There are different ways to quote the sensitivity of cameras. Usually it's quoted in ISO or ASA.

ASA and/or ISO is usually reasonably well-defined in the absence of any deviating statement as ISO 5800. Yet there are additional, newer ISO norms, like ISO 12232. Photron quotes their speeds in that norm and I don't quite get how they can be converted so that I can compare to stats of other vendors. Can anyone enlighten me? Is there somewhere a conversion-table I can make use of?

  • 1
    \$\begingroup\$ Sorry for the rant, but: Damn those paid ISO articles! "Want to know how our standard works, ey? Better send a few bucks in our direction, then!" \$\endgroup\$
    – flolilo
    Oct 19, 2018 at 11:20
  • \$\begingroup\$ @flolilolilo the uber type-A's of the world have to get paid somehow...right? \$\endgroup\$
    – OnBreak.
    Oct 19, 2018 at 15:34
  • \$\begingroup\$ @Hueco Sure thing. Would make more sense to pay for the certification and have free access to the certification requirements IMHO, though. \$\endgroup\$
    – flolilo
    Oct 19, 2018 at 15:38
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    \$\begingroup\$ @flolilolilo oh I'm right there with you. Doesn't make sense to hide the criteria from the average consumer. We've come to know and understand ISO/ASA - but it sure would be nice to have access to the official docs that detail exactly what that means. \$\endgroup\$
    – OnBreak.
    Oct 19, 2018 at 15:41
  • \$\begingroup\$ There used to be two standards, ASA and DIN (plus a third, GOST, in some eastern European countries). ISO is simply the ASA number with a slash and then the DIN number, so what used to be ASA 125/21 DIN is now ISO 100/21°. However, almost universally, the slash and the old DIN number have disappeared from the standard. Regardless, both ASA and DIN are now deprecated as terms. \$\endgroup\$ Oct 19, 2018 at 19:28

1 Answer 1


There are five different methods for measuring ISO "speed" of a given image recording system. Photon is reporting the speed as determined from the saturation method.

Class Leading Light Sensitivity: 
ISO 12232 Ssat 
• ISO 40,000 monochrome 
• ISO 16,000 color 

According to the ISO standard, Ssat should be reported if noise-based measurements would lead to poorer exposure. In other words, the manufacturer is given its recommended ISO setting to put into an exposure meter in order to determine shutter speed (in this case probably determined by frame-rate) and f-stop settings to provide a proper exposure. There should be no need to "convert" this value to anything else (other than based on your own aesthetic choices); the "Ssat" is just indicating that this speed rating was determined using the saturation measurement and calculation method.


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