pinhole aperture
Not losing the quality of rodenstock
expose times should be fastest hand or elastic band operatable
These requirements are mutually exclusive. The project cannot be done.6X24 or larger 120 spooled mid format film
So, you don't actually mean pinhole aperture then. I think you mean fixed aperture.
I've inserted a fixed f/22 aperture in a postcard-size rollfilm camera lens before. I did that because the lens had been worked on and was missing its aperture blades. It did work. I made it out of black plastic card.
The projected slit needs to expose each part of the film for the duration specified. You set the angular velocity to match the combination of the projected slit width and the desired exposure time.how slit and speed of motor might be optimized to make film exposure times 1/15-1/125-1/250 ?
There you go; they'll solve this for you.My friends are experts on that.
Movement of the slit, not the shutter. What you want to determine is the angular velocity.Movement speed of shutter: 24 cm per second
anamorphic cylinder camera.
We will have lens at the top of the cylinder and pinhole aperture after the lens.
a widelux time sweeping camera
Movement of the slit, not the shutter. What you want to determine is the angular velocity.
I'm confused. You seem to be describing two different camera designs.
- sweeping camera: the lens is on the axis of the [|film] cylinder, right in front of the film
- anamorphic cylinder camera: the film is also along a cylinder, but the lens is (as you state) along the axis of the cylinder, above the film; completely different from first one
From the Widelux manual (buktus.org)
View attachment 410246
View attachment 410247
from: http://ericconstantineau.com/photo/review_anya_en.html
"anamorphic cylinder camera (...) have lens at the top of the cylinder" as per your statement
The camera is a big empty tube, the sheet of film is inside, on the side of the tube, and the pinhole is at the center of the top plate.
I'm also confused. Maybe a sketch of sorts would help. Are you trying to build a cylindrical camera but with an optical lens? I don't think that would work due to narrow depth of focus. Why do you need a sweeping slit shutter vs. a guillotine shutter for example?
Members of this forum can't help if you do not communicate in a clear way your design. A sketch would help a lot, and not only other forum members. I have found myself, more than once, that putting ideas on paper helps to clarify and discover possible internal contradictions.Can you please help me to optimize those ?
My confusion just thickens, like @OAPOli
Maybe I'm thick? I still don't know which of the two kinds of cameras pictured in my post above you are planning to design. Possibly some hybrid, but which one?
Members of this forum can't help if you do not communicate in a clear way your design. A sketch would help a lot, and not only other forum members. I have found myself, more than once, that putting ideas on paper helps to clarify and discover possible internal contradictions.
So, if you do not have the resources to produce such a conceptual drawing, you might just forget about that project, that will require a lot more, and much more detailed, design work.
Hello Bernard,
these are anamorphic pinhole cameras. I replace pinhole with enlarger lens.
As you see film is rolled on rails or glass tubes - I prefer rails-
Let me tell you what am I doing.
Lets look at glass tube , there is film around it , I put a second black tube inside of glass tube. This second tube have long slit on it and it rotates with motor.
When slit starts and stops , it uses few seconds and this is time sweeping
What's the image angle of that optical lens and how does it relate to the physical design of your camera? Keep in mind that a pinhole in a reasonably flat angle can have a very wide angle (with considerable falloff, evidently). An optical lens is more limited. Did you include this in your concept?Ok , you drill a small hole to make pinhole. Put a bigger hole to the same place and install there a optical lens.
My lens have 80mm focal lenght so the camera could be made 6X33 but we prefer 6X24.
You have to focus to the bottom end part of the film.
For a pinhole I can conceptualize the image formation by drawing straight lines from the subject to the film via the pinhole. But I'm not sure what the image would look like for a lens given that the film is parallel to the optical axis. Something similar surely when the aperture is stopped down, but still I think you would get a only narrow band where the subject is in focus. Or maybe it's okay if the subject is parallel to the axis as well. Could be cool.Ok , you drill a small hole to make pinhole. Put a bigger hole to the same place and install there a optical lens.
Pinhole anamorphic cameras are generally 6X17cm format , you use a 60mm focal lenght pinhole.
My lens have 80mm focal lenght so the camera could be made 6X33 but we prefer 6X24.
You have to focus to the bottom end part of the film.
What's the image angle of that optical lens and how does it relate to the physical design of your camera? Keep in mind that a pinhole in a reasonably flat angle can have a very wide angle (with considerable falloff, evidently). An optical lens is more limited. Did you include this in your concept?
I suggest two small exercises. First decide on the cylinder diameter, height, and position of the lens; does not need to be final values, this exercise is generally called a strawman design. Assume for the exercise a landscape at "large" distance (you may later introduce the complications of "near" objects)
Another question, already asked I think by someone else. What is the purpose of the moving slit? For a camera like the Widelux, the purpose is clear: allow to image a wide horizontal field of view while at any given time not exceeding the capability of the lens.
- The lens will image the scene in a plane (the image plane) located 80mm behind the rear principal plane.
- where is that located relative to the width of your film?
- for a nominal value of the lens operating f-number (f/8? f/11?) what is the diameter of the circle of confusion at points of the film that are outside the image plane? Is that be better or worse that what would be achieved with a, say, 0.3mm pinhole (and no lens)?- What is the maximum angle of rays (relative to the lens's optical axis; If I understand your design, that will occur at the edge of the film closest to the lens. How does that compare with one half the field of view given by the specifications of your lens?
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