn, simulates the human eye, which
in turn leads to our PERCIEVED view of a scene.
IV. 3D Studio, Lightwave, and ALIAS, ect., should then therefore adhere to the
laws of optics for depth-of-field, or we will PERCIEVE a "difference" with an
image which we will PERCIEVE as "not correct" because we are exposed to the
world through our EYES (normal vision) and CAMERAS (Film/Photography) every day
we live. (Unless you are blind and have no vision.)
AO>Scott,<
AO>Please relax, take some Nyquil and get some rest. I really don't even want
to argue AO>this with you.<
He's better now.
SR>In your sample image the table is in focus, the wall is out of focus. The
distance from SR>the viewer to the table + the distance from the table to the
wall cannot be shorter SR>than the distance from the viewer to the wall. So
the wall's depth is between that of SR>the table top and the reflection of the
wall. It isn't possible to have an out of focus
AO>If this logic is true, then by every law of triangles that I'm aware of, it
would never be AO>possible for a reflection of an object to be in focus if the
same object is in focus,
Check out text such as Raymond Fielding's SPFX Cinematography and you will see
that to focus on an object in a mirror, you must measure from the camera to
mirror to object. Add in DOF and I believe your TEST image is not correct.
I find it absolutely incredible that any discussion of depth-of-field has not
mentioned the following items:
1. Focal Length of lens
2. f-stop
3. Distance
4. Light level
It's school time! The following is excerped from CINEMATOGRAPHY revised ed.
1986 by J. Kris Malkiewicz. pub by Prentice Hall.
DEPTH OF FIELD AND CIRCLE OF CONFUSION
If we were to photograph only one distant point, such as a light, the lens
would be in focus when if projects a point onto the film. Because the lens can
be focused for only one distance at a time, objects closer and farther away
will be slightly out of focus. In the above example a second, closer light
would have its image formed behind the film plane and be represented on the
film as a circle. A third light, farther away, would form its image in front
of the film plane and also appear on the film as a circle. These circles are
called "circles of confusion," and they vary in size depending on how far out
of focus they are. The "confusion" is that circles smaller than 1/1000 inch
confuse our eye and are seen as points in focus. This allows us to see
pictures of three-dimensional objects that appear in focus.
We have a range in which objects will appear sharp. It runs between the
closest and farthest objects as circles of confusion smaller than 1/1000 inch.
This range is called "depth of field" (and is sometimes incorrectly called
"depth of focus").
The depth of field varies with the effective diamater of the lens opening and
hence with the f-stop. By '"effective diameter" we mean the actual size of the
iris opening, not the f-stop number…….
…..These general principles govern depth of field:
Greater DOF Less DOF
——————————————————————-
Wide-angle lens Telephoto lens
High f-stop (small Aperture) Low f-stop (wide Aperture)
Subject far away form CAMERA Subject close to CAMERA
Smaller format (such as 8mm) Larger format (such as 35mm)
With greater depth of field more elements in the picture are in sharp focus.
This causes the image to appear harder and of higher contrast. Therefore,
using a higher f-stop number introduces apparently higher constrast.
Depth-of field characteristics for lenses of various focal lenght under
different conditions are available in many publications, such as the American
Cinematographer Manual. (A must have – DrS) Given the focal length and f-stop
and the subject-to-film-plane distance, we can determine the range of the depth
of field and the dimensions of the field of view at that distance.
For each lens and f-stop the chart also gives the hyperfocal distance. This is
the point of greatest depth of field. It is a precalculated figure indicating
that if the given lens at the given f-stop is focused at this hyperfocal
distance, everything from half this distance to infinity will be in acceptable
focus. For example, if for a given lens and f-stop the hyperfocal distance is
20 feet, by focusing at 20 feet we would obtain everything in focus from 10
feet to infinity.
