It is weekend, so here are my tips:
Making a B/W is all about the distribution of gray matter (pun intended
).
At shooting time, this distribution has two aspects:
[1] where on the image do you see things (translates to composition)
[2] what is the light-value of the gray (translates to exposure and filter use).
Effects on composition
Going from color to B/W is a difficult thing to grasp, because the development procedure determines the final appearance of these two distributions.
Lets illustrate this with the following (hypothetical) situation.
Suppose I found some chips of paint and made a composition like:
Original Paint chips
not a great composition but it will do for this tutorial.
If I convert this in photoshop (by image|mode|gray scale) I get:
Gray conversion
all the same value gray, and so a dull composition.
The gray scale conversion is a monochrome color mixer with value: 30%Red+59%Green+11%Blue simulating the relative high absorbance of the cones for the value green
(see this
link for more info ).
In searching for these paint chips I did my utmost best (only the best is good enough for the camel
) to find specific colors so that a conversion to Agfa 200X film (simulated by channelmixer settings: 18%Red+41%Green+41%Blue) would give the same grayvalue (try it in PS if you don't believe it):
Agfa 200X conversion
So here we have an image that can be converted in two complete different ways to the same B/W image.
In setting up the composition you have to see through this whole proces to get it right for the final image.
You learn it by practice, but you can also use some tooling for this (all based on a wratten #90 filter):
Contrast viewers. In this way you can really (learn to) see in Black and White.
Since we loose color information it is worthwhile to pay attention to the recognition -subconscious or not- of building blocks like graphical shapes and distribution of light.
This brings me to the second part: what is the light-value of the gray?
This light value is determined by the choosen exposure and the fact that you can increase or decrease the lightness by using filters.
First the exposure.
I assume you are shooting digital. In that case you have to expose for the highlights and develop for the shadows.
I use spotmetering and meter the lightest part of the scene that I want to have some texture (in the zone-system nomenclature you place this highlight at zone IX).
Suppose this is f/8;1/30s @ISO 100. Since the meter thinks that this lightness value equals 18% gray (that is regarded as zone V in zone system parlance), you have to let in 4 (=IX-V) stops more light. Keeping the same aperture value this gives: f/8;1/4s@ISO 100.
Finally the use of filters.
In order to enhance some colors, you can add a filter at exposure time.
To understand this well, you have to know these three basic facts:
[1] An filter enhances (i.e. lightens up) the same color as the filter and darkens the opposite color.
So a yellow filter will lighten yellow colors and darken the blues.
[2] There are three important filters: yellow,red,green.
[*] yellow is used for landscape/water scenes in order to get the blues right
[*] red is used for darkening the sky
[*] green is used for rendering leaves and portraits.
[3] each filter comes in different strengths, for instance a yellow filter is normally #8 that gives a correction to panchromatic films, but there is also a stronger version (often designated as #12) that has the nickname: minus blue filter: virtually all the blue light is absorbed.
For more info on filters, check out the following links:
[*]
Tiffen Black and white images
[*] chapter 5 of Ansel Adams book:
The negative
[*] the free
opanda photo filter tool
[*] the just recently released expensive but real good:
Tiffen filter Dfx suite
To make the story complete you can see below the paint chips image as throug a yellow/red/green filter:
Yellow filter
Red filter
Green filter
To get you going, some old filmsettings for the channelmixer:
Film %R %G %B
Agfa 200X 18,41,41
Agfapan 25 25,39,36
Agfapan 100 21,40,39
Agfapan 400 20,41,39
Ilford Delta 100 21,42,37
Ilford Delta 400 22,42,36
Ilford Delta 400 Pro 31,36,33
Ilford FP4 28,41,31
Ilford HP5 23,37,40
Ilford Pan F 33,36,31
Ilford SFX 36,31,33
Ilford XP2 Super 21,42,37
Kodak Tmax 100 24,37,39
Kodak Tmax 400 27,36,37
Kodak Tri-X 25,35,40
Normal Contrast 43,33,30
High Contrast 40,34,60
Finally, you could check out
this book for checking out both the conversion process and the setup for B/W photo's.