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Re: [OM] Re(2): pushing film

Subject: Re: [OM] Re(2): pushing film
From: "Shawn Wright" <swright@xxxxxxxxx>
Date: Fri, 9 Jan 1998 09:59:07 -0800
On  9 Jan 98 at 12:00, Peter Leyssens wrote:
> 
> Again, a summary :
> 1) Gene : So, if I take your point that Rodinal has sharp edges on the
> grains, the fact that you get a lot of grain by pushing can be explained
> because there's more contrast in the picture.  Because the grain next to
> this one will be a big difference in tone and therefore you notice the
> grain more, right ?
This combined with the extended development cause more grain. Remember also 
that the grain you *see* is actually the gaps *between* grains on the negative.

> 2) Gene : So Uncle Ansel is really saying : overexpose to get as much
> info on the negative, then develop in such a way that the darkest spots
> still show textured black.  And I'm saying : I don't want a lot of info
> on my negative, but I want to see it all anyway !  Right, I can
> understand that you won't get the results the film manufacturer wants
> you to get if you mistreat your film this way.
This is what I thought also. But, I have just finished books 1 & 2, and 
Ansel does not say this. He states that it is critical to only expose the film 
enough to produce a zone 1 density (for a zone 1 subject area) at the intended 
development. (or a zone 2/3 density for 2/3 subject, when taking the 
picture.) The zone 1 level is used for testing film speed/dev times, whereas 
the zone 2/3 is more realistic for picture taking, since this is the minimum 
acceptable level of shadow detail which can be printed. Any additional exposure 
results in excess density which equates to excess grain, especially in 35mm. 
One thing which impressed me about these books is how much 35mm specific 
content he has added in these revisions (done in 1980). I suspect this comment 
may not have been present in the original text.

> 3) Shawn : I should get myself a copy of The Negative.  I can feel it in
> my toes that this is a book I'm going to learn one hell of a lot from,
> but at this moment, those Roman figures are driving me nuts.  I've
> written down the ISBN number already ...  Now : am I going to wait for
> my birthday (end of march) to ask it as a present, or will the
> temptation be to large ?
They are truly wonderful books. I am dying for "The Print" but it was sold out, 
and I can't afford it now anyway... (post christmas poverty has struck... ;-(

> 4) Shawn : how do you do that, measure the negatives on a light table
> with the spot meter ?
Several references (including "The Negative") have mentioned this technique 
when a densitometer is not available. 
Since Zone 1 = .1 about fb+f, this will mean a 1/3 stop difference between a 
clear, developed frame (film base+fog), and a zone 1 frame. Therefore, use 
a 4-T, or other spot meter to measure a blank frame and a batch of Zone 1 test 
frames, until you find the one which is closest to a 1/3 stop difference. Since 
the test frames should be 1/3 stop apart in exposure, it *should* be fairly 
easy to see the transition from a 1/3 to 2/3 stop density change (0.10 to 0.20 
density). Be aware that depending upon the "toe" of the film, you may find 
several frames which are 1/3 stop above fb+f, then one which becomes 2/3 stop 
above fb+f. The one which indicates correct film speed is the highest frame 
giving a 1/3 stop difference.
In theory, one could also use this method to measure zone 5 and above, but it 
may not be too accurate - Ansel recommends using a Kodak standard negative 
density for this purpose. You then have a standard to compare zone 5, 7, 10, 
etc. which is probably more accurate than calculating 4 stops above fb+f for 
zone 5.
ie: Zone 5 = ~ 0.60-0.65 for condenser enlargers, you can compare directly with 
a Kodak test neg of this density. I suspect for the purposes of pushing film, 
comparing to fb+f and adding 4 stops may be accurate enough.
All of this assumes that the 4T or spot meter used is sensitive enough, which 
of course I cannot say...

> 5) Lars : 'grain like macadam', got to remember that expression.  If I
> understand Gene correctly, the grain doesn't get larger, only more
> noticable.  Or is it really possible to get a "Single-Grain Negative"
> (tm) ?
Not sure what you mean by this...

> 6) Lars : Thanks for mentioning the pre-exposure !  There are tricks
> like that that I have forgotten (because I only knew they existed and I
> never tried them).  A pre-expose button would be great and would
> certainly position the OM-5 as a professional camera !  More like
> Hasselblad than like Leica.
Ansel also goes into this of course - it is a very interesting method, and one 
which the OM-2000 should handle very nicely. (although, since critical 
alignment is not needed, any OM *can* do the multiple exposure).

> 7) Marco : What is the procedure for pre-exposing (or rather -
> post-exposing) in the darkroom ?  You can't just turn on the light with
> the film laying there, the exposure would be too uneven and the time
> would be uncontrolled, wouldn't it ?
I'd prefer to mark the film when loading, so it can be reloaded at the same 
point, then re-expose the frames needed using an even light source (which 
you'll need for the zone tests anyway), calculating a zone 2 or even zone 3 
pre(post)-exposure, which should move the shadows up the scale enough, but have 
minimal effect of the middle and upper zones. 

All this talk has got me going now, too bad I can't count on my OM-10 to give 
me accurate shutter speeds... Hmmm, maybe my Yashica TLR will do the trick. 
(and it *has* multi-exposure)


========================
Shawn Wright
Computer Systems Manager
Shawnigan Lake School
250-743-6240
swright@xxxxxxxxx

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