[rollei_list] Re: JOBO development tips
- From: "mail1" <mail1@xxxxxxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Wed, 18 Dec 2013 12:54:45 -0800
Thor, read this piece by Barry Thornton. His writing was really entertaining
and informative. This should give you a simple understanding and an answer
to your question.
http://www.awh-imaging.co.uk/barrythornton/unzone.htm
Jonathan
jonathan@xxxxxxxxxxxxxxxxx
P.S.
I can answer your question in greater technical detail, but I think Barry's
answer may suit you better.
-----Original Message-----
From: rollei_list-bounce@xxxxxxxxxxxxx
[mailto:rollei_list-bounce@xxxxxxxxxxxxx] On Behalf Of Thor Legvold
Sent: Monday, December 16, 2013 11:30 PM
To: rollei_list@xxxxxxxxxxxxx
Subject: [rollei_list] Re: JOBO development tips
Ok,
let me ask in a different way.
How do I know if my negatives are over or under processed?
I had taken 10 frames of a grey wall, just to check exposure (loosely
following the zone methodology). Since I didn't focus carefully, nor were
there any clear features on the wall, the test roll didn't tell me a whole
lot.
I did get 10 frames of differing density and two of the clear base, but
can't be sure if the actual eposure, acutance and all the rest is
appropriate.
I'm sure there must be a standard way to test this to find correct
development times, right?
Thanks,
Thor
On 17. des. 2013, at 01:06, Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote:
>
> ----- Original Message ----- From: "CarlosMFreaza"
> <cmfreaza@xxxxxxxxx>
> To: <rollei_list@xxxxxxxxxxxxx>
> Sent: Monday, December 16, 2013 8:17 AM
> Subject: [rollei_list] Re: JOBO development tips
>
>
> Thor:
> I couldn't share my experience with you because I do manual
> B&W film processing and never used an ATL 1500 nor prewash;anyway
> developing times have to do with the negative contrast, I think you
> need to find the best neg contrast for your purposes, f.e. print via
> condenser (flatter negatives) or diffuser enlargers ( higher
> contrast); it looks like a contrast for a diffuser enlarger is better
> to scan negs for digital prints. BTW, variable contrast papers and
> their filters help very much to compensate the negative features and
> the differences Condenser vs Diffuser enlargers are not so
> significant.
>
> Carlos
>
> The presoak affects the take up time for the developer so it has some
effect on total development time for a given contrast. The effect depends
on everything, film, temperature, developer, and must be determined by
experiment. Kodak used to recommend a pre-soak for processing sheet film by
hand to prevent the sheets from sticking together when first introduced to
the developer. I think JOBO recommends a pre-soak to slow the penetration of
the developer when it is poured into the tank so as to eliminate streaks due
to uneven development.
> To add to what Carlos says above, Kodak philosophy was to standardize
development contrast based on the expected type of printer with an aim gamma
to match "normal" grade paper and then chosing contrast grade to correct as
necessary. This is as opposed to zone system processing where development
is adjusted to obtain a fixed negative contrast based on the scene contrast,
again so that all print on "normal" grade paper. The problem is that the
reproduced contrast of a scene may be considerably distorted from the
original contrast even though the entire range of brightness will be
reproduced as shades of gray. the Kodak method gives you essentially 1 to 1
brightness reproduction for some selected range of scene brightness. The
eye likes to have mid-gray tones reproduced 1:1 even if shadows and
highlights are compressed or clipped, otherwise the scene may look grayed
out or overly contrasty.
> Development charts vary with manufacturer: Kodak charts used to be
based on suitable contrast index for diffusion printing sources, about one
paper grade more contrasty than ideal for a typical semi-diffusing condenser
source while Ilford uses a compromise value. In any case, as Carlos points
out, with variable contrast paper this is of little significance since the
print contrast can be adjusted for best visual effect from any reasonable
negative.
>
>
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickburk@xxxxxxxxxxxxx
>
>
> ---
> Rollei List
>
> - Post to rollei_list@xxxxxxxxxxxxx
>
> - Subscribe at rollei_list-request@xxxxxxxxxxxxx with 'subscribe' in
> the subject field OR by logging into www.freelists.org
>
> - Unsubscribe at rollei_list-request@xxxxxxxxxxxxx with 'unsubscribe'
> in the subject field OR by logging into www.freelists.org
>
> - Online, searchable archives are available at
> //www.freelists.org/archives/rollei_list
>
---
Rollei List
- Post to rollei_list@xxxxxxxxxxxxx
- Subscribe at rollei_list-request@xxxxxxxxxxxxx with 'subscribe'
in the subject field OR by logging into www.freelists.org
- Unsubscribe at rollei_list-request@xxxxxxxxxxxxx with 'unsubscribe' in the
subject field OR by logging into www.freelists.org
- Online, searchable archives are available at
//www.freelists.org/archives/rollei_list
---
Rollei List
- Post to rollei_list@xxxxxxxxxxxxx
- Subscribe at rollei_list-request@xxxxxxxxxxxxx with 'subscribe'
in the subject field OR by logging into www.freelists.org
- Unsubscribe at rollei_list-request@xxxxxxxxxxxxx with
'unsubscribe' in the subject field OR by logging into www.freelists.org
- Online, searchable archives are available at
//www.freelists.org/archives/rollei_list
Other related posts:
