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More on long exposure photography
|Click on the thumbnail images for high resolution images|
|The Light Craft Worksop Fader ND Mk II costs £99.99 (for the 77mm fit). It is a variable neutral-density filter, absorbing from two stops (left) up to nine stops (right).|
Digital photography has brought many creative techniques to the fore and made them accessible to more photographers than ever before. Infrared photography is one such technique, HDR is another and so too is long exposure photography. If you want to read about about the technique, click here.
And this is where dense, light absorbing filters like the B+W 10 stop and the Lee Filters Big Stopper enter the scene. They are designed to absorb lots of light to give you even greater freedom when it comes to aperture and shutter speed choice.
Light Craft Workshop (LCW) has three types of powerful light-absorbing ND filters and are sold through Premier Ink & Photographic.
In this review we try the Fader ND Mk II, which is a variable neutral density filter. If you want to read the LCD ND500 MC review please click here.
Light Craft Workshop Fader ND MkII: Features
|Click on the thumbnail images for high resolution images|
|There is a scale to help correct alignment but its practical use is limited.||The Fader is relatively thick for a filter but the front section is wider to avoid cut-off.|
The unique selling point about this filter is that you can vary the amount of light absorption to suit the creative result you are after. It offers a controllable range from two stops (ND4) to about nine stops (ND500) – this range is not exact and depends on the focal length of the lens in use and whether you are using a APS-C or full-frame sensor camera.
The information below shows the degree of light loss you can achieve at different focal lengths on a cropped sensor DSLR.
12mm: ND4 to ND8 3 stop operating range
15mm: ND4 to ND16 4 stop operating range
18mm: ND4 to ND32 5 stop operating range
24mm: ND4 to ND64 6 stop operating range
35mm: ND4 to ND125 7 stop operating range
40mm: ND4 to ND175 7.5 stop operating range
50mm: ND4 to ND250 8 stop operating range
70mm: ND4 to ND350 8.5 stop operating range
100mm: ND4 to ND500 9 stop operating range
The filter consists of two pieces of opposing polarizers. The rear piece stays in position while the front piece is in a rotating mount and this is adjusted to vary the amount of light transmitted. The front section is a wider diameter than the non-rotating section to avoid vignetting. There is a marked scale on the rotating part of the filter, marked from Min to Max. The markings are on a logarithmic scale so the effect is greatly towards the Max end of the scale; they are not an indication of f/stops.
If the two polarizers are aligned to give their maximum density you will see a distinct cross in the viewfinder so this setting should not be used. You can plainly see the cross effect in daylight, but it is more difficult in the dark so you need to take care with this otherwise you won't realise until you have wasted a few minutes of your life.
Light Craft Workshop Fader ND MkII: Handling
Handling is straightforward. The Fader fits onto lenses just like any screw-in filter. One slight difference is that when the filter is on the lens, the wider diameter of the front polarizer mount means that your normal lens cap will not fit. Handily, LCW supply a 82mm cap in the case of the 77mm filter I used.
The rotating front polarizer operates smoothly but with enough stiffness for it to stay in position once the optimum setting has been ascertained.
I found the Min/Max scale had limited use. For a start when I fitted it to the Nikon 24-70mm, the index mark was at the six o'clock position so tricky to view, especially when shooting from a low camera position.
The varying nature of polarized light also means that the scale and the index do not always have a close relationship. In all, I found it easier to determine the amount of light loss by keeping an eye on the shutter speed readout in the viewfinder as the front polarizer was rotated.
Light Craft Workshop Fader ND MkII: Performance
Extreme long exposure photography needs thinking about to get great results and you certainly have lots to think about when you are using this LCW filter.
Its variable neutral density is very useful and does mean you have greater control over the final result. The downside is that to enjoy its potential nine-stop operating range means you have to be shooting with a telephoto lens – at least a 100mm with a cropped sensor DSLR.
If you are a keen wide-angler and want to enjoy this filter with a 12-24mm zoom set to its widest setting, for example, your options are limited to a three stop operating range from ND4 (two stops) to ND8 (three stops). Zoom back to 24mm, however, and you have a six stop operating range and a ND64. That is getting there for long exposures, but still not the nine stops that is possible with the filter on a telephoto zoom.
I tried the Fader II on a 24-70mm and 70-200mm Nikon zooms, mostly the former because I am more of a wide-angler. As you can see from the above chart, you get less ND and I certainly found this to be the case.
For example, the unfiltered image of Brighton Pier shown here was exposed for 1/15sec at ISO 100. You can see from the accompanying images below taken on a 24mm lens that an exposure of 10secs produced an uneven effect and even at 6secs you can see signs of unevenness. From 1/15sec to 6secs is just over six stops – the suggested six stops loss from the above chart was about right.
The MkI suffered from vignetting and sharpness was less than brilliant. The vignetting has been sorted in the MKII with the wide front section of the filter and I saw no problem with cut-off even with my 24-70mm at its widest setting.
I must admit in my tests I didn't notice any significant image quality issues either. I shot on a variety of lenses – Nikon and Tamron – and sharpness remained of a very high order.
