Review: K&F Concept 58mm Variable Neutral Density Filter
Neutral density filters(ND) are one of the staple components of virtually every serious landscape photographer's gear bag. The great thing ND filters allow us to do is to shoot longer exposures in a bright light without overexposure. A good analogy I always like to use is that ND filters are light sunglasses for your lens. Neutral density filters are a great way to remain flexible with your shooting even when conditions aren’t ideal.
Like most photographic equipment, you often get what you pay for…. That doesn’t mean that every piece of budget gear isn’t capable of yielding great results. The K&F Concept 58mm ND Fader Variable Neutral Density Adjustable ND Filter is quite a mouthful to say, but essentially it is a neutral density filter that is capable of shooting at various shades of darkening. This particular filter ranges from ND2-ND400. If we’re speaking in terms of f-stops, then it equates to 1-8 ⅔ stops of light reduction. The version I tested was the 58mm size and I used it with my trusty Canon EF 50mm F1.4.
Build Quality
The filter arrived well packaged and included a nice micro-fiber cloth along with a standard padded plastic filter case.
Overall, I was extremely impressed with the build of this ND filter from K&F. The material of the two elements is listed by the manufacturer as “optical quality glass” with the body of the filter likely being aluminum. Originally I had thought the housing was made from some type of resin but after a scratch test it turned out to indeed be metallic.
I was also pleased to note that both the stock lens cap and lens hood still worked perfectly while the filter was attached.
The filter itself functions by turning the outer ring to the desired darkening setting is reached. This ND filter functioned extremely smoothly with no binding or sticking points.
Optical Performance
As I mentioned earlier, there is most often an unavoidable compromise between cost and quality(with a few exceptions) when it comes to camera gear. The K&F Concept variable ND is a budget ND filter currently retailing for around $20US from both Kentfaith.com. The performance of the filter was a mix of great to, well, not so great. When used at it’s lowest optical darkening setting, the results were wonderful for a filter at this price point.
Moving a little darker to approximately 3 stops of light reduction, the results were still great and allowed me to shoot long exposures with no real color tinting or vignetting to speak of from a practical standpoint.
Now, moving onto the darkest setting of ND400, or approximately 8 ⅔ stops, we see some extreme problems arise in terms of color tinting and image degradation.
For a $20 ND filter, I was honestly surprised at how well the filter performed up till now. And from a real world point of view, the filtration offered between ND2 and ND400(1-8 ⅔ stops) was outstanding. This lends me to believe that he overall results from this filter are perfectly workable from approximately 1 to 3-4 stops of darkening. Here are three more images showing the progression of image quality across the range of filtration. It’s interesting to note that while the last image shows significant quality reduction, the massively apparent purple tinting observed in the previous example is virtually nonexistent. This is possibly due to the lengthy exposure of 25 seconds used for the image above. The white balance of my camera was set to ‘Auto’.
