Film speed converter
ISO combines the arithmetic ASA and logarithmic DIN scales. Enter any speed to see all of them — handy for old dials marked in DIN or GOST.
ISO is written as ASA/DIN, e.g. 400/27°. Post-1987 GOST equals ISO; older Soviet GOST ran about 0.9× the ASA value.
About this tool
Film speed appears in several scales, and older cameras or datasheets may not use the ISO number you know. Enter an ISO (ASA) value and the converter returns the DIN degrees and the old Soviet GOST equivalent. Full ISO notation combines both, so ISO 400 is written as 400/27 degrees.
How to use it
- Enter the film's ISO or ASA speed, for example 400.
- Read the matching DIN value shown in degrees.
- Read the GOST equivalent for older Soviet-era gear.
- Note the combined ISO form, such as 400/27 degrees.
FAQ
How do ASA and DIN relate?
ASA is a linear arithmetic scale, so doubling ASA doubles sensitivity. DIN is logarithmic, adding three degrees for every doubling, which is why 400 ASA equals 27 DIN.
Is GOST still used?
GOST was the Soviet standard and is mostly historical now. It is close to ASA but not identical, so the converter is handy when reading old Soviet cameras and film boxes.