the size of photographed objects on the photogram depends:

• on Focal Lenght -Equivalent Focal Lenght- (in mm.) used
• on angular diameter (in arc-seconds) of the photographed object

as shown:

dnof diameter in mm. on photogram of the photographed object  F Focal Lenght (Equivalent Focal Lenght) in mm.  daof angular diameter in arc-seconds of the photographed object  206265 number of seconds (arc-seconds) in one radian

this formula allows you to evaluate the diameter in mm. that the photographed object will assume on film, if you know:

• the Focal Lenght in mm. used
• the angular diameter in arc-seconds of the object

from formula      you algebrically obtain this formula:

dnof diameter in mm. on photogram of the photographed object  F Focal Lenght (Equivalent Focal Lenght) in mm.  daof angular diameter in arc-seconds of the photographed object  206265 number of seconds (arc-seconds) in one radian

that allows to evaluate which is the right Focal Lenght to obtain on film the desired size of the photographed object (of known angular diameter)

the size of the photographed object (dnof) is proportional to the Focal Lenght (F) used:

• doubling the Focal Lenght (F) will double the size of the photographed object (dnof) on the photogram
• halving the Focal Lenght (F) will halve the size of the photographed object (dnof) on the photogram

• to double the size of the photographed object (dnof) on the photogram double the Focal Lenght (F)
• to halve the size of the photographed object (dnof) on the photogram halve the Focal Lenght (F)

0,5 to 10 mm circles on 24x36 (35mm) film to evaluate the size of the photographed object related to film size (1:1 scale)

0,5 to 10 mm circles on 24x36 (35mm) film to evaluate the size of the photographed object related to film size (2:1 scale)

---

Sun (diameter in mm. on photogram)	compute the diameter of Sun (in mm.) on photogram
Moon (diameter in mm. on photogram)	compute the diameter of Moon (in mm.) on photogram
Mercury (diameter in mm. on photogram)	compute the diameter of Mercury (in mm.) on photogram
Venus (diameter in mm. on photogram)	compute the diameter of Venus (in mm.) on photogram
Mars (diameter in mm. on photogram)	compute the diameter of Mars (in mm.) on photogram
Jupiter (diameter in mm. on photogram)	compute the diameter of Jupiter (in mm.) on photogram
Saturn (diameter in mm. on photogram)	compute the diameter of Saturn (in mm.) on photogram
Uranus (diameter in mm. on photogram)	compute the diameter of Uranus (in mm.) on photogram
Neptune (diameter in mm. on photogram)	compute the diameter of Neptune (in mm.) on photogram
Pluto (diameter in mm. on photogram)	compute the diameter of Pluto (in mm.) on photogram
for the diameter calculation of photographic objects not listed mail to Maurizio De Marco the request will be inserted in TAF

---

under construction