@MikeSowsunwrote:
@TCampbellwrote:
Mike, I'm not sure if you've ever worked with hexadecimal numbers.
Your serial number of 402a5f in hex would be 4205151 in decimal.
Is that 4205151 the serial number you see printed on the lens?
You are right, I have never worked with them but I just found an online hex encoder. Encode Decode / HexEncode
Am I doing this right?
My EF-S 55-250mm STM shows 300ace EXIF data (333030616365), but has 080130389 for it's serial number.
My EF 24-105mm 4.0L IS USM shows 407782 EXIF data (343037373832), but has 4070954 for it's serial number.
My EF 70-200mm 2.8L IS II USM shows 402a5f EXIF data (343032613566), but has 129952 for it's serial number.
The website you linked is doing something different. It's converting ASCII into hex. E.g. since computers are all based on numbers, everything has to be represented by a number... even text messages are really just stored as numbers. The character sets are based on something called ASCII (an acronym for American Standard Code for Information Interchange).
But that's a system for encoding "text" characters into a numerical representation ... not the same as converting a numerical value from one base to another base.
When I use my hex calcuator and convert 0x300ace (the "0x" prefix is a shorthand for "hex value" and if you see that on a number it means the digits are really base-16 instead of base-10). The number works out to 3148494 in decimal. But that doesn't match your serial number of 080130389.
So I'm not sure where it's gettting that value for a lens serial number ... but it's even more mysterious that one lens gets it right and the others do not.
I would have guessed (but this would be wrong) that maybe since the old EXIF specs seemed to not support lens serial numbers, but the current EXIF specs do support serial numbers... maybe "old" lenses don't bother to send it (since it wasn't in the spec) and "newer" lenses do send it.
Except that hypothesis falls apart becuase your 70-200 f/2.8L version II is a "newer" lens... as is the "STM" lens. But the 24-105 f/4L... those have been around for a while. And yet your 24-105 gets the right number in the field and the other two do not..
Another hypothesis is... there is lots of meta-data that isn't "officially" part of the EXIF spec (or at least did not used to be part of the spec in the past) but that wouldn't stop a company from being able to use it anyway. So possibly it was part of an extension but not really part of the standard. If that's true... then maybe the "newer" lenses have simply changed how they transmit the serial number info and your software doesn't know how to read the new method.
The latest EXIF 2.31 standard now supports things like weather data (ambient temperature, humidity, pressure) and they FINALLY updated the "time" so that it properly supports "time zones" (time zone info was not previously part of the official EXIF standard prior to EXIF 2.31... that was a surprise to me, but I found a blog post on it.)
My 5D IV's most recent firmware update has release notes that said the new firmware also gives the camera support for EXIF 2.31. Of course, the 5D IV doesn't have any weather instruments on it... so it's not like it's actually going to populate the temperature, humidity, etc. But maybe it'll start properly supporting time zones (that was a problem when I shot the last solar eclipse. The science organizations that wanted our image data needed to know the clocks on the cameras were precise to the second (they wanted us to use GPS to set the clocks) and they were also fussy about the time zones. I had to find a program that was able to re-write the time on each image in the original RAW files (normally you never modify the RAW) just so the data could be ingested with correct time encoded because EXIF didn't really support it at that time.
Tim Campbell
5D III, 5D IV, 60Da
