Assessing the quality of the lens
Lens selection. 7 Key Factors
In this article, we'll answer 7 key questions you should ask yourself before buying a new lens. In addition, we will talk about the main factors that you should pay attention to when buying a lens.
The lens is a tube, either plastic or metal, with glass at each end, and the lens can hold up to 20 (or so) individual lenses, arranged in several (up to ten) groups.
Other lens elements include aperture blades and an autofocus motor. All these elements ensure correct and high-quality operation of the lens. Obviously, for the average user, the complex optical system of the lens is quite easy to use, and no special skills are required to learn how to use the lens.
The quality of your photos will depend on the lens you choose and attach to your camera, so choosing the right one is the key to future success. The main factor is the focal length. Focal length is the distance between the optical center of the lens and the sensor and is easier to visualize.
For a camera with a full-size sensor, the standard lens is 50mm. Lenses with a focal length shorter than 50mm are called wide-angle lenses, and lenses with a focal length greater than 50mm are called telephoto lenses.
Which one is right for you will depend on what you plan to photograph and the distance at which the subject will be located.
7 Questions to Answer When Buying a Lens
What focal length do I need?
Think about what you plan to photograph, then you can determine what focal length your lens should have. If you already have a wide-angle lens, you may need to consider purchasing a telescopic lens, and vice versa.
If your financial capabilities allow, you can choose for yourself a so-called universal lens, the focal length of which covers the range of 18-200 mm, that is, from wide-angle to telescopic.
What is the lens aperture?
A lens with a maximum aperture between f/1.2 and f/4 is often called a “bright” lens. Lenses with a wider aperture allow a lot of light to pass through, allowing for high shutter speeds. With these lenses you can take beautiful images in low light conditions.
Bright lenses are usually very high quality, but they are often bulky and expensive, so not every photographer can afford to buy such optics.
Less bright lenses are usually much cheaper and lighter, but when shooting in low light, you will need to increase the ISO setting (which subsequently results in loss of quality and noise in the image).
For example, if a lens with a maximum aperture of f/2.8 allows you to set the shutter speed to 1/125 sec. at 100 ISO, a lens with a maximum aperture of f/5.6 will allow you to set the same shutter speed at ISO 400 under the same conditions.
A wider aperture also allows for shallower depth of field, which is especially useful in portrait photography.
Image quality?
Only by using a lens can you truly know the quality of the photos it takes. Therefore, before you give preference to one or another option, read the reviews and talk to people who already work with this optics. This is the only way you can find out how clear and sharp pictures a particular lens takes, and decide for yourself whether you are satisfied with such a result.
What is the minimum focusing distance?
How close you need to get to your subject so that the lens can focus on it. This is a very important point to consider when choosing a lens, especially when choosing a telescopic lens.
Of course, a lens that can bring the subject close many times is very good, but if you cannot take a photo from a close enough distance, (for example, if you want to take a portrait) then you will have to purchase special rings that increase the physical size of the lens, thereby allowing you to shoot from a closer distance.
Does the filter ring rotate?
For relatively inexpensive lenses, the front element rotates while the lens is focused. This causes some problems if you have a polarizing filter attached. The only solution to this problem is to focus and then turn on autofocus and switch to manual focus mode.
How much do you expect?
Buying a new lens is always quite expensive. Even the most common and inexpensive lens will cost at least $100. Realistically assess your capabilities and determine the amount you will agree to spend on new optics.
A more expensive lens will generally be brighter and will allow you to photograph in low light with ease without having to raise your ISO, while cheaper lenses will be less bright at f/3.5 at wide and 5.6 at telephoto.
When working with an inexpensive, less bright lens, you will have to set the ISO value high, which means losing image quality. At the same time, with such optics you will not achieve a shallow depth of field. High quality lenses are more resistant to chromatic aberration and distortion. But remember, there is no perfect lens.
physical characteristics
The external features of the lens should also not be overlooked, because they affect the ease of working with this optics. Pay attention to the weight, texture, dimensions of the new purchase. Cheap zoom lenses can be wobbly and unstable, while more expensive ones mount securely to the camera.
What should you pay attention to when purchasing?
