Reviews
Processing good. Uneven light distribution especially at high stops.
I tested the variable gray filter from K&F on a Tamron 28-200mm F/2.8-5.6 DI III RXD lens and a Sony SEL-20F18G, on a neutral white background.
Since I already use fixed ND filters from K&F and am quite satisfied with them, I was curious how this variable filter would perform.
Advantages of the variable gray filter from K&F:
- Significantly less expensive than purchasing multiple fixed density filters.
- Takes up less space and weight.
- When filming, among other things, smooth aperture transitions can be realized without post-processing.
- Pleasant feel.
- Handle for adjusting very well solved.
My conclusion: The filter from K&F achieves good results especially at low stops between 1.5 and 4 f-stops. Beyond that, however, the uneven light distribution at the edges of the image increases. This becomes more noticeable the shorter (e.g. at 20mm) the focal length is. At 10 f-stops, the X-effect then also becomes visible. The color fidelity is not really neutral and has a slight yellow cast, but can be easily corrected afterwards via the white balance in RAW images. An assessment of the set density via the scale on the filter is only roughly possible, which makes it almost impossible to calculate the exposure times manually. However, modern cameras like the Sony a7 series can reliably calculate the exposure time through the filter. To be fair, it must also be said that the aforementioned weaknesses occur to a greater or lesser extent with every variable gray filter. Therefore, my recommendation for ambitious photographers is to rather rely on ND filters with fixed density. In the range of 1.5 to 4 f-stops, however, the variable filter from K&F is quite usable for qualitatively good photo shots. Especially for filmmakers, the K&F should be an attractive filter, at a reasonable price. In my opinion, the disadvantages are less important here. The processing is successful in every respect. The filter can be operated well, without accidentally touching the glasses with your fingers.
Since I already use fixed ND filters from K&F and am quite satisfied with them, I was curious how this variable filter would perform.
Advantages of the variable gray filter from K&F:
- Significantly less expensive than purchasing multiple fixed density filters.
- Takes up less space and weight.
- When filming, among other things, smooth aperture transitions can be realized without post-processing.
- Pleasant feel.
- Handle for adjusting very well solved.
My conclusion: The filter from K&F achieves good results especially at low stops between 1.5 and 4 f-stops. Beyond that, however, the uneven light distribution at the edges of the image increases. This becomes more noticeable the shorter (e.g. at 20mm) the focal length is. At 10 f-stops, the X-effect then also becomes visible. The color fidelity is not really neutral and has a slight yellow cast, but can be easily corrected afterwards via the white balance in RAW images. An assessment of the set density via the scale on the filter is only roughly possible, which makes it almost impossible to calculate the exposure times manually. However, modern cameras like the Sony a7 series can reliably calculate the exposure time through the filter. To be fair, it must also be said that the aforementioned weaknesses occur to a greater or lesser extent with every variable gray filter. Therefore, my recommendation for ambitious photographers is to rather rely on ND filters with fixed density. In the range of 1.5 to 4 f-stops, however, the variable filter from K&F is quite usable for qualitatively good photo shots. Especially for filmmakers, the K&F should be an attractive filter, at a reasonable price. In my opinion, the disadvantages are less important here. The processing is successful in every respect. The filter can be operated well, without accidentally touching the glasses with your fingers.
28/12/2022