This filter is very effective for when you want to dramatically increase contrast in your black-and-white photography.
Download our last printed traditional catalog containing our best selling traditional products. We are not talking about taking photos with cameras that are sensitive to infrared heat radiation, like police helicopters use to find people hiding at night. To take an infrared photo, you'll need a camera that is sensitive to infrared light, and a filter that passes infrared light while blocking visible light. You can test if your camera is sensitive to infrared light by taking a photo while pointing a TV remote at the camera lens. Take the photo in a dark spot, so it will be clear if the camera is picking up infrared light from the TV remote. If your camera is not sensitive to infrared light, you can purchase infrared cameras, or have an existing camera modified to shoot infrared. You can find cameras already converted to infrared for sale on eBay, for example from the seller Digital Landscapes.
Sigma DSLRs are particularly suitable for infrared photography, as they feature a user removable infrared cut filter. There are some differences between a camera that is sensitive to infrared light, one that has been converted specially for infrared photography, and one that is a full spectrum camera. A full spectrum camera is one that has no blocking filters installed, and so captures ultraviolet, visible, and infrared light. But you need to fit the correct filter to the front of the camera's lens to block the wavelengths of light you don't want to capture, while passing the wavelengths of light you do want to capture.
With a converted infrared camera, the infrared cut filter which is normally attached in front of the sensor, is removed. The benefit of this is that you don't need to use any additional infrared filters in front of the camera's lens, as the filter is already installed in the camera. Infrared sensitive cameras are those that have an infrared cut filter installed, but the filter isn't very strong and still lets some infrared light through. The disadvantage of these cameras is that because they have the infrared cut filter still installed, they are not as sensitive to infrared light as a full spectrum or converted infrared camera. The other problem is the same as with full spectrum cameras - you need to attach an infrared filter to the front of the lens to record infrared photos.
The good point is that the camera can be used as a normal camera with no extra filters needed. Light is a form of electromagnetic radiation, and is measured by its wavelength in nanometers.
Infrared filters that let through some visible red light as well can be used to produce false color infrared photos. Probably the most popular filters for infrared photography are those that cut visible light below 720 nm.
Unlike normal photography, sunrise and sunset are not particularly special (they're not bad either though). Infrared photography may not be to everyone's taste, but it does give you a chance to show the world in a different light (literally). Then find a red filter (a piece of red cellophane may do in a pinch), and see how the photos come out.
We are most sensitive to yellow light, which is right in the middle of the visible spectrum.
If we look at different colors of light, all with exactly the same light intensity, yellow appears the brightest, followed by green and orange, followed by red and blue, with violet the darkest. Due to atmospheric conditions, excessive amounts of blue and violet light are present outdoors.
Excessive blue and violet light cause haziness on the film, so we need to selectively filter out the excess amounts of blue and violet light, in order to produce clear detailed photographs.
In addition to the biological sensitivity of our vision, our brain automatically makes color corrections, and our vision makes automatic adjustments as well. Our brain and vision make adjustments to normalize our experience with changing illumination.
We need to acknowledge that our color vision allows us to see contrast between objects, when those objects reflect the same amount of light. Unfiltered panchromatic film records a dramatic blue sky with white clouds as almost completely white. It is necessary to correct this “imbalance” by selectively filtering out excess blue and violet light, in order to make black & white photographs capture the same impression as our color vision. Ultraviolet “light” is actually invisible ultraviolet radiation, which is higher frequency than visible violet light. The first reason, as discussed, is to remove excess blue and violet light, in order to “correct” the black & white photograph.
Another way of describing this, is to say that we have automatic correction built into our visual process, so we must manually filter panchromatic film in order to produce the same effect we experience. The second reason for using filters is to produce contrast between different colored objects that reflect the same amount of light.
In black & white, a red filter will lighten up the brick to light shades of grey, and will unveil details in the brick that are barely visible in color. The same red filter can be used in landscape photography, to dramatically darken blue skies, and produce deep shadow effects.
A difference of 25% to 50% in light is barely noticeable to our vision, but makes a whopping difference on film.


