Infrared photography. Detailed analysis of infrared photography. Setting up and Capturing How to Make an Infrared Filter for a Camera

It is not yet warm, but it is no longer light.
How to get an infrared image on a conventional camera. How to make an IR filter from improvised materials. specialized cameras. Difficulties when shooting and how to get around them. Choice of lenses, cameras and filters.
Interesting plots in the infrared range.

Let's try to process them together using live examples of infrared images. Get turnkey solutions on image processing and together we will analyze how these solutions work.

THEORETICAL PART

Introduction to infrared, visible and ultraviolet radiation. The difference between infrared and thermal radiation.

Infrared radiation was discovered in 1800 by the English scientist W. Herschel, who discovered that in the spectrum of the sun obtained with the help of a prism beyond the red light boundary (that is, in the invisible part of the spectrum), the temperature of the thermometer rises. At the same time, it was proved that this radiation obeys the laws of optics and, therefore, has the same nature as visible light.

Fig.1 Decomposition into the spectrum of solar radiation

On the opposite side, beyond the violet band of the spectrum is ultraviolet radiation. It is also invisible, but it also heats the thermometer a little.

Far infrared radiation (the longest wavelength) is used in medicine in physiotherapy. It penetrates the skin and heats internal organs without burning the skin.

Middle infrared radiation is recorded by thermal imagers. The most popular applications for thermal imaging cameras are heat leak detection and non-contact temperature monitoring.

Rice. 2. Thermal imager (mid-infrared)

We are most interested in the near (the shortest wavelength) infrared radiation. This is no longer the thermal radiation of surrounding objects at room temperature, but not yet visible light.
In this frequency range, objects heated to a noticeable red glow radiate quite strongly. For example, a nail heated red-hot on a gas stove flame in infrared light is bright white (Fig. 3). Cooler areas (the redness of which is imperceptible in the visible spectrum) remain dark in IR.

Rice. 3 NIR

It is this range of radiation that "works" when objects are heated in the sun or under incandescent lamps. And the same radiation is absorbed by the "thermal" windows of cars and home energy-saving double-glazed windows.
Its most popular application is remotes. remote control(Fig. 4), infrared surveillance cameras with infrared spotlights.
At one time, data transmission using the IrDA standard was popular. The same infrared port in phones and laptops.

Rice. 4. Remote control

In digital, as well as film photography, the sensitivity of the camera to infrared radiation is undesirable. It leads to color distortion - black velor jackets look blue, the saturation of red is selectively lost.
Therefore, in modern cameras, they are struggling with it in every possible way with a variety of methods. However, residual sensitivity is still there, albeit quite small.

Differences between black and white and infrared images.

Filters are quite popular on the Internet that make a color photo look like an infrared one. However, they cannot work correctly because there is no information about the reflectivity of materials in the infrared spectrum in the color picture. Roughly speaking, they cannot distinguish between a green car and green foliage and make all green objects in the frame white. In the same way, everything blue becomes black.
In the same way, infrared photography is not obtained behind a simple red filter, no matter if it is film or digital.

How to get an infrared image

In order to obtain a true infrared image, in the simplest case, visible radiation must not pass into the lens, so that the residual sensitivity of the camera to infrared radiation forms an image.

Infrared films

In the case of film photography, this is ensured by the use of special Kodak High Speed Infrared HIE, Konica Infrared 750 and the most popular Ilford SFX 200 films. However, the film is not enough, you still need to install a filter that will cut off visible light. Otherwise, the film turns into an ordinary black-and-white panchromatic film with increased grain. A completely uninteresting combination.
Infrared film is very demanding on storage conditions - it is strongly recommended to store in the refrigerator. It is necessary to load the film into the camera in complete darkness, because the tail of the film acts as a light guide and illuminates up to half of the film. Plus, the frame counters in film cameras also light up the film. In no case should the film be exposed to light when scanning luggage at the airport, and it is almost impossible to do this in modern security measures - the security service rears up and urges you to show what is in the box.
After exposure, the film must be developed using the classic black-and-white process in pitch darkness and preferably in a metal container.
In summary, infrared film photography is more heroic than practical.

Digital cameras

IN digital photography everything is much more interesting. Most of the popular digital cameras the matrix has a residual sensitivity to the infrared range sufficient to take pictures in the sun with a shutter speed of a few seconds.

Rice. 5. Infrared photography. Canon EOS 40D, F8, 30”. Slide film filter.

Although digital camera sensors are infrared sensitive, they are thousands of times more sensitive to visible light, so in order to take an infrared photo, you need to block the visible light with a special filter.
For example, Canon cameras EOS 40D and 300D in the summer sun required a shutter speed of 10 ... 15 seconds with an aperture of F5.6 and ISO 100. In similar conditions, the Nikon D70 allowed you to work with a shutter speed of ½ ... 1 second (which indicates a much weaker IR filter in the camera) .
If you are not afraid of long exposures, then it is quite possible to work in this mode - just install an infrared filter in front of the lens and take pictures from a tripod.
The disadvantage of such a solution is not only in slow shutter speeds, but also in the inability to crop the picture - nothing is visible in the optical viewfinder. You always have to use LiveView, and not all cameras have it.

