I extensively tested this magnetic filter kit from K&F Concept (Nano-X series, 82mm) on my Sony A7 IV with the Sigma 24-70mm F2.8 DG DN II Art lens. Especially with this razor-sharp lens and the 33MP sensor, I was curious to see if the image quality would suffer – the result pleasantly surprised me.

Scope of Delivery & First Impressions

The set comes in very high-quality packaging. Included are:

* The magnetic base adapter ring.

* A variable ND filter (ND2-32) combined with a CPL (polarizing filter).

* A 1/4" Black Diffusion filter (for a "cinematic look").

* A magnetic metal lens cap.

* A high-quality storage pouch with a fabric look.

The Magnetic System in Use
Handling it on the Sigma 24-70 is a dream. You simply screw the adapter ring onto the 82mm thread once, and then the filters magnetically click into place.

* Speed: In "run and gun" situations with the A7 IV, this saves a tremendous amount of time. No screwing, no tilting.

* Secure hold: The magnets are very strong; the filters sit rock-solid on the lens.

Image quality & vignetting (with the Sigma 24-70mm II)
This was my biggest concern, but it proved unfounded:

* Sharpness: The image quality of the Sigma Art lens is fully preserved. Even when zooming in on the 33MP files, I couldn't detect any loss of sharpness.

* Vignetting at 24mm: Because the magnetic system is very thin, I didn't notice any distracting vignetting (edge ​​darkening), even at 24mm wide angle. This is often a problem with screw-in filters, but it's perfectly solved here.

* Color fidelity: The variable ND filter has no discernible "X-cross" effect and barely, if at all, distorts the Sony's colors.


* Color accuracy: The variable ND filter has no noticeable "X-cross" effect and barely, if at all, distorts the Sony's colors.

* The Look

* ND2-32 + CPL: The small orange grip is buttery smooth to use. Perfect for filming at wide apertures (f/2.8) and adhering to the shutter rule.

* Black Diffusion 1/4: Softens the "harshness" of the Sony's digital image. Highlights bloom slightly (halation), giving portraits and atmospheric shots an organic look.

The Bag

The bag isn't just a freebie; it's genuinely useful. It's divided (K&F Orange), protects the filters well, and can be attached to a belt with a loop.

Conclusion
Anyone using a high-quality camera setup like the A7 IV with G-Master or Sigma Art lenses shouldn't skimp on the glass in front of the lens. K&F Concept delivers professional quality here. The magnets significantly speed up the workflow.

A clear recommendation for all Sony shooters who want to professionalize their setup!