Review: K&F Concept Variable Star filter

Capturing star effects on lights usually requires a tripod, apertures of f/16 or smaller, and long exposures — a painstaking, often hit-and-miss process.

That’s where star effect filters come in. In theory, they can be used at any aperture and in a wider range of lighting scenarios - well at least that was my experience with the budget-friendly K&F Concept Variable 4&8 Star Nano C Series HMC Filter (how's that for a name!).

The tech

The filter features a knurled aluminium rotating ring holding two Japanese-made optical glass elements. K&F claims 18 nanometre coatings to reduce glare and reflections.

Each glass has a grid-like pattern: when aligned, you get 4-ray stars. Twist the ring to cross the lines and create 8 rays, adjusting the alignment to taste.

In use

Not all light sources produce stars. You’ll need to experiment to see where the effect works — piercing light in full darkness is most effective.

I tested the filter in a range of situations: daytime, night, concerts, markets, and city streets. With the right light, it creates striking, if not entirely natural-looking, results.

For handheld night shooting, it opens creative options. At concerts, for example, you can capture star effects at wider apertures and faster shutter speeds — though the look probably won’t be for everyone.

On long exposures, where stars are often achieved naturally by stopping down to f/16 or more, the filter exaggerates the effect. Used in moderation, that can be quite pleasing.

Image quality

There’s no obvious image degradation despite the dual-glass construction. Once you learn where it works best, the results are solid — especially at this price point.

The results

The filter can deliver interesting, eye-catching images, but it takes practice to know when and how to use it. Dialling in the star effect slows things down, so it’s less suited to quick “run-and-gun” shooting.

Ratings

Build Quality: ★ ★ ★ ★

Solid overall, though prone to scratches, which is probably expected at this price.

Features: ★ ★ ★ ★

Simple but effective — 4 or 8 star options with a twist. No frills, just works.

Image Quality: ★ ★ ★  1/2

Good for a budget filter. Not outstanding, but no major drawbacks either.

Value for Money: ★ ★ ★ ★

Excellent value. Hard to justify paying many times more for what’s likely an occasional-use accessory.

The wrap-up

This filter can create fun, creative images, though not always with the lights you might expect. Its real advantage however is handheld use, freeing you from f/16 apertures and tripods. Despite this, it's probably not an everyday essential, but rather a handy, affordable addition to keep in your camera bag.