Ilyina Marina Andreevna 4111
Looking for unusual ideas for photographs and video material, the cameraman sometimes looks into the most remote corners of the planet, looking for fantastic shooting points and even goes beyond the capabilities of the human eye.
To implement the latter, the operator comes to the aid of a set of specially designed additions to the lenses. In the photo and video environment, they are called light filters. Often, when using them, a really fantastic and unexpected picture is obtained.
It is precisely this property that the hero of this review has - an infrared filter for the lens.
It is a dark, often completely black, glass. When shooting, the IR filter limits the flow from the subject to the collecting surface - the matrix of the camera or video camera - of any rays other than infrared. You should not think that infrared filters allow you to register your own "thermal" rays emitted by any heated body. The images created with their help are obtained by registering those rays that this body can reflect in the infrared range.
What is the result? In order to understand this before shooting, the following rule is used: the stronger the object absorbs infrared radiation, the more it heats up (for example, in the sun) and the darker it will turn out in a photograph or in a video frame.
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Privezite | 8 375 R | |
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Electrozon | 1 750 R |
Let's look around: leaves, grass and snow reflect infrared rays well (and, therefore, they will turn out light or even white). They absorb the same - asphalt, water and sky, which makes them dark or even black in the images.
Shooting with an infrared filter allows you to create truly surreal shots. Overly contrasting white clouds against a black sky, foliage as if covered with a thick layer of ash, deliberately pale faces with black eyes give unexpected sound and drama even to the simplest images.
If you decide to try shooting with an infrared filter, then pay attention to the following points:
- Not all cameras and video cameras allow you to create frames with an infrared filter. Often manufacturers of photo and video equipment put their own infrared filter inside the camera, in front of the matrix. This is done in order to cut off any IR rays, which are considered noise during "ordinary" shooting, on the matrix. To find out if your camera is capable of shooting in IR, you can only experimentally.
- Infrared rays are much weaker than rays in the visible range. And, therefore, for shooting with an infrared filter, you just need to use a tripod.
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We need a piece of non-exposed, but developed reversible (that is, “slide”) film. Taking off 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 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.
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 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 certain 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 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 that not everyone knows what infrared photography is, but in vain, this is a rather 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 in the summer in sunny days, there was enough light, at ISO 200 it was possible 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 a variety of 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.
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DIY infrared digital camera
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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 over a printed barcode or overlaminated film 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 information reading 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.
All of the listed types of electromagnetic radiation are also generated by space objects and are successfully studied using rockets, artificial satellites of the Earth 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.
Video surveillance (CCTV) is a cost-effective crime prevention tool, also has some other useful features. When employees and customers know they are being monitored and their activities are being recorded, it serves as a powerful deterrent against any breaches. This is especially useful given the high crime rates in some countries. Properly used video surveillance systems have been proven to reduce up to 90% of malfeasance and can even improve productivity and service levels, thereby saving a significant financial investment. A video surveillance system is a popular tool used in many industries due to its reliability and affordability compared to stand-alone facilities and a security company. Cameras don't sleep, don't be late, and don't make demands. However, a video surveillance system can be a very effective tool when paired with remote monitoring and armed response from a security system to reduce the risk of damage from criminals and promptly respond to suspicious activity or hacking attempts. The benefits are also clear when a closed circuit television system functions as a passive monitoring tool, such as night time recording in stores, warehouses and workshops. Personnel movements and actions can be monitored or recorded for future viewing, and video feeds can be used for other security systems. Finally, a video surveillance system can be a very useful tool in customer relations. More than once, CCTV footage has been used to avoid malpractice. Analog camera system. Analog signals can be converted to a digital signal to allow recordings to be stored on a computer as digital information. In this case, the analog camera must be connected directly to the video capture card in the computer, and the card will convert the analog signal to digital. These boards are relatively cheap and the resulting digital signals are compressed 5:1 (MPEG compression). Another way to store and record digital video is through a digital video recorder (DVR). Such a device, close in functionality to a PC using a video capture card with the appropriate software to record video. Unlike PCs, most DVRs require less maintenance and are easier to install serviceable devices than PC based DVRs for medium to high volume analog cameras. Some DVRs also allow digital video broadcasting to the network and act as a network IP camera. If the device does allow video streaming but does not record, then it is called a video server. An Internet protocol camera, or IP camera, is a type of digital video camera commonly used for surveillance that, unlike analog CCTV, can transmit and receive data via computer network and the Internet. Although most cameras that also work in this way are webcams (IP camera or Netcam), special video surveillance cameras are used for video surveillance.