Cameras with retractable infrared filter (NightVision)

At one time, when digital SLR cameras had not yet gained today's popularity, Sony DSC-F707/717/828 cameras enjoyed authority among photographers.

Fig6. Sony cameras DSC-F717/828/707

Their feature was the shooting mode night shot- in it, a filter was removed from the camera matrix that absorbs infrared radiation. This made it possible to install a special filter in front of the lens that only allows infrared radiation to pass through and get an honest infrared image with relatively fast shutter speeds. Albeit with a lot of limitations of automation, but this made it possible to photograph portraits in the IR range.
There is a legend that cameras designed for astrophotography, Canon EOS 20Da and Canon EOS 60Da are adapted for infrared photography, but this is not true. They have a different Low-Pass filter and increased sensitivity in the red range. However, they are also insensitive to the infrared range.

Modification of the camera for infrared shooting.

If the capabilities of a conventional camera with a filter seem to be insufficient and you want to take infrared photographs with short exposures, then you can remove the filter that cuts off infrared radiation (Hot Mirror) from the camera and get a camera with a fairly high sensitivity to the IR range. In ordinary visible light, the camera will stop working normally - the colors will be constantly distorted, and this can be dealt with only by installing the Hot Mirror filter already on the lens. Therefore, for shooting in the IR range, they often use an old camera that has already served its purpose and it is not so a pity to break it.
And since there is interference in the camera, you can directly put the infrared filter right in front of the matrix. The advantages of this solution are that the picture is visible in the viewfinder again, and there is no need to put an infrared filter in front of the lens. And since a filter is not needed, then lenses with different thread diameters for a light filter can be used.
At home, it is theoretically possible to change the filter in front of the matrix, but in practice it is more profitable to give the camera for revision to a specialist - the result will be much better, and the camera will not be broken. Again, a knowledgeable person will test the camera's autofocus for infrared shooting and make adjustments if necessary.

infrared filters

Shooting in the infrared range almost always requires the use of infrared filters (Infrared passing filter). Filters that do not transmit visible light, but are transparent to infrared radiation.
And in this case, the simplest assistant is photographic film: the developed color film is transparent in the IR range. And this means that the illuminated and developed negative or simply developed slide film will turn out to be black in the visible range, but transparent in the infrared.
By the way, it is the IR transparency of the film that film scanners with automatic dust removal use. They take an additional shot in the IR range - the dust remains visible against the background of the transparent film. And this is a finished dust mask.

Fig.7. slide film

And if so, then you can cut a circle of the desired diameter from a suitable film and put it between the protective filter and the lens. If the effect is not enough, you can put in several layers of film. The picture will lose some contrast and sharpness, but the infrared component will become apparent.

Fig.7A Slide film and IR radiation

You can also look for black CD-R discs. They were popular for recording music, but in recent times, with the decline in popularity of CDs, they have become hard to find. If you remove the cover from such a disk, you get a black disk that is transparent in the IR range.

Fig.8. Black CD.

Many variants of off-the-shelf IR filters are produced. The most popular in Russia is the Hoya R72 filter. It blocks radiation shorter than 720 nanometers, and this is just the boundary of visible light. The Schneider B + W 093 filter is a little less popular - it also completely blocks visible radiation.
Schneider B+W 092 and Cokin P007 filters do not completely block visible radiation, so the picture is only slightly colored. Slide film shows an intermediate result, so it has to be folded in several layers.

Lenses

One light filter for shooting is not enough - you need to form an image with something else. The difficulty with infrared photography is that the lens will be used in an abnormal application for it. The wavelength of light is at least a little, but longer than the visible one, which means that the refraction of light will be less (recall the prism from Fig. 1), which means that the scale of the picture will change. The lens will become slightly longer telephoto. At the same time, a whole scattering of problems arises, which somewhere have a stronger effect, and somewhere weaker. Let's consider them in more detail

Focusing

If the lens is pointed to infinity in visible light, then in the IR range it will be pointed a little closer. The front focus appears. But there is also good side this error - it is stable and it is enough just to turn the focus ring to a certain angle. It is for this that Soviet lenses (for example, Jupiter-37A, Jupiter-9, Helios 44M-8 and some others) have an additional red mark R. For correct focusing in IR, you must first focus in visible light, and then turn the focus ring to the mark R.
With modern lenses, this mark is quite rare, and for zoom lenses, its position depends on the focal length. Therefore, the usual phase autofocus of SLR cameras should not be particularly trusted. You can get around the problem either by using Live View and hovering over the contrast or focus manually by controlling the sharpness on the screen. If the camera does not have Live View, then you can simply aperture the lens harder and thereby hide the focus error in the depth of field.

Fig.9 Infrared mark on the focus scale.

On lenses with constant focal length you can set this mark yourself by taking several shots and choosing a position with maximum sharpness. The position of this mark does not depend on the focusing distance and aperture, so it is enough just to draw it once and use this correction in the future.

The quality of enlightenment

The antireflection coating on the lenses is several layers of thin films, on the border of which the light beam is reflected, interferes with the main beam and significantly reduces the reflection intensity. That is, each layer of enlightenment is designed for a certain wavelength. However, for infrared radiation there may not be its own layer of enlightenment. Therefore, some lenses start to "catch hares", show quite strong glare and lose micro-sharpness. And some - normally work in the infrared range.

