• Tom Lee

Collodion/Macbeth comparison

When making #Wet #Plate #Collodion prints, it can be confusing as to why some images are better than others. I decided to take a look at the effect of #colour and its relationship to Collodion resolution.

Collodion is a #monochromatic process which resolves colour images (in reverse) on extremely low #sensitivity chemical layers on either metal or glass plates. I decided to use my trusty #GetagMacbeth colour checker chart as a comparison. The colour chart is #scientifically designed to ensure true to life images under any lighting condition. It gives an #accurate representation of colours in nature and is accepted as an #industry #standard.

Without going into depth of the collodion process itself, suffice is to say that it does not behave in a way that most of us would associate with ‘normal’ black and white imagery, either digital or film processes and has a sensitivity range of about ISO1. Exposure is also dependant on the available #UV #light, rather than the normal visible light spectrum to resolve the image on the #sensitised plate.

The collodion #tonal #range is somewhat muted and compressed. We can see that comparing the colour patches with the collodion patches that warmer colours render darker from the midtone grey (Patch 16), and the cooler tones render lighter from midtone. Greens appear to more representative of mid grey in the sample.

The tonal range of collodion seems to be rendered into three distinct areas of lights, darks and midtones.

· Darks – Patches 2, 11, 22 and 24

· Midtones – Patches 1, 7, 13, 15, 18 and 20

· Lights – Patches 3, 4, 5, 6, 8, 9, 10, 12, 14, 16, 17, 19, 21 and 23

So how does this help us?

Lets take a seascape – difficult to do with collodion as everything has to be produced on location….we may have blue sky, white clouds and turquoise waters. (Patches 3, 4, 6, 8, 9, 12, 16, 20, 21 and 23). All the patches are in the Lights range meaning that the differences are minimal, making for an image with restricted tonal range. A digital image converted to black and white would be easy to manipulate the tones to give a pleasant image, however this is not possible in collodion prints. What you see is what you get.

Even in a studio portrait, a person with ruddy complexion and freckles wearing a red t-shirt will all reproduce in darker or midtones, also rendering a muddy or compressed tonal range.

If we look at the greyscale patches (white to black), the difference is extremely nuanced until squares 20 and 24. This means that the image will have to rely on the shadows and contrast contained in the image to provide separation in the tonal ranges. So, when choosing clothing and backgrounds for our portraits, the selection of clothing can play a big part in enhancing the result.

My conclusion is that the choice of colour within a portrait or scene is equally important as the composition. If the portrait subject has dark or ruddy skin, choose a contrasting clothing colour such a white, blue or green, then use lighting direction to produce sculpted shadows to provide depth.

It’s not always possible (particularly in a landscape), but if we understand colour relationship it may affect our choice of viewpoint.

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