What are the main lens features you should pay attention to when purchasing a new lens:
- Focal length and the ability to change it;
- Lens field of view angle (part of the scene that fits into the frame);
- Aperture, that is, the ratio of the diameter of the maximum open aperture to the focal length;
- Resolution, that is, the ability of the lens to take clear pictures;
- Bayonet type and thread diameter for attaching to the camera;
- Availability of mount for filters;
- Image stabilization, whether it is in the lens or not;
- Switch between manual focusing and automatic;
- The presence or absence of a hood (an accessory necessary for protection from bright sunlight).
Lens markings explained
If you are new to photography and buying a lens for the first time, you have probably noticed a lot of strange symbols and abbreviations used in lens labeling.
This cheat sheet will help you understand the basic symbols used when marking a lens.
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Lens selection. Part V “Lens Disadvantages”
DISADVANTAGES OF LENSES
Typical types of aberrations
The light rays that form the image are concentrated on the film plane using objective lenses. Modern lenses consist of a large number of lenses . Since it is impossible to make one “ideal lens” that would behave in accordance with the theory, the designers took a different route. The deficiencies of each lens are compensated for by the next lens in the hope of improving the quality of the entire optical design. Lenses have certain optical aberrations , that is, defects expressed to a greater or lesser extent depending on the design and purpose. Let's list the main ones.
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Spherical aberration.
Light rays passing through the periphery of a normal lens with spherical surfaces converge closer to the lens than rays passing through the center. Thus, rays emanating from one point will not converge to one point on the film plane, resulting in a loss of resolution.
Spherical aberration is most noticeable when shooting at full aperture. Stopping the lens improves image quality by eliminating peripheral rays that reduce resolution.
Coma.
Can be considered as a spherical aberration of rays passing through the lens at a non-zero angle to the optical axis. The image of the dot becomes deformed and multiplies, acquiring a comet-like appearance. Coma is most pronounced at maximum aperture. This can be suppressed by stopping down the lens. Some lenses are nearly coma-free due to the use of specially treated (non-spherical) lenses.
Astigmatism.
This is an aberration in which a point located off the optical axis is projected onto two slightly divergent planes in the form of two orthogonal segments that cannot be focused simultaneously. Stopping the lens down makes this drawback less noticeable. But the point here is not a higher quality of optical correction, but an increase in the depth of field of the lens: two images of a point simply merge into one.
Field curvature aberration.
It depends on the design of the lens and appears even in the absence of the above-mentioned aberrations: the image surface is not flat. Stopping the lens does not eliminate this aberration, but makes it less noticeable by increasing the depth of field, just as in the case of astigmatism.
Distortion.
The image is correctly focused on the film plane, but the points formed by the rays tilted to the optical axis are slightly shifted from their ideal location, and as a result, straight lines are distorted. Depending on whether straight lines become convex or concave, the distortion is called barrel or pincushion distortion. The photographer cannot correct the distortion in any way: it does not depend on the degree of opening of the aperture, but on its “position” in the optical design of the lens (and, therefore, depends on the design chosen by the designer).
Axial chromatic aberration.
Appears near the optical axis of the lens: blue rays are focused in front of red ones when viewed relative to the film plane. Stopping the lens has no effect on this type of aberration, especially when shooting in color. When shooting in black and white, stopping down a large aperture can have some benefit as it increases depth of field and slightly improves apparent sharpness. True correction of axial chromatic aberration is a matter for designers, who often use special types of glass for this purpose.
Diffraction.
Light rays, after passing through a very small diameter diaphragm hole, diverge slightly. This phenomenon is called diffraction. In photography, diffraction causes loss of image sharpness and occurs under special shooting conditions when, as in macro photography, photographers close the lens aperture as much as possible to increase the depth of field. If there is no need, it is advisable to shoot at an average aperture for a given lens (for example, f/11 is preferable to f/22).
Shift focus.
The combination of all the aberrations present in the lens can result in a defect such as focus shift. This defect can be reduced, but not completely eliminated, by closing the lens aperture as much as possible. This problem is sometimes encountered in macro photography, when focusing with the aperture wide open to increase the brightness of the viewfinder image, and shooting with the lens aperture closed as far as possible to provide a large depth of field. When shooting with high magnification, it is advisable to focus with an aperture that is more open than the working one, but still close enough to it.
Glare and reflections.
When a bright beam of light passes through the objective lenses, stray reflections may occur at the air-glass interface, as well as inside each lens. The term "flare" refers to an internal reflection that resembles flames. In the photograph, luminous “tails”, halos, or even a geometric image of the diaphragm reflected from the interlens surfaces can be seen. Light rays scattered on the lens can reduce contrast, leading to veiling of the entire image.