Field unevenness, Hot-Spot

Another problem with infrared optics is reflections at the junctions of lenses in the lens. For especially multi-lens lenses, they sometimes add up so unsuccessfully that a bright spot of illumination appears in the middle of the resulting image - Hot-spot (Fig. 10). The effect is stronger at closed apertures, and at short focal lengths. If you remember that the matrix often has a hot-miror filter that reflects infrared radiation back into the lens, the picture is completely bleak.

Fig.10 Hot-spot

It's a shame that this effect most often occurs with ultra-wide-angle zoom lenses. It is those lenses that produce the most interesting infrared images.

Glare

Most lenses are not designed for infrared photography. Therefore, blackening of internal surfaces, anti-reflection protection, and positioning of actuators inside the lens can lead to strong glare when direct sunlight enters the lens. You have to use deep blends, shoot from the shadows or take several shots with different positions of highlights and collect mosaic panoramas from them.

Rice. 11 Glare

All of the features listed are largely dependent on the type of lens and may vary slightly depending on the instance or camera. There are reviews on the Web of various lenses, tables describing the suitability and problems that arise with lenses. You can find them by searching for "lenses suitable for infrared photography". But this does not mean that pictures with other lenses will not work at all. They may require some additional attention - for example, cover them from the sun, or frame them a little differently. But in my experience, there was not a single lens that was completely unsuitable.
The only case of complete unsuitability for IR shooting is cameras with a lens set to hyperfocal distance (cameras without autofocus). In their IR range, the zone of sharpness moves forward, and there is simply nothing to correct the focus. But such cameras are almost never found in the form individual cameras. They can be found only in the most inexpensive phones or as a front camera on tablets. I don’t think that shooting in the IR range on the front camera of the tablet can make even the slightest sense.

Practical part

Infrared photography is good for its unusualness, difference from ordinary photography. The fact that familiar objects begin to look different. Therefore, it makes sense to focus on stories that emphasize this difference.
In the IR range, it is possible to get a picture with a very high contrast. It is somewhat reminiscent of the contrast of a black and white photograph behind a rich red K-8X filter, but the picture is even more contrast. Basically, infrared photography is good in landscapes. Both urban and natural landscapes. With an abundance of sky, foliage and space.

Fig. 12 Gradient in the sky in the backlight

The sky is interesting. Clear skies appear black because they do not reflect infrared radiation. Cirrus clouds, in turn, very well reflect solar and scattered infrared radiation, so they look bright white against a black sky. But thunderclouds, as containing large raindrops and large volumes of water, are already absorbing IR. This is why storm clouds look black. The picture is similar to the sky, shot through a dense red filter, but much more contrast. At the same time, even the smallest clouds are visible in the IR range, which are almost imperceptible in the visible range.

Fig.13 Water and sky in IR

In our latitudes, there is practically no dry and cloudless sky. There is almost always a slight haze in the sky and therefore the sky becomes very light in backlight. This makes shooting 360° panoramas difficult, but looks quite natural in wide-angle shots even with the sun in the frame, as shown in Figures 11 and 12.
If the sun is hidden, for example, behind trees, as is done in Figure 12, then it turns out to get rid of two problems at once - both glare from direct sunlight and gradients in the sky.
The water surface in the IR range looks very unusual (Figure 13). Water absorbs infrared radiation better than visible and looks much darker in the infrared than in the visible. However, the reflectivity is slightly better than in visible light. These factors together create the feeling of a dark mirror.
The leaves of trees and grass are greatly transformed in the IR range. They become very light, almost white. Which, however, is quite logical - the leaves in the sun should not heat up, and the largest amount of solar energy enters the IR. Tree trunks and dried vegetation absorb IR radiation and appear much darker. This feature of IR images is used in aerial photography for the needs Agriculture to highlight areas with dead vegetation.
Pictures with an abundance of foliage become like winter landscapes. Flowers in IR can be both light and dark.
Insects most often turn out to be very dark - since they cannot maintain their body temperature, it is beneficial for them to absorb solar heat as well as possible.

Rice. 14 Flowers in IR

The urban landscape is also fraught with unexpected twists - the brightness of paint pigments in infrared light can be very different from the visible one, and the dark windows of buildings turn out to be transparent (or mirrored - dark, as in photo 13). All this, combined with the contrasting sky and white foliage, makes the landscape unusual and therefore interesting.
With portraits in IR, everything is not easy. Lips are equal in brightness with the skin of the face, eyebrows and eyelashes turn pale. The skin looks much lighter than in the visible range. Lost volume. The eyes look very dark against the background of lightened skin.
In people with fair skin, blood vessels protrude (Fig. 15). Adds uncertainty and cosmetics - you never get to guess in advance whether lipstick, shadows or foundation will turn out to be dark or light in IR. Dyed hair also becomes unpredictable, but most often becomes dark. Uncolored hair is brighter.
Inexpensive plastic sunglasses most often become transparent, and clothing changes brightness. All this makes the result unpredictable when shooting large portraits, however, shooting in growth, and even in combination with the landscape, can diversify the photo session. Due to the remoteness of the figures, the faces can be hidden, while the unusual contrast and transmission of tones will remain.
If you have a portrait infrared photo shoot, then it is advisable to check all the means used for adequacy before the make-up - it will be very sad if the powder that the make-up artist applies to the forehead and cheeks suddenly turns out to be saturated black in the infrared range. If it is possible to persuade the model not to wear makeup before the IR photo session, then it is better to do so. It is easier to draw a black and white pattern during processing than to try to correct all the errors that appeared in the IR. But if you are unlucky and makeup in IR does not work, then you can limit yourself to general plans, and make the missing large portraits in visible light.

