Originally posted by BruceBanner .................Two more points;
1) You can't vary the 'strength' with linear, like rotate it like you can a CPL and decide how much polarising effect to go for, with linear it's all or nothing?
2) Can you use linear (or even CPL for that matter) with ND filters if you feel you want to block out even more light. Perhaps for example a 1-2min very bright day with clouds scene to get the clouds really moving etc.
1) I think you're missing something here Bruce. A CPL
is a linear polarizer (with a retarder) hence they both behave almost identically. The difference is that with a CPL the polarized light produced by the linear polarizer is "scrambled" so it doesn't affect those AF systems which are susceptible to polarized light. So yes, you can vary the strength of either - they both behave identically
relative to the scene. If you hold a linear and a CP side-by-side and look through them, you would see exactly the same thing and as they rotate, the changes would be identical.
2) Yes, an ND filter doesn't care is light is polarized or not (nor linearly or circularly). It just reduces light intensity. Therefore, you can use a standard ND with a polarizer with no issues. (Exception: Variable ND filters use crossed polarizers and aren't compatible with polarizers). It could be argued which should be on the camera side, but technically, it makes no difference. (One thing to keep in mind is that with wide-angle lenses, stacked filters may start to show and produce vignetting in the photo - just watch out if the filter rims are wide.)
And - that one point is well taken - it may be harder to find a quality linear polarizer these days since both to address the issues with some camera's metering systems, and as a market ploy (to imply a CP is has some advantage over a LP), many manufactures only offer CPs and have discontinued LPs.
Last edited by Bob 256; 04-18-2018 at 08:17 AM.