It is better if the front element of the lens is always protected by a lens hood. When shooting in backlight, it is advisable to avoid using filters in order to reduce the number of air-glass boundaries. In some lenses, reducing the influence of parasitic glare is ensured at a design level: the effect is achieved by anti-reflective multilayer coating of lenses (coating of optics) to suppress internal reflections in the lens system, bluing of the aperture blades, and coating of the internal surfaces of the camera body with black varnish or velvet fabric. The degree of flare may vary depending on the aperture magnification factor and is determined by the photographer specifically for each lens based on experience.
Lens characteristics
To select a lens, you need to be guided by the characteristics. We will tell you what the lens characteristics mean and which ones are especially important to pay attention to.
Focal length
The focal length determines what will fit in your frame. The shorter the focal length (for example, 18 mm), the wider the viewing angle and the more objects you can fit in the frame.
But, the distortion of perspective in the frame also depends on the focal length. At a short focal length, objects may become distorted. It is believed that the focal length that is closest to how a person sees the world is 50 mm.
Based on focal length, lenses are divided into the following types:
- Ultra wide angle – from 7 mm (circular fisheye) to 24 mm
- Lenses with these focal lengths greatly distort the image by “stretching” the perspective. Used for shooting in confined spaces and interiors and other situations where you need to cover the maximum angle of view. For example, 14mm is often used in landscape. Blurring the background is very difficult.
- Wide angle — from 24 to 35 mm
- Distortion here is noticeably less, as is the coverage angle. This range is considered convenient for street photography and genre. Also suitable for landscape photography and group portraits.
- Normal - from 35 to 85 mm.
- You can shoot full-length portraits and landscapes. Not suitable for shooting large portraits, as it distorts the proportions of the face.
- Long focal length (telephoto lenses) — from 85 mm
- Starting from 85 mm, there is virtually no perspective distortion.
For a portrait, the ideal range is 85-135 mm. After 135 mm, the space shrinks, which also distorts the portrait. Long focal length lenses are also used to photograph wildlife, sports and anything that is difficult to get close to. The higher the focal length, the more the background is blurred, all other things being equal.
- Starting from 85 mm, there is virtually no perspective distortion.
The distortion of facial proportions at different focal lengths is clearly shown below. Note that at 200mm the space is greatly compressed, again distorting the image of the face.
The example below shows how perspective shrinks at different focal lengths:
The focal length on the lens is indicated for a full-frame sensor. On other matrices, the image will simply be cropped and the focal length will be recalculated.
For example, if you have an APS-C matrix, your crop factor will be 1.5 - 1.6x. If the format is micro 4/3, then 2x.
Recalculating the focal length will make it clear how much you can “bring the object closer”. But the distortion will not go away and 50mm in terms of conversion will become almost a portrait focal length of 75mm, but with the same distortions.
Maximum aperture
This is the maximum possible aperture value for this lens. For zoom lenses, the range of the maximum possible aperture is often specified. For example, f/3.5-5.6 for a lens with a focal length of 18-105mm means that at 18mm the maximum aperture will be f/3.5, and at 105mm it will be f/5.6.
As you know, the smaller the aperture value, the shallower the depth of field and the more blurred the background. All lenses show maximum image quality at average aperture values of f/8 - f/11.
Aperture
This is an indicator of the maximum aperture of the lens and the quality of the optics. The lower the f number (for example f/1.4), the faster the lens.
High-aperture lenses use high-quality glass and special anti-reflective coatings that reduce reflections. Therefore, fast lenses are a priori considered to be of very high quality.
Manual and automatic focusing
Most lenses are available with autofocus. The exception is lenses from Carl Zeiss, Samyang and other third-party manufacturers that produce non-autofocus lenses.
Old lenses that can be found in the consignment departments of a photo store are also not autofocus. Non-autofocus lenses have their advantages. This is the price and individual design and bokeh.
Minimum focusing distance
Everything is simple here - this is the minimum distance to the subject required for the lens to focus. One important point is that this distance is measured from the camera matrix; this point is marked on the camera body.
Focus design
There are two types of lens focusing designs - external and internal. When focusing externally, some external parts of the lens may move (for example, move forward).
Internal focusing means that the external parts of the lens do not rotate when focusing. Accordingly, when shooting, you can safely hold onto the lens, as well as use a polarizing filter, since the front element of the lens does not rotate when focusing.