Rice. 15 Portrait in IR.

Fig.16 Channel mixer

After that, the sky will turn not red, but blue, and the foliage will no longer be blue.
It remains to align the white balance, and Image -> Auto Color does a great job with this.
These two operations can be written into a separate Action and then simply called it, rather than looking for tools on the menu.
It remains to bring the picture to the ideal with curves and masks and, if necessary, convert the image to black and white mode in any way convenient for you.

Rice. 17 The result of replacing the blue and red channels

Bibliography

Hayman R. Light filters. - M.: Mir, 1988. - 216 p.
Soloviev S.M. Photographing in infrared rays. - M.: Art, 1957. - 90s.
Joe Farace Complete Guide to Digital Infrared Photography. – Lark Books, 2008. – 160c.
Cyrill Harnischmacher Digital Infrared Photography. - Rocky Nook, 2008. - 112p.
Deborah Sandidge Digital Infrared Photography (Photo Workshop). – Wiley, 2009 – 256c.
David D. Busch David Busch's Digital Infrared Pro Secrets. - Course Technology PTR, 2007 - 288c.

We need a piece of non-exposed, but developed reversible (that is, “slide”) film. Shooting with a digital camera through this cut of the slide, we get infrared images. In this case, the film acts as an infrared light filter.

The fact that such a film is completely opaque and black in appearance should not alarm us. The unexposed developed emulsion itself delays the radiation of the spectral range to which the film is sensitive (that is, the entire visible range), passing everything else (that is, the ultraviolet and infrared ranges). But, despite such "democracy" of the emulsion in relation to the invisible range, the plastic substrate of the film is not able to pass ultraviolet. Therefore, the combination "emulsion / substrate" remains to transmit only infrared radiation.

The matrix digital camera, as we know, is able to fix it, despite the efforts of manufacturers in reverse direction. Since the lens of a camera, especially a reflex camera, has a fairly large diameter, it is recommended to use 120 format film. The width of such a film is 6 cm, so you can cut a piece of the desired size from it, unlike narrow-format film. It is not at all necessary to buy such a film and immediately develop it: ready-made unnecessary trimmings can be begged from the operator in any prolab. As a holder of such a "light filter", you can use everything that is at hand, including the hand itself. If our homemade IR filter has a convex-concave shape, then it must be straightened by putting it in the middle of a heavy book for a couple of days.

It is better to use film Fujichrome Velvia 100F or Agfachrome RSX II 100 which gives no worse result.

The disadvantages of the described method include reduced contrast, compared to real infrared images taken through a filter, and the low mechanical strength of a self-made "filter".

How do IR cameras work?

Infrared radiation is one of the types of radiation that cannot be seen by human eyes. Its wavelength is longer than that of light in the visible spectrum. Infrared illumination allows the camera to "see" even in complete darkness. This is made possible by a lamp or diodes that emit infrared light of a specific wavelength. Three wavelengths of 715 nm, 850 nm and 940 nm are common to infrared illuminators. The human eye is able to see up to 780nm and therefore can see slightly to illuminators that use 715nm. For true stealth night vision, IR illuminators operating at 850nm and 940nm must be used.

The lamp light is filtered so that only the pre-defined wavelengths of 715 nm, 850 nm and 940 nm are emitted.

DIY infrared filter for creative lighting nikon

These numbers are the starting points for the frequency of the emitted waves - they are the absolute lower limit of the spectrum used by the camera. If a person gets close enough, they will be able to tell that the camera is infrared, although they won't be able to see the wavelengths being used.

The ability of a camera to capture images based on light levels is measured in lux. The lower the lux value, the better the camera can see in low light conditions. All IR cameras are set to 0 lux, which means they can see in pitch darkness. Color IR cameras switch to black and white for video surveillance at night to achieve maximum sensitivity. A photocell inside the chamber monitors daylight and determines when a switch is needed. A distinction must be made between IR cameras and Day/Night cameras. Day/night cameras can work effectively in low light conditions, but they are not equipped with LEDs, which makes them impossible to work in complete darkness, unlike cameras with IR illumination.

When using IR cameras for outdoor use, it is better to use ready-made sets of outdoor cameras with a casing or cameras with an IR illuminator. Combining an indoor IR camera with an outdoor housing may not work well because the IR light can be reflected off the glass of the housing. In addition, when buying an IR camera or illuminator, you should always look at the value of the beam range. By installing IR cameras indoors with a wider range than the size of the room, blurry images can be obtained. It should be noted that IR cameras cannot see through smoke. In order to achieve this, a thermal imaging camera must be used.