A similar principle is valuable when "splitting the focus" between two objects
at different distances. They will both be equally sharp if we focus for a
point not halfway between them, but a third of the seperation distance form the
closer object. For example, two objects at 10 and 16 feet respectively would
both be equally in focus if you focus for 12 feet. This is often referred to
as the one-third-distance principle……..
_____________________________________________________________________
I will upload diagrams from the above text if you would like to see them.
Based on my earlier assumptions, than LensFX would need to EMULATE a
lens-focal-system in software. It would have to have a software equivilent of
an f-stop and use 3DS's CAMERA focal-length from the KEYFRAMMER. By doing this
than the physics is black and white if you have CAMERA Depth-of-Field,
Hyperfocal Distance & Field of View charts (lookup tables or calculated).
I am curious as to how LenzFX handles the idea of an f-stop?
In Lightwave under the CAMERA menu I do the following:
1. Choose level of Antialiasing (MED or HIGH – Number of passes)
2. Choose Film Size (11 choices)
3. Choose Zoom Factor – Focal Length mm, controlled by Envelope over
time
4. Choose Focal Distance – Variable and controlled by Envelope over
time
5. Choose Lens f-stop – Variable and controlled by envelope over time
AO>And no, I'm not TRYING to avoid any point at all, and in fact your friend is
dead on AO>correct about there not being any access to refraction during 3D
studio rendering.
Thanks! I must be smarter than I look. <BG>
AO>However, the Z-focus module of LenZFX is nothing short of a miracle in a
scan-line
But if it's not a true representation of DOF, I guess I'll be using it for it's
lens flare and it's other stuff. And I'll use Lightwave for my DOF stuff.
AO>renderer. Take for example, the focal capability of LightWave. It is
limited to a focal AO>point of 0 distance from the camera. So the focal point
can never go out into the
WRONG!
AO>scene like you can with ZFocus. And to top it all off, LightWave will
render the scene AO>8 TIMES to achieve this affect! And it's a raytracer ….
And its done directly from
Not quite right, you can actually have up to 16(?) passes. Each pass is a
level of blur (focus). Ask Allen Hastings on the Internet for an explaination
as it's quite interesting what he is doing with this. Do you use Lightwave
regularly? I do, as well as 3DS and others.
AO>Z-Focus is not the only module of LenZFX. It also includes spectacular aura
and AO>starlight effects as well as a proprietary system to create
user-definable lens flares AO>that even make the mouths of ALIAS users water.
All completely controllable by the AO>user through keyframable spline envelopes
and automatic object detection!
This sounds really great! I can't wait to see this stuff work. Sign me up!
AO>LenZFX is a tool just like any other. Just like 3D Studio. None of this
stuff is 100% AO>intuitive. If it was, we wouldn't need animators. We'd all be
playing in holodecks by AO>now. Now this is just my opinion, but I think
LenZFX is about as user-friendly as any AO>of this complicated mess gets, and
its a great tool. If you've decided, however, that AO>you don't want it on the
basis of a liberal amount of armchair philosophy and one AO>image done with a
BETA version of the software then that's your right. But don't AO>blame me
when your 3D Studio animations compared against the work of a AO>3DS/LenZFX
professional look like they were done by a 5 year old with a crayon.
This last sentence is pretty harsh, Aaron. Do you know Scott (SCAATT) Roberts?
I do. For just about 15 years now. In fact I tripped<BG> over his art works
in our apartment for 6 years. His paintings, photographs, sculptures, and
writings seemed very professional to me and he didn't have LensFX when he did
any of them.
…..3DS/LenZFX professional? Give me a break…………..
…..5 year old with a crayon. Sounds like someone here needs to grow a bit.
When you see the work Scott is doing you'll see that he's a bit older than
five. I feel partly responsible for Scott choosing 3DS as a platform and when
I see his work I ALMOST wish I had told him his first choice, the MAC was
RIGHT. You see, now that he's on 3DS I will have to work a bit harder so that
he doesn't grab the whole marketplace up here. <BG>
AO>Aaron >>>
Just speaking my onions,
David.