Before us are two filters through which nothing is visible. More precisely, through one of them, which has a dark red, almost black color, you still manage to see something. This infrared filter B+W Infrared Dark Red 092 manufactured by Schneider Optics, a subsidiary of Schneider-Kreuznach.
Be this one filter one, given material, most likely would not have appeared. Cokin 007, Hoya R72, Heliopan RG715- these filters, which have long been presented on our market and have already been fully mastered by photographers, are practically analogues of the "ninety-second". And in this regard, it is unlikely B+W 092 no surprises to be expected.
But from completely black B + W Infrared Black 093, and this is the second considered filter surprises are quite possible. Their reason is in the spectral characteristics of this filter in relation to artistic photography, fundamentally different from the characteristics of B + W Infrared Dark Red 092.
B+W filter Infrared Dark Red 092 blocks visible light up to 650 nm, transmits 50% at 700 nm. From 730 to 2000 nm transmits more than 90% of the radiation. Recommended for artistic photography on black and white infrared materials. Increasing exposure for various materials can be 20-40x.
The B+W Infrared Black 093 filter blocks visible light up to 800 nm, transmits 88% at 900 nm. Designed primarily for scientific photography. Rarely used in fine art photography due to the catastrophic drop in light sensitivity of general purpose black and white infrared films.
To put it very briefly, filter 093 passes only infrared radiation, while in the passband of the 092 filter there is a certain portion of the visible spectrum, which can be recorded, for example, by digital camera sensors.
Filters available in round threaded frames with diameters from 30.5 mm to 77 mm. True, you will not find such an abundance in Moscow stores, and the presented assortment is usually limited to the most popular diameters, ranging from 58 mm and above.
Received for testing filters with a diameter of 72 mm. Frankly, we would like 77 mm to work with professional fast zooms (recall that these lenses, as a rule, have just such a connecting thread for filters). A way out, however, was found - a transitional lowering ring 72/77 mm.
There will be vignetting from the frame filter or not depends on the design of the lens barrel and its focal length(more precisely, the angle of the field of view). The only lens we saw vignetting was the Sigma 10-20/3.5-5.6 EX DC HSM (for APS-C sensor DSLRs). But even at focuses of 10–12 mm, only slight cutting of the corners of the frame was observed, and starting from f = 13 mm it completely disappeared.
Cameras
The fact that the tested light filters threaded, and of large diameter, predetermined the choice of the type of test camera - a reflex camera with interchangeable lenses. And although we still filmed a clip of infrared black-and-white film, the main testing tool was a digital camera.
On the Internet, there is information about the suitability of a particular digital camera for infrared shooting. The matrix itself is sensitive, sometimes even very significantly, to infrared radiation. But in front of the digital sensor is light filter(internal IR cut filter), which delays this radiation. And from what are the spectral characteristics of the matrix and this filter, depends on how suitable a particular camera is for infrared photography. However, we somehow cannot believe in the absolute unsuitability of modern DSLRs ...
We chose Nikon D50 and Canon EOS 350D as test cameras. The first one is considered to be a good fit. for infrared photography, and the second - not so much.
Most of the shooting was done with Nikkor AF 24-120/3.5-5.6, Tokina AF 20-35/2.8 and Tokina AF 80-400/4.5-5.6 lenses on a Nikon D50 camera; EF-S 17-55/2.8 IS USM and EF 28-105/3.5-4.5 II USM on Canon EOS 350D.
