79 lines
2.5 KiB
Plaintext
79 lines
2.5 KiB
Plaintext
---
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title: "Photography calculations"
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---
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```{r}
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#| label: setup
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library(tidyverse)
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library(gt)
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coc_fx <- 0.025
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coc_dx <- 0.020
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apertures <- c(2.0, 2.8, 4, 5.6, 8)
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distances <- c(2, 4, 6, 8, 10) # meters
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# Source of equations: https://dofmaster.com/equations.html
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# Returns the hyperfocal distance in millimeters given a focal length in mm,
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# an aperture, and a circle of confucion (CoC)
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hyperfocal_distance <- function(focal_length, aperture, circle_of_confusion) {
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focal_length^2 / (aperture * circle_of_confusion) + focal_length
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}
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# Returns the near focus limit in millimeters given a focal length in mm,
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# a distance in mm, and a hyperfocal distance in mm
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near_focus <- function(focal_length, distance, hyperfocal_distance) {
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(hyperfocal_distance - focal_length) * distance / (hyperfocal_distance + distance - 2 * focal_length)
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}
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# Returns the far focus limit in millimeters given a focal length in mm,
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# a distance in mm, and a hyperfocal distance in mm
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far_focus <- function(focal_length, distance, hyperfocal_distance) {
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(hyperfocal_distance - focal_length) * distance / (hyperfocal_distance - distance)
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}
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# Returns the depth of field in millimeters given a focal length of the lens,
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# an aperture, a distance of the focused object, and a circle of confusion.
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# All distances in millimeters.
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depth_of_field <- function(focal_length, aperture, distance, circle_of_confusion) {
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h <- hyperfocal_distance(focal_length, aperture, circle_of_confusion)
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ff <- far_focus(focal_length, distance, h)
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nf <- near_focus(focal_length, distance, h)
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dof <- ff - nf
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ifelse(dof >= 0, dof, Inf)
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}
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```
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# Full frame with tele lens 150 mm
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```{r}
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#| label: tele_lens
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expand_grid(aperture = apertures, distance = distances) |>
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mutate(dof = round(depth_of_field(150, aperture, distance * 1000, coc_fx) / 10, 1)) |>
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pivot_wider(names_from = distance, values_from = dof) |>
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gt() |>
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tab_spanner("Object distance (m)", columns = -aperture) |>
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cols_label(aperture = "F") |>
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tab_header(
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title = "Depth of field in centimeters",
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subtitle = "full frame, 150 mm focal length"
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)
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```
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# Full frame with wide-angle lens 20 mm
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```{r}
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#| label: wide_angle
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expand_grid(aperture = apertures, distance = distances) |>
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mutate(dof = round(depth_of_field(20, aperture, distance * 1000, coc_fx) / 10, 1)) |>
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pivot_wider(names_from = distance, values_from = dof) |>
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gt() |>
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tab_spanner("Object distance (m)", columns = -aperture) |>
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cols_label(aperture = "F") |>
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tab_header(
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title = "Depth of field in centimeters",
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subtitle = "full frame, 20 mm focal length"
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)
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```
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