 Pieter J. Roelofse |
Neutral Density Filters I have a question about exposure when using neutral density filters. Sometimes I go to our beach and the sun is very bright shining off the surface of the water which obviously influences exposure. I have read to use a ND filter to cut the light. Well, I bought a one stop ND2 filter and it works well, cutting the light that is by one stop. I know the filter cuts the light by one stop, without changing the color balance. Take the following example. My camera without an ND filter and 50mm lens. APerture priory,f16, smallest fstop on my lens. Exposure meter recommends faster than 1/1000 sec, which is the max of my camera shutter speeds. So, I ad the ND2 filter. Now the camera is on f/16 shutter 1/500. The camera just compensated for the lack of light (due to the ND2 filter). I am very confused about the use of ND filters. I just want to cut down on the extreme bright conditions. HELP !! I am an advanced amatuer, but this has given me troubles, just the bright condition scenario, I know how to handle other condition with my ND filter and I know how they work. Any suggestions or advice will be appreciated, thanks for a great website, keep up your good work. Thanks
|
|
|
|
||
|
Jon Close |
According to the "Sunny 16" rule, in the bright sunny (no clouds or haze) situation if you set your aperture to f/16 then the correct shutter speed will be 1/film ISO (assuming no filter is used). See http://photographytips.com/page.cfm/123 I'll guess that you were using 400 speed film, so that in your beach situation the correct expsosure (with no filter) would have been f/16 and 1/400 (1/500). Your camera meter is calibrated for light reflected from a medium tone (18% Gray). When your scene is predominantly lighter than that (snow, white beach ...) or darker (groomsmen in black tuxedos ...) the meter reading will give you under or overexposure, so you should apply exposure compensation to the meter reading. For white/light subject like your beach you add exposure (longer shutter or wider aperture), and for dark you subtract (faster shutter or smaller aperture). Thus at the beach when your camera meter was suggesting f/16 and 1/1000 (or higher) you should add +1 or +2 stop exposure compensation for the bright white scene, which would get you to the f/16 and 1/500 suggested by the sunny 16 rule. If you want to use a slower shutter (allow motion to blur) or wider aperture (limit depth of field) you can add the ND filter or use a polarizing filter. The polarizing filter will remove glare off the water and saturate colors (deeper blue sky), and it decreases the light to the film by about 2 stops. In the beach situation, if you add a polarizer then your camera meter will suggest f/16 and f/250. Again apply +1 or +2 stops exposure compensation for the white sand scene and your exposure becomes f/16 and f/60. You are now no longer butting into your camera's shutter speed limit and can choose to shoot your scene at say f/8 & 1/250, or f/4 & 1/1000.
|
|
|
|
||
|
Jeff S. Kennedy |
A ND filter isn't going to make a scene appear less bright. All it does is cut out the amount of light to your camera. Another way to think about it is a ND filter changes your effective ISO. If you are shooting at ISO200 and then slap a 1 stop ND on the lens you have just changed to ISO100. The scene is still the same. You just need more exposure in camera. If you want the scene to look less bright then underexpose but you don't need a ND filter to do that unless the scene is so bright that you cant stop down enough.
|
|
|
|
||
|
This old forum is now archived. Use improved Forum here
Report this Thread |
||