# Photography Calculators

This page contains several calculators of use to photographers.
All of the calculators are written using Javascript, which means
you'll need a Javascript enabled browser (IE/Firefox/Opera/Chrome/etc.) to use
this page. It also means that you can download/save this page to
your computer and use the calculators without being connected to the
internet. Fields displayed on the left of the
"compute" button are for user input. Fields on the right of the "compute" button are where
the results are displayed.

This calculator computes depth of field, based on aperture,
focal length, distance to subject and Circle of Confusion (CoC). A
CoC of .03 is generally accepted as appropriate for a 35mm camera.
For most modern digital SLR cameras with a "cropped frame" sensor
(e.g. Canon 20D/30D/40D/50D/XTi/XSi/T1i, Nikon D40/D60/D90/D200/D300/D5000, etc.),
a smaller CoC is probably more appropriate.
Because the sensor size on these cameras is smaller than a 35mm
negative, the image must be enlarged to a greater extent for any
given print size. A CoC of 0.019 is a reasonable value for these
cameras. For small-sensor, compact digital
cameras (e.g. Canon A650, Canon G9) with a 1/1.8" sensor (7.18 x 5.32 mm),
a value of about 0.006 is appropriate.

This calculator computes the degree of parallax error that
occurs when a camera is rotated around a point that isn't the nodal
point. This is useful for photographers who take a sequence of
images to be stitched into a panorama. The Nodal Point Offset field
is the distance (in mm) between the actual point of camera rotation
and the nodal point. The calculator computes how much two objects
that are at different distances (i.e. one "near" and one "far") from
the camera appear to shift in relation to each other as the camera
is rotated through the specified angle. Put another way, if the two
objects are perfectly aligned (so that the near object appears
directly in front of the far object) before rotation, they will be
seperated by the angular distance determined by the calculator after
rotation. The result is expressed as an angular distance (in
degrees), and the number of pixels. For any given angular shift,
images with larger dimension (i.e. more pixels) and/or smaller
fields of view will show a larger pixel shift.

This calculator computes the angular field of view for a lens of
a specified focal length on a 35mm camera. For most modern consumer level
digital SLR cameras, a
focal length multiplier of greater than 1 is appropriate because
these cameras have a smaller sensor than a 35mm negative. For these
cameras a focal length multiplier of approximately 1.5-1.6 is
appropriate. Note: By default, this calculator assumes a standard width/height
image size ratio of 3:2 (typical of most DSLRs), but this can be changed
to 4:3 (more common for phone and small compact cameras).

This calculator computes the field of view, measured in
feet or meters, for a lens of a specified focal length on a 35mm camera.
For most modern consumer level digital SLR cameras, a
focal length multiplier of greater than 1 is appropriate because
these cameras have a smaller sensor than a 35mm negative. For these
cameras a focal length multiplier of approximately 1.5-1.6 is
appropriate. Note: This calculator assumes a standard width/height
image ratio of 3:2.

This calculator computes the number of images and lens focal
lengths required to create a mosaic image covering
the same field of view as a single image. For any given field of
view, overlap percentage, and focal length multiplier (1.6 for most
modern digital SLR cameras) the calculator determines the focal
length of the lens that is needed for each shot in a mosaic
consisting of different numbers of images.

This calculator computes the equivalent lens focal length and
aperture necessary to produce the same angular field of view and depth of
field on two cameras with different sensor sizes. For example, a
DSLR camera like the Canon T4i, Canon 60D or Canon 7D (with their sensor sizes of 22.3 x 14.9mm)
can be compared to a compact camera like the Canon G12
(sensor size of 7.6 x 5.7mm), Sony RX100 (sensor size of 13.2 x 8.8mm)
or a four-thirds format camera (sensor size of 17.3 x 13.0mm). Cameras with smaller
sensors need shorter focal length lenses to achieve the same field of view
as the DSLR, and do not need to stop down as much as the DSLR to achieve
the same depth of field. A 50mm lens on the Canon T4i/60D/7D,
stopped down to F11, gives the same angular field of view and
depth of field as the Canon G12 at 17.7mm/F4, the Sony RX100 at 29.6mm/F6.5
and a four-thirds camera at 40.3mm/F8.9.

This calculator also computes the maximum number of megapixels that the sensor can contain before becoming diffraction limited. In other words, for any given aperture and sensor dimension (in millimeters), this calculator computes the number of megapixels at which the system becomes diffraction limited...the point beyond which adding more megapixels to the sensor is futile, because those extra pixels do not resolve any more detail. Note: This calculation is based on a wavelength of green light (510 nanometers, approximately in the middle of the visible spectrum), and the Rayleigh criterion for calculating when objects are said to be "just resolved". More details about this here and here.

This calculator also computes the maximum number of megapixels that the sensor can contain before becoming diffraction limited. In other words, for any given aperture and sensor dimension (in millimeters), this calculator computes the number of megapixels at which the system becomes diffraction limited...the point beyond which adding more megapixels to the sensor is futile, because those extra pixels do not resolve any more detail. Note: This calculation is based on a wavelength of green light (510 nanometers, approximately in the middle of the visible spectrum), and the Rayleigh criterion for calculating when objects are said to be "just resolved". More details about this here and here.