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An image that is cropped appears as if it was taken with a lens of higher focal length (i.e. a smaller field of view), but does not magnify the image. The cropping effect can be quantified using an adjusted focal length (defined as the crop factor multiplied by the lens focal length). For example, an image taken using a 1" format, 50 mm focal length lens with a 1/2" format sensor will produce an image with an adjusted focal length of 100 mm. While the field of view is reduced as if using a 100 mm lens, objects in the image will remain at the same size. The table to the right lists all of the lenses offered on this page with the adjusted focal length for different sensor formats.

A pair of uvex IR-ex spectacles can provide you with optimum protection against the effects of infrared in your workplace. To determine which spectacles have the correct level of protection, establish the average temperature of the source of radiation – i.e. the burning object (such radiation measurements are performed as part of the workplace risk assessment in larger companies). The table provided sets out the official levels of protection of the relevant EN 171 standard and the level of protection that uvex infrared spectacles offer:

In the infrared light risk assessment for your workplace (for eyes and skin), your distance from the source of radiation and the amount of time spent in front of the radiation source are also relevant in determining the strength of your IR radiation exposure.

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There are three general classifications for lenses related to the image field of view. A lens with a focal length close to the diagonal length of the sensor format produces an image with a near-human field of view and is considered a "normal" lens for that sensor format. A wide-angle lens has a focal length shorter than normal, which produces a wider field of view but has a tendency to exhibit barrel distortion effects towards the edge of the image. Finally, a lens with a focal length longer than normal is known as a telephoto lens, which has a smaller field of view and a greater magnification of objects in the image.

All filters of the infrared safety spectacles and of other PPE in this range must meet the transmission requirements of EN 171 and are divided into defined levels of protection accordingly. Standard 166 for general personal eye protection stipulates further requirements for infrared safety spectacles. You can find illustrations and other explanations of these specifications and the applicable standards for safety spectacles on our website.

Camera lenses that can collect a lot of light (i.e., a low f-number) are known as fast lenses as they can be used with shorter exposure times and are ideal for low-light conditions. For example, a 50 mm focal length lens with a f/1.4 aperture has a bigger aperture and is therefore faster than a lens at the same focal length with a f/2.5 aperture. While using larger apertures increases light collection, doing so reduces the axial in-focus region of the image, known as the depth of field. To illustrate the effect of different aperture sizes visually, the table below shows a sequence of images taken with the same lens (MVL12M43 on a DCU224C 1/2" format camera) for increasing f-numbers. Because the images were taken at constant exposure, for each f/# increase (by a factor of ~1.4) the amount of light collected by the lens is reduced by half.

The aperture of the lens controls the amount of light that a lens can collect; the more light a lens collects, the brighter the image. Because of this, the aperture size affects the exposure time and therefore the speed of the camera. Thorlabs provides the maximum aperture size in the tables below for each lens in terms of the f-number, which is expressed using the symbol f/# (e.g., f/1.4). As the f-number increases, the aperture opening becomes smaller and less light is collected by the lens.

Comparing the two standards and the protective effect mentioned therein of welding safety spectacles and infrared safety spectacles, it quickly becomes clear that IR spectacles are capable of absorbing five to ten times more radiation within the 700 to 2,700 nm spectrum than welding spectacles – while still allowing just as much visual radiation through. Our professional uvex IR-ex infrared safety spectacles therefore provide effective protection when working with both types of radiation, meet both standards (EN 169 and EN 171) and are way ahead of welding spectacles when it comes to the protection that they offer. And, because our IR-ex spectacles also provide protection from UV radiation up to 400 nanometres, the requirements of EN 170 for UV filters are also met. Our IR-ex tint therefore offers multiple types of protection for virtually all hazards posed by optical radiation. This multi-certification allows our infrared spectacles to be used for protection when welding and from solar radiation as well. Conversely, a pair of welding safety spectacles does not provide sufficient protection against infrared!

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Jun 27, 2022 — Angular Field of View (AFOV) is typically specified as the full angle in degrees. Sized/Length Field of View (object size) is typically ...

Ultra-telephoto zoom lenses let you fill the frame with far-off subjects and are especially useful for wildlife photography and even landscapes where you want ...

CroppingWhen the lens format is larger than the camera format, the effect on the resultant image is known as cropping. In this case, a full image is produced but at a smaller size (i.e. cropped) because the sensor is only capturing a fraction of the complete image. A crop factor or focal length multiplier quantifies the amount of cropping and is defined as the ratio of the diagonal length of the lens' design format divided by the diagonal length of the sensor format. The crop factor for all possible 1/3", 1/2.9", 1/2", 1/1.8", 2/3", 1", and 4/3" format lens/sensor combinations are shown in the table to the right.

