# Red filter? for B&W landscapes...



## CRman (May 22, 2008)

Have a polarizer filter for my wide angle and have heard stacking a Red filter on it can add to a dramtic  black and white landscape photo. Something I'd like to try. Looked through Adorama and couldnt seem to find one specified as "red" filter. Am I not looking for the correct thing? Anyone have any advice or links on one, experience with using? Thanks in advance.


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## Josh66 (May 22, 2008)

http://www.bhphotovideo.com/bnh/con...13&shs=&at=Color_Red&basicSubmit=Submit+Query

Someone else will have to give the tips on how to use it, but there's all kinds of red filters here.


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## Helen B (May 22, 2008)

The most common red filter is usually known by its 'Wratten number'* which is 25. It used to be a Wratten A back in the days when Wratten filters had alphabetical codes, so it is also known as a Wratten 25A, though that is not a correct Wratten number.

The 25 effectively cuts out all green and blue light. There is a deeper red filter, the Wratten 29 (old designation Wratten F), which cuts out some red light (if you think of the spectrum as being divided neatly into three). 

The B+W (that's B+W the filter manufacturer, not B&W as in black and white) equivalents are the 90 for the 25 and the 91 for the 29.

Both filters have a fairly large filter factor and, as many films are not sensitive to the deep reds that we can see, the increase in exposure can be large when you use the 29. It's worth doing some experimentation. If you use a TTL meter, start off by simply using the TTL reading, and bracketing to see what exposure compensation gives you the effect you want. Metering of blue or green objects through a red filter can lead to severe overexposure of the reds.

Because much green foliage reflects and emits some deep red light (chlorophyll fluoresces in the deep red), films that are sensitive to deep red may show foliage as being lighter than you would expect. This effect is most obvious when using film that has extended red or near infrared sensitivity.

Cloudy skies will be particularly dramatic, and unlike a polarizing filter the effect will depend only on the sky colour, not the angle to the sun.

*Wratten and Wainwright was a filter manufacturer in Croydon, England that was bought by Kodak. Kodak kept the name 'Wratten' for their filters.

Best,
Helen


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## CRman (May 22, 2008)

cool, thanks for the info. Keep it comming. As for the B&W, I meant black and white, sorry for the confussion. I do own a few B+W and like them.


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## Garbz (May 22, 2008)

For the record I don't see a film camera listed in your signature. With a digital camera colour filters can be easily made in post processing.

For instance in photoshop use the channel mixer, set the output to be greyscale, and setting red green and blue to 100% 0% 0% will give you a near identical image to a photo taken with a Number 25A red filter converted to black and white.

The benefits of the post processing method is you don't need every filter. A little tweaking can turn it into a 29A deep red, by setting red to 120% blue to -10% and green to -10%. A yellow filter can be simulated with 50% red 50% green 0% blue, etc etc.


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## mulletbay1 (Feb 10, 2011)

Helen,

I am new to the site and as by luck, in a search for red filters and b&w, I linked here!!!
You seem very knowledgable so I would like to ask a ?
I am shooting dig b&w using a Hoya 25a filter{trying to get the clouds to pop from a dark sky}. I started to read about a B+W 29 and 30 red filter.
In your opinion, should I add one of these to my 25a for more pop than the 25a alone? I already tried the 25a with a cir. polarizer, that works nicely.

Thanks for your time.

P.S. Please check out my site at:  perrelliphoto.com  and unusualphotos.shutterfly.com

Best,
William


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## mulletbay1 (Feb 10, 2011)

Helen,

I noticed further on in your post that settings in PS will simulate the filters.
Can I ask if there is a site with info on the settings you provided or do you have any more to share?

Thanks,
William


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## Big Mike (Feb 10, 2011)

Welcome to the forum.

You'll have more luck getting replies if you start a new thread, rather than posting in one that died in 2008.  

As mentioned above, any sort of colored filter effect can easily be replicated with software (especially Photoshop).

For more info, just Google B&W + Photoshop.


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