Michael,
I wouldn't work the development times like that, as there are other issues
involved and it varies with every developer. I strictly use the tables for
development for my chosen developer. But I almost exclusively use Ilfotec
DD-X.
The rule of thumb for push/pull/zone exposure/processing is to Expose For
the Shadows, Develop for the Highlights.
Determine you minimum exposure to get Zone I. Set the camera for that. Spot
meter your highlights and determine how many stops you need to pull them up
or down. That's your N+ or N- development. But you already know that.
As I use DD-X as my primary developer, it's more of a push/pull developer
than a contrast control developer, so I don't do zone-system development
with it, but you certainly can with D76. For that, there are many published
tables.
Ken Norton
On Thu, Apr 9, 2015 at 10:14 AM, Michael Wong <mialop.wong@xxxxxxxxx> wrote:
> It makes me confused and I do not get an affirmative answer yet.
>
> As my knowledge (pls correct me if I am wrong), if I need to push one stop
> for film development, I have to plus 1.4X of the time of development, such
> as 8.4 mins for push one stop for normal developing time 7 mins at 20ºC
> water. If I need to pull down one stop, then I have to reduce 1.4X timing
> for development, i.e. 5 mins for normal 7 mins development.
>
> For B&W shooting, if I found the high light area is at zone 8 and I need to
> put there to zone 7 and I cannot change the exposure value for shadow area.
> That I have to reduce developing time as N-1. I read some local books that
> declared the reducing time is 20% of normal developing time, N-2 is less
> 40% normal developing time. As same factor to calculate N+1 & N+2
> developing time so on.
>
> I'm confusing that I have experiences to push & pull one stop by factor
> 1.4X are OK. Then should I reduce 20% or 40% for N-1 is correct?
>
> Thanks all.
>
> (I'll reply your feedback tomorrow since I have to go to bed because I have
> to wake up early tomorrow morning for a promotion interview :p)
>
>
> Cheers,
> Michael
> --
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>
--
Ken Norton
ken@xxxxxxxxxxx
http://www.zone-10.com
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