The CLS is committed to providing a safe working environment for all staff and protecting the general public and environment from risks. As part of our commitment to safety, we utilize personnel safety systems, equipment protection systems and emergency shutdown processes.

Over time, the number of electrons stored in the ring will decline. This is inevitable because the vacuum isn’t perfect. Electrons collide with one another and the few particles that are present causing them to be lost. To maintain 220 mA of beam current, the CLS runs in Top-Up mode where a small amount of electrons are automatically injected every few minutes.

Electrons travel from the LINAC to the Booster Ring where a specifically-designed Radio Frequency (RF) cavity raises the energy of the electrons from 250 MeV to 2900 MeV as they circulate in the booster ring. Following this boost in energy, the electrons are transferred to the storage sing.

Oh, the primary apertures aren't the problem: f/1, f/1.4, f/2, f/2.8, etc. These all are easy enough to calculate (multiply by 1.4 to get the next aperture in the sequence). Well, okay, that's not exactly true, as rounding starts to come into play (and the 1.4 value itself is a rounded number); still it's close enough for quick understanding of the one-stop differences.Â

Aperture pronunciation

The booster ring has a cylindrical cavity that delivers a high-energy kick to the electron bunches during each turn around the ring. It operates with a RF of 500 MHz.

While the storage ring looks circular from the outside, it is really a series of 12 straight sections each with a series of magnets for bending the electrons' path and focusing the electron beam. Electrons normally travel in a straight line, so their path is bent by large (6800 kg) magnets at each turn, and this also causes the electrons to emit synchrotron light. There are also special magnetic arrays called insertion devices that produce a brighter light for certain beamlines.

When you look at Nikon's choices for Z-mount primes so far, you'll see that they've almost always chosen wide, clear differences: f/1.2, f/1.8, and f/2.8 (the exception is the 40mm f/2). That's an exposure change of ~1.2 stops from f/1.2 to f/1.8, and 1.3 stops from f/1.8 to f/2.8. Those detail-oriented Nikon engineers are nothing if not (mostly) careful and consistent in their design tactics.Â

That last bit is what we had to do in the film world, as our ISO constraints were much more rigid and filled with peril. But given the state of noise reduction software these days, I feel ISO bump is a reasonable choice now, particularly since a faster lens probably is only going to give you a stop or so advantage from what you'd normally use.Â

There are three main types of electro-magnets used at the CLS. There are the dipole magnets, the quadrupole magnets, and the sextupole magnets. The magnetic field created by the blue dipole (two-pole) magnets is used to direct the electrons around the booster and storage rings. The field of the green quadrupole (four-pole) and red sextupole (six-pole) magnets are used to force bunches of electrons into a fine beam within the vacuum chamber. The booster ring uses only dipole and quadrupole magnets, whereas the storage ring uses dipole, quadrupole, and sextupole magnets.

Thus, the implication of a faster or slower aperture in the same light—less or more filtering—means that your shutter speed changes to create the same exposure at the image sensor.

For more specific questions, including things like "What if someone gets hit by a beamline?", check out our Safety FAQs page.

Some would argue that they don't want the big f/1.2 optics, nor do they want just an f/1.8 optic. In other words, they only want to buy one set of primes, and they want that to be f/1.4. But you wouldn't get f/1.4 for free. Size and cost start to go up from the f/1.8 primes, or optical qualities have to come down. You can already see that some with the Chinese f/1.4 primes that are starting to appear: to keep size and price down they tend to sacrifice outer area traits of their lenses: more vignetting, more spherical aberration, more chromatic aberration, and more.Â

The CLS is one of the brightest synchrotrons in the world despite being one tenth the size of similarly bright synchrotrons. One of the ways that CLS achieves its brightness is through insertion devices. While dipole magnets change the direction of the electrons producing light, the multi-magnet insertion devices called wigglers and undulators placed in the straight section of the storage ring move or ‘wiggle’ electrons back and forth multiple times creating a narrow beam of highly intense light.

Though a synchrotron is not the only way to generate IR, UV or X-Ray light, we experience substantial benefits in brightness, experiment quality and speed, along with increased ability to select specific light wavelengths. Synchrotron light is emitted when the path of an electron beam is altered via extremely powerful magnets.

In the electron source, bursts of electrons are injected into an ultra-high vacuum stainless steel tube. These electrons will eventually create the synchrotron light that we use for research.

