In summary
Without having other variable ND filters for comparison, we can’t make definitive comments on whether the Syrp filter is superior. But we can say that it provides a compact and versatile addition to a photographer’s or videographer’s kit.
Provided you can allow for the inherent vignetting (which is likely to be a feature with all ND filters) and fit it to make the density indicators easy to see, this filter does an excellent job without compromising other aspects of imaging performance. Our tests showed it had no effect on image colour reproduction, which is admirable.
The solid build quality and excellent packaging of the Syrp filter are also to be commended. Its neat leather case is small enough to slip into a pocket and durable enough to protect the filter while you’re in transit between locations. A lot of fun can result from adding it to your kit.
Full review
The Syrp variable ND filter kit. (Source: Syrp.)
The Small kit (RRP$139) is based upon a 67 mm filter, while the Large (RRP $189) kit is based on an 82 mm filter. Each kit includes two step-up rings to allow lenses with smaller diameters to use the filter. The Small kit has 52-67 mm and 58-67 mm step-up rings, while the Large kit has 72-82 mm and 77-82 mm step-up rings. A Syrp lens cloth is provided with each kit and the kits are packed in a genuine leather case with a secure zip closure.
What is it?
Neutral density (ND) filters reduce the intensity of light entering a lens without altering its colour. They allow photographers to use slower shutter speeds and/or lower sensitivities than would be otherwise possible in order to control depth of field or capture motion blurring.
In most cases, ND filters reduce exposure by a specific amount, indicated by their optical density or f-stop reduction. The optical power of these filters is calibrated logarithmically. Thus, an ND2 filter reduces exposures by one f-stop, an ND4 by two stops, an ND8 filter by three stops, and so on.
Unlike regular ND filters which only block a specified amount of light, variable ND filters can cover a range of f-stops that is continuously adjustable. This enables photographers to carry a range of different NDs without having to pack several different filters and change filters to match different situations.
How does it work?
Most variable ND filters rely on sandwiching two polarising filters together and enabling one of them to rotate. The static polariser cuts light in one plane and, as the other polariser is rotated, it progressively reduces the light intensity reaching a maximum reduction when it is perpendicular to the fixed filter.
The Syrp variable ND filter is graded in nine steps, which are indicated on the outer, rotating filter by vertical lines. You can select a particular step by lining it up against a vertical line on the non-rotating filter. Alternatively, you can set the filter anywhere between two steps if you require an intermediate value.
This system provides almost infinite control of the amount of light passing to the camera’s sensor. Effectively, it gives photographers the advantage of multiple ND filters in a single unit.
There’s a small price to pay for this convenience in the form of a slight reduction in image sharpness resulting from combining two polarising filters. This occurs because the imaging light has to pass through two layers of polarising glass, which have the potential to introduce small aberrations.
What’s it for?
ND filters have six popular applications:
1. To enable slow shutter speeds to be used to blur movement when shooting subjects such as water, clouds or moving vehicles.
2. For exposure control in bright situations where photographers want to use wide apertures to reduce depth of field, making it easier to separate subjects from potentially distracting backgrounds.
3. To eliminate people from street scenes by allowing very long exposures to be used with small aperture settings and low ISO values. People who move fast enough will be recorded as faint blurs ““ or not recorded at all ““ if exposure times are long enough.
4. To allow cine and video cameras with fixed shutter speeds to record subjects in situations dominated by snow, sand or other bright environments, which could cause overexposure.
5. When shooting with high speed film (above ISO 400), to allow it to be used outdoors in bright situations without requiring the lens to be stopped right down.
6. To produce creative effects from blurring produced by moving the camera or zooming the lens during long exposures.
Competition
Syrp isn’t the only company making variable ND filters. We did a Google search and discovered 18 brands (not all available in Australia, although most can be purchased online). Prices range from about $20 for a 58 mm filter to more than $500 for a 77 mm filter.
The feature that makes the Syrp filter stand out from this pack is the inclusion of step-up rings. Most variable ND filters are manufactured with a single thread diameter, which means they can only be used on the equivalent lens.
If you buy a Small Syrp filter, it is designed for 67 mm-threaded lenses but the step-up filters also allow it to be used with 52 mm and 58 mm lenses. The Large Syrp filter is designed for lenses with 82 mm filter threads but can also be used on 72 mm and 77 mm lenses with the step-up filters. If you own lenses with different filter diameters, this can be a genuine money-saver.
Competing filters may not cover the same exposure range. Most claim a maximum reduction of nine f-stops but some start at around three f-stops, which may not suit situations where only a small reduction in light transmission is required.
Performance
We feel a couple of changes could be made to improve the performance and usability of the Syrp variable ND filter. For starters, we found the exposure indicators weren’t always aligned along the top of the lens when the filter was attached and the camera was used in standard landscape orientation.