Focusing
Despite the fact that with the installed light filter 092 the picture in the viewfinder is barely visible, the autofocus system of both cameras turned out to be efficient. In conditions of sufficient illumination, for example, during the day in nature, the cameras focused quite clearly on the object (only he was hardly visible in the viewfinder).
Does it follow from this that one can rely on camera automation? The answer will be this: depending on which camera, and even then not always. The point is that in the infrared part of the spectrum the focal plane turns out to be somewhat shifted, i.e. the lens draws a sharp image slightly in the wrong plane than for the visible part of the spectrum. And autofocus is set to work in the visible range.
Here, however, there are some nuances. So, the Nikon D50 camera without and with the 092 filter installed focused strictly at the same distance. And this means that frames shot with autofocus through this infrared light filter, will be out of focus.
With the Canon EOS 350D digital camera, the picture is different. With the filter on, it autofocused at a slightly closer distance, the pictures turned out to be quite sharp, so manual focus correction can be omitted. As practice has shown, when using the Canon EOS 350D, the correction scale for shooting in the infrared range is suitable for a strong 093 filter, and for the 092 filter, the mark should be moved about twice as close to the usual focus mark in the visible range.
Speaking of focus correction, we mean the following. Sometimes on the frames of the lenses, more precisely on the distance scale, one or several (in the case of a zoom lens) marks additional to the main one are applied. Their purpose is to correct the focus of the lens in such a way that after installation infrared filter the image in the focal plane of the camera remained sharp. Proceed as follows. First without light filter focus on the object - automatically or manually. Then, setting the filter and setting the camera's autofocus to manual mode, shift the meter scale of the lens so that the focusing distance opposite the main mark moves to "infrared".
When working c light filter 093 has to do just that. And although cameras were sometimes able to focus through such a black filter, it’s still worth recognizing that autofocus systems are not designed to work with it.
Performing such a focus correction with a 092 filter, every time we got crystal-sharp sharpness on the Nikon D50 camera. infrared shots, and on a fully open aperture. Under exactly the same conditions, the image with the 093 filter turned out to be slightly soapy.
But what if there are no infrared focusing marks on the lens (as a rule, these are budget inexpensive lenses)? You need to try on your own in a practical way to determine at least approximately the necessary movement and greatly aperture the lens. Aperture, however, will noticeably lengthen shutter speeds, and they are already large with infrared shooting. If not long-term.
exposition
Shooting c infrared filters requires an increase in exposure, in practical terms - the shutter speed worked out by the shutter. For light filter 092 this increase is significant, for 093 it is very significant.
The Nikon D50 metering works quite accurately through the 092 filter, while the exposure increase is about 5-6 steps, which is very good. Let's call this exposure the base exposure for infrared photography. But even if the camera's exposure metering worked inaccurately with the filter or didn't work at all (like c 093), it's not difficult to find the base exposure, at least from the image's histogram - it should be "good". By the way, having found the discrepancy between the base and normal exposures (i.e. for shooting in the visible range of the spectrum) in steps of EV, you can not use the camera exposure system, but measure with an external exposure meter.
The metering on the Canon EOS 350D also works through the 092 filter, but the pictures come out dark (heavy underexposure), and an additional 4-5 steps need to be added. In this case, the total increase in exposure to the base is 10-11 steps.
Compared to 092, filter 093 will require an increase in exposure by another 4 steps. Thus, when shooting through it, you will have to increase exposure: for Nikon D50 by 10 steps, for Canon EOS 350D - by 16 (!).
What are the 16 steps in practice? Let's say on a sunny day at ISO 200, your shutter speed at f/5.6 could be 1/2000s. An increase of 16 steps lengthens it to ... 30 s! And in cloudy weather with poor lighting, the account will go for minutes. So work at high ISO (at the same time, shutter speeds will be shorter) for Canon cameras the measure is forced, but the image does not benefit. Long exposures and high ISO- these are just the reasons that complicate the infrared shooting of the Canon EOS 350D.