Translation of Hi-Tech Security. Source: http://www.surveillance-video.com/ea-ir.html

Homemade infrared light filter

I think what infrared photography is, not everyone knows, but in vain, it's quite interesting thing. You can make an infrared filter out of film, but this article will focus on how to make an infrared filter out of a CD. The CD itself should be dark red, such discs are sold in many stores. What we need first of all is to take a cover from any plastic bottle, in my case it is mineral water, and cut a hole of as large a diameter as possible. The plastic bottle cap worked well as a lens attachment.

Photo #1

Next, the cut hole must be cleaned of burrs and painted with black car paint from a spray can or any other - just to hold on.

To clean the disc from the top layer, you need to draw a line from the middle to the edge with a knife, and under the pressure of water the top layer will quickly be washed off. Then three or two squares of the same size should be cut out of the disk and glued. Our homemade filter is ready, it remains only to stick it on a pre-prepared cap from a plastic bottle. Done, put the filter on the soap dish and go to photograph.

Photo #2

We will take pictures in the photo shooting mode " M", since we need access to all the settings of the soap box. It is advisable to take a tripod, but since I photographed on sunny days in the summer, there was enough light, at ISO 200 I was able to photograph landscapes handheld, the aperture was open, which reduced the sharpness of the picture.

Photo #3

With additional processing in Adobe Photoshop you can get the most different results: Reduce noise, tone or color the photo to your heart's content.

Photo #4

The pictures show that the infrared filter from the CD is not sharp enough, moreover, it rather creates the effect of a monocle. If you look at the channels of the image, then the red is constantly overexposed, and if it is present, then its sharpness is extremely low, the blue channel is the most contrasting, the green is not so, but the image is seen quite well.

Photo #5

Photographs taken with this filter are reminiscent of infrared shots: green foliage brightens, blue skies and water darken.

Photo #6

And if your soapbox supports the RAW format, the image can be made much more attractive, try it, and I'm sure you will do just as well! About the phototv site.

Why do I need SplitCam?

Free program for webcam SplitCam allows you to add colorful webcam effects to your videos that will add fun to you and your friends! In addition, SplitCam is a simple and convenient way to split a video stream from a webcam.

DIY infrared digital camera

With SplitCam, you can video chat with all your friends, share videos on online services, and all at the same time! Read more…

Colorful webcam effects

Add our webcam effects to your video during video calls
and get a lot of positive emotions from communicating with friends! Examples of cool SplitCam effects: face distortion and face replacement with another object, distorted mirror, background swap…
� Split video stream and connect multiple applications

With SplitCam you can connect your webcam to multiple apps at once
and not get an error with the message that "the webcam is already in use."
Believe me, your webcam can do more!
� realistic 3D masks

SplitCam is a simple webcam software that allows you to virtually replace your head with any 3D object. The 3D webcam effects look especially attractive. It can be, for example, the head of an elephant or another animal, which repeats all the movements of your real head. You can also appear in front of your interlocutor in a 3D mask from a popular movie, for example, in the mask of Darth Vader.
Support for all popular services

Skype, Windows Live Messenger, Yahoo Messenger, AOL AIM, ICQ, Camfrog, Gtalk, YouTube, ooVoo, Justin.tv, Ustream and more...
Broadcast video on popular services

Send videos to Livestream, Ustream, Justin.tv, TinyChat and more in a few clicks. The free SplitCam webcam software will make your broadcasts more colorful and flexible.
Support for various video resolutions, including HD

Send videos from your HD camera without quality loss. Choose any of the available resolutions: 320x180, 320x240, 400x225, 400x300, 512x384, 640x360, 640x480, 800x600, 960x540, 1024x768, 1280x720, 1280x960, 1400x1050, 1600x900, 1600x1200, 1920x1080, 1920x1440, 2048x1536
� Various video sources

With SplitCam you can distribute video from your webcam, video file, slideshow or desktop (whole desktop or selected part of it)!
Using an IP Camera as a Source

Connect to any IP camera and send video from it to your favorite video messengers and video services.
Small but useful video features

Record video without specialized programs and upload it to YouTube in a few clicks directly from the SplitCam window!
Enlarging/reducing video (Zoom)

In SplitCam, you can enlarge and transfer only the part of the video you want. You can zoom in/out the video using the keyboard and mouse.

In addition to the well-known paints for painting, there are special types of paints. They are used to protect the barcode and block infrared rays. Knowledge about them will expand our horizons and may even come in handy.

Paints for protection of a bar code (bar code). Designed to protect the original barcode from photocopying.
IR-blocking - paints that block infrared rays. Designed for printing on transparent PVC films, for the production of transparent plastic cards. These paints block or reflect infrared light. Radiation sources: ATMs or other similar reading devices.

Paints for protection of a bar code (bar code)
These inks are designed to protect the original barcode from photocopying. If such black ink is used, the original barcode will always be invisible to human vision. You can also apply this blocking ink under the overlaminate and then print the original barcode on the card on top. After lamination, it is no longer possible to separate the top layer from the base without damaging the barcode. All these paints do not contain carbon.