In some instances, they ended up around the side of the lens, a situation that would have been useful if the camera was re-orientated into portrait format (provided it was tilted the right way). If the camera is used in landscape format it forces users to bend their necks when attempting to align the indicators with the reference mark.
Although Syrp claims on their website that regular lens caps can be fitted, this only applies to lens caps with the same diameter as the filter itself. When the normal lens cap isn’t the same diameter as the Syrp filter, you can’t use it.
And don’t try fitting a lens hood with the filter. Although it’s possible to screw the filter in after the lens hood is in position, it means you can’t see any of the calibration marks and it’s very difficult to rotate the front filter. Lens hoods will also increase the existing tendency of the filter to vignette the image frame.
Conclusion
Without having other variable ND filters for comparison, we can’t make definitive comments on whether the Syrp filter is superior. But we can say that it provides a compact and versatile addition to a photographer’s or videographer’s kit.
Provided you can allow for the inherent vignetting (which is likely to be a feature with all ND filters) and fit it to make the density indicators easy to see, this filter does an excellent job without compromising other aspects of imaging performance. Our tests showed it had no effect on image colour reproduction, which is admirable.
The solid build quality and excellent packaging of the Syrp filter are also to be commended. Its neat leather case is small enough to slip into a pocket and durable enough to protect the filter while you’re in transit between locations. A lot of fun can result from adding it to your kit.
TESTS
How we tested
We tested the Syrp filter with the Canon EF 24-105mm f/4 lens on our EOS 5D Mark II camera body, using two focal lengths: 24mm and 70mm. Our test target was a large sheet of white card, set up perpendicular to the camera. The lens was set for manual focusing.
The camera’s metering system was used to set exposures, based upon the evaluative pattern. ISO 100 sensitivity and the maximum aperture setting of f/4 were used for all shots, which were taken with a 10-second delay, using the self-timer.
Variable ND filters often vignette the image frame, simply because they add a few millimetres to the length of the lens barrel (which aren’t allowed for in the lens design). This isn’t a serious flaw, in itself, as most modern cameras come with in-camera peripheral illumination corrections and vignetting can normally be eliminated with a decent image editor.
They are also known to produce cross patterns at higher density settings so our first test involved taking exposures of the white test card at each density setting to reveal whether either problem was evident with the Syrp filter. We were also interested in whether the filter introduced any colour casts. The results of these tests are shown below.
Vignetting with 24mm focal length:
Step 1 on the filter ND range.
Step 4 on the filter ND range.
Step 6 on the filter ND range.
Step 9 (the maximum setting) on the filter ND range. Note the cross pattern.
Vignetting with 70mm focal length:
Step 1 on the filter ND range.
Step 4 on the filter ND range.
Step 6 on the filter ND range.
Step 9 on the filter ND range.
The final factors we wanted to check were whether the filter softened images. For the first we used Imatest testing to compare the resolution of shots taken without and with the ND filter. The results of our Imatest tests are shown below.
No filter; 1/2 second at f/5.6, 67mm focal length.
ND filter on Step 5 setting; 1.6 seconds at f/5.6, 67mm focal length.
Note: The slight differences between these results can be largely explained by the addition of the filter. Inserting an extra piece of glass is likely to cause a slight reduction in image quality ““ although it probably won’t be visible in actual images. If the filter also contains a layer of plastic polarising film (as a variable ND filter does), the reduction in quality is a little greater. Whether the difference could be actually seen in images is debatable.
We also looked at some of the creative applications for the filter, examples of which are shown in the Samples tab.
SAMPLES
Motion blurring with the camera tripod mounted:
No filter; 105mm focal length, ISO 200, 1/320 second at f/7.1.
ND filter on Step 9 setting; 105mm focal length, ISO 200, 15 seconds at f/22.
No filter; 105mm focal length, ISO 200, 1/640 second at f/10.
ND filter on Step 9 setting; 105mm focal length, ISO 200, 20 seconds at f/22.
Zooming with the camera tripod mounted:
No filter; 24mm focal length, ISO 200, 1/13 second at f/11.
ND filter on Step 8 setting; 24-105mm zoom range, ISO 200, 20 seconds at f/13.
Camera movement with the camera hand-held:
No filter; 105mm focal length, ISO 200, 1/30 second at f/4.
ND filter on Step 6 setting; 105mm focal length, ISO 200, 6 seconds at f/5.6.
No filter; 100mm focal length, ISO 200, 1/60 second at f/4.
ND filter on Step 5 setting; 100mm focal length, ISO 200, 2 seconds at f/10.
ND filter on Step 9 setting; 105mm focal length, ISO 200, 8 seconds at f/10.
Rating
RRP: Small kit US$139; Large kit US$189
- Build: 8.8
- Ease of use: 8.5
- Versatility: 9.0