You can find more information on our professional IR products in our online brochure for uvex IR-ex. We also have glare safety spectacles, welding safety spectacles and UV safety spectacles in our range. You can also use our handy tint app to help you to select the correct tint.

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Depending on its intensity, proximity and the duration of exposure, infrared radiation can be harmful to the eyes as well as to the skin. The eyes generally react much sooner and are much more sensitive than the skin to the effects of IR radiation, which can be harmful from a certain degree of intensity and exposure. The heat can in fact be beneficial to skin to a certain extent: infrared heat in the form of infrared lamps is used for medical purposes such as treating pain, circulation problems, stiff joints, inflammation etc. However, excessive heat can also cause heat cramps, heat exhaustion, heatstroke and burns.

Infrared is radiation with a wavelength between 780 nanometres and one millimetre on the electromagnetic spectrum. This IR radiation cannot be perceived by the naked eye, even if the heat emitted by the radiation can be felt. Particular caution is therefore required when dealing with extremely warm and prolonged radiation. Infrared light is divided into three types depending on the wavelength: IR-A, IR-B and IR-C. The longer the waves of the IR radiation, the less able they are to penetrate fabric or dermal layers. At 780 nm to 1,400 nm, the comparatively short-wave IR-A radiation is therefore the most harmful type in terms of human health (greatest degree of penetration). UV light is also invisible, but its wavelength spectrum is below 400 nm and it therefore has a shorter wavelength than radiation within the visible range of the spectrum.

The focal length (FL) is roughly defined as the distance from principal plane to the focal plane. For a camera lens, the focal length determines the field of view of the camera system; the longer the focal length, the smaller the field of view. As a general guideline, a 50 mm focal length lens and 35 mm format camera combination produces roughly the same field of view as the human eye (~53° diagonal). The table below lists the focal lengths needed to achieve the same field of view as the human eye for different sensor formats.

VignettingVignetting occurs when the lens format is smaller than the camera format. When this occurs, the area of the sensor is incompletely exposed, causing a dark ring to appear around the borders of the image. The vignetting effect is illustrated in the two images below, which were both captured using the same 4/3" format camera. In the image to the left, using a 12 mm focal length, 4/3" format lens produces a full image with slight dimming around the edges. This minor example of vignetting is due to the lens design which has decreased transmission at the edge of the lens. On the other hand, a 2/3" format lens at the same focal length produces a prominent dark ring around the photo edge. As the latter example is very visually apparent, we do not recommend using lenses with smaller formats than the camera sensor for imaging.

6 days ago — The meaning of INFRARED is situated outside the visible spectrum at its red end —used of radiation having a wavelength between about 700 ...

Protect your eyes and those of your employees when working with infrared radiation: rely on the durability, transparency and colour fidelity of uvex IR-ex safety spectacles! Use the temperature of the radiation source to determine the correct level of protection, and please do not hesitate to contact us if you have any questions. You can contact us by telephone (+49 (0)911 97 36 360), by email (serviceteam@uvex.de) or via our contact form.

83D biconcave lens facilitates viewing the fundus in an air-filled vitreous cavity in phakic and pseudophakic eyes. Lens is clear with image magnification ...

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Specifically, f-number is defined as:where f/# is the f-number, f is the focal length and d is the entrance pupil diameter.

Note that Thorlabs' camera lenses are designed to correct for optical aberrations witin a specified range of object distances. The modification of the specified minimum object distance with an extension tube may reduce the ability of these lenses to eliminate aberrations.

When these images use different polarizing directions, and you use matching polarizers, one over each eye, your brain perceives this as a 3D image. Supplies: 3D ...

Feb 27, 2022 — Most of the aberrations (CA, astigmatism, coma, vignetting) are often non-uniform and greatly increase towards the corners. At least for web ...

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Whether you work right in front of a furnace in a foundry or a certain distance away, appropriate eye and face protection – plus where necessary the right heat protection clothing – are essential for you to be able to work safely.

As well as the acute risks posed by overheating, the chronic effects of infrared light on the eyes (damage to lenses and retina) are good reason to wear appropriate personal protective equipment when working with infrared radiation.

The images below illustrate this effect visually using two images taken using the same lens with 1/2" and 1/3" format cameras. The image taken using the smaller 1/3" format camera produces an image that is cropped compared to the image taken using the 1/2" format camera. Note, however, that the objects in both images remain at the same magnification.

