ARRI Alexa Internal Filter Module IFM-1
This filter module allows for the use of behind-the-lens ND filters in all ARRI Alexa cameras except the Studio, which already has a built-in filter system. Internal filters reduce reflections, protect the sensor from dirt during lens changes, and are lighter than matte box filters. Using this filter system also frees up space in your matte box, giving you room for other filters. The Full Spectrum Neutral Density (FSND) filters used with the IFM-1 are specially designed to have a neutral color balance at all densities. They are made of precision polished water-white optical galss that provides high image sharpness, and have an anti-refelective multi-coating to maintain a high contrast image.