[sbtm]

Hi everyone,

I have a quick one: whats the difference between the UV filter and ND Grad filter? and which one adds more saturation and gives more dept to the skies?

Thanks

[_MB_]

UV filters out UV light, that's it. Their main purpose is protection.

An ND (neutral density) filter should filter all colours of light at the same level, so you can use a slow exposure and retain detail. These tend to double in strength so ND1 makes everything 1 stop dimmer, ND2 is 2 stops dimmer, ND3 is 4 stops dimmer. Nomenclature varies between manufacturers.

An ND grad is a graduated filter, such that one end will be dark, one end will be clear. There's different kinds such as hard, where its roughly 50% ND and 50% clear with a sharp divide, and soft, where it's 50:50 but the gradation is finer.

For saturation and depth to skies, you'd probably want a polariser filter.

[Dabhand16]

A UV filter looks like plain glass. It does what it says on the tin - it reduces the amount of the UV wavelength in white light that passes through it. The main benefit is that it reduces the blueish tint that photos taken at higher altitudes tend to have because of the higher percentage of UV in the light that is not filtered by the atmosphere. At lower 'normal' altitudes they make little difference to the images and many people use them as lens protectors.

Graduated ND's are a very different beast. First they are visibly different. one side will be clear and there will be a graduated change across the filter, usually in the centre, to a dark grey or black appearance on the opposite side. The purpose of these filters is to allow the photographer to reduce the exposure of one part of the picture in relation to the rest. Usually, this is the sky which as you probably know, will be overexposed if the other parts of the picture are correctly exposed. They come in different strengths - 2x, 4x etc which tells you how dense the dark part is in relation to the clear part.

Why are they called neutral? That is because they will not interfere with the colours by introducing a caste - you can get graduated filters that will do just that, the most popular is probably the tobacco grad that will make great sunsets out of almost any scene at any time!

[sbtm]

Thanks Dabhand16 & _MB_ you guys cleared the filters in my mind

The filter I was looking for was the polorizer filter as _MB_ mentioned. Thanks again!

[Markulous]

Originally Posted by sbtm

Thanks Dabhand16 & _MB_ you guys cleared the filters in my mind

The filter I was looking for was the polorizer filter as _MB_ mentioned. Thanks again!

Just a small comment on polarisers: if you use a digital camera you'll almost certainly need a Circular rather than the cheaper Linear (which very often interferes with the focussing system)

[tim0306blue]

As an additional question to this thread - I have just bought a polarising filter and can see that it can be rotated. How do I know how to align it? As it is a circular filter does it matter?

[Markulous]

Light is polarised at right angles to the sun, so put the sun at left or right shoulder and then rotate the ring to see effect. Or point at reflections in water, off buildings or plants, and rotate.

There's usually a mark on the outer ring - aligning this to the sun will maximise the polarising effect

[sbtm]

Originally Posted by Markulous

Just a small comment on polarisers: if you use a digital camera you'll almost certainly need a Circular rather than the cheaper Linear (which very often interferes with the focussing system)

But is there any difference in the end result?

[Markulous]

Originally Posted by sbtm

But is there any difference in the end result?

In theory, no, the results should look the same.

[M1ke A]

I understood that linear polarisers (can) affect the AF of a camera? If that's the case then yes you could end up with out of focus pics which would be a different end result

[Les Meehan]

Originally Posted by tim0306blue

As an additional question to this thread - I have just bought a polarising filter and can see that it can be rotated. How do I know how to align it? As it is a circular filter does it matter?

A pola filter is aligned visually as you look thru the viewfinder. Most users of pola filters tend to always use the maximum effect BUT this is not exploiting the full capability of the filter. Instead of locking yourself into the usual mind set of 'max is best' try to think of the pola filter as an infinitely variable 'controller of reflections'. For example, most people doing a scene full of foliage would probably max out the pola for color saturation reasons BUT this can kill the life out of the surface of the leaves by dulling them too much. Most foliage has a shiny surface and your image can actually benefit by retaining some of that shine.

As another common example, when using a pola to 'control' (note I said control not remove!) the reflections in a shop window, it might actually improve your image to retain a little of the reflection in the glass rather than removing it entirely. Of course, the best thing might be to remove the reflection entirely BUT NOT ALWAYS!

Thus when using a pola, use it creatively and with some thought as to the end result. As you rotate the filter look carefully at the effect and make a decision based on the final image desired and not simply on some dogmatic idea that 'max is best'.

As with many of the tools and techniques of photography, using them creatively involves thinking about their effect and not simply doing one thing all the time.

Have fun with that filter!

Cheers

[_MB_]

This is a good point well made.