Calculating the correct exposure for black and white film.


When shooting large format photography calculating the correct exposure is key to gaining a beautiful correctly exposed black and white negative from which the print. For me, using a handheld spot metre is essential to assessing the correct exposure,

So let's start by looking at The Ansel Adams Zone System.. Ansel Adams developed the zone system, diagrammed below. He broke all of the tones that you would expect to see in a black and white image down and graded them from zero to ten. Zero being no detail in the shadows to Zone Ten having no detail in the highlights.


Once you have an idea of the zone system you can then assess the scene that you're looking at through your viewfinder of the camera. Try to see the scene in zones of grey rather than colour and using the Ansel Adams zone system point your spot metre either at zone 2 or zone 3 depending on the light and conditions and take a reading. Set your shutter and aperture to that reading and you should achieve the perfect exposure.

To explain further.. When shooting black and white images especially landscapes using large format you need to expose the film for the shadow detail and not 18% grey which is zone 5 which is why you need to take a spot meter reading from zone 2 or 3 to expose for the shadow detail. This is important as by doing so it will give you a perfectly exposed negative from which to print.

Let me give you an example: I went for a day out to the Fisherman's Quay at North Shields with my MPP large format camera. I spotted two fishermen on the Quayside talking whilst setting up my camera.

The camera and lens was pointing into the sun, I didn't want the fisherman to be in silhouette which would be normal if exposed in zone 5. Calculating the correct exposure in this situation can be difficult so I used my spot metre to take a reading from zone 2 on the Ansel Adams zone system. I set my shutter speed and aperture to that reading and Bob's your uncle here is the scan with no manipulation.

The film was Ilford FP4 developed in ID11 at 20c for 8 minutes.

I am offering large format photography workshops covid safe on a one-to-one basis. www.keithmossphotography.co.uk


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