When shooting through the 092 filter, we would recommend not limiting yourself to the basic exposure, but taking an additional 2-3 frames, increasing the shutter speed by one step each time. In this case, the picture on the camera's LCD screen will look just awful, and the histogram will show strong overexposure, but it is still desirable to make these additional "defective" frames. Why - we will tell a little later.
Treatment
When shooting with both filters resulting in highly colored images. For 092, the predominant shade is red-orange, for 093 - red-violet. In any case, most outdoor shots with a Nikon camera were just that. (The hue depends on the spectral composition of the lighting, the characteristics of the infrared filter, the characteristics of the internal cut filter and color filters on the sensor, as well as the color interpretation algorithm of the camera processor or computer program.) Therefore, strong white balance correction is inevitable, and it is better to do it in a RAW file. We used Adobe Camera Raw (ACR) and Pixmantec RawShooter 2006 (RS 2006) converters.
When converting the image to black and white, the 093 filter turned out to be almost completely problem-free. It is enough to set the white balance with an eyedropper, as the image becomes monochrome gray (or almost so). Yes, it is sluggish, the contrast is greatly reduced, but it is easily corrected directly in the converter or later in the editor. In short, filter 093 is an easy and fast conversion of an infrared image to black and white.
The same cannot be said about the 092 filter. In this case, the picture will not turn out to be pure black and white. The reason is that this light filter, in addition to infrared, also passes part of the visible part of the spectrum, so the image in the picture is a combination of ordinary and infrared. So in the converter, despite the fact that the picture will look like color, you need to create a good base in order to get a visually pleasing infrared effect later in the editor. In a word, you have to tinker.
How to distinguish ordinary black and white shot from infrared? First of all, according to the tonality of green vegetation - it becomes light gray and even almost white. Everything is correct - the green reflects infrared radiation well, therefore it should look light. Such highlighting in the picture is called the wood effect, but this has nothing to do with the tree. (In fact, the effect is named after the famous experimental physicist who used ultraviolet and infrared imaging in his research - Robert Wood / Robert Wood).
As we have noticed, some images were converted to a black-and-white infrared image quite easily, others were quite troublesome. In terms of the distribution of tonalities, the image differed from the usual black and white, but it did not look much like infrared either. It is clear that the infrared component of the picture is somehow distributed over the RGB channels of the image. It is important to be able to find this information and extract it most effectively.
In the pictures taken by Nikon D50, in most cases, the infrared signal was in the blue channel of the image, sometimes in green and very rarely in red or in all three at the same time. (For other cameras, this relationship may remain, but may be different, so study your model.)
In order not to pull out the “weak” blue channel, we advise you to take several takes when shooting, increasing the exposure relative to the base one. Overexposure in 2-3 steps will be quite enough.
With such a supply of source material, the procedure for converting images taken through the 092 filter is greatly facilitated. You need to select a frame with the best blue channel and "pull" this channel, not paying attention to the rest. Takova general scheme details may vary on a case-by-case basis.
And further. Initially, a good fullness of the "infrared channel" (for example, blue) will require less of its transformations in the converter, and therefore, there will also be less noise and artifacts in the final image. For example, we received absolutely clean, noise-free infrared images, although the original color frame looked more like a frank marriage.
So the time spent on shooting duplicates is fully justified.
Conclusion
Which of the considered infrared filters give preference? For photographers still sticking to film, this is unlikely to be B+W Infrared Black 093. It requires films that are sensitized far into the infrared region.
But this one light filter allows you to quickly (if you do not take into account very long shutter speeds when shooting) and easily get digital black and white photographs.
Light filter B+W Infrared Dark Red 092 can be considered universal, suitable for film and digital photography. And some of the hassle that may arise when processing shots taken with its help is more than offset by the operational advantages - a working automatic camera and faster shutter speeds when shooting.
