R&R PHOTO

I'm in the process of learning so I can teach a class on Pin Hole Cameras. Hickham AFB Photo Lab purchased four of the 4x5 3" models. This will allow us to use standard 4x5 film backs for either Film or paper negatives.

Leonardo Pinhole Cameras ©
4"x5", 5"x7", and 8"x10" models
designed by Eric Renner

Special Price for Web Visitors: Mention you saw our site and you can take $10 off all 4"x5" Leonardo Pinhole Cameras

We are making the Leonardo pinhole camera at the Pinhole Resource. This wooden camera features a moveable shutter, a positive locking film holder mechanism and two tripod mounts. Brass shimstock laser pinhole is approximately .010 inch pinhole for 1.5 inch camera, .012 inch pinhole for 3 inch camera, .017 inch pinhole for 6 inch camera. The 4.5 inch focal length 5"x7" uses a .016 inch pinhole. 4x5 Leonardo pinhole cameras accept 4x5 film holders and the Polaroid 545i and 545 backs*, 5x7 Leonardo pinhole cameras accept 5x7 film holders*, and 8x10 Leonardo pinhole cameras accept 8x10 film holders and 8x10 Polaroid film holders*. Each camera numbered and signed by Eric Renner. Each camera postpaid.

 

Prices: 4"x5" models:

1.5 inch focal length (super wide angle) $85 - normally $95
3 inch focal length (wide angle) $87.50 - normally $97.50
6 inch focal length (normal) $89.50 - normally $99.50

http://www.pinholeresource.com/products.html#leonardo

Camera Info:

4"x5" camera excepts standard 4x5 film backs (two shots per back)

Focal Length = 3" thus a wide angle with a view of 75 degrees (the same as 28mm lens on a 35mm camera)

Pin Hole Size = .012" in the 4x5 camera will give a f/250

Approximate exposure times using Tri-X (asa 400) film in bright sun is 4 - 6 seconds.

Introduction

       The rebirth of Pinhole photography in the 1970's and 1980's was a reaction to ever increasing automation in photography which distanced photographers from the fundamental elements their craft. Terrence Pitts sums up this reactionary (and purist), appeal of Pinhole photography in his introduction to Lauren Smiths excellent book, The Visionary Pinhole,  "Pinhole photographers often seem to be the type of people who have chucked their old cameras into storage and headed off to the frontiers of photography. ...Where pure science reigns without much interference from technology. No matter how crude or fancy, cheap or expensive the construction of the camera may be, the major factors determining the image quality are the precision of one's mathematics and the strength of ones personal vision, not the cost of one's equipment"

    The English scientist, Sir David Brewster, coined the name Pin-hole photography in the 1850's to describe image making by a lens-less camera. Today, Pinhole photography and its counterparts, Zone Plate, Slit and Pinspeck photography, merit closer consideration by serious photographers. In spite of its apparently naive technology and unpretentious trappings, the revival of lens-less photography as this century draws to a close is not surprising. As at the end of the last century. It has again moved from being regarded as a photographic curiosity into a "real" picture-making medium. Creative photographers and scientists have re-discovered that lens-less photography is a tool which allows them to explore ideas and spaces which no other means of imaging has yet been able to achieve. By approaching photography from the fundamental elements of time, light and an image receptor, lens-less photographers have used the unique optical properties of the system to express memorable visions.
 

Light

    Pinhole photography demonstrates the two main descriptions of light. Sometimes it behaves like a stream of particles, at others times it behaves as if it were a wave motion. Light travels in straight lines. When light is reflected from an object, each point of that object reflects rays of light in all directions. Some will travel towards the pinhole camera and a small cone of light rays from the point source will enter the pinhole. If the pinhole is small enough it will restrict the size of the cone of light rays so that an image of that portion of the object can form on a light receptive surface inside the camera. If the pinhole is large, the diverging rays of light passing into the pinhole camera will cause the image to be blurred. Each point on the object will be projected as a circular patch of light on the film. If the pinhole is made extremely small, the divergence of the cone of light rays is restricted and should theoretically lead to sharper image. (Leonardo DA Vinci theorized that it would be possible to isolate a single ray of light with a small pinhole.) But, as the pinhole becomes smaller, a certain point is reached when diffraction (bending) of the rays will occur as they pass the edges of the pinhole. The result will be an increasingly blurred image as the pinhole reduces in size. However, with a large diameter pinhole, the spreading of the light by diffraction as it passes the boundary of the pinhole is small. There is thus two opposing effects present when considering the sharpest image that will be possible from a pinhole. An optimum pinhole size will be a compromise between these two opposing characteristics and this will considered under Sharpest Image with a Pinhole


Image Characteristics

    The image formed by a pinhole will be inverted, laterally reversed and have the characteristic of being slightly out of focus. However, since the image is not formed by a lens system, provided the receiving surface is parallel with the plane of the pinhole, the image will be free of rectilinear distortion and chromatic aberrations. Furthermore, as far as the eye can discern, the image will have the same degree of focus throughout the whole image; objects from just in front of the pinhole, to those at infinity will appear equally sharp. (Or equally fuzzy if your glass is half-empty). An almost infinite depth of field. Exposures range from a few seconds to several hours.

Choice of Light sensitive material

This list is not exhaustive, but it will give an indication of what might be achieved with different materials.

 

 
Speed

    Assuming that the camera is loaded with film or photographic paper, then the material will have a standard sensitivity to light, usually expressed as the ASA or DIN of the material. Most photographic papers and darkroom films (those designed to be exposed under an enlarger) have an ASA of approximately 4 or 6. Conventional films range from 25 ASA to 1000 ASA and faster.
Pinhole photographs require long exposures. It is important that the camera is firmly mounted during the exposure to prevent unintentional blurring of detail. The long exposures also require that the reciprocity of the film needs to be taken into account if accurate exposures are required. This will be considered shortly.