US Door & More Inc is the manufacturer and supplier of various wood and MDF doors. The company offers high quality and flexible door size and design at a ...

To illustrate this, the sequence of three images to the right were taken with the same camera with three different lenses. As focal length of the lens increases, magnification of the objects in the photos increases while the field of view decreases. The items in the image are each roughly spaced in 10" (254 mm) increments in the following order: Polaris™ Fixed Monolithic Mirror Mount (10" from camera), Ø1/2" post with KM100 mirror mount (20" from camera), and post-mounted RSP1 rotation mount (30" from camera). The MVL4WA used to shoot the first image is a wide angle lens which clearly distorts the door frame on the left edge of the image.

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When it comes to the long-term dangers posed by infrared radiation, the key question is how to provide employees with effective, reliable protection to keep them healthy while they work.

Alternative text: We also have the precise spectacles tint for many other applications, offering you the best protection and comfort for your work. Find out more here: uvex lens tint (uvex-safety.com)

First of all, welding spectacles and infrared safety spectacles are subject to two different safety standards: while welding spectacles are designed specifically for welding applications and the respective output from the welding machine in accordance with EN 169, infrared safety spectacles are designed in accordance with EN 171; this standard intends for the eye protection to be selected according to the average temperature of the radiating heat source.

The machine illustrated in Figure 10.31 is a three-axis diamond turning and grinding machine. It uses interferometry to achieve position resolution of 1.25 nm ...

In professional settings, employees working in glass production and the processing of metals or plastics are among those exposed to the potentially harmful effects of infrared radiation, which is invisible to the naked eye. This article will set out the dangers posed by infrared, list the areas in which IR radiation is found and provide clarification on effective measures to tackle the problem.

by PA Howarth · 1986 · Cited by 187 — Abstract. The human eye suffers from longitudinal chromatic aberration, and this has been thought to average approximately 1.75 D between 420 and 660 nm. In ...

Modern cameras that use CCD or CMOS sensors are specified for a camera sensor format, and similarly, lenses are designed to provide optimal imaging for a specific camera format. This format designation (e.g., 1/2", 2/3", 4/3") is a hold-over convention from when video was recorded using cathode-ray tubes and refers to the outer diameter of the video tube required for a given image size. The diagram to the right illustrates the size difference between several standard camera formats. In the ideal imaging system, a camera and lens would be designed for the same format, however, it is also possible to use camera/lens combinations with different formats. Doing this will have an effect, either vignetting or cropping, on the resulting image.

Infrared radiation, or thermal radiation, was discovered in the year 1800 by Friedrich Wilhelm (William) Herschel, musician and astronomer. Everyday sources of infrared radiation include:

Our infrared light spectacles also meet the requirements of U.S. standard ANSI/ISEA Z87.1 and Japanese standard JIS T8141. This multi-certification allows our infrared spectacles to be used for protection when welding and from solar radiation as well. Conversely, a pair of welding safety spectacles does not provide sufficient protection against infrared!

Thorlabs' Camera Lenses for Machine Vision each have a characteristic range of object distances. Objects placed within this range can be brought to a sharp focus on the sensor of the C-Mount camera. As seen in the image sequence below, the addition of an C-mount extension tube or spacer between the camera and the lens changes this range of object distances and allows the system to focus on objects closer to the lens. This increases the magnification of the image on the camera while decreasing the depth of field. The following table lists the range of possible object distances for various combinations of Thorlabs' C-Mount extension tubes and machine vision lenses.

Particular caution is advised in the event of infrared coming into excessively long direct contact with the eyes because its harmful effect on eye health varies depending on how deeply the IR radiation manages to penetrate the eye tissue:

If you operate in areas with particularly high levels of infrared radiation – right in front of the iron-melting furnace, for instance – heat protection clothing and special heat protection are indispensable.

For workplaces where less-intense heat sources do not pose an immediate threat but lasting exposure to infrared poses a hazard, uvex has developed a special range of safety spectacles to provide protection from IR radiation: uvex IR-ex. Combining safety with a clear view, these safety spectacles have the following impressive properties:

This calculator will help you assess what camera settings are required to achieve a desired level of sharpness.

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Aside from the aforementioned situations in people’s personal lives, there are many industrial settings in which infrared radiation is used in a variety of ways. Typical examples include:

Our infrared safety spectacles feature our proven uvex supravision coating technology to pair top protection with a superbly clear view! Choose from the sporty uvex pheos cx2 and the uvex super f OTG as overspecs for prescription spectacle wearers. Experience the quality of our infrared spectacles for yourself and try out the colour recognition on our uvex IR-ex page!