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Archive 2013 · Why L 0.3, 0.7 1.0?
  
 
theSuede
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p.2 #1 · p.2 #1 · Why L 0.3, 0.7 1.0?


Actually, none of the explanations in the thread is 100% right.

This answer isn't 100% right either, but more truthful (or at least more conformant to reality):
The "H" and "L" monikers are used by Nikon to signify that a range has past the a sensor post-processing outer linear limit. This usually signifies that something other than normal has been done to the raw values; usually a clipping, a color reconstruction or an increase in noise reduction.

The maximum ISO that the camera in itself can reach before it has to (or rather - "switches to") digital scaling in stead of analog amplification is usually much lower than the maximum numerical ISO stated in the camera.

A D800, D7000, D600 class sensor usually only uses analog gain up to about ISO1000. EVERYTHING higher than this is realized by digital multiplication of the values at maximum sensor amplification. In that type of sensor there is absolutely no information quality gain by relying on increased amplification any further, in fact it would harm image quality in the lower end of the amplification range without making any sense in the higher range.

D3 and later sensors of that type (non-Exmor, having AD converters off-chip) usually use native amplifiers on the sensor with higher selectable gains, up to about 50x (33dB) is normal. In that case you lose base ISO performance (DR), but you allow the signal to be transported off-chip before AD with much less signal degradation.

So, the numerical range of the ISOs signify what Nikon consider to be the "normal" working range of the camera - and this does NOT include any hint about the maximum analog gain from the sensor ("native ISO"). It does however by very natural reasons show you the LOWER limit of the amplification, the "L" marked ISOs are always clipped values from the lowest numerical ISO. And the image results are always clipped highlight results of the lowest real ISO.



Jan 04, 2013 at 05:23 AM
Rodolfo Paiz
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p.2 #2 · p.2 #2 · Why L 0.3, 0.7 1.0?


theSuede wrote:
Actually, none of the explanations in the thread is 100% right.

This answer isn't 100% right either, but more truthful (or at least more conformant to reality):
The "H" and "L" monikers are used by Nikon to signify that a range has past the a sensor post-processing outer linear limit. This usually signifies that something other than normal has been done to the raw values; usually a clipping, a color reconstruction or an increase in noise reduction.


And that's one of the reasons I love these forums. Learn something new every day.



Jan 04, 2013 at 08:14 PM
SoundHound
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p.2 #3 · p.2 #3 · Why L 0.3, 0.7 1.0?


Which seems to indicate that any L or H ISO equivalent values can be recreated in photoshop (if you shoot RAW) with equivalent (and sometimes betters results for fractional push or pulls) than in-camera manipulation of these extreme hi or low ISOs.


Jan 06, 2013 at 11:20 AM
Graystar
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p.2 #4 · p.2 #4 · Why L 0.3, 0.7 1.0?


480sparky wrote:
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 50, 64 and 80 (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
...Show more
Nikon's have been using the "L" label for a long time. My D90 has those settings.

When you use those settings, you lose dynamic range at the highlight end. Basically, you're trading highlight DR for less noise.

This works fine if there are no bright highlights in your image...in which case you didn't need all that highlight DR to begin with. This is actually the basis of ETTR, and I refer to the "L" settings as having ETTR built into my camera.



Jan 06, 2013 at 09:39 PM
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