Standard colors:

S 3374- red ink blocking a barcode that can be read with optical readers.
S 4500- black and blue ink that blocks the barcode, which can be read using infrared readers.
S4501- black-brown ink that blocks the barcode, which can be read using infrared readers.

Seal: Suitable for all types of stencils, except Stenplex Amber and Solvent self-adhesive films. It is recommended to use monofilament nets 77 T-90 T. When using a net with 90T cells, the covering power of the paint is 35-35 sq.m / kg.

Fixing:
Drying takes from 30 minutes to 1 hour depending on conditions. You can use jet drying.

Lamination: These inks can be printed directly on top of a printed barcode or overlaminate and then laminated in the usual way.

Usage: Manufacture of credit cards and tickets where barcode protection from photocopying is required.

Barcode blocking inks for printing on polyester films can also be supplied

IR-blocking

These inks are transparent inks that block or reflect infrared light. Radiation sources: ATMs or other similar reading devices.

Standard colors are transparent yellow and green.

Do-it-yourself infrared filter from a CD to a soap dish

These paints have different reflectivity. They are designed for printing on transparent PVC films, for the production of transparent plastic cards. These inks can be used for printing both on base films and laminating films.

Standard colors:

S 17699- green IR blocker with a maximum absorption of 860-900 nm
S18203- yellow IR blocker with a maximum absorption of 980 nm
Both of these colors match ISO standard when printing through a grid of 90T.
S21143- highly concentrated IR blocker with a maximum absorption of 980 nm
This ink is ISO compliant when printed on 120T mesh.

To obtain other color shades, these inks can be overprinted with other transparent inks.

Seal:
Suitable for any type of stencil except Stenplex Amber and Solvent adhesive films. It is recommended to use monofilament mesh No. 90T, while the covering power of the paint is 60 sq.m / kg.

Fixing:
Drying takes from 30 minutes to 1 hour depending on the drying conditions. You can use jet drying.

Lamination:
These inks can be used to print directly onto a base film or onto a laminate, then laminated in the usual way.

Usage:
Production of transparent credit cards for reading information through infrared readers and for identification by automatic teller machines.

"Cool! Physics" - on Youtube

Infrared and ultraviolet radiation.
Electromagnetic wave scale

« Physics - Grade 11 "

Infrared radiation

Electromagnetic radiation with frequencies in the range from 3 10 11 to 3.75 10 14 Hz is called infrared radiation.
It is emitted by any heated body, even if it does not glow.
For example, radiators in an apartment emit infrared waves that cause noticeable heating of the surrounding bodies.
Therefore, infrared waves are often called thermal waves.

Infrared waves not perceived by the eye have wavelengths exceeding the wavelength of red light (wavelength λ = 780 nm - 1 mm).
The maximum radiation energy of an electric arc and an incandescent lamp falls on infrared rays.

Infrared radiation is used for drying paintwork, vegetables, fruits, etc.
Devices have been created in which the infrared image of an object, invisible to the eye, is converted into a visible one.
Binoculars and optical sights are made that allow you to see in the dark.

Ultraviolet radiation

Electromagnetic radiation with frequencies in the range from 8 10 14 to 3 10 16 Hz is called ultraviolet radiation(wavelength λ = 10-380 nm).

You can detect ultraviolet radiation using a screen coated with a luminescent substance.
The screen begins to glow in the part on which rays fall beyond the violet region of the spectrum.

Ultraviolet radiation is highly reactive.
Photo emulsion has increased sensitivity to ultraviolet radiation.
This can be verified by projecting the spectrum in a darkened room onto photographic paper.
After developing, the paper will blacken beyond the violet end of the spectrum more strongly than in the visible spectrum.

Ultraviolet rays do not cause visual images: they are invisible.
But their effect on the retina and skin is great and destructive.
The ultraviolet radiation from the sun is not sufficiently absorbed by the upper atmosphere.
Therefore, high in the mountains, you can not stay for a long time without clothes and without dark glasses.
Glass glasses that are transparent to the visible spectrum protect your eyes from ultraviolet radiation, since glass strongly absorbs ultraviolet rays.

However, in small doses, ultraviolet rays have a healing effect.
Moderate exposure to the sun is beneficial, especially at a young age: ultraviolet rays contribute to the growth and strengthening of the body.
In addition to a direct effect on skin tissue (formation of a protective pigment - sunburn, vitamin D 2), ultraviolet rays affect the central nervous system, stimulating a number of important vital functions in the body.

Ultraviolet rays also have a bactericidal effect.
They kill pathogenic bacteria and are used for this purpose in medicine.

So,
A heated body emits predominantly infrared radiation with wavelengths exceeding the wavelengths of visible radiation.

Do-it-yourself infrared filter No. 2

Ultraviolet radiation is shorter wavelength and has a high chemical activity.

Electromagnetic wave scale

The length of electromagnetic waves varies over a wide range. Regardless of the wavelength, all electromagnetic waves have the same properties. Significant differences are observed when interacting with matter: the absorption and reflection coefficients depend on the wavelength.

The length of electromagnetic waves is very different: from 10 3 m (radio waves) to 10 -10 m (X-rays).
Light is an insignificant part of the wide spectrum of electromagnetic waves.
In the study of this small part of the spectrum, other radiations with unusual properties were discovered.

