Having performed some basic tests on the STC ND64 clip filter earlier, it was decided to take the testing a little further. The filter displayed excellent results using a Sigma 24-60mm lens, using the 60mm end. We wanted to know what would happen when used with more extreme focal length lenses, so we once again ventured out to test it.
Most people tend to use a ND filter with wide angle lenses. However, we were interested to see what happened when using a long telephoto lens, so this time we used a Sigma 15-30mm f3.5 for the wide angle tests, a Nikon 24-85mm f3.5- f4.5 for the mid range tests and a Sigma 100-300 f4 lens for the telephoto lens tests. These were fitted to a Nikon D800 camera body and mounted on a Manfrotto 055 tripod. The camera was set to Jpeg fine and white balance set to Daylight.
Why use an STC clip filter?
As stated previously, the total cost of providing a filter for each lens owned could prove to be an expensive option compared with a single clip filter.
Also, it is almost impossible to fit a filter to the front of an extremely wide angle or fisheye lens due to the shape of the front element combined with the angle of view of the lens itself.
Sigma 15-30mm at 15mm
Sigma 15-30mm at 15mm with STC
Nikon 24-85mm at 85mm
Nikon 24-85mm at 85mm with STC
Sigma 100-300mm at 300mm
Sigma 100-300mm at 300mm with STC
Since the camera must be used in Live View when using the clip filter, the autofocusing system in the camera switches from phase detection to contrast comparison. Autofocus works adequately with wide angle lenses in combination with the clip filter. However the autofocus struggled with focal lengths longer than approximately 100mm, so we had to switch to manual focus for longer focal length lenses. An important note here is to not rely on the focus scale on the lens, but instead, focus using the camera screen.
Wide angle lenses by their very nature have a wider depth of field, so they are more forgiving if focus is slightly off. This is not the case with telephoto lenses, hence care needs to be taken when focusing with these lenses. There is very little room for error, even when the lens is stopped down to minimum aperture.
A further observation we made was, when using wide angle lenses we would recommend using spot metering for a more accurate exposure.
Having already previously seen some impressive results from the STC ND 64 filter, we stand by our conclusion, that regardless of the focal length of lens used, the STC ND64 clip filter is capable of producing superb results.
If further proof were needed, below is an image taken using a 19-35mm f3.5/f4.5 Vivitar lens in combination with the STC ND64 clip filter.
Source: GCM Photographic (http://gcmphotographic.com/?p=1061)