What to look for in an ND filter

We take a closer look at the Lee ProGlass IRND filter system

Filter holder

Initially set up to hold two filters, the Lee filter holder can be adapted to take up to four. This is the holder for the regular 100mm system, but there is a smaller Seven5 holder too, and an SW150 holder for ultra-wide lenses.

Filter strengths

The ProGlass IRND filters come in a range of strengths, from 0.6ND (two stops) right up to 4.5ND (15 stops). With Lee’s square filter system, you can use a polariser or ND grad at the same time if you need to.

Filter sizes

Lee makes three different filter systems: the Seven5 system is for smaller cameras and lenses; the 100mm system is the standard size for most photographers; and the SW150 system is for ultra-wide lenses.

Colour and exposure accuracy

Lee claims virtually no colour shift and extremely accurate stop values to make long-exposure calculations more reliable. These filters block both infrared and ultraviolet light pollution.

Adaptor ring

You’ll need the right size adaptor to attach the filter holder to your camera lens’s filter ring. These are available in a wide variety of sizes, from 49mm right up to 105mm. There are special low-profile wide-angle adaptor rings too.

Foam seal

Included on darker ProGlass ND filters such as the six-stop version, this seals the back of the filter against the holder to reduce reflections, and maintains high contrast and clarity during long exposures.

Filter protection Good-quality ND filters are expensive, especially if you need to invest in different strengths, so make sure you keep them both organised and protected in a proper filter pouch.