Exposure of 248secs at f/32 at Castlerigg Stone Circle.
You might have noticed that digital capture has many advantages. There is no reciprocity law failure (RLF) for a start. Film is affected by RLF and a typical colour film would lose effective ISO speed and there would be a colour shift with exposures longer than one second. This means that very long exposures are tricky.
With digital capture, RLF has no impact at all so there is no loss of effective film speed. In practical terms, if you determine that an exposure is one second at f/4, you can set either 2secs at f/5.6, 4secs at f/8, 8 secs at f/11, 16secs at f/16 or 32secs at f/22 and you get the same image density. Having the freedom to be so adventurous with your camera settings opens up many creative opportunities.
It is because of this creative freedom that there has been such great interest in using strong neutral density filters, such as the Lee Filters Big Stopper, and the Light Craft ND500MC, the 77mm version of which sells for £65 from Premier Ink & Photographic.
If you want to explore very long exposures, you will definitely need a stable tripod, perhaps something like a Manfrotto
055, and a lockable remote release to hold the shutter open on the B (bulb) setting.
A stopwatch will help you keep track of your long exposures.
With eyepiece over.
|Both images were taken at 66secs at f/11 and these are straight Raw conversions so no colour or density corrections have been done. Nor has any cloning been done.You can see, however, the problem, if the viewfinder eyepiece is not covered.
The Light Craft ND500MC is a fixed nine-stop multi-coated neutral density filter. A nine-stop filter absorbs a great of light so it is very dark and if the light is very poor, you will not be able to focus or compose through it, so you need to do that first – with the camera on the tripod. In good daylight, you will able to see to compose if you take your time and your DSLR might be able to focus.
Then you need to determine the exposure. You might be able to use your camera’s autoexposure mode, but remember that most cameras are limited to around 30secs in these modes.
Or you could take a meter reading in the manual mode and so some simple arithmetic, switching to the B mode to make the exposure. Clearly, if the determined exposure is beyond 30secs you need to use B rather than an auto mode anyway.
The arithmetic I mentioned is simple once you get used to how to count it out. Let’s assume that you have determined the exposure to be 1sec at f/11, this is how to work it out keeping the aperture constant and adjusting the shutter speed.
+1 stop 2secs
+2 stops 4secs
+3 stops 8secs
+4 stops 16secs
+5 stops 32secs
+6 stops 64secs
+7 stops 128secs
+8 stops 256secs
+9 stops 512secs – that’s 8.5 minutes.
So with a metered unfiltered exposure of 1sec at f/11, slipping on the ND500MC, means you need to keep the shutter open for nearly nine minutes. This is why a stable tripod and good camera technique is absolutely essential.
Before you open the shutter, make sure your battery has plenty of charge because if you run out of power at the end of an exposure, the image will not be saved to card and you will not be vary happy. Then cover the viewfinder eyepiece. Some DSLRS have an eyepiece blind to do this. If not, drape a item of clothing over the eyepiece or use some gaffer tape. For relatively short long exposures you can just hold your hand over the eyepiece, but it is not ideal for anything longer than 30secs. Light entering the eyepiece can ruin the image so this is important.
In terms of white-balance, try AWB and shoot Raw. Images might be slightly on the cool side so having Raw enables easy tweaking.
All you have to do now is find some subjects that suit this style of photography. Moving subjects will not record (or might do so as blurred streaks, depending on the exposure length) and still subjects will, so you could try a busy area where there are people or traffic moving around. In landscape, a scene with slow moving water (the sea) can look wonderful, or a sky dotted with fast-moving fluffy white clouds can look awesome too.
Find the tripod to suit your needs at www.manfrotto.co.uk
Watch this space for more related reviews.
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