It reads the code; it just may not read all possible values. The ISO code is
| SQUARE
ISO | 2 3 4 5 6
----------------
25 *
32 *
40 * *
50 * *
64 * *
80 * * *
100 * *
125 * *
160 * * *
200 * * *
250 * * *
320 * * * *
400 * *
500 * *
640 * * *
800 * * *
1000 * * *
1280 * * * *
1600 * * *
2000 * * *
2500 * * * *
3200 * * * *
4000 * * * *
5000 * * * * *
If you hold the cartridge with the long spool end to the left,
the squares 1-6 are L to R on the top row.
Manufacturers can save whole pennies in manufacturing cost per
camera by leaving off sensor pins for "unneeded" ISO speeds.
A 5c saving means a 25c profit at retail, which for a 4 million
camera run means a million dollars in profit. 5 pins will sense
all possible ISO values. But only 2 and 4 are needed to sense
the difference between 100, 200, 400, and 800, which will do for
most P&Ses, 2,3&4 will get all the ISO=25*2**n, n=0,7 values.
Adding pin 5 or 6 will catch the occasional roll of ISO 64, but
not the ISO 160 & 320 pro films. (With 5, 160 will round to
100; with 6, 160 will round to 125 - apparently the IS-30 does
this.) Look in the film compartment of your cameras. Some sense
squares with pairs of pins. Others have a ground pin in square
1 (which is always present for that purpose) and single pins
for the ISO squares. Some really cheap cameras will have only
pin 4 or 5 to sense 100 vs. 400.
>
> Well, this just shows how little I know about DX. I had no idea the camera
> would
> read anything other than the code on the film canister. It's a good thing I've
> never used DX on my OM-PC. I have no choice with the Stylus Epic, however. I
> find this rounding down a bit thick. Of course, even cameras where you set the
> ISO number manually don't provide every possible value, but at least they
> don't
> just swag it. I don't think I'd buy a computer that could only resolve numbers
> to within ten digits of the entered value. Well, that would be a Wintel with
> the
> early Pentium chip, wouldn't it?
>
> >>> "Hans van Veluwen" <hcvanveluwen@xxxxxxxxx> 08/24/00 04:11pm >>>
>
> : I have no idea how this is possible. Please splain.
> :
> : <<OTOH the iS-3000 gives ...a more
> : accurate DX decoding,>>
>
>
> The iS-3(000) can decode:
>
> 25,32,40,50,64,80,100,125,160,200,250,320,400,500,640,800,1000,1250,1600,200
> 0,2500,3200,4000,5000
>
>
> The iS-30(0) can decode:
>
> 25,32,50,64,100,125,200,250,400,500,800,1000,1600,2000,3200
>
>
> Intermediate values will be rounded downwards; so 160 ASA film will be rated
> 125, 320 ASA film will be rated 250. Bad news for users of Ektachrome 160T,
> users of films like Portra 160 or Tri-X Pan 320 probably won't mind the 1/3
> stop off-DX decoding?
>
> Btw, pushing a film with the iS-3000 can also be a nightmare; one hit on the
> reset button also cancels exposure compensation, which is the only way to
> overrule this DX decoding :((
>
>
> hnz
>
>
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