Radiation is energy that comes from, or radiates from, a source and travels through material or through space. Sources of radiation include light, heat and sound. There are many natural sources of radiation, including the sun and various elements in the earth.

The selected wavelengths of synchrotron light are focused by the mirrors in the optics hutch onto the sample in an endstation located in the experimental hutch. Each endstation is designed specifically for the types of experiments conducted on that beamline. In general, each one consists of a sample holder and a detection system, as well computers through which the researchers control their experiments and view data as it is recorded.

If you were to expose a 1 mm x 1mm sample, similar to what a researcher might put under a regular light microscope, to a number of different light sources and measure the amount of energy the matter in that sample interacted with, you would find that the energy generated by a synchrotron using insertion devices is considerably higher than what is produced by other light sources.

The CLS has 22 beamlines accessible to scientists using the synchrotron as part of their research. A beamline consists of an optics hutch where synchrotron light is focused and wavelength is selected, an experimentation hutch where the appropriate technique is selected for the experiment, and work stations where scientists operate the beamline and measure light as it is absorbed, reflected, refracted, or scattered by the sample.

A synchrotron produces different kinds of light in order to study the structural and chemical properties of materials at the molecular level. This is possible by looking at the ways light interacts with the individual molecules of a material.

At the fast end of the maximum aperture spectrum (f/1 to f/2.8), the implication is that you can hold a 1/60 second shutter speed into dimmer and dimmer light with faster apertures. 1/60 is a good marker because slower than that is difficult to handhold well and anything slower is absolutely subject to subject motion.Â

*In particle physics, the standard unit to measure energy is mega-electron volts or MeV which is 1*106 eV. One eV is the amount of energy that an electron gains when it moves through a potential difference of 1 volt in a vacuum.*

As fast (and slow) lenses come out with aperture values that weren't common in the DSLR era, I'm finding a lot of misunderstanding about the aperture progression.Â

For comparison, the typical atmospheric molecule has an energy of about 0.03 eV and the energy of charged particles in a nuclear explosion can range from 0.3 to 3 MeV.

The CLS synchrotron produces light by accelerating electrons to nearly the speed of light and directing the electrons around a ring. The electrons are directed around the ring by a combination of radio frequency waves and powerful electromagnets. When the electrons go around the bends, they give off energy in the form of incredibly bright and highly focused light. Different types of light, primarily infrared and X-ray, are directed down to the end of beamlines, where researchers use the light for their experiments at endstations. Each beamline and endstation at the CLS is designed for a specific type of experiment.

In the case of an emergency the synchrotron can be shut down automatically in less than 20 milliseconds from the control room and from several other locations manually.

The CLS uses two radio frequency (RF) cavities - one in the booster ring and one in the storage ring- to boost the energy of circulating electrons using microwaves.

A synchrotron can be used to probe matter and analyze many physical, chemical, geological, and biological processes. Information obtained by scientists from these analyses can be used to help design new medications, build next-generation technology, examine surfaces and materials to make more effective products like motor oils, develop new materials for safer medical implants, help with the clean-up of mining wastes, and find innovative ways to combat climate change to name just a few applications.

Aperture in microscope

In addition, each element absorbs energy at a known level. Being able to select a specific wavelength, or range of wavelengths, allows researchers the flexibility to direct their research towards specific questions.

Control Room management is an important part of ensuring personnel safety throughout the facility. From the control room we monitor:

Aperture in biology

So at both ends of the aperture range there are intersecting issues you need to consider. The real question is how often do you encounter those, and what would you do about them if you did? Generally speaking, the thing that most people end up doing is bumping up their ISO when they don't have a "fast enough" lens. So the real question is this: how often are you bumping ISO up because you don't have a fast enough lens? And are you sure that you can't do the other obvious thing, and add light?Â

The biggest problem I'm seeing with photographers comes up in comparing f/1.2 versus f/1.4, or f/1.4 versus f/1.8. These don't at first seem to be big differences, but each step is a half or two-thirds of a stop, which can make a significant difference in exposure in lower light conditions and has a fairly clear depth of field difference at the 35mm+ focal lengths.Â

At the slow end of the aperture range (e.g. with telephoto focal lengths), we're now seeing lenses that weren't really possible (with autofocus) in the DSLR era, where there was a fairly strong cut-out of phase detect focus performance beyond f/5.6 due to the geometries involved. It's now more common to see f/6.3, f/6.7, f/7, and f/8 as maximum apertures in mirrorless at the telephoto focal lengths. Some people panic over f/6.3 versus f/5.6, but that's only a third of a stop, not something dramatic. Even f/8 is only a stop slower than we used to see in the DSLRs.Â

For scientists, the main purpose of a synchrotron is research. The different areas of research that the CLS synchrotron conducts can be split into 4 categories of technical information, each with their own subcategories.