There is a wonderful kind of photography that opens up a different, "parallel" world, hidden from the human eye - infrared photography. Images obtained with the help of infrared filters allow us to get into a fairy tale, which at the same time is an integral part of our everyday space.
Infrared photography began in the film era, when special films capable of recording infrared radiation appeared. But since digital SLR Cameras much more popular than film ones and it has become quite difficult to get a special film (besides, it should be noted that not every film DSLR will allow you to shoot on IR film due to the presence of an infrared sensor inside the camera that will illuminate the frames), in this photo tutorial we will only touch on aspects infrared photography with digital SLR cameras.
To begin with, in order to understand the process of obtaining an infrared image, it is necessary to understand the theory. The radiation forming a color image perceived by the human eye has a wavelength ranging from 0.38 µm (purple) to 0.74 µm (red). The peak of the sensitivity of the eye falls, as you know, on the green color, which has a wavelength of approximately 0.55 microns. The wavelength range with a wavelength of less than 0.38 microns is called ultraviolet, and more than 0.74 microns (and up to 2000 microns) is called infrared. Sources of infrared radiation are all heated bodies.
Reflected solar infrared radiation most often forms an image on a film or camera matrix. Since infrared photography has found the most common use in the landscape genre, it should be noted that grass, leaves and needles reflect IR radiation best of all, and therefore they turn out white in the pictures. All bodies that absorb infrared radiation appear dark in the images (water, earth, tree trunks and branches).
Now we can move on to the practical part.
Let's start with filters. To obtain an infrared image, it is necessary to use IR filters that cut off most or all of the visible radiation. In stores you can find, for example, B + W 092 (transmits radiation from 0.65 microns and longer), B + W 093 (0.83 microns and longer), Hoya RM-72 (0.74 microns and longer), Tiffen 87 (0.78 µm and longer), Cokin P007 (0.72 µm and longer). All filters except the last one are ordinary threaded filters that are screwed onto the lens. Filters from the French company Cokin must be used with a proprietary mount, which consists of a threaded ring for the lens and a filter holder. The peculiarity of such a system is that for lenses with different thread diameters, you only need to purchase the appropriate ring, while the filter and holder remain the same, which is much cheaper than purchasing the same threaded filters for each lens. In addition, up to three filters with different effects can be mounted in the standard holder.
Since we are only looking at IR photography with digital SLR cameras, it should be noted that different camera models have different ability to detect infrared radiation. Camera matrices themselves perceive infrared radiation quite well, however, manufacturers install a filter (the so-called Hot Mirror Filter) in front of the matrix, which cuts off most of the infrared waves.
This is done to minimize the appearance of unwanted effects in the pictures (for example, moiré). How strongly the IR radiation is filtered determines whether the camera can be used for IR imaging. For example, a Nikon D70 camera with a Cokin P007 filter can be shot handheld, but for a Canon EOS 350D and most other cameras, due to long exposure always need a tripod. Some photographers who are passionate about IR photography resort to modifying the camera by removing the infrared filter.
Now let's touch on the processing of images in Photoshop. The resulting frames, depending on the white balance setting, will have a red or purple tonality. To get a classic black and white infrared image, you will need to desaturate the image, for example, using a gradient map, after adjusting the levels and contrast. There are also several ways to get very effective color infrared photographs. For example, you can use the Channel Mixer tool by first setting the red channel to Red - 0%, Blue - 100%, for blue - Red - 100%, Blue - 0%, and then by slightly manipulating the percentage of one or another color in channels to choose such values at which the picture will look most attractive.
In conclusion, we note the main advantages of infrared photography: the absence of haze in the pictures and the sky is always well-detailed, the absence of debris, since it does not reflect IR rays, and, of course, what was said at the very beginning is most important - the ability to see unusual, a non-everyday world in which, in addition to the fabulous color, all moving objects disappear or turn into "ghosts".
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