# Why L 0.3, 0.7 1.0?



## 480sparky (Jan 3, 2013)

My response to "Why do Nikons use H 0.3, 0.7, 1.0 and 2.0 instead of ISO  12,500, 16,000 etc." were always answered with, "Because the ISO  (International Standards Organization) does not recognize any film or  digital speed higher that 10,000.  So to avoid getting into trouble,  Nikon uses the H designations."

Well, my theory worked until I  got my D600.  And instead of finding ISOs of 80, 64 and 50 (familiar ASA  numbers from my film days), I find L 0.3, 0.6 and 1.0.

Obviously,  ISO speeds of 50, 64 and 80 exist and are perfectly acceptable by the  ISO.  So why use the L system instead of actual ISO ratings that have  existed for years?


FWIW, if given my druthers, I'd like to see a DSLR with a range of ISOs from 10 up to 1600 max.


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## AlexanderB (Jan 3, 2013)

This is likely because at these "extended" ISO settings there is an abrupt drop in quality in some way, like dynamic range at L's or noise at H's. With a different designation it is easier to distinguish them from "normal" ISO's.


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## 480sparky (Jan 3, 2013)

AlexanderB said:


> This is likely because at these "extended" ISO settings there is an abrupt drop in quality in some way, like dynamic range at L's or noise at H's. With a different designation it is easier to distinguish them from "normal" ISO's.



Well, every sensor has a 'native' ISO, usually 100 or 200.  And every step away from them is a trip down Lower Dyanamic Range Street in Noiseland.  But I still have ISOs of 800, 1600, 3200, 6400 and the like.


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## Derrel (Jan 3, 2013)

480sparky said:


> My response to "Why do Nikons use H 0.3, 0.7, 1.0 and 2.0 instead of ISO  12,500, 16,000 etc." were always answered with, "Because the ISO  (International Standards Organization) does not recognize any film or  digital speed higher that 10,000.  So to avoid getting into trouble,  Nikon uses the H designations."
> 
> Well, my theory worked until I  got my D600.  And instead of finding ISOs of 80, 64 and 50 (familiar ASA  numbers from my film days), I find L 0.3, 0.6 and 1.0.
> 
> ...



Because the ISO standards are ACCURATE values. Nikon does not bullspit its users: the Hi- values are NOT "accurate", but are rather "approximations", and do not meet what Nikon considers to be appropriate degrees of conformity with ISO standards. So...Nikon lists those elevated, or artificially lowered settings as approximations with the prefixes of Hi- and Lo-.

If the camera did or could actually CONFORM to the ISO standards, I am sure Nikon would use the ISO standard. But, since they are not all about BS'ing, they use Lo- and Hi-.


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## KmH (Jan 3, 2013)

Both ends - L and H - are done with software downstream of the A/D converter.

Native ISO is done with analog electronic amplification upstream from the A/D converter.

The International Standards Organization can set a standard for analog electronic amplification. They cannot set a standard for software manipulation of image data.


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## gsgary (Jan 3, 2013)

Derrel said:


> 480sparky said:
> 
> 
> > My response to "Why do Nikons use H 0.3, 0.7, 1.0 and 2.0 instead of ISO  12,500, 16,000 etc." were always answered with, "Because the ISO  (International Standards Organization) does not recognize any film or  digital speed higher that 10,000.  So to avoid getting into trouble,  Nikon uses the H designations."
> ...



So when people compare the 5Dmk3 against the D600 at iso 12500 the D600 might be at a lower rating so there is not a fair comparison


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## amolitor (Jan 3, 2013)

According to Ctein, the ISO settings for digital from the manufacturers are in fact based on International Standards Organization standards, but include a distressing amount of manufacturer fudge factor. I forget the details, but the manufacturers pick some parameters out of the air, and then run it through the standard's formulae and so on, to produce the number.

It's not like film where the standard was in fact the standard and it meant something very very specific and reproducible about how the film behaved, no manufacturer parameter-picking involved.


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## Scuba (Jan 3, 2013)

Interesting topic.  I understand about the standards, however if a setting allows for a 1 stop bump in shutter or aperture then can't the ISO setting be confirmed to be accurate?


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## nycphotography (Jan 3, 2013)

Scuba said:


> Interesting topic.  I understand about the standards, however if a setting allows for a 1 stop bump in shutter or aperture then can't the ISO setting be confirmed to be accurate?



I'm kindof in this camp.  If I can shoot it, and it's "accurately" a stop higher or lower, I'd rather see the ISO listed.
The quality will fall off, but that's expected, at least on the high end and I can learn to expect it on the low end.

But I also have no problem doubling ISO to get the real number.  And while I will adjust an exposure, and the variables in an exposure, I don't calculate exposures in my head using sunny16 type rules, so Hi 1 and Hi 2 are fine for me.

It IS an interesting topic.  Part science, part marketing, part politics.  ;-)


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## amolitor (Jan 3, 2013)

The relevant Ctein piece is here:

The Online Photographer: Why ISO Isn't ISO


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## Scuba (Jan 3, 2013)

I get what that article says but then I don't.  I get the pixel size issue, however if two sensors allow the same image with the same settings then that ISO is the same regardless of pixel size or anything else.  My head hurts right now.  It seems so simple but complex at the same time.


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## greybeard (Jan 3, 2013)

KmH said:


> Both ends - L and H - are done with software downstream of the A/D converter.
> 
> Native ISO is done with analog electronic amplification upstream from the A/D converter.
> 
> The International Standards Organization can set a standard for analog electronic amplification. They cannot set a standard for software manipulation of image data.


This is the only explanation that makes any sense.


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## Mayo (Jan 4, 2013)

I have know idea what y'all are taking about... Haha.... But it's interesting and I'm learning.. This DSLR is a lot different from film


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## Scuba (Jan 4, 2013)

greybeard said:


> KmH said:
> 
> 
> > Both ends - L and H - are done with software downstream of the A/D converter.
> ...



After reading it again it does make a lot of sense.


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## unpopular (Jan 4, 2013)

480sparky said:


> My response to "Why do Nikons use H 0.3, 0.7, 1.0 and 2.0 instead of ISO  12,500, 16,000 etc." were always answered with, "Because the ISO  (International Standards Organization) does not recognize any film or  digital speed higher that 10,000.  So to avoid getting into trouble,  Nikon uses the H designations."



It should be noted that ISO 12232:1998 was withdrawn and replaced with ISO 12232:2006



> Photography -- Digital still cameras -- Determination of exposure index, ISO speed ratings, standard output sensitivity, and recommended exposure index
> 
> ISO 12232:2006 specifies the method for assigning and reporting ISO speed ratings, ISO speed latitude ratings, standard output sensitivity values, and recommended exposure index values, for digital still cameras. ISO 12232:2006 is applicable to both monochrome and colour digital still cameras.


http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=37777

I don't have access to this ATM, and I don't really want to pay $100 for it. But it could probably be assumed that this issue has been addressed. KMH's explanation may make more sense.


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