Thread diameter for filter
This characteristic is indicated on the lens and shows what diameter filters can be used with this lens.
Typically, lens weight varies from 400 to 800 grams. There are, of course, lighter 50mm primes weighing 200 grams and heavier telephotos weighing 1500 grams.
Weight itself does not matter. But all other things being equal, it is better to choose a lighter lens. Experience shows that at the end of an active shooting day, even a man gets tired of holding a camera with a heavy lens. Well, the girl, you know, will get even more tired.
It is also more convenient to hold a camera with a lighter lens with one hand, for example, when your other hand is occupied with an external flash.
Image stabilization system
The stabilizer compensates for minor vibrations when shooting and allows you to get sharp shots. This is true for shooting in low light, when the shutter speed becomes short, as well as when shooting at long focal lengths - 100mm or more.
Lenses with a stabilizer are more expensive, but when choosing a primary lens, it is advisable to choose a model with a stabilizer.
If you have a stabilizer built into your camera, then, as a rule, the effect of the joint work of two stabilizers is enhanced.
Lens resolution
You will not find this characteristic in the description of the lens in the store. But you must understand what it is and what it is needed for.
Resolution reflects the detail of the image conveyed by the lens. Measured in the number of lines a lens can project per millimeter of sensor (or film). Accordingly, the more lines, the more detailed image you will get.
This parameter is relevant for matrices with a resolution of 40 megapixels and higher. Almost all relatively modern lenses are suitable for less.
Drawing
This is what they say about the picture that is obtained with this or that lens. Each lens has its own image and it can only be described by subjective sensations - sharp/not sharp, loose, etc. The bokeh of the lenses also differs.
This is a pattern created by the lens in the out-of-focus area. The wider the aperture is, the stronger the bokeh. Each lens model has its own individual bokeh.
Knowing the characteristics of the lens will help you choose exactly the optics you need. But when buying a lens, it is important to pay attention to possible defects in the optics. Read about them in our article - “Optical image defects“
Basic criteria when choosing a lens
It's quite common to hear the following statement: "This is the sharpest lens I've ever used." But how do you know which lens is sharp and which is not? And is sharpness the only criterion for choosing a lens?
In this article, we will introduce you to the main criteria for evaluating lenses and tell you how to properly test them.
Criteria
Before purchasing a lens, you need to determine the criteria for its selection. Subjective assessments such as ease of use, appearance, and versatility of a lens are very important, but they cannot be measured and evaluated.
It is also necessary to take into account other parameters that can be checked:
- Lens sharpness
- Lens aperture (F/2.8 is less than F/5.6, and the lower the f-number, the better)
- Minimum focusing distance
- Number and type of lens elements
- Can be used with film cameras only, digital cameras only, or both (lenses designed specifically for use with digital cameras are not always compatible with film cameras)
- Lens Flare (the effect of sunlight hitting the camera lens - flare)
- Number of chromatic aberrations
- Bokeh (the part of the image that is out of focus in the photo)
- Vignetting (darkening around the edge of an image)
- Lens weight
- Lens design and assembly standards
- Focus speed
- Image stabilization
- Ergonomics
- Price
Now let's look in more detail at each parameter and the possibility of assessing it.
Sharpness. How can I check this parameter? You need to attach a newspaper to the wall and illuminate it from both sides using two powerful lamps. Place your camera on a tripod and set the exposure according to the distance scale on the lens or using autofocus. Set the minimum shutter speed possible under the given lighting conditions and choose the largest aperture (smaller F number). Then take several pictures at different apertures to compare the results.
Now compare the images at 100% magnification. Pay attention to the level of sharpness in the center of the image and at the edges of the frame. Even low-quality lenses provide good sharpness in the center of the image and blur at the edges. Compare results with different apertures. They will be different.
In this way you can evaluate the sharpness of your lens.
Lens aperture is a parameter that is very important when shooting in low light conditions. A large aperture is also an indicator of the high quality of the lens. Most manufacturers use the best optics in their lenses. If you have the opportunity, we recommend buying a lens with a large aperture. It should also be taken into account that lenses with a constant aperture value (for example, a Sigma 300-800 lens with an aperture of F/5.6 at any focal length) are superior to lenses with a variable aperture, when the lens aperture changes with the focal length.
