Putting a lens on a pinhole?

[Rain Dance]

I am planning on buying a 5x7 pinhole camera that a friend is offering me. I saw some of his contact prints and they were really nice, the pictures were not as soft as I thought they would be. But what if you put a lens element ( I have no idea what to put yet, I will maybe look at Surplus Shed once I know what to put) in front of the pinhole? Will this affect the focal length or aperture of the pinhole? I guess it won't be called a pinhole camera anymore once it has a lens element.

[Maris Rusis]

I am planning on buying a 5x7 pinhole camera that a friend is offering me. I saw some of his contact prints and they were really nice, the pictures were not as soft as I thought they would be. But what if you put a lens element ( I have no idea what to put yet, I will maybe look at Surplus Shed once I know what to put) in front of the pinhole? Will this affect the focal length or aperture of the pinhole? I guess it won't be called a pinhole camera anymore once it has a lens element.

I tried this on a f600 8x10 pinhole camera and the presence or absence of glass made no visible difference. Later I tried my Fujinon-W f5.6 300mm 8x10 lens stopped down to f300 using a custom made waterhouse stop. This time the image obtained when front and rear lens groups were present was very slightly sharper than the result from the waterhouse stop alone. I reckon at the very small apertures used in pinhole photography diffraction dominates everything else.

[Jim Jones]

Authorities agree with Maris about the lens making little difference at pinhole size apertures if the lens is correctly focused. We could experiment with pinhole apertures used with focused lenses. Remember, there will be a focus shift as a simple lens is stopped down. The classic box camera used a meniscus lens behind the aperture with the convex surface facing the film. This arrangement provided the best possible coverage over the whole image. Some later simple cameras used a meniscus lens in front of the aperture with the convex surface facing the subject. This made the camera more compact, but introduced considerable curvature of field. Sometimes the film was curved to partly correct for this.

[Jac@stafford.net]

I put a very small aperture into a modern lens over 4x5" film as an experiment. The diffraction was profound and pictures sucked.

[Emmanuel BIGLER]

Hello from France

May be you could remove the pinhole and with a minimum of hand work, add a conventional large formart camera lens in front and get a fixed-focus camera. You'll need a ground glass, or something equivalent to a ground glass in order to properly focus the lens before fixing it at the right place.

You can have a look at this project of a home-made fixed-focus 5x7" wooden camera by Gilles Barbier ; the text is in French, but hopefully the images a self-explanatory.
http://www.galerie-photo.com/barbier-hybis-90.html
Gilles Barbier uses a 5x7" (or 13x18cm) film holder and a good old 90mm Schneider Angulon lens, compact and lightweight.

[Rain Dance]

Thank you for the replies and information, I appreciate it. I guess I will stick with the pinhole first, then maybe try a hyperfocus box camera.

[ic-racer]

I am planning on buying a 5x7 pinhole camera that a friend is offering me. I saw some of his contact prints and they were really nice, the pictures were not as soft as I thought they would be. But what if you put a lens element ( I have no idea what to put yet, I will maybe look at Surplus Shed once I know what to put) in front of the pinhole? Will this affect the focal length or aperture of the pinhole? I guess it won't be called a pinhole camera anymore once it has a lens element.

Are you familiar with the Polaroid pinhole lenscap? The lens stays in place when it is in use.

[JoeV]

If the pinhole is optimized in size to the focal length, as per the Rayleigh criterium, there will be no difference in sharpness with and without the lens. But if you are using a larger than optimal pinhole, the lens will provide some additional benefit.

What interests me, and I have not as yet explored, are hybrid optics, a glass lens stopped down enough so as to provide very wide DOF, but which still offers better focus than a mere pinhole, a trade off between optimal sharpness and not needing to focus the lens at all, like a severe hyper focal camera.

~Joe