I was asked to review part of the K100-Slim system (K8 filter holder) for Kase UK that might be relevant to me. This is primarily designed for use with the K100 100mm filters which allows the use of a non-threaded polariser and other filters, which attach to the filter holder using a magnet.
However if you don’t use graduated filters, like me, you still probably use circular ND filters and polarisers. The beauty of using screw-in filters is that there is no issue with light bleeds from behind or water and spray getting in behind the filter; it seals your front element and also there is no issue with wind blowing your filters off once screwed in or dropping off.
The magnetic system would seem to sit in between, allowing for a speedy change between filters (and a reduction in the chance of mis-threading your lens mounts) and the bonus of having no gaps.
I was sent the 82-86mm (82 inch thread) adapter from the K100 system and also a mag ND1000 (10 Stop) 86mm filter to test.
- Anti-Reflection Coating, Super Water & Stain Resistant
- 8HD Ultra Hardness
- Ultra Thin Milled Frame, Matt Black Superfine Frosted Frame
- 3, 6 and 10 Stop Exposures (10 stop featured), No Color Cast, Smooth Surface Finish
- Ultra Thin Filter Frames Reduce Vignetting on Super Wide Angle Lenses.
- All Materials Meet the Requirements of the European Union’s Standards of Environment Protection-ROHS (Restrictions on Hazardous Substances).
- Geared adapter ring 82-86mm – non-magnetic (other diameters also available)
- Step down ring adapters can be used for different lens diameters
- Primarily for the K8 Holder / K100 filter system but can but used just with magnetic circular filters
I am not going to review the performance of the 10 stop filter as it’s the same filtration used in the screw-in system I tested earlier this year in Lofoten, Norway.
The main aim was to assess the usefulness of using this magnetic system for those who don’t use the 100mm K100 system, ie. graduated filters, particularly if you either shoot low contrast scenes, have a high dynamic range camera or use exposure blending.
Aymer Cove at 40 mins before Sunset , Kase Mag Circular ND1000, ISO 100, 25mm, f10 and 2.5s
Aymer Cove at 10 mins before Sunset , Kase 82mm G-CPL screw-in, ISO 500, 29mm, f10 and 2s
As previously mentioned the filters have an anti-reflection coating and were very easy to clean the salt spray off if with a cloth with very little smearing. Dust, from the sands, also seemed very easy to clean off too.
The bezel on the adapter, being toothed, was very easy to twist (for use with a Mag CPL) with cold hands or big fat fingers (if you have them). Also it’s easy to screw in and unscrew. The ring does protrude more widely and thus you can’t use a hood with this system, unlike the screw-in filters. The disadvantage with the latter, with a CPL, is if you want easily modify the amount of filtration with a lens hood on – so horses for courses.
The ND filter contains the magnet rather than the filter adapter which is good news. Having the adapter magnetic might cause issues in your bag if you leave it on. The filter snaps in very firmly and there were no issues with light bleed. This mean less faffing unlike the 100mm systems, from other manufacturers for example, where they use a foam seal which often degrades with time.
I see some potential issues with removing the mag filter, from the adapter, perhaps when your hands are cold or you bite your nails. There is small recess below the filter teeth so you can prise the filter off. I wonder if there would be an easier eject systems though? If all else fails then of course you could unscrew the adapter and push it out from behind.
I didn’t have the conditions to try the filter out in very high winds, more moderate winds (3 trips in total to the coast), but I can’t envisage the filter falling out, given the low profile of the exposed edges, and it’s more of less sealed to the elements (I thankfully I didn’t try full immersion in water!). I didn’t get any dust or spray on the lens’s front element at all, so like a screw in system.
I had no vignetting at 16mm or 24mm on either of my Sony GM 16-35 or 24-70 Lenses. However I did want to use polarisation at the same time , but withe the Kase G-CPL I have, this was restricted, like the above, to longer focal lengths due to heavy vignetting (past 28mm).
As previously stated I found these Kase filters to be of a very high standard.
I was going to write a lengthy conclusion but I thought bullet points might be easier to follow:
- Reduces the need to constantly screw and unscrew filters (reduces the chance of mis-threading)
- The same filter can be swapped on different lenses quickly (if you have adapters on those)
- Different filters can be swapped on the same lenses quickly
- The front lens element is protected from the elements
- Light bleed is not an issue using NDof CPL filters or rear reflections
- Probably more robust than using a non-circular ND system, smaller, lighter and more compact
- Glass can be made thinner so likely less issues with aberrations
- The adapter was easy to use and easy to rotate if a magnetic CPL is installed
- Sits securely as the filters are flush
- A step down ring can be used for multiple filter thread sizes
- Cost effective ND solution for multiple lens use
- Mag filters can’t be stacked at present (*See below)
- When stacked with a screw-in CPL, vignetting was obtrusive at wide angles
- Slightly tricky to remove filter with gloves, cold hands or no finger nails (one more reason not to bit your finger nails) etc.
- Adapter is wider than most hoods so they can’t be fitted
- A lens cap can’t be installed (unlike circular screw-in filters but Kase can supply a cap)
A the time of publication I have been given two additional pieces of information.
- Kase are developing a combination ND3 stop and G-CPL circular filter – giving approximately 4 to 5.5 stops of filtration.
- *Kase international have developed a system to allow for stacking of 2 magnetic filters with a low profile to reduce vignetting
Hopefully I might be able to test this new stackable system soon – a combination of stackable magnetic CPL/NDs would pretty handy and eliminate most of the cons I mention above. You could for example, if you are into super long-exposure work, go from 10 stops to 20 stops, just by snapping in another mag filter.
So if you need to change filters and/or lenses quickly and you use ND filters, it’s certainly a rapid and easy solution, in the system can easily be adapted between a wide range of lenses using either different adapters or step down rings. It’s probably quite a cost effective solution for those on a budget too.
Disclaimer: I was not paid to write this article nor was I given the filters to keep. I returned the filters in the condition they were sent to me by Kase.