The figure shows a scale of electromagnetic waves indicating the wavelengths and frequencies of various radiations:

It is customary to single out:
low frequency radiation
radio emission,
infrared rays,
visible light,
ultra-violet rays,
X-rays,
γ radiation.

There is no fundamental difference between the individual radiations.
All of them are electromagnetic waves generated by charged particles.

Electromagnetic waves are detected mainly by their action on charged particles.
In a vacuum, electromagnetic radiation of any wavelength travels at a speed of 300,000 km/s.
The boundaries between individual areas of the radiation scale are very arbitrary.

Radiations of different wavelengths differ from each other in the methods of their production (radiation from an antenna, thermal radiation, radiation during deceleration of fast electrons, etc.) and methods of registration.

Everything listed species electromagnetic radiation are also generated by space objects and are successfully studied with the help of rockets, artificial earth satellites and spaceships.
First of all, this applies to x-rays and y-radiations, which are strongly absorbed by the atmosphere.
As the wavelength decreases, quantitative differences in wavelengths lead to significant qualitative differences.

Radiations of different wavelengths differ greatly from each other in terms of their absorption by matter.
Short-wave radiation (X-rays and especially γ-rays) are weakly absorbed.
Substances that are opaque to optical wavelengths are transparent to these radiations.

The reflection coefficient of electromagnetic waves also depends on the wavelength.

It is probably not worth recalling the benefits of such a little thing as a light filter, which helps to convert or suppress part of the light spectrum. The infrared (IR) filter is one such filter.

From the name, we can conclude that it passes only the infrared part of the spectrum, and delays everything else. And it really is. Infrared filters have been and remain in favor when shooting on film. But, for some reason, in digital photography they are used less and less, despite the interesting, original effect that can be obtained with their help.…

The thing is that the same effect is achieved by processing the image on a computer. So why screw a filter that costs a lot of money to the lens.

Take, for example, this image:

Now let's use the popular graphic editor Photoshop CS3.

After opening the selected photo, make a duplicate of the layer:

After that, go to the menu Image-Adjustments-Black & White or simply press the following key combination Alt+Shift+Ctrl+B:

As a result of the performed manipulations, the following window appears:

Here we select Infrared and press the OK button.

As you can see, we got this classic IR image:

After that, you can work with the photo as much as you like, for example, make the infrared filter layer translucent, which will give the image color:

Enjoy your time and good luck!!!

The matrix of a digital camera, as we know, is able to fix it, despite the efforts of manufacturers in the opposite direction. Since the lens of a camera, especially a reflex camera, has a fairly large diameter, it is recommended to use 120 format film. The width of such a film is 6 cm, so you can cut a piece of the desired size from it, unlike narrow-format film. It is not at all necessary to buy such a film and immediately develop it: ready-made unnecessary trimmings can be begged from the operator in any prolab. As a holder of such a "light filter", you can use everything that is at hand, including the hand itself. If our homemade IR filter has a convex-concave shape, then it must be straightened by putting it in the middle of a heavy book for a couple of days.

What film to choose?

It is better to use film Fujichrome Velvia 100F or Agfachrome RSX II 100 which gives no worse result.

The disadvantages of the described method include reduced contrast, compared to real infrared images taken through a filter, and the low mechanical strength of a self-made "filter".

Infrared photography is a very complex form of photography. During the lessons, you need to be very attentive to the process of setting up equipment and shooting. I have prepared a list for you, according to which it is convenient to check your actions. I advise you to print it out and put it in your bag along with the camera. All items on the list will be discussed later in the lesson.

Can your camera receive infrared rays?

Before you go out and buy a filter, test your camera for infrared sensitivity. Some cameras cannot do this. The easiest way to check this is to point the camera at the remote's LED light and press a few buttons on it. If you notice that the red light is flashing, then the camera is detecting infrared rays.

If the light from the LED is dim, then the camera detects infrared rays, but the exposure time will increase due to the internal filter blocking them.

If you don't see the LED blinking, set a long exposure and take a few shots while pressing the remote control buttons pointed at the camera lens. The photos should show the red light from the LED. If it is not there, then your camera cannot receive infrared rays, and this lesson will not help you.

Purchasing a filter

I have several suggestions when choosing an infrared filter. These are spin-on filters like Hoya, and square filters from Cokin.

Spin-on filters are a very good tool for infrared photography. One, they are relatively expensive. I advise buying filters from reputable brands for the best results. For example, I have a Hoya R72 filter, which impressed me very much with its results, even though it costs more than $100.

Square filters are quicker to put on or take off. At this point, the risk of spoiling the image with light rays is much higher than when working with winding filters. The average price for such a filter is $60.

If you're going to buy a large spin-on filter, get an adapter ring as well so that this filter will fit all other lenses. This saves you from having to buy a separate filter for each lens.

Wavelength and other options

The 720nm filter is considered the standard for infrared photography. I think it's worth starting with him. There are other options, for example, 900nm (RM90), but the prices for such filters are very high, they exceed $300. These filters are designed for professional infrared photographers with "big pockets".

