dinsdag 22 mei 2012

Cokin Blue / yellow polarizer

This filter is amazing, it already starts when you look through it the first time. If you have a clear sky, you are able to make it very blue, or turn the blue away and create a yellow sky. (if you can think away the colour-cast) And that’s also the strength of this filter, blue and yellow are two important colours in landscape photography. you can either make reflections look warmish, or coldish. I say –ish because the effect is easily overdone. It is very easy to overdo the effect, and make your photos look artificial.

How to use it:
There are two ways you can use this filter, with or without additional polarizer. Without the polarizer this filter mostly affects reflections in your scene. This is really cool to improve the sky, play with the colours in the water, or with any other reflections. The results are still relatively close to what you actually saw, at least compared to using it with an additional polarizer.

If you put a polarizer behind it, you will be able to affect all the colours of the scene. You are able to give the whole photo a yellow or blue hue. This is very strong, and I can’t think of any other way of using it, than a blue / yellow filter for black and white photography. But Cokin suggests it as a way of using the filter in its brochure, so just to let you know.

I have yet to develop my first roll of film shot with this polarizer, but this filter shows a very magenta kind of colourcast. If it doesn’t polarize, it becomes quite obvious. My impression is that the more light comes through it, the less visible it becomes, but nevertheless I always have to adjust the tint-slider. (green – magenta colour channel in the white balance dialogue of Capture NX) Although this can also be a cool effect on an overcast day to add some colour to your images.

Image quality:
I paid only 16 euros (A-size) for this filter, one can hardly expect tremendous image quality for that money. There is some loss in sharpness, but I think you can solve that in post. The images hold up rather well. Besides that I think the effect of this filter on your photo will be more than significant enough to justify using it, even with the sharpness loss. Of course there are more expensive alternatives (from Sing-Ray), but to me this filter is good enough.
I heard that the loss of sharpness becomes larger when you use longer lenses, but until now I haven’t used it on these lenses. I feel that this filter is more appropriate for shorter lenses, because I want to have as much reflective surfaces in my shot as possible.

As mentioned, the filter has quite a strong magenta cast. This is easily solvable in post, but it makes it a bit harder to pre-visualize how your photo will eventually look like. Besides that, this filter is virtually impossible to use with a graduated ND filter. This filter uses the same slots as the GND-filters in the Cokin holder. There are ways to avoid this, by tearing the filter holder apart, and fitting it in the filter holder of a normal polarizer, or star filter of Cokin. Perhaps I will do that in the future, but for now I leave it in its original casing.

But I still recommend this filter, its effect is amazing. It gives you control over the colours in your scene, and the change it makes is quite dramatic. One of the things I really like to use it for is to shoot right into the sun. As with normal polarizers the sky isn’t affected when shooting directly against the sun, but it does the reflections on the water. Now you’re able to create an incredibly large colourcontrast between the water and the sky. In this photo you can see that pretty good: the sun is just out of the frame on the left, leaving little to polarize in the sky. But when you get further to the right the filter kicks in, giving a very blue sky, which wasn’t as distinct as it is now.

This filter is also amazing when everything is wet after some rain, obviously there are a lot of reflections then, and you’re able to give everything your desired colourcast.
The only thing I am bothered a bit with, is that its effect can be quite unpredictable. I still have trouble deciding whether this filter would be useful in a particular scene, but when it is, it is a rewarding filter to use.

By the way, Cokin went bankrupt, and is bought by Tokina and Kenko. Although after the sale nothing is heard from them again about Cokin, so you might want to get your Cokin filters quickly. 

I made a post how to post process your images you made with this filter, as there is a strong colour cast.