We choose filters by using these principles, to select the best overall contrast in our photographs.
Over filtering to produce one desirable effect, can cause us to lose details somewhere else in the photograph.
A Green filter illuminated with white light looks green, because it absorbs red light (the complement of green).
A Green filter absorbs some blue light, but has the effect of lightening blue, because of the Filter Factor adjustment.
A Green filter with a 3X Factor requires the camera to open 1?-stops to compensate for the filter absorbing light. Black & White photographers use filters to selectively remove unwanted wavebands of light, like sculptors removing unwanted marble from a statue. Without a filter, all the different hues of green would be rendered as the same shade of grey.
The #21 and #22 Red Orange filters are stronger than the #16, and have an effect similar to the Red 25A filter. The Red filter is unique, because it is at the bottom of the visual spectrum, and behaves like a Low Pass filter.
Produces dramatic skies with clouds, and for good contrast in scenes that have pale blue skies and oceans. Since I recently bought the Hoya 25A Red filter for false colour infrared photography, I decided to see how well it would work for black and white photos. I tested the filter on my Fuji IS Pro, taking a photo in colour (using the UV-IR cut filter to cut UV and IR light), a photo with the UV-IR cut filter plus the 25A Red filter, and an infrared photo with just the 25A Red filter.
The first thing I noticed when taking the photos was that when using the UV-IR cut filter and the 25A Red filter together (so the camera only receives red visible light), a slow shutter speed was needed. I thought that the photo taken with the red filter would have a darker sky than the colour photo converted to B&W, but they are both about the same. I also tried doing B&W adjustments to the photo taken with the red filter, but it is very difficult since the only colour is red. So, my conclusion is that it's not worth using colour filters (at least not the 25A red filter anyway) for black and white photography with a digital camera.
By using a camera that is sensitive to infrared and a filter that blocks the visible light, we end up with an infrared photo. Most plants and trees reflect a lot of infrared light, which is why they look so bright in infrared photos. However, on some older models, this filter was not very strong, and so still let through some infrared light.
Alternatively, you can purchase an old camera that has not been converted, but is still sensitive to infrared light.
The camera can easily be converted back to a normal camera by just putting the infrared cut filter back again. This means it can be used for ultraviolet photography, normal (visible light) photography, and infrared photography when used with the appropriate filter. So for capturing infrared photographs, you would need to purchase an infrared filter, and mount it in front of the camera's lens.
If the camera uses a through the lens optical viewfinder (most DSLRs), then you won't be able to see anything through the viewfinder with an infrared filter attached. For cameras with through the lens optical viewfinders, it means the viewfinder is not affected at all. You will need to use longer shutter speeds to gather enough light, and probably require a tripod.
This means that you can't see through the viewfinder with an IR filter attached when using a camera with a through the lens optical viewfinder. If you already have a camera that is sensitive to infrared light, this is the cheapest way to get into infrared photography since it only requires an infrared filter. Some filters capture only infrared light (above 750 nm), while others capture some visible and infrared light. This is usually done by swapping the red and blue channels of a photo using photo editing software. This produces a photo captured with a portion of visible red light, but mostly infrared light. This produces images with more visible red color, which allows for stronger colors in the captured image.
Sunny days where fluffy clouds float across the sky are also very good for infrared photography.
To create a false color infrared photo, with a blue sky, you can switch the blue and red channels. If you want to give it a try without spending on a converted camera, I would suggest testing any old digital cameras you have to see if they are IR sensitive.
Light Intensity (the number of photons per square inch) is what determines what shade of grey gets produced on film. Blue and violet light have short wavelengths, and do not focus well on the film plane, like longer wavelength light. When using black & white film, we need to understand this in order to choose the right filter, to produce the photographic effects we desire. When we look at sky with clouds, we easily see the contrast between the blue sky and white clouds because of color. Ultraviolet light has a shorter wavelength than visible light, and causes the worst haziness on black and white film.


If the orange and blue are the same shade (reflect the same amount of light), they would wind up the same shade of grey on film. The Red filter would be used to make Green trees look the darkest against snow topped mountains. For natural effect, use the #11 Yellow-Green filter (Hoya) in a garden that contains yellow-green plants. The Yellow-Green filter passes light that is yellow-green, so yellow-green plants rendition as light grey on black & white film. The #13 Green filter will make green-green plants look lighter, with blue-green plants a darker shade of grey. These filters work well on architecture and landscapes, especially distant scenes, mountains, etc.
It passes long wavelength light, and filters out the high frequency short wavelength light. With digital, you can do this instead in Photoshop (or similar software) as part of the B&W conversion process from a colour image.
Would it have any benefits over just shooting in colour normally and then converting to black & white? This is not surprising really, but it does mean that on a windy day it is harder to get a shot where everything is sharp.
That gives me an idea actually - what would an image taken with the UV-IR cut filter and the Hitech infrared filter (720 nm cut off) look like? These images have just had white balance, exposure, and curves adjustments, and desaturated. The flowers of the rape are brighter in the photo with the red filter though, giving them more 'pop'.
You can perform some adjustments by using the channel mixer, with a desaturation layer above. Processing: Curves adjustment selectively applied to enhance sky and darken fields either side of track.
Processing: CornerFix not applied (leaves the vignette in place), Topaz Adjust 5 using High Key I preset. Processing: Curves adjustment to increase contrast, Topaz Adjust 5 applied using modified High Key I preset. In addition, this filter can also be used with black-and-white infra-red film (although we recommend an R72 or R87 filter to get the maximum infra-red effect). This infrared light is reflected from objects, just like visible light, but we can't see it. So by pressing a button on the remote while pointing it at the camera, the remote will emit infrared light.
Cameras sensitive to infrared light are normally sensitive to light up to around a wavelength of 1000 nm. Those that pass infrared light only cannot capture any color (since we can't see infrared), so are used to produce black and white images.
An example of an infrared filter that cuts visible light below 720 nm is the Hoya R72 filter. Because they capture no color information, they are good for strong black and white infrared photos.
If you use Photoshop Elements, you will need to download and install the Channel Mixer as an add-on. The product will still cost you the same as if you went direct, and the commission helps pay for running this site. The solution would be to choose a filter that would lighten the shirt a bit, and darken the pants a bit. The Red filter would also darken Blue skies dramatically, as Blue is 4-color bands away from Red (2nd complement). Blue objects, although slightly darkened by the Green filter, lighten up after the 1?-stops adjustment is made. Our vision sees the yellow-green plants as the brightest, followed by the green-green, and the blue-green as the darkest.
In reality I think that the long exposure needed is more likely to result in loss of image detail (by everything blowing about in the wind during the exposure). It can be downloaded for free as part of Grant's Tools from the Photoshop Elements and more website. The black & white photo would then exhibit nice contrast, a shirt that appears lighter than the pants.
And I find it easier to get a nice black and white conversion by working with a full colour image. The #8 Medium Yellow filter can be used probably 60% of the time for black & white photography.
The Yellow filter is unique, because it lies in the middle of the visible spectrum, and makes everything look natural.



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Comments to «25a red filter for black and white photography»

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