Calculating the exposure time

    This is best done by taking an exposure reading from the scene with a conventional light meter or using the light meter in an older type manual SLR camera with the ASA set to the speed of the material being used. Next calculate what the exposure would be for the aperture (f/stop) of your pinhole. Since most light meters and cameras do not have an aperture range that extends beyond f/32, the following simple device enables the exposure time to be quickly calculated.

    On two pieces of narrow card, divide the length into equidistant blocks. On one, write the progression of exposure time in one stop increments, on the other write the progression of f/numbers in one stop increments. (Moving from one f/stop to another halves or doubles the area of the aperture, therefore halving or doubling the amount of light that can pass through the pinhole. The same occurs with a change in the exposure time.)

 

Time (secs)

Aperture (f/stop)

The exposure time for the pinhole size can be calculated by placing the light meter readings opposite each other on the two scales. The exposure time for the pinhole will then be opposite the f/number for the pinhole.

For example our 4x5 3" Leonardo Camera has a F/number of f/250. If the light meter reading indicated an exposure with 100 ASA film of 1/2 second @ f/22, then the required exposure for the same speed film in the pinhole camera would be 64 seconds @ f/250 before allowing for reciprocity failure.

Exposure time (seconds)

Aperture (f/stop)

Reciprocity Failure

    Over a certain exposure range photographic films respond to light in a linear fashion. If the exposure time is doubled this will result in the negative being twice as dense. For most films, when exposures are longer than 1 or 2 seconds, they no longer respond to the light in a linear fashion. This is known as reciprocity failure. Lens photographers seldom have to deal with reciprocity failure except for specialized applications requiring exposures shorter than 1/10,000th second or greater than 1 second. For pinhole photographers, reciprocity failure in film is a way of life! The result is that exposures have to be increased even more to get a correctly exposed negative. Not all films are equally affected. Type L films are designed for longer exposures without reciprocity affecting color balance under tungsten light. Darkroom films and photographic papers are designed for long exposures and therefore less prone to reciprocity.

    The following exposure compensation chart is from published data by film manufacturers for black and white film. It is a good starting point but remember that each film and paper has a different characteristic curve. (For example photographic paper may not show reciprocity failure until exposures are longer than 2 minutes or more, Type L and daylight films for 4 seconds and some transparency film for up to 30 seconds.) A degree of experimentation is required to determine the relationship of this chart to your own sensitive material. Often a simple adjustment, for example, -50% or +100%, will be all that is required to get exposures within 1/4 stop of ideal.


 

Reciprocity: Other considerations

    In "normal" conditions, the emulsion layers on color films are designed to be equally sensitive to light. Under conditions of reciprocity this equal relationship also begins to break down. One layer becomes more exposed than the others with the result that there is a color bias in the color material. Small shifts can be adjusted by the use of a filter to compensate. Larger shifts require stronger filtration which leads to increased exposure time which leads to greater filtration and so on. A situation known as galloping reciprocity. In practice most pinhole photographers simply ignore the color shifts as that part of the process that they do not want to control. After all, all manufactured films have a bias in order to emphasize their principle use. (Flesh tones, red/green, contrast in commercial work etc.)

The final exposure time

    In the example above the metered exposure was 1/2 sec. @ f/22. This translated into an exposure of 16 seconds @ f/125. (The aperture of the pinhole.) Allowing for reciprocity from the exposure compensation chart, this becomes an exposure of 32 seconds @ f/125.

This may sound a lot of calculation to do in the field. By keeping notes of exposure times and then assessing the results, it is possible to build a simple chart that relates basic light meter readings to the final exposure without referring to conversion charts and reciprocity tables. This enables the photographer to enjoy the moment and forget the math! Alternatively there are a number of "ready reckoners" available for varying light conditions and apertures. One is published in Eric Renners book Pinhole Photography (Focal Press) and another at Byron Bignall's Web site. See Resources


Adjusted development for Black and White Films

Under conditions of reciprocity, reducing the development times on B&W films can help to maintain a manageable negative contrast level.
 

Processing and Printing

Processing film and paper is as diverse as the materials used in pinhole cameras and it is impractical to cover it here in detail.

Generally pinhole photographs are best contact printed or enlarged a minimal amount for normal viewing distances. Alternatively enlarge them as much as possible so that the viewer has to adjust their viewing distance in order that the image can be "read"

B&W Paper negatives can be contact printed on to another sheet of paper by placing the emulsions in contact with each other. The grain of the paper negative will break up the image slightly. Similarly color paper negatives can be exhibited on their own or contact printed.


My First Attempt

 Click on the Thumbs for a larger view.

Both images were taken about one hour before sunset. I metered the scene to be a one stop less than sunny f/16. I had some 4x5 film backs loaded with Ilford HP5+ ASA 400 film from another project so decided to use them. Using an Exposure Wheel and a f/250 pin hole I determined a shutter speed of 1 second add 1 second for reciprocity failure. This was my starting exposure with out a stop watch I used the old one-thousand and one, one-thousand and two. I exposed three sheets of film at 2, 4, 8 seconds. I later retested my times and found that my one-thousand and two is a little slow 1.6 sec but that turned out to be the best exposure .... 2 seconds.

The sheet film was developed in my normal HP5 Development and contact printed using a number 3 contrast filter for 8 seconds I dodged the bottom (land) for 2 seconds. All in all not bad for a first try.  The other negatives are all printable and would probably give fairly good results.

l Images are the copyrighted © property of David Richert  please contact me for any usage.