At CLS, radiation is mainly used as another word for light. Often, people use the word radiation instead of light when they are talking about the wavelengths, or types, of light that the human eye can't see, like UV light from the sun.

The booster ring cannot increase the speed of the electrons to, or beyond, the speed of light, but the electrons travel at about 99.999998% of the speed of light.

I'm going to be watching closely as these companies get bigger and start seeing the headwinds of that growth. Moreover, at the moment, shipping directly from China into the United States, for example, is basically done without tariff, customs, and includes incentivized shipping costs. Those benefits are likely to go away. I've already seen governmental lobbying from the Japanese about the disparities they see.Â

By producing high flux light across a significant portion of the spectrum, a synchrotron offers many different techniques to researchers in one building. In order to gather information, the wavelength of the light has to be appropriate for the size of the matter of interest. Shorter wavelengths allow scientists to gather information about smaller things.

The linear accelerator, or LINAC, accelerates electrons in a straight line. Electrons produced by the electron gun enter the LINAC, where a series of radio frequency cavities with fields at 2,856 MHz accelerate the electrons to an energy of 250 million electron volts, or 250 MeV. At this energy the electrons are travelling at 99.9998% of the speed of light (3.0 x 108 m/s).

Sigma now has 35mm and 50mm lenses at f/1.2, f/1.4 (half stop change), and f/2 (full stop change). Sony is a bit less consistent with 50mm lenses at f/1.2, f/1.4 (half stop change), f/1.8 (two-third stop change), f/2.5 (full stop change), and f/2.8 (third stop change).Â

The electron source uses a tungsten button as the cathode. As electricity flows through the cathode, it becomes heated (at about 1000°C) to incandescence which gives some electrons enough energy to leave the surface of the cathode, essentially boiling electrons off. As this is happening, a nearby screen is given a short, strong positive charge which pulls the electrons away from the cathode towards the LINAC. (This process is similar to that found in a cathode ray tube (CRT) television). The high voltage electricity running through the cathode  also repels the electrons being produced by the cathode and accelerates them towards the LINAC.

The high energy electrons from the booster ring are transferred into the storage ring when they reach 2900 MeV where they circulate for 4 to 12 hours, producing light for beamlines. The transfer process repeats once per second for up to 600 cycles (about 10 minutes), as required, to reach an average circulating current in the storage ring of 220 mA.

Aperture of mirror

Aperture of lens

Because the Canadian Light Source uses a high-energy electron accelerator to make synchrotron radiation, a licence to operate from the Canadian Nuclear Safety Commission (CNSC) is required. Some radiation produced at a synchrotron facility can be harmful. Protection of workers and scientists at the synchrotron starts with the facility design. Thick concrete walls contain radiation produced by the electron beam, and the synchrotron radiation used for science is contained within lead- and steel-lined rooms. A safety system keeps people out of these areas when the beam is on, and turns the beam off instantly if someone attempts to enter. Radiation levels in areas where someone can be present are constantly measured in different ways to ensure radiation exposures to workers and scientists are kept well below the CNSC regulatory limits. No one at the Canadian Light Source has ever received a radiation exposure greater than the CNSC public limit.

At the slow end of the maximum aperture spectrum (f/5.6 to f/11), the implication is that your shutter speed is going to get clipped and/or your ISO boosted, potentially even in decent light. The Sunny 16 formula is 1/ISO shutter speed at f/16. So to hold a 1/1000 shutter speed in sunlight on a base ISO 64 camera you need f/4 or faster as the aperture, otherwise you need to start bumping your ISO value. A rule of thumb is that you'll lose about a stop of dynamic range with each stop of ISO bump, though, so you want to avoid that, if possible.Â

Side note: The Chinese lens makers at the moment have a few attributes that help them undercut the established Japanese lens producers on price. First, the Chinese are all entrepreneurial at the moment, don't much care about intellectual property rights, are in a region where labor costs are lower, and they first and foremost promote selling directly. Overall they have lower costs and are taking less profit (some of the latter is due to having to use distributors for some regions or in-store sales).

