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[OM] Re: Dynamic range of films (and digits)

Subject: [OM] Re: Dynamic range of films (and digits)
From: Joe Gwinn <joegwinn@xxxxxxxxxxx>
Date: Fri, 28 May 2004 08:53:33 -0400
At 3:30 AM +0200 5/28/04, Listar wrote:
>From: "C.H.Ling" <chling@xxxxxxxxxxxxx>
>Subject: [OM] Re: Dynamic range of films (and digits)
>Date: Thu, 27 May 2004 21:27:55 +0800
>
>
>I believe slide has a D-range of over 3.6 or close to 4.0, that is over
>3000:1.

Well CH, you've forced me to do some research, rather than to rely on 
memory.  More later.  I have the datasheets somewhere.  Film response 
(HD) curves are often very gradual, a stretched S-shape, so it's a 
bit arbitrary where one declares the limits to be, which can lead to 
practical-vs-theoretical debates.

Looks like Sensia, Velvia and Provia should be included in the research.


>For DC, the highlight is easily clipped but shadow does not, [so] I
>always shoot under and adjust it later. A curve can compress the highlight
>(not cut it off), while maintaining the picture a brilliant look. The sky
>will keep without wash-out.

If I understand, you are underexposing the frame (less light), to 
ensure enough of the highlight is captured that you can later 
compress it using the curve, and just living with the resulting loss 
of shadow detail.  In bright light, the loss won't be that great, and 
getting the highlights (and sky) right makes the most difference.

The wider the linear range, the easier it is to do this, as the 
exposure becomes less critical.  And, more shadow detail can be kept.


At 3:30 AM +0200 5/28/04, Listar wrote:
>Date: Thu, 27 May 2004 04:35:22 -0700 (PDT)
>From: AG Schnozz <agschnozz@xxxxxxxxx>
>Subject: [OM] Re: Dynamic range of films (and digits)
>
>  > I think the big difference between film and digital sensors is that ...
>
>Tube vs Solid State Amplifiers.  Boy does history repeat itself or what?

And, one can buy solid state amplifiers with added electronics that 
make the amp distort (sound) just like a tube amplifier.  Sort of 
like what CH is doing manually in his digital camera.  History does 
repeat.

Joe Gwinn


>C.H.Ling
>
>----- Original Message -----
>From: "Joe Gwinn" <joegwinn@xxxxxxxxxxx>
>
>>  I recall from reading film datasheets that most films had a response
>>  (incoming light) range of 100:1 (6.6 stops), while some managed
>>  1000:1 (10 stops).  The density range was always around 100:1, maybe
>>  a little more, and the films with wider response ranges were less
>>  linear.  Tri-X was the standout.
>>
>>  I think the big difference between film and digital sensors is that
>>  film has a gradual cutoff at the top (highlights) and bottom
>>  (shadows), while digital sensors tend to have abrupt cutoff at both
>>  ends, but to be very linear in between.  The sharp cutoff is probably
>>  why exposure is so critical, and overexposure looks bad.  In time,
>>  the march of progress will make the linear part of the range large
>>  enough that it will no longer matter in practice.
>>
>  > Joe Gwinn

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