Cs6 slides do not clear (very dark)

Yes, but at the time these films were designed, and mostly used, scanning was not so common.

That was then, this is now. And most film shot these days is destined for scanning, only to end up as a digital file that could have been got cheaper, quicker and easier with a digital camera!

The point is that the so-called 1600 EI film is no such thing. The -3.0 log Lux-second (0.001 Lux-seconds) barrier isn't broken at all.

Taking the B&W film ISO rating specification as a guide, the darkest parts of the curve would have to start curving downwards at -3.3 log Lux-seconds for 1600 ISO to be acheived. That's clearly not the case, and the real ISO rating of that film is only around 400, maybe a little higher if we're really generous.

As far as I know, the ISO rules are different for reversal films, and I at least sort-of

understand the reasons for the rules for negative film. Among others, normally

you don't use all of the curve for negatives, where you do for reversal.

Looking at the middle of the curve, which is where most actual parts of

scenes are, the 1600 is a little more negative, maybe 1 to 1.5 stops

compared to the 400x.

The 1600 curves are still going up at -3.0, so it seems that they should have

kept the graph going to -4.0.

In any case, if you want to use film for scanning, it should be negative film.

As far as I know, the ISO rules are different for reversal films,

Indeed they are, but since the ISO want to keep that methodology 'secret' unless you pay them an exhorbitant 58 Swiss Francs (and the ISO rigorously scan the web for infringement of 'copyright'), then those standards may as well not exist.

I thought standards existed for everyone's general benefit - not to line the pockets of a bunch of Swiss gnomes - but there you go. That's the modern world.

The 1600 curves are still going up at -3.0, so it seems that they should have

kept the graph going to -4.0.

But the RGB density curves have already vastly separated at -3.0 Log lux-seconds, and the slopes at that point are almost identical to those of Ektachrome 200. So is it ISO 200, or EI 1600? Because there really doesn't seem to be much difference in the shadow density change.

Indeed they are, but since the ISO want to keep that methodology 'secret' unless you pay them an exhorbitant 58 Swiss Francs (and the ISO rigorously scan the web for infringement of 'copyright'), then those standards may as well not exist.

 

I thought standards existed for everyone's general benefit - not to line the pockets of a bunch of Swiss gnomes - but there you go. That's the modern world.

In the cases of the Fortran and C standard, yes, you have to pay for the official standard. But the last of the draft standard, just before the final vote, seems to be free.

If you are selling an actual product, you can't base it on an unofficial version of the standard.

And even though the negative standard is also not free, we know it close enough.

(I forget the exact numbers, though.)

I don't remember the exact rule, but many of the Ethernet standards are also free.

There is a process for getting a free (for personal use) copy of the US national electrical code.

When you download it, it sends a watermarked copy with your name and email address on it.

If you distribute it, they will know it was you.