PlasDIC questions

[microscopeboi]

hello, ive been looking into plasdic, as i think i will soon be ready to purchase a prism or two. So, from my understanding, rather than using the analyzer prism you replace it with a 'slit' patch stop and the length/width of the slit effects the amount of contrast? additionally, i understand that you can use this, or varying dimensions of this, to replace all need for analyzer prisms, is this true? if so, what would be the difference between a lower NA slit and a higher NA slit? Additionally, ive read that plasdic doesnt really work for higher (<.65 NA) objectives, could the combination of oblique and plasDIC be used to compensate for a higher NA? lastly, if not, does anyone know how to get it to work at higher NA's? Thanks!