How can I shoot wide angle zone plate photography?

Question

I like the look that is possible with zone plate photography. I've google around a bit and it seems that pinhole and zone plate photography on a DSLR, especially a crop body DSLR, results in medium telephoto type shots. It also seems that the focal length is dependent upon the distance from the plate (or pinhole) to the sensor.

You could take a body cap and inset it some into the camera body, but it will eventually strike the mirror. Going one step further, I could use mirror lockup and and get the zone plate even closer to the sensor. If I do that, what sorts of problems am I likely to see. And this raises an interesting question, does the Canon 40D even have a mechanical shutter and would this inset device interfere with that?

Asked by Paul Cezanne

Answer

One option is to use a zone plate optic with a wide-angle converter lens in front. An off-the-shelf solution is Lensbaby's zone plate optic + wide angle 0.6× or super-wide angle 0.42× conversion kit. Since the optic gives a focal length of roughly 55mm, the results will be about 33mm or 23mm.

Examples are available on Lensbaby's site with the zone plate with super-wide converter and regular wide converter.

Answered by mattdm

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Why does depth of field occur?

Question

I wonder why depth of field occur in the first place. This is not a question about what changes the effect/size of field. We all know that.

Aperture, Focal Length, Focus Length (distance to subject), sensor size.

But why it happens in the first place?

When we think of pinhole cameras (camera obscura), and when we widen the pinhole, the image that drops to surface will be blurred, and we all know that hole is replaced by aperture on lenses.

Yet this still does not give a proven, explained reason of it.

Any ideas?

Answer

There are a couple of concepts that you really need to understand to grasp depth of field.

First, lenses focus on a plane. You can envisage this as, basically, a razor thin slice of reality and everything in that slice will be perfectly in focus. Everything in front, or behind, will not be.

Second, there is a range out of the focal plane that we will perceive to be acceptably sharp. When we reach a point before or after the focal plane where a point is sufficiently blurry for us to perceive it (a circle of confusion), it is out of the depth of field. So the depth of field becomes where the circle confusion is from the front to behind the focal plane.

Cambridge in Colour has a tutorial on this subject with more depth to it, no pun intended, as does Wikipedia. Wiki even has the physics behind it.

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Can a dSLR be safely made into a pinhole camera?

Question

What exactly is pinhole camera? The wikipedia article says

A pinhole camera is a simple camera without a lens and with a single small aperture — effectively a light-proof box with a small hole in one side. Light from a scene passes through this single point and projects an inverted image on the opposite side of the box.

Can I make my dSLR into one? Is it safe to try this, since there will be no lens? Will the results be interesting?

Answer

Is it safe to try this setup on my DSLR(since there will be no lens), mine is Canon EOS 1000D?

It is possible to make a pinhole from a DSLR. Basically, buy a spare body cap, then make a small hole in its center. Don't destroy the only cap which comes with your camera, you may need it later. Google for "DIY DSLR pinhole" for multiple instructions.

But you should remember that it is still a hole, not a glass, so some dust or liquids may come through it into the camera. On the other hand, when you change lens, even larger quantities of dust may come in.

Dust on the mirror or even on the sensor is not dangerous, but you need to be careful when you clean it later. Dust on the mirror does not affect the quality of the image, but it is visible in the viewfinder, and sooner or later it may reach the sensor. The dust on the sensor is not visible in the viewfinder, but it is visible on the shots with small aperture (large f-number) and, surprise, on pinhole shots. You should not touch the mirror when you clean it, it can be easily scratched; use only a special photographic air bulb to clean it. To clean the sensor you'll need to buy special cleaning kits and have enough patience, but sometimes the air bulb is enough. Sooner or later all photographers have to do it.

Has anyone tried it and got interesting result ?

There is a whole group on Flickr dedicated to Digital Pinhole Photography

An alternative design: a pinhole box.

They also suggest an alternative digital pinhole design in the group description. It is safer, because doesn't require to open the camera and is compatible also with compact cameras:

A ready to use pinhole

If you want to spend some money, you may buy a ready to use pinhole (f/177) from Lensbaby (you'll need to acquire their adapter too) or from other producers (see answers from @Jay Lance Photography and @Stan Rogers).

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