Minimum focusing distance. This parameter is very important when choosing a lens, but only you can know what minimum distance you will need to shoot. As a rule, high quality lenses have a fairly short minimum focusing distance, but not always. To check the minimum focusing distance, measure the distance between the focal plane of the lens and the subject. Manufacturers do not always provide accurate data.
Lens elements. The performance of a lens directly depends on the material from which its elements are made. Using low dispersion glass in lenses reduces chromatic aberration, which negatively affects image contrast and sharpness.
Apochromatic and aspherical elements reduce distortion and add contrast and sharpness to images. The more such elements in the lens, the better. In this case, you will have to trust the manufacturer, since you will not be able to disassemble the lens to check the presence of certain elements in it.
Digital camera lenses are not compatible with all digital cameras and are completely incompatible with film cameras. Before you buy a lens, check whether it can be used with your camera. Some lenses will only work with APS digital cameras. Such lenses can also be used with full-frame film cameras. However, they are not compatible with full frame DSLR cameras. Therefore, if you shoot with both digital and film cameras, do not use lenses designed only for digital cameras.
Lens Flare. These are glares that appear in images taken under backlighting. The lens flare effect is not noticeable in the viewfinder eyepiece and results in a decrease in contrast. Professional lenses have special coatings or attachments to suppress the lens flare effect.
You can test the lens by photographing the subject in backlight.
Chromatic aberration. This defect in the form of a color fringing or halo that appears around contrasting objects is typical for lenses with low dispersion glass. In this case, the image does not look bright enough. This defect is easier to notice when using larger apertures.
You can check your lens for chromatic aberration by taking a few shots in an open area, focusing on a high-contrast object. Chromatic aberration can be seen when the print is enlarged.
All lenses have chromatic aberration. You can correct this defect in Photoshop or using a professional lens, and the correction is minimal.
Bokeh. A term describing the subjective artistic merit of a portion of an image that is out of focus in a photograph. The characteristics of bokeh can be determined through the blur discs. Outside the focus area, each light point becomes a disk. Take a few photos of greenery or forest at least 4.5 meters away from the camera. Now look at the background of the photo: if you see a disk with bright edges, this means that your lens has poor bokeh. This parameter is very subjective and in this case, the higher the lens aperture, the better the bokeh.
Vignetting. You can test this lens setting by taking a few pictures of the sky outdoors. In an image taken with a lens with good vignetting characteristics, the lighting should be uniform across the entire image area.
Lens weight is a parameter that can be checked very simply. You need to compare the weight of the lens with others, so you can choose the lightest lens in this category.
Lens design and assembly standards are criteria that will help you determine the strength and durability of your future lens. Cheap plastic lenses are inferior to magnesium alloy lenses. Lenses with a metal mount do not deform, which cannot be said about plastic mounts. Sealed lenses are less susceptible to the negative effects of dust and humidity than non-sealed lenses.
If a lens seems cheap, it probably is. The lens shouldn't be heavy, it should be durable and meet build standards. It is these criteria that underlie the quality of the lens.
Focusing speed is a very important parameter for some shooting scenes. Since most 35mm film lenses have an autofocus system, you want the lens to focus quickly and accurately. To check this parameter, you need to take several pictures with the lens you are testing. In this case, you will need an assistant who will time the time using a stopwatch. Set up a signal in your camera to indicate that the camera is fully focused. The assistant must start the stopwatch at the same time as pressing the button to start focusing. Stop the stopwatch when you hear the beep. The time from pressing the shutter button to the signal is the autofocus speed. The less time it takes to focus, the better.
The image stabilization system is more typical for professional lenses. If you are using a long focal length 300mm lens, image stabilization is a very important parameter. But not all stabilization systems are the same. For example, Canon has three versions of the stabilization system, Nikon has two. Tripods are also used to stabilize the image. Therefore, before you buy a lens with image stabilization, check how it works.
Ergonomics manifests itself in the ease of use of the lens. Do the focusing rings turn easily? Does the lens feel comfortable in your hands? Can you easily rotate the polarizing filter when the lens hood is attached? All of these questions are very important when testing a lens, and the quality of the pictures taken with this lens depends on the answers.
Price is one of the determining factors for every photographer. We recommend comparing all the above criteria and comparing each with price. A lens with three ED glass elements costs much more than one with one element. Perhaps in this case, for your type of photography, a lens with two elements made of low-dispersion glass will be the best option.