There is another option in case you don't want to use a filter. You can customize your dslr camera on the constant perception of the infrared spectrum. To do this, you need to calibrate the camera and lens. This is a very expensive service, after which your camera will only shoot in infrared mode.

When and where to shoot?

One of the most popular genres of infrared photography is landscape photography. Due to the effects created when shooting, the foliage can turn white when rendered, which will make the photo very gloomy and memorable. You can experiment with trees, flowers and grass.

The ideal shooting conditions are sunny days. In the rendering process (with incorrect color processing), the sky will be a deep blue color, and the leaves will be white. But this does not mean that in bad weather it is impossible to achieve the desired result.

If you set a long exposure time for the infrared filter, the results are almost the same as when working with Neutral Density (ND) filter. The photos will have a strong effect of movement.

Don't be afraid to experiment and don't limit yourself to simple situations and objects.

Lens Problems

Some lenses may produce anomalous infrared effects such as hot pixels. When this happens, you may notice a light, colorless spot in the center of the image. It happens that stripes appear throughout the photo. They can be removed in post-processing, but it takes a lot of time and effort.

Currently, there is no complete list of lenses that work correctly and those that produce colorless spots. The site dpanswers.com provides a rather large list of most lenses and their problems.

1. Customization

Camera setup is very important to get good infrared photography. Do not install a filter until you have adjusted the focus, exposure, and white balance.

First, set up your camera on a tripod. Hang your camera bag on a tripod hook to maximize the entire tripod and minimize movement.

The following tips will help you get a clean image:

Shooting in RAW format. Shooting in RAW will allow you to easily change the white balance in post-production. Never shoot in JPEG format, otherwise you will get noise and other defects that will be very noticeable.
Turn off Long exposure noise reduction. Since a long exposure time is necessary for infrared photography, you need to turn this option off. There will be no noise during processing. It will also help you change the intensity of the noise in post-processing.
Turn on Exposure delay mode / Mirror Lock-Up. If you turn on any of these modes, you will minimize vibration when you release the shutter.
Remote shutter release or timer. Using the remote control is not necessary, but can reduce the amount of vibration since you are not touching the camera while shooting. Alternatively, you can set the timer to 2 seconds.

2. White Balance

White balance is very good with infrared. You can use the preset values or Pre-White Balance to get a normal balance under current conditions. In any case, you will need to take time for this in the post-processing process.

There is nothing wrong with using presets. For example, the Incandescent setting is the most appropriate.

Go to the White Balance menu and select PRE. Then do the following:

Click OK.
Select Measure and press OK.
Select Yes and overwrite the existing information.
Make sure the main part of the subject is green in the viewfinder. You can point the camera at a patch of grass.
Take a picture and wait for the camera to respond. “Data Acquired” or “Gd” should appear.
If the camera shows "Unable to acquire" or "No Gd", then check the exposure.

The result should be a photo with a strong red-orange-magenta tint. We will fix it in post-processing.

3. Focus and stabilization

Focusing can take a long time if there are no infrared markings on the lens. It's best to use a small aperture, such as f/20, to get good depth of field and minimize focus issues.

If your lens has IR focus marks, adjust the focus according to the focal length. If there are no such marks, then it will not be easy to focus on the object. The best thing you can do is set a small aperture to get a large depth of field. This will give your shots a good amount of sharpness, but that doesn't mean you can use a large aperture for a shallow depth of field. Without calibrating the lens for continuous infrared shooting, it is impossible to achieve the desired focus with a large aperture.

Focus on the subject first with normal Auto Focus. Then switch to manual mode. If you have a camera with a rotating ring on the lens, then be careful not to move the ring.

Any stabilization system must be disabled. The use of VR/IS/OS is not recommended because the camera is mounted on a tripod and because the lens will make unnecessary corrections that can cause blur.

4. Aperture

One of the important settings for IR photography is a small aperture. It gives greater depth of field and minimizes the focusing problems described above.

5.ISO

In most cases, it is best to use the lowest light sensitivity (ISO) to minimize the amount of noise. Take into account the length of the exposure. I would recommend using an ISO of no more than 800 for shooting between 10 seconds and a minute. For exposures longer than 1 minute, use ISO 400 or less.

Any values that exceed these limits increase the risk of getting a lot of noise and hot pixels in post-processing.

If you use ISO from 100 to 200, then the waiting time for IR exposure will be halved. An 8 minute exposure at ISO 100 will be reduced to 4 minutes at ISO 200. The amount of noise will increase slightly, but it will help you when time is very short.

6. Shutter speed.

Finally, let's talk about shutter speed. First you need to determine the exposure time. Get your stopwatch ready.

IR filters require a slow shutter speed. As with ND filters, you can calculate the amount of delay to compensate using the Exposure Calculator.

For example, if the visible light exposure is 1/30, ISO 100, f/11, and the best IR result is 1 second, then you should have a 5-stop light-blocking filter.

7. Take a picture!

Now you can screw the IR filter to the lens. After that, do not change the settings and do not twist the focus ring. Press the shutter button and wait for the result!

In the second part of the lesson, we will deal with the processing of IR images in Lightroom.

Share a lesson

legal information

Translated from the site photo.tutsplus.com, the author of the translation is indicated at the beginning of the lesson.

It might be useful to read: