Sunday, April 1, 2012

Filters continued...

Last time when I wrote about filters I had mentioned about staking filters and neutral density filters, so this time it made sense to continue the filter theme. Before I delve into staking filters I'll give you a brief about few more filters. One of those are neutral density (ND) filters ( I had mentioned those in the previous post as well).

Neutral density filters, as the name suggest, when added in front of the camera, will have a neutral impact on the light i.e. to say there will not add any colour to the light which enters the lens. Think of it like a pair of sunglasses for your camera. The amount of light which is cut out is measured in stops (f-stops) so you have a 1 stop ND filter 2 stop so on. Some of the use cases are for when slow shutter speed is required like a waterfalls and in some cases for studio photography as well..

Let's start with the motion blur, say you are a water fall at mid day (sometimes life can give you such surprises...) and you cant wait till evening. So you do the you close the aperture to f16 and bring the ISO to 100 or 50 (if your camera goes that low) and the light meter in your camera gives you shutter speed of 1/50. Now you are reluctant to go to F22 but you want a shutter speed of 1/30'th or lower because that's when you start picking up the motion blur. Now that 1 stop ND filter is just the perfect answer. You use the filter and cut the light and you are done. Even if you have 1 stop filter you will cut the shutter speed to 1/25 and your task is done. Now lets say you want to get to 1 sec exposure have two a 1ND filter and 3 stop filter. You STACK the two filters and you have 4 stops less which is almost 1 sec and you are done.


Another use case may be to remove traffic from the road. ( You could use a 9 stops ND filter and remove moving traffic from a the road by giving an extended exposer, though you would need an awesome tripod which does soaks up the vehicular movement and does not move your camera during the long exposure)

I mentioned studios earlier so lets say you are in a small studio and you power down your strobes down but don't want to go lower or can't go lower because of various reasons. Your light meter measures f 5.6 at the lowest at ISO 100 and you wan't to shoot at 2.8 because you want a shallow DOF on your images. Add the ND filter and you have the F stop you want.

The other kinds filters are, Colour filters, Graduated ND filter and Graduated colour filters. You can use the Graduated ND filters have a stop difference between the top and bottom of the filter. These are perfect for landscapes when you an underexpose the sky and expose landscape well. This is an alternative to doing HDR. 
View of the lake

Another option would be add a sunset filter(aka tobacco filter) to get a sun set during the day. You can also saturate the colours of the sunrise/sunset by using the colour filters. 

However, every thing comes at a price. When you add a filter you reduce the quality of light and sharpness of the image (especially in case of cheaper filters) Some people are dead against adding any filter in front of the camera and prefer to add the colour cast in software. It's a personal preference. If you are like me who does not like editing too much. (every hour I am editing I not doing something else I like) What ever your take on filters they are certainly worth a try.

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