I also tried it in the studio with mains flash when even the lowest output setting and ISO value still meant I could not set the widest aperture value. This filter let me achieve what I wanted although I had to experiment a little with output (no TTL metering here!) but I could not have managed it without the help of this filter.
The filter has a very neutral effect and while images do pick up a slight cool colour cast it is not objectionable and easy enough to correct in Photoshop.
One technique point to remember with this form of photography is to use the eyepiece blind if your camera has one. Or use a sheet of card hanging down from the camera hot-shoe or just drape a piece of dark material over the eyepiece. You could even shield the eyepiece with your hand although this is not fun for an eight minute exposure. Light entering the viewfinder eyepiece can cause internal reflections and ghosting can record on the image. It is easy to forget to do this and that can be very frustrating and a waste of time.
Light Craft Workshop Fader ND MkII: Verdict
The LCW Fader ND Mk II costs £99.99 for the 77mm fit so it is significantly more expensive than the fixed eight-stop ND500 filter that sells for £64.99, so the question whether the extra money is justified is one that has to be answered by you.
I think it is justifiable if you want to use it for a broad range of subjects rather than just blurry scenics. Being able to control the degree of neutral density, for example, is handy for action panning technique or for shooting portraits at wide apertures in bright light.
If you want a ND filter specially for long exposure landscapes, especially if you like wide-angles, buy LCW's ND500 MC filter. To be fair, Premier Ink say this themselves on their website. Or check out the LCW Fader ND Ultra MkII. This is adjustable between nine (ND500) and 12 (ND4000) stops, but much more expensive at £179.99 for the 77mm fitting.
|Light Craft Worksop Fader ND MkII: Pros|
|Opens up lots of creative opportunities|
|Variable ND great for creative work|
|High optical quality|
|Light Craft Worksop Fader ND MkII: Cons
|Focal length dependent in terms of ND strength|
|Scale not much use|
Light Craft Workshop Fader ND MkII: Specification
|Price:||£99.99 for 77mm fit|
|Sizes available:||52mm, 55mm, 58mm, 62mm, 67mm, 72mm, 77mm, 82mm|
|Weight:||60g (for 77mm fitting)|
More on long exposure photography
With film, making an exposure greater than one second with a normal colour slide film meant a colour shift and a loss of effective film speed – this was referred to as reciprocity law failure.
In practice, this meant that you had to think more about your exposures when shooting longer than one second with film. Let's say you were photographing a night scene and you determined the exposure to be 1sec at f/8. If you now decide that you wanted to use an aperture of f/16 this would mean that to get the same image density you have to increase the shutter speed to give two more stops of light to allow for the smaller aperture – in theory. As you know, aperture and shutter speeds have a reciprocal relationship so, in theory, one stop over 1sec is 2secs and two stops over is 4secs, so for an aperture of f/16 you need an exposure time of 4secs. Easy.
However, with film, there is a breakdown in the cosy reciprocal relationship between aperture and shutter speeds. In practice, 4secs at f/16 would give an underexposed result and to give the correct image density the exposure would have to be 8secs at f/16 or even 16sec at f/16. The speed loss characteristics of individual films varied greatly but the longer the exposure the greater the effective speed loss.
Sorry about preamble but it helps to understand why very long exposures with film was painful yet with digital it is the proverbial piece of cake. In our example above, make digital exposures of 1sec at f/8, 2secs at f/11, 4secs at f/16, 8secs at f/22, 16secs at f/32 and 32secs at f/45 and you get exactly the same image density. There is no speed loss, and that is why long exposure photography with digital is easy. Of course, there are still issues to sort, but reciprocity law failure is not one of them.
This theory stuff is all well and good, but you are probably wondering what are the advantages of shooting such stupidly long exposures and what have Light Craft Workshop, Lee Filters and B+W neutral density filters got to do with it.
Long exposures means you can take pictures by moonlight and in other similar extreme low light situations. But long exposures is also a way of being creative and suits all sorts of photographic subjects. For example, a four minute exposure of a busy shopping centre would result in everyone that moved within the scene during the exposure 'disappearing' or looking ghostly. Everyone who stayed still during the exposure – and obviously the buildings – would come out solid. The effect can be awesome.
The thing is, though, that setting a four minute (or however long) exposure and getting correctly exposed images is not as easy as it might seem.
You stand a chance when light levels are very low, ie in poor light, at dusk, night, but in anything like decent light, even setting the lowest ISO and the smallest aperture your lens can offer might not be enough to get you down to longer than 1sec at f/22. In other words, the exposure is nowhere long enough to blur the scene. Our shoppers in the example above would just be a little blurred but still plainly in evidence.
Using slow shutter speeds in bright light is one technique that you can enjoy with these light absorbing filters, the other is being able to set very wide lens apertures for shallow depth-of-field in similar lighting conditions. In bright light you might be at the lowest ISO setting your DSLR offers but an aperture of f/2.8 might require a shutter speed of 1/8000sec or more, which be beyond the camera's range. Fit a strong neutral density filter and again you stand a chance. Having a variable neutral density gives even more flexibility.