At the beamline, the synchrotron light passes through the optics hutch on its way to the sample. There, the monochromator enables researchers to choose the wavelength of light best-suited to the experiment they are conducting. The monochromator is the device that separates different wavelengths of light (much like a prism). This is done using either optical dispersion (as in a prism), or as diffraction, using a grating which separates the wavelengths of light and filters out the light that isn’t required. Each of the beamlines at CLS is unique and have markedly different monochromators specific to their design.

Generally speaking, synchrotron sources pack more photons into a smaller beam of light. This offers researchers more information about their sample and makes a greater variety of techniques available to use to learn about their sample.

For the general public, the main purpose of a synchrotron is the research news that is published and the eductional programs for students and educators that are offered.

Aperture photography

Another advantage to some synchrotron techniques is the ability to conduct experiments in situ, or as they are – without treatment. There are a number of research techniques that require the scientist to treat their sample (crush it; make a solution; slice it; etc). While this is also required for some synchrotron techniques, there are also some that allow for the sample to be analyzed without treatment or with less treatment, which can be a significant advantage.

Aperture in camera

CLS scientists work with industrial teams to develop an experimental plan based on the client’s needs, providing key answers to critical questions. Learn more about the opportunities for industry professionals at the CLS.

As electrons circulate the 103 m Booster Ring approximately 1.5 million times in 0.6 seconds, they receive a boost in energy from microwave fields generated in the RF cavity at 500 MHz to reach a total energy of 2900 MeV. How much energy is 2900 MeV? If we were to instead try to boost the electrons' energy using household batteries, it would take about 2 billion batteries connected in a row!

Aperture in physics

Technically, before the CIPA-agreed rounding, the full aperture sequence goes 1, 1.41, 1.99, 2.78, 3.92, 5.53, 7.80, 11, 15.51, 21.87. The above charts use the agreed-upon rounding numbers. The marks on a Japanese-produced lens will conform to the CIPA rounding with the lens focused at infinity. In other words, there's a lot of wiggle room in the actual numbers, which is partly the reason why trying to stick more lenses into the equation at minimal aperture differential is a fool's errand.

The storage ring uses an RF cavity to replace the energy lost by electrons as they produce light. The RF cavity in the storage ring is also superconducting. Superconductivity means that there is no resistance in the flow of electric current in certain metals and alloys at temperatures near absolute zero. The operating temperature of the storage ring RF cavity is -270°C (-273°C is absolute zero, the point at which all motion stops). Operating at such cold temperatures eliminates most power loss, while the RF field provides energy to the electrons.

As a third generation synchrotron, the CLS is comprised of several components including the Electron Gun, Linear Accelerator, Booster Ring, and Storage Ring. Each of these sections contributes to producing a beam of synchrotron light, which is then harnessed in a beamline, using an optics hutch, experimental hutch and work stations.

But getting back to the misunderstandings that prompted this article, I see, for instance, quite a few people saying Nikon should create a line of f/1.4 primes in addition to their f/1.2 and f/1.8 ones. Personally, I don't see how chopping the choices so finely—f/1.2, f/1.4, f/1.8—does anything other than increase the cost of your gear closet. The half to two-thirds stop difference that f/1.4 option would make isn't enough for me to try to add another set of lenses: I can deal with a half to two-thirds stop ISO change.Â

When a synchrotron accelerates electrons, they are "bent" around corners using magnets. When the particles go around the corners they release photons, or little bits of all kinds of light. We can then filter out the spectra, or kinds, of light we want such as Infrared (IR), Ultra-Violet (UV), and X-Ray light.

Everything from the electron gun to the beamlines is under vacuum. The electrons (and later the photons) must travel in a vacuum to avoid colliding into particles and disappearing. The storage ring vacuum chamber pressure is generally around 10^-10 torr. This means there are fewer than 10 particles per cubic centimeter present in our vacuum system.

CLS offers a variety of short- and long-term programming for students as well as educators from across Canada. Learn more about getting synchrotron science into the classroom.

Academic clients can submit proposals through a peer review process, get access to beam time, and more. Learn more about individual beamlines and techniques offered by CLS.

CLS scientists work with industrial teams to develop an experimental plan based on the client’s needs, providing key answers to critical questions. Learn more about the opportunities for industry professionals at the CLS.

Due to the extreme brightness of the light, it does not take as long to conduct the same experiment using a synchrotron source of light as it does with a ‘table top’ source for some techniques.