Monochrome (B&W) shooting with filters.

[JohnF]

Is there a simple answer here?

RED has a Bayer format single chip detector, will this mean that if I do a B&W shoot using red, orange or yellow filters to control image contrast that this will drop the resolution of the image as the green and blue detectors would effectively not be used?

Or will RED have a B&W filming mode that would somehow get round this issue.

JohnF

[martinnoweck]

John,

i am not sure if orange or red (!) filters to enhance clouds, etc.work with electronic cameras at all - any experience with other electronic cameras?

M

[JohnF]

Yes it works with B&W single chip cameras. But colour cameras are variable in quality due to the various ways they encode colour information to the recording medium and the way the camera interprets a colour image.

The use of filters creates an optical effect that helps cut out the light that is scattered by water vapour in the atmosphere. By using filters this controls the amount of contrast any camera would see. Move t'ward red and contrast increases move t'wards blue and contrast decreases.

JohnF

[Dominic Jones]

Yes, they do work, but unless you're trying to stop blow-out on lower latitude systems there's no advantage to doing them optically (i.e. in camera) as opposed to electronically (i.e. in post), and of course you get more control/flexibility/bites at the cherry in post...

Interesting question though, regarding resolution on Bayer CFA systems using optical filters - I suspect the answer is that it will not affect the resultion, simply suppress the colour values for those pixels which are colour filtered different colours, which is what it should do, of course. The question, I suspect, is more of an issue of how the demosaicing software handles this, and if it throws up any nasties...

Interesting question, but if it does prove a problem shooting colour and doing your desatch in post would allow you to get the same effects in almost all cases, especially considering the very high latitude of the Red system.

[JohnF]

I'm confident that RED in post will be fantastically versatile but there are some types of images that one simply cannot replicate after the shoot.

The question I pose here is about making sure the camera does not record the scattered photons which will "muddy" an image.

Another example of an effect that cannot be replicated in post is polarizing filters that is until such a time as CCD's can also record polarization of light as well as colour and brightness!

JohnF

[Graeme Nattress]

For shooting B&W on a DSLR, it's best to shoot colour, and then convert to black and white by taking a specific RGB Mix in post production raw development and not use filters over the lens. This method effectively allows you to decide in post what balance of filters to use because of the filters on the pixels. Works well. You can do this to an extent in REDCINE by altering the RGB gain, or the Kelvin white balance of a desaturated image.

Graeme

[Anders Holck]

Here is a great example of doing B/H color filtering from a RAW image.
Scroll down to the bottom, any try the rollover:
http://www.dpreview.com/reviews/canoneos5d/page16.asp

[Ace]

I used to use coloured filters alot when shooting with Ilford film, with excellent results, but as Greame pointed out.. the imaging chips physically have coloured filters infront of the pixels, so all you would be doing is putting a filter infront of the another set of filters.

[JohnF]

Great answers folks!!!

Now will there be a B&W function on REDCINE similar to the Canon software that Anders Holck referred to and what will the impact be on resolution?

By that I mean if one chooses to use the red end of the filtering could that mean that res will drop by 2/3rds as the green and blue would not be used?

JohnF

[Paris Remillard]

Really, the only filters that can't be emulated are polarizers, NDs and ND grads. For the most part.

[Graeme Nattress]

In stills we simlate ND grads by taking two exposures and blending. We can't really do that on moving images. Polarizers must be used infront of the lens if you want their effect as it can't be simulated.

Looking here at a test image, if you used red and red only, it's a touch softer than a more balanced black and white, but not by anywhere near as much as you'd expect by looking at a bayer pattern.

Graeme

[Ryan Manes]

So does this mean I shouldn't invest in a matte box and set of filters, like a graduated neutral density filter to control overexposed skies.

[Dominic Jones]

No, you should really have a mattebox (because it will increase the contrast and fidelity of your images anyway, regardless of using filters), plus a polarizer, ND grad or two, a couple of ND's (for controlling DoF, when necessary) and a UV (this is the other filter that can't really be emulated for it's haze removal).

Personally I like to carry some grades of black and white pro-mist and a low-con as well, although the low-con will get the drop when I'm working with the 11+ stops of latitude of the Red, I suspect...