We recommend that you always be critical of the price. You need to know what you are paying for and what you need from the lens.
conclusions
When testing a lens, you need to keep in mind that modern optics are an order of magnitude superior in performance to lenses that could be purchased 30 years ago. The cheapest entry-level lenses are now much better than the most expensive professional lenses of the time. Modern lenses feature improved zoom technology and autofocus systems.
Before choosing a lens, we recommend that you carefully study each of its parameters and, with all this knowledge, make the best choice. And if some “Internet genius” on one of the photo forums sharply criticizes your choice, you can safely ignore him if he cannot name all 15 criteria for choosing a lens.
Testing the lens before purchasing
How to properly test a lens when purchasing it.
In this small blog, I’ll tell you how to check a lens in a store so that you don’t feel sorry for wasted money, nerves and spoiled mood.
After reading a lot of information, listening to a lot of advice, you decide on the choice of that very lens (camera). Clutching the required amount of money in your hands, you rush to the store where there is a limit to your current aspirations.
Now the main thing is not to rush - the lens is a fragile and quite expensive thing, so the choice must be approached extremely scrupulously. As soon as the seller brings out the box with your product, do not rush to the cash register and pay. I advise you to take a few simple steps that will help you avoid buying a faulty product.
So:
1) Carefully inspect the packaging! The box should not have any dents, abrasions, or traces of exposure to moisture or dirt. The presence of such damage indicates that the product was not stored properly in the warehouse, which can lead to lens failure.
2) Having opened the box, also carefully inspect the delivery package - everything should be in stock according to the list that is present in the box (it is usually printed in the lens passport). The manufacturer's warranty card must have the proper form and markings.
3) Inspect the lens itself for damage. There should be no scuffs or stains on the lens. The markings must be clear and free of blurring and defects. All rubber bands and O-rings must be in place and free from play or damage. If the lens has a variable focal length, then check the operation of the zoom - the zoom ring should rotate with the same force throughout the entire stroke. At the maximum zoom level, also inspect for dust and other elements.
4) Remove the protective covers and carefully inspect the lenses and the inner surface of the lens. There must be no traces of dust, moisture, oxidation, foreign inclusions in the lenses (bubbles, small particles), abrasions or scratches. Inspect the front lens to ensure that the protective coating is even and free of damage.
5) Mount the lens on the camera. After turning on the camera, check the functionality of all lens modes (Manual and automatic focusing, stabilizer operation, aperture operation, zoom function). Take a few test shots and listen to how the internal mechanisms of the camera work.
Now the most difficult part of the test is checking for front and back focus.
What it is. Front focus is when the lens focuses in front of an imaginary focus line (the subject of focus). Back focus is when the lens focuses behind the focus line (the subject of focus).
You can check this quite simply and quickly. First, prepare your camera:
a) turn it on and set the shooting mode to aperture priority (the mode is usually marked A, Av),
b) set the photosensitivity to 100 units. (ISO 100), maximum image quality,
c) set the autofocus mode to “Single Zone” or “Central” (this may be called differently on different cameras),
d) set the focus point - focusing on the central point,
e) The aperture value is set to the minimum value (maximum open).
As a target, you can use test targets that are available in almost all stores selling photographic products, if not, you can download them from the Internet
(I did just that).
Take a photo of the target from the minimum distance supported by the lens at an angle of 45 degrees (it is advisable to use a tripod for more accurate focusing). If the lens is a zoom lens, then take several shots by changing the focal length - before shooting the target again after changing the focal length, focus the lens on a different object, and then focus on the target again.
Download the resulting images to your computer or other device with a large screen. Look at the result. If the lens focuses at the focusing point / (it is indicated on the target)
(the focusing area is shown in red, the focusing area is shown in blue), then everything is in order and you can safely pay for the purchase of this lens.
If the focus is lower
focus - then I would not recommend purchasing this product and would ask the seller to provide another copy.
That's all. I wish you a successful purchase and success in shooting.
PS If a store refuses to give you this test, then just leave the store!
Sorry, I don’t have a photo of the front and back focus (my lens works fine) - I had to download it from the Internet
Dear users - if you put a minus, then it is advisable to comment on such an action.
Assessing the quality of the lens
Quality standards in commercial photography.
Published with kind permission of Stanislav Perov
Short review.
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| Commercial photography places particularly high demands on the technical quality of photographs. Photographs intended for commercial use often serve as the face of a product or service, a way to promote it, and they are often printed in large format. It is not surprising that companies that buy photographs want to purchase only the highest quality product, they are not interested in the difficulties that the photographer encountered during filming, the details of computer processing, etc. things, the main thing is an excellent result.
In this article we will talk specifically about the technical side of photography without analyzing the idea, artistry, composition, etc. In addition to the above goal of “pleasing the buyer,” strict technical control of photographs has another useful function: it disciplines the photographer. Having initially understood what a quality standard is, in the future it is much easier to improve your skills, violating some principles, creating more non-standard things. Another way: initially ignoring the technical quality of photographs, in the expectation that, for example, the artistry will “pull out”, is quite dangerous, as it often leads to the uncontrolled and unreasonable use of any techniques and effects. Ideally, the artistic beauty of a photograph should be combined with its excellent technical quality. Since most modern photographers work with digital cameras, this article discusses digital photography. Among digital cameras, there are devices of completely different classes: costing from hundreds of dollars to tens of thousands. It's no secret that the optimal choice for most commercial photographers is a digital SLR (reflex) camera. Inexpensive compact cameras, also called point-and-shoot cameras, are too limited in functionality and do not allow you to take high-quality photographs. The most advanced medium format digital cameras are too expensive for most photographers, and the circle of specialists working with them is very limited. Therefore, this article will consider the most versatile, quite affordable and capable of obtaining images of very decent quality digital SLR cameras. Thus, in a more comprehensive manner, you can add “. for digital SLR cameras." However, the quality of photographs obtained with the best modern models of SLR cameras is quite suitable for the majority of both viewers and buyers, so the material presented below is quite universal. Below is an overview of the main technical details that a photographer should pay attention to. Almost all photographs are shown without processing and adjustments in a RAW converter, except for some where this was necessary. In those examples where, in addition to the image itself, individual fragments of it are shown, the scale of these fragments is always 100%. Having finished with the introduction, let's move on to the essence of the issue. Help me evaluate the quality of a Canon lens.Let me try the Kenon 17-55 lens, help me evaluate the quality of the pictures from it. I'll post a link to the photo now. Ivan Petrov, Alexander Popov, thank you for your opinion! Good average lens. If you don’t plan to switch to full frame, use it for your health. Requires careful handling - no dust, no moisture protection, obviously cannot be dropped. I haven’t personally come across it, but some argue that it is necessary to check for defects and defects when purchasing. Maximilian Skobichevsky, so I’m trying to check the quality of the picture of a specific specimen I’m not a Muscovite, but you can ask an experienced friend, or a decent acquaintance who shoots with such a lens, to help check it when purchasing, so that later you don’t have to run around to service centers. Don't be offended, but it's hard to judge this particular lens based on these pictures. Ivan Petrov, PS To be honest, I’m not sure that this is the most convenient zoom from Kenon, and at the same time it is the most expensive crop lens. Based on my experience, I really missed the kit 18-55; I had to change lenses on the fly. Only if the price is somehow good... I would recommend the 15-85 IS, it is noticeably cheaper and, in my opinion, more convenient. It’s probably hard to come up with a better zoom for crop. And excellent sharpness. Although 17-55 has its charms, obviously. PS It’s best to read about lenses first-hand here https://www.artem-kashkanov.ru/lenstest.html Maximilian Skobichevsky, Ivan Petrov, Well, if I’m Mowgli, then you’re probably Shere Khan, or Tabaki? Another writer. PS I wrote to you, as a person, don’t shit, don’t be ashamed of the shit... And you, oops... Your number will soon be 5. Not yet, but it’s getting close. After loading on board it will be late to rush about.. https://upload.wikimedia.org/wikipedia/commons/a/a2/Jheronimus_Bosch_011.jpg Gerhard Neufeld, Ivan Petrov, Alexander Popov, thanks for the detailed answer! How can I check the lens? Assessing the quality of the lens Link to main publicationFor any suggestions regarding the site: [email protected]
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At the same time, they were called beginners, that is, with little experience. At the same time, you are trying to advise ANYTHING on the substance of the question posed, which is not comme il faut. That is, you are purely showing off as some strange aspiring guru. I understand that we lived in a country of Soviets, but we need to end this. If you have nothing ESSENTIAL to say, don’t blow people’s minds. Or, if you do, then study and look for the necessary material. Otherwise, you will remain chronically unlucky with websites. You are our Mowgli.. By the way, do you know that in the original source Bagheera was a male panther? 
Soon they'll probably be allowed to smoke at home... