Kase K9 Filter Holder (Review)

I present you the new Kase K9 holder that I have been able to test in various situations since last August. I start by saying that my photographic style and my work often lead me to make long trips in the mountains with a very heavy backpack, for this reason I’m looking for equipment that is as light and small as possible but, without sacrificing quality. This applies to everything, from the backpack, to the tent, to the sleeping bag, to the camera, to the tripod, to the filters and everything that accompanies me on my adventures.

Let’s go back to talking about Kase’s new small holder, the k9!

Since I discovered it, it has satisfied me so much that I think of selling all the equipment I have, can you believe it?

Yes, that’s right, it convinced me to sell the big wide angle lenses on which I could only mount the 150 mm or 170 mm system to take lenses that can be used with this K9 holder and consequently switch to the mirrorless system. What a revolution, but what a satisfaction to walk lightly with a backpack and to handle small equipment that is really easy to manage.


As you can see from the photo, the box is well made and looks very good. As soon as you open the box you can immediately see the K9 Kase holder then, lifting the upper part of the box you will see the 90 mm diameter CPL magnetic polarizing filter, two 77mm and 82mm magnetic adapter rings ( to fix the K9 holder to the lenses of diameter 77mm and 82mm ), the magnetic polarizer will fit on one of these two rings. Then you will also find two step-up rings, which are 67-82 mm and 72-82 mm adapter rings that allow you to use this system with lower thread lenses.

At the end there are the mounting tools, such as a small screwdriver and two other pairs of slots where the plate filters will slide, thus allowing the assembly of three plate filters in front of the polarizer.


The thing that surprised me the most?

This holder is really small and light! I might as well keep it in my pants pocket without even realizing it. This, as I told you before, is a huge advantage for me and I think for many of you too.

The second thing that surprised me the most?

It’s so easy to mount on the lens that as soon as I finished fixing everything I wondered, will I have made a mistake or forgotten something? I double checked everything several times and everything was in the right place, so yes, the assembly is so easy and fast that it seems incomplete but is actually perfect. 

Having said the two things that struck me the most, I continue with the more “normal” things.

The K9 holter holder 100 mm system has the advantage ( which we have already seen in other brands ) of being able to use the circular polarizer, thus being able to polarize in a zonal way by rotating the circular filter. 

Certainly the circular polarizer offers a more precise polarization of light than a plate polarizer. This filter rotates independently from the ND and GND plate filters that you are going to mount in front.

Another advantage is that the polarizer is really small and light, with its 90 mm diameter it can be handled very easily and by placing it in front of the magnetic ring it’s fixed so well that it does not seem real. 

For years I’ve managed a polarizer to be screwed onto the ring and not magnetic, I assure you that in the cold, with gloves it’s really difficult to screw well and the risk of breaking it is high.

The build quality of the holder, even if small and light, is really good, so I can confirm that it’s also sturdy. It’s built with aircraft grade aluminum and has a black anodized finish, designed to reduce reflections.

It has an adjustment wheel that is used to adjust the orientation, in red and in aluminum.

Once tightened, the holder no longer rotates and remains fixed on the magnetic ring screwed to the lens.

On the opposite side there is another notched wheel which is used to rotate the magnetic circular polarizing filter, thus adjusting the polarization of the light.

Installation and tips on use

  1. The first thing to do is screw the magnetic adapter ring onto your lens, the outer part of the ring adapts perfectly to the thread of the lens. I used the Nikon 20mm f1.8 to show you the installation here in the picture. Having a diameter of 77 mm, I used the 77 mm magnetic adapter ring. 
    Remember that Kase also offers 67-82mm and 72-82 step-up rings inside the box and another 82mm magnetic adapter angel to adapt the K9 holder to different threads.
    You can also use this Holder K9 on lenses with a thread less than 77 mm by purchasing a step-up ring for example of 67 mm.
  2. When you have screwed the magnetic adapter ring onto the lens, you can very simply fix the K9 holder on it. Just unscrew the red adjustment wheel, fit the holder in the correct position and then screw the adjustment wheel back on. By slightly screwing and unscrewing this wheel we can also adjust the rotation of the plate filters, in order to position a hard GND filter in the right position for example.
  3. Now it’s time to mount the CPL polarizing filter, before obviously mounting the plate filters. Here we are faced with another great advantage of this Kase K9 holder: the polarizer is sufficient to place it on the ring and a powerful magnet fixes it in the right position without the need to screw or adjust anything. Wow! My hands thank you, I no longer need to take off my gloves at minus ten degrees hoping not to drop the polarizer while I screw it in! This is great!
    I recommend only to put it in the right direction, the writings on the frame of the polarizer must be towards the magnetic adapter ring.
    With the red wheel on the opposite side of the adjustment wheel, you can rotate the polarizer managing the polarization of the light in a zonal way.
    A very convenient thing is that there are two notches in the holder that allow you to remove the CPL magnetic polarizer more easily.
  4. The last step is to insert the plate filters into the slots. I found the sliding very smooth compared to other holders.
    Remember that if the first filter to be mounted in front of the holder is definitely the ND filter ( for long exposures ), then the most external is the GND filter ( to balance the difference in light between the sky and the foreground ).
    The ND filter must be placed on the holder in the special black velvet supports which are used to minimize stray light, this is important to avoid light infiltrations during a long exposure.


Surely the size and the ease of assembly made me satisfied and convinced me to use this Kase Holder K9 system. After the first assemblies you will see that in 30 seconds you will have fixed the holder, the polarizer and the two plates. Try to check the time and let me know! 

All this without sacrificing quality and safety which are two fundamental elements for my work that I could never do without. 

The author
The author

Giulio Cobianchi

“My name is Giulio Cobianchi and I am a landscape and adventure photographer. Born in 1984 in Italy, near the Dolomites, which I consider my cradle photo-picture.”