K&F Concept ND1,000,000 ND filter review: a practical eclipse travel filter best used with mirrorless cameras

Photographing the sun safely has traditionally meant one of two things: building a DIY filter using specialist solar film, or investing in a dedicated astronomical solar filter system. The K&F Concept ND1,000,000 takes a different approach.

Rather than using a dedicated solar film, it’s essentially an extremely dark 20-stop neutral-density filter that reduces sunlight by a factor of 1,000,000. Designed primarily for ultra-long-exposure photography, it’s a convenient, durable, and straightforward screw-in design.

Compared to fragile Baader AstroSolar Safety Film or foldable universal filters like the Daystar Universal Lens Filter, the K&F filter is much easier to travel with. There’s no cardboard to crush in your luggage, no delicate film to puncture or stretch, and no tape-covered DIY construction rattling around your camera bag.

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For this review, I tested the filter primarily on a DSLR camera with a 100-400mm telephoto lens. The results were surprisingly impressive – though not without important compromises and safety considerations.

K&F Concept ND1,000,000: Specifications

K&F Concept ND1,000,000: Price

The K&F Concept ND1,000,000 is simple and reasonably affordable. Available in 49mm, 52mm, 58mm, 62mm, 67mm, 72mm, 77mm, 82mm, and 95mm sizes, prices typically hover around the $50 / £38 mark for the 77mm size, and there are frequent discounts.

That’s competitive pricing considering the filter also doubles as a creative long-exposure tool outside eclipse seasons. Unlike specialist solar film that may sit unused for years between eclipses, the K&F ND1,000,000 can also be used for ultra-long daytime exposures, smoothing water, removing crowds, cloud streak effects, and minimalist landscape photography. So it should appeal to photographers worried about investing in niche eclipse gear.

However, dedicated solar filters still offer advantages in thermal management and safety certification. The K&F is ultimately a photographic ND filter first and foremost, not a purpose-built astronomical solar filter.

K&F Concept ND1,000,000: Design & Handling

Safety first. The K&F ND1,000,000 is a photographic filter, not a certified visual solar observing filter. You should never look directly at the sun through it – or via a DSLR's optical viewfinder. Mirrorless EVFs and rear LCD Live View systems are the safest workflows to use (besides, zooming in on a Live View image of the sun is the best way to manually sharpen the image).

The K&F ND1,000,000 feels surprisingly well-made for the money. The aluminum frame threads smoothly with no cross-threading issues, the grip texture is easy to handle even with gloves, and the included hard protective case is tough. It occupies almost no space in a camera bag and feels substantially more durable than solar film systems.

However, there are practical trade-offs. Glass solar filters absorb and retain heat far more than solar film systems do. After prolonged shooting sessions in direct sunlight – the definition of an eclipse shoot, which can last over three hours – the filter becomes distinctly hot to the touch. This makes removing the filter quickly before totality slightly trickier than with lightweight slip-on film filters, which typically rely on cardboard or tough plastic housings.

That said, you don’t necessarily need to fully tighten the filter during eclipse photography. Leaving it slightly loosened allows much faster removal just before totality while still remaining secure enough for shooting the partial phases.

K&F Concept ND1,000,000: Performance

Considering its intended purpose as a creative long-exposure filter rather than a specialist astronomy product, the K&F ND1,000,000 performs impressively well. Mounted on a Canon 100-400mm telephoto lens attached to a mirrorless camera, image quality was genuinely good. Contrast remained strong, flare was well controlled, and the filter introduced no obvious vignetting or focusing issues during testing. The ND1,000,000 should be the only filter mounted on the lens when imaging the sun to avoid ghost reflections.

Compared to DIY solar film filters, the screw-in design makes setup dramatically simpler, especially while traveling. There’s no concern about crushed filter cells, wrinkled film, or masking tape-secured housings. For lightweight eclipse expeditions, that convenience becomes extremely appealing. Dedicated solar film systems still hold a clear optical advantage.

With ISO100 and f/8 dialed in, exposures between 1/13 sec and 1/100 sec produce usable images, with 1/50 sec superior. Compared to Baader AstroSolar Safety Film, the K&F filter produces a yellow-tinted and slightly softer image of sunspots and the solar limb, as well as a little less contrast across the sun’s disk. The difference isn’t huge for casual use, but experienced eclipse photographers will notice it.

The K&F Concept ND1,000,000 ND filter gets hot. Dedicated solar film reflects much of the sun’s energy away before it enters the lens, whereas dense glass ND filters absorb more internally. Since prolonged Live View sessions in hot environments may increase thermal stress on both the filter and camera, it’s something to consider.

Without formal solar certification documentation, the K&F ND1,000,000 should be considered for occasional mirrorless solar photography with moderate telephoto zooms – thereby avoiding the need for optical viewfinders. With those caveats in mind, it works far better than many photographers might expect.

K&F Concept ND1,000,000: Verdict

The K&F Concept ND1,000,000 is not a replacement for dedicated astronomical solar filters, but that’s not really the point. What it offers instead is one of the most practical, compact, and travel-friendly ways to occasionally photograph the sun with a mirrorless camera. For eclipse travelers wanting a lightweight setup without DIY filter construction, it makes sense. Image quality is solid, handling is straightforward, and the screw-in design is dramatically easier to travel with than delicate solar film systems. The ability to repurpose it for creative long exposures outside eclipse season also helps justify the purchase.

However, the compromises are real. Dedicated solar film from Baader or Thousand Oaks remains cheaper, sharper, and better able to handle heat. This filter should also never be treated as suitable for direct visual observing.

For casual eclipse photography and lightweight travel kits, the K&F ND1,000,000 is an excellent option. But for publication-grade solar imaging at long focal lengths, specialist solar film still leads the way.

Alternatives

Baader AstroSolar Safety Film
Baader AstroSolar film remains the benchmark for serious eclipse photography thanks to its exceptional sharpness, superior detail, and strong contrast. It’s delicate, so less convenient to travel with, but for long telephoto work and heavy cropping, it delivers cleaner results.

Daystar Universal Lens Filter
The Daystar Universal Lens Filter uses trusted Thousand Oaks SolarLite film in a practical slip-on design that packs completely flat. It’s also safer and better purpose-built for visual solar observing and photography. It’s larger than the K&F when flat-packed, but easy to travel with and offers more reassuring solar-specific protection – as well as a pleasing warm orange solar disk straight out of the camera.