Pinhole Photography for the DSLR Scott Hull GSFC Photo Club 4/20/2011

History Also known as a camera obscura Effect described as early as 5 th century BC Aristotle, Bacon, and da Vinci all studied it Initially a room, with the image projected on a wall Portable versions with projection screens for drawing First known pinhole photograph in 1850 Popular mostly in late 19 th century Revived in the 1960’s for artistic purposes Has been used in spacecraft for X-ray imaging

Basic Idea

Resources Cameras – Many are homemade – Commercial cameras are available – Modifications for the DSLR Photographic Medium – Film – Photographic paper – CCD Information – Dozens of web sites – Very big in the UK

Making the Aperture (1) Materials – Aluminum can – Aluminum foil – Brass shim stock Punch – Needle or pin – Mounted in a pencil eraser – Can be sharpened with sandpaper Technique – Thin the stock to weaken it, and provide better optics – Punch and twist, to get a round hole – Sand any burrs flat

Making the Aperture (2)

Practical Aspects DSLR makes things much easier – Light meter – High ISO values available for short exposures – “Film” is cheap Use a tripod for long exposures Dust on the sensor is a big problem – Remove with a low pressure puff of air (don’t blow it!) Consider movement - blurring – Usually not desirable – Can be an interesting effect

My Examples 0.16 mm aperture

Theoretical Optimum Hole Size R = 0.95 √ (λ d) R = radius of the hole λ = wavelength (550 nm average) d = focal distance (usually 50 mm) For most DSLRs, then R = mm (hole diameter = mm) Aperture: f = d/2R = f 159

Actual Optimization Smaller is better Roundness is critical Flatness is important Stock thickness has an effect as well – Thinner is better – Wider field of view with thinner stock vs.

Others’ Examples

More Examples

Extreme Example SIX MONTH exposure onto photo paper Notice the lines traced by the sun as it crossed the sky day after day, after day…

Worldwide Pinhole Photography Day Last Sunday in April every year April 23 to May 1 this year, because of Easter Take as many images as you want, but only submit one Submit photos as a part of the Goddard Photo Club workshop: "NASA/Goddard:Greenbelt"