A telephoto lens generally has a focal length of 60mm or longer. This goes for both prime and zoom lenses. You can have a telephoto prime lens, and a telephoto zoom lens.

A macro lens is used for taking photo or video extremely close to a subject. With a macro lens, you can fill the entire frame and have everything be in focus. Most zoom lenses and prime lenses wouldn’t be able to focus this closely on a subject, blurring the image. Macro lenses are generally telephoto, typically with focal lengths from about 100 to 200 mm.

Compound parabolic concentratorsolar collector

One large parabolic mirror with a second mirror sitting tangent to the parabolic axis with an end at mirror #1’s focus. The distance between the two upper ends of the parabolas is labeled aperture (2a) and the bottom two ends is labeled receiver. Dashed lines connect one top end to the opposite bottom end. The angle between their y intercept, y-axis and upper tip represents the acceptance half-angle.

If you have a 35mm lens for a full-frame camera, and put it on a crop sensor camera, it’s effectively a 50mm lens. This is because crop-sensor cameras offer a cropped view of a 35mm format. If you’re shooting with a cropped APSC sensor, then you could purchase lenses that are compatible with your camera and account for the cropped sensor.There are a few common cropped sizes for digital sensors. APSC, Super 35, Micro Four Thirds, Super 16.

CPC lens

A prime lens has a fixed focal length (e.g., 35mm). This means you only have a 35mm focal length on one lens. Like a zoom lens, a prime lens has its own pros and cons:

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Parabolicdish collector diagram

Authors: Mark Fedkin, John A. Dutton e-Education Institute, College of Earth and Mineral Sciences, Penn State University.

Full-frame refers to a DSLR camera with an image sensor that is the same size as 35mm format film, measuring 36 x 24mm. For comparison, the more popular APS-C sensor size found in most DSLRs measures 22 x 15mm. Full-frame sensors have more than 2.5 times the surface area of an APS-C sensor. When you compare a crop sensor and a full-frame sensor, the most noticeable difference between full frame and crop sensor is their field of view. If you put a 35mm lens that’s designed for a full-frame camera on a crop sensor the field of view will be cropped in. Speaking of crop sensors, let’s jump into what a crop sensor is and how it affect your images.

The compound parabolic concentrators (CPC) are typical representatives of non-imaging concentrators, which are capable of collecting all available radiation - both beam and diffuse - and directing it to the receiver. These concentrators do not have such strict requirements for the incidence angle as the parabolic troughs have, which makes them attractive from the point of view of system simplicity and flexibility. Like parabolic and other shapes, CPC concentrators can be applied in both linear (troughs) and three-dimensional (parabolocylinder) versions. The same as in "pure" parabola case, troughs are most widespread and useful for this type of concentrator.

Compound parabolic concentratorequation

Section 7.6. of this book covers the fundamental optical principles of CPC collectors and also considers particular cases of truncated collector. Some practical examples are also presented. Section 7.7. talks about the orientation of CPC collectors. While CPC technology does not require continuous tracking, proper orientation with respect to the sun position is crucial to maximize absorbed radiation. The theoretical material in this section is also supported by practical examples.

Parabolicdish collector

The main difference is that a zoom lens has a variable focal length while a prime lens has a fixed focal length. Here’s more on the differences:

1 mm = 1000 µm. Ignore the knee-jerk reactions to American (official) spelling of meter vs British metre. I will give them that a micrometer ...

Essentially, focal length is the angle of view, or how much of the scene will be captured and the magnification of the image. The longer the focal length, or the higher the mm of the lens, the narrower the angle of view is and the higher the magnification of the image. The shorter the focal length, or the lower the mm of the lens, the wider the angle of view and the lower the magnification of the image.

The commonly accepted focal length of our eyes is around 22mm-24mm. Our visual attention is about 55 degrees wide. So, on a 35mm full frame DSLR, this gives you a 43mm lens. This focal length provides exactly the same viewing angle as a human eye.This is why many photographers and cinematorgraphers find a 50 mm lens pleasing for quality video production, because it is very close to our own eyes.

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A wide angle lens is any lens that has a short focal length: shorter than 24mm. So, lenses from 14mm-24mm are considered wide angle lenses.

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Compound parabolic concentratorPDF

If the origin assembly is a mechanism, the mirror assembly will also be one with the same groups and joints. Joints are kept. An ...

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A zoom lens has a variable focal length (e.g., 16–35mm). This gives you a wide variety of focal lengths in one lens. There are pros and cons to having a zoom lens:

Compound parabolic concentratorwikipedia

Eyepiece Lens: the lens at the top that you look through, usually 10x or 15x power. Tube: Connects the eyepiece to the objective lenses. Arm: Supports the tube ...

Parabolictroughconcentrator

When you use a camera with a crop sensor, it affects how the lens works on the camera, measured by its multiplier. For example, a crop sensor could have a 1.5x multiplier. When you attach a 50mm lens, the focal length is multiplied by 1.5x. So, this means a 50mm lens acts like a 75mm lens on a crop sensor DSLR. This essentially crops out the edges of the frame, which increases the focal length.

Book chapter: Duffie, J.A. Beckman, W., Solar Engineering of Thermal Processes, Chapter 7: Sections 7.6 and 7.7 - pp. 337-349. This book is available online through the PSU Library system and can also be accessed through e-reserves (via the Library Resources tab).

There are some other useful expressions that describe the design of CPC concentrators. The following equations relate the focal distance of the side parabola (f) to the acceptance angle, receiver size, and height of the collector (Duffie and Beckman, 2013):

Crop sensor refers to a DSLR sensor that mimics a full-frame 35mm format, but is not a true 35mm format. If you’re using a crop sensor camera, it basically is a “cropped” view of a full-frame 35mm camera.

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The geometry of a CPC collector is demonstrated in Figure 2.12. If we consider a CPC trough, this diagram represents its cross-section. Each side of the shape is a parabola, and each of the parabolas has its focus at the lower edge of the other parabola (e.g., F is the focus of the right-hand parabola in Figure 2.12). Each parabola axis is tilted relative to the axis of the CPC shape. One of its key parameters is acceptance half-angle ( θ c), which is the angle between the axis of the collector and the line connecting the focus of one of the parabolas with the opposite edge of the aperture. The collector is designed in such a way that each ray coming into the CPC aperture at an angle smaller that θ reaches the receiver; if this angle is greater than θ c , the ray will return (Figure 2.13). The relationship between the size of the aperture (2a), the size of the receiver (2a') and the acceptance half-angle is expressed through the following equation:

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The main difference is that a wide angle lens has a short focal length and a telephoto lens has a long focal length. Here’s more on that:

Knowing that the geometric concentration ratio is the quotient of the aperture area to the receiver area (see Section 2.3), for a linear CPC concentrator, we can obtain the relationship between the concentration ratio and the acceptance angle:

When you compare a crop sensor to a full-frame sensor, the most noticeable difference is how much of what you’re seeing is being captured by the sensor.

The John A. Dutton Institute for Teaching and Learning Excellence is the learning design unit of the College of Earth and Mineral Sciences at The Pennsylvania State University.

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Focal length is the main optical property of a camera lens. It’s displayed in millimeters and by a number that looks like this: 35mm, 50mm, or 100mm. Lenses are named by these numbers and used when refferencing different types of lenses.

A single number, like 24mm, on a lens represents a prime or fixed lens. This means the lens isn’t capable of zooming. A 24mm prime lens is made for only a 24mm focal length. If you want a range of focal lengths, you could use a different lens, like a 24–70mm zoom lens, which gives you the ability to change your focal length in the range of 24mm to 70mm.

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