Often who take pinhole shots think that to obtain pictures with a low difraction effect is fundamental using a camera with a good quality pinhole lens. This is true, but this could be a limit, this means that you could't ask nothing more from your camera and all pictures obtained will be well executed only thanks to the photographer capability. Actualy not so, Auloma in addtition to supply cameras with high quality pinhole lens, is a company with compentences in optic field and so know which other elements can enhance your pinhole pictures.
Who know the Airy disc? If you take shots using a pinhole camera surely you must know it, because is the fisic effect that distinguish pinhole photography. Exist a wide literature that describe in which way the light rays through a pinhole casting light points on the film making a picture, we can say that this description isn't false but is rather simplistic. to obtain pictures well executed with your pinhole camera is fundamental know what happen at the light when pass through the pinhole lens. Now we won't be professors and won't boring you with a long discussion about fundamentals of waveform phenomenon interference, we prefer be solid and assert that the light is a waveform phenomenon, the wavelengths of visible light range from 400nm (violet light) to 700nm (red light). Cause this property the light when pass through the pinhole lens is diffracted and on the base of Huygens studies, also the diffraction can be considered an interference issue, thus the pinhole lens can't be considered such as a point light source, but in reality its extension influences in some way the pattern, in other words the shape of of light that impressive the film isn't a point but the Airy disc.
To be clearer, if we illuminate a very thin slit, a pinhole in our case, the corpuscular model predicts that a single point of light, surrounded by shadow, is formed on a screen behind it (film). What actually happens is that the light, as it passes through the slit, creates a projection on the screen consisting of a series of bright fringes, alternating with dark areas (patterns).
The shape of this projection is a series of concentric rings where the projected light is maximum at the centre of the disc and gradually dims as the rings move away from the centre.
The disc diameter depends by the illuminating light wavelength and the pinhole diameter. There is a mathematical formula to determine the size of Airy's disc and it is as follows:
Where Λ is the illuminating light wavelength expressed in meters
d is the pinhole diameter expressed in meters
sinΘ is the sine of the angle formed between the focal length and the film plane produced by the light beam
So as the diameter of Airy's disc increases, there will be more diffraction and the resolution of our photographs will be worse.
How to enhance pinhole camera resolution
When you buy a pinhole camera you know the pinhole diameter and the focal lenght, this two parameters can't be changed, so the variations of the Airy's disc dimensions depending only from the wavelenght of the light that pass through the pinhole, from the formula to determinate the Airy's disc dimension we understand that when we shooting when the wavelenght light is close to the violet at 400-500nm, our pictures will be more sharpnes than we shooting when the wavelenght light is close to the red at 625-740nm. The question is, we can always waiting the best time to have the perfect light to shooting? This isn't possible to doing ever, also because is a good practice have the sun at your back when take a shoot with a pinhole camera and this often don't happen at the best light conditions, thus if at sunrise or at sunset the sun is in the wrong position waht we can do? What we can doing to take sharpned pictures ever in whichever moment of the day? This is possible if you take black and white shots thanks to the lens filters. A skilled use of lens filters enhance the sharpness of pinhole cameras, tehorically using a blue or violet filter the light wavelenght that pass through the camera cam be reduced until 380nm and obtain an Airy's disc very thin, thus pictures more sharpened, but in this case the light energy that pass through a blu or violet filter is less intense and so the Airy's disc brightness is reduced, furthermore the ble and violet filters reduce the contrast and is necessary operate during the print. To enhance the sharpness of your pinhole pictures, the best results is possible using a green filter with a tone away the yellow, such us our green filter Aulomacolor capable of filtering the light and obtain a wavelenght of 510nm, this value maintain the Airy's disc brightness elevate and reducing its diameter than an Airy's disc obtained using a red filter. In addition we must consider that the best contrasts among light and shadows are available during the middle of the day, so with the support of the Aulomacolor green filter when the sun brightening strong, youe can obtain the best contrast in your pictures, the best pictures sharpness and increase the exposure time of 3 stops, this last thing is a big advantages because for example in brightness conditions, if you shooting with a ISO100 film without a filter, maybe your exposure time is less a second with a risk of an overexposure.
To find out about our Aulomacolor filters, please visit our dedicated pageBlack and White Filters ❱
To view our pinhole cameras visit our pinhole camera pagePinhole Camera ❱
Or go directly to our shop onlineGo to e-shop Attaphoto ❱