Hi, I have a nikon D5200 and I am going to the Galapagos and wanted to take some cool photos with motion blur. I know for photos on sunny days with long shutter speeds you need a neutral density filter and I was wondering if you had any filters you recommended. I would like to go on the inexpensive side, but not so cheap that I am starting to lose quality in my photos
The first should be a circular polarizer. It needs to be circular because it has a quarter wave plate after the polarizing filter, which de-polarizes the light. Your camera's auto-exposure system needs unpolarized light to function properly. This can double as your everyday polarizer filter, which you'll want anyway to remove reflections and darken the sky. If you're a serious photographer, you probably already have one of these.
The second should be a linear polarizer. A circular polarizer will not work for this application. By itself a linear polarizer is pretty useless as it will mess up your DSLR's auto-exposure system.
Screw the circular polarizer on the lens. Then screw the linear polarizer on the circular polarizer. It has to be in this order - the quarter wave plate on the circular polarizer that de-polarizes the light will still be the last thing the light hits, so your camera's auto-exposure system will still work. (For this reason, a "slim" circular polarizer will not work - those don't have screw threads in front for mounting another filter on it.)
When mounted this way, if you rotate the linear polarizer relative to the circular polarizer, you will get a variable ND filter. It can cut the light anywhere from 50% (same alignment as the circular polarizer) to 100% (90 degrees offset from the circular polarizer), and any percentage in between.
the problem with this would be if you are shooting wide the stacked filters will show in your frame. i've have this experience before . only solution was to crop in post. try the hoya ndx400. you'll fine a lot of cheap ones on ebay too (come in 2 stop, 4 stop, 8 stop & 10stop). you can choose the filter as per the light and exposure time.