[pure-silver] Re: Modified Agfa 108 with multigrade paper
- From: "Mike Kirwan" <mkirwan@xxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 15 Mar 2007 20:11:39 -0700
I apologize for jumping into this thread a little late. But do have a couple
of questions. Your enlarger is pretty good quality and you should be getting
even illumination. Have you checked to make sure the condensers are
correctly adjusted for the negative size you are using. I saw this problem
all the time at the school where I TA'ed and spent at least an hour per
session correctly adjusting the condenser height. Many of these enlargers
had a scale on the right hand side showing the correct condenser height.
Your lens is of really good quality and has coverage at least to 6x9 cm so
more than adequate for your 6x6 negatives.
So the only other variable I can think of is your print agitation method.
Again have seen this with students who just slide the print into the
developer - quick shake of the tray and let it sit for 2 minutes. I
recommend at least constant agitation for the first 45-60 seconds.
Have you checked to see if you have the right bulb installed? That also
could be a problem - regular household bulbs will give uneven lighting and
could also be the problem.
My guess is either the condenser or the bulb - get that knocked and you
should be able to go back to using your contrast filters.
Mike
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of hksvk
Sent: Thursday, March 15, 2007 4:38 PM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Modified Agfa 108 with multigrade paper
Thank you for your helpful responses, especially the one correcting my
notion that I should be able to increase contrast to the extent I want by
using a high contrast developer with the same paper.
I am using the El-Nikkor 105f5.6 enlarging lens. Isn't this a pretty good
one? It shouldn't be a cause for uneven or irregular densities, should it?
When intensifying a negative with Kodak Rapid Selenium Toner, is it
necessary to first treat it to 'harden' it, ie., to prevent blotching or
other unevenness? with formaldehyde?
Harry
>
>
>> I have the following formula for Agfa 108 paper developer:
>> metol...5
>> grams/liter, sodium sulfite...40 g/l hydroquinone...6
>> g/l potassium
>> carbonate...40 g/l potassium bromide...2 g/l
>>
>>
>> I have tested this Agfa 108 with Ilford multigrade fiber paper
>> without (for reasons detailed below) a polycontrast filter , but find
>> that my prints need more contrast than this already high contrast
>> developer provides. So, in an effort to gain contrast, I have
>> modified the developer as
>> follows: reduced
>> metol to 2 grams/liter, increased hydroquinone to 14 grams/liter,
>> and, for the accelerator, substituted 4 grams/liter sodium hydroxide
>> for the potassium carbonate.
>>
>> Having seen no substantial gain in contrast with these modifications,
>> I then increased the bromide in 1 or 2 gram/liter increments until
>> reaching 10 grams/liter potassium bromide. Still, I am seeing no
>> appreciable increase in contrast.
>>
>> Is there something about modern paper emulsions that makes them
>> unresponsive to these strategies to increase contrast? Or is this
>> problem due to some property of the multigrade paper? Would a modern
>> graded paper respond to these manipulations?
>>
>> The 2.25 inch square negatives I am printing from require absolutely
>> even edge-to-edge and corner-to corner illumination from the light
>> source of my Beseler 4x5M series enlarger with condenser head and
>> PH212 lamp. With no negative in the glassless negative carrier, when
>> I expose a sheet of the 16x20 paper at a very low density (zone 8 or
>> so), I get a pattern of increased density, even after improving the
>> unevenness of illumination that I encountered initially. The
>> polycontrast filter that I would require (3.5 or 4) exaggerates this
>> unevenness and makes it too apparent when printing from the negative.
>> These negatives are extremely nerve-wracking if not impossible to
>> dodge and/or burn in.
>>
>> I know, one solution would be to produce a set of more contrasty
>> negatives, but this would be very difficult to do.
>>
>> Is there someone on the list who could kindly help me with this
>> problem? If a graded paper might work for me in this situation, is
>> there one that could be recommended?
>>
>> Many thanks.
>>
>
> Since paper emulsions are developed to obtain maximum density the
> contrast is pretty much a matter of how the emulsion is made. There is
> only a very narrow range of variation possible with change in
> developer. Modifying a developer as above will probably only make it
> work faster.
> If you don't have printing filters for the paper you can try using
> camera filters over the enlarging lens. A blue filter will expose
> mostly the high contrast part of the emulsion, a Green or yellow
> filter will give you low contrast. You will probably have to make
> partial exposures through two filters to obtain the contrast you want.
> Most VC papers are around Grade 2.5 with no filter on a typical
> tungsten lamp enlarger.
> Note that the method of increasing the printing contrast will make no
> difference in the uniformity of the illumination, anything which
> increases printing contrast will exagerate illumination problems,
> including the inherent drop-off of the enlarging lens.
> There is some benifit from using a long lens. The drop-off will be
> less because the image angles will be smaller. A long lens will
> require refocusing the condenser for best uniformity. If you have an
> enlarging exposure meter it will help to get the illumination uniform.
> If the problem is only drop-off toward the corners or edges you can
> burn in the corners. I have to do this routinely when using a 135mm
> lens for 4x5 negatives unless I am cropping them a lot.
> If the illumination is blotchy check the condensers for blemishes or
> dirt. Also, if you are using a glass-sandwich negative holder the
> increased contrast will also exagerate any dirt or blemishes on the
> surfaces. If the glass is not good quality optical glass you may also
> be bringing up uneven transmission due to inhomogeniety in the glass.
> Another approach is to intensify the negatives. There is always a
> hazard in any chemical treatment of a negative but it is fairly safe
> to use Selenium toner. It is capable of increasing contrast perhaps a
> paper grade and will protect the image. Use KRST at 1:9 or even a bit
> stronger. It will work slowly enough to be controllable at this
> dilution. Many other intensifiers do not produce permanent images or
> can damage the emulsion or have other vices but KRST is pretty safe.
> Kodak Brown Toner is also safe and will result in well protected
> images but I don't know how much intensification it produces.
>
> ---
> Richard Knoppow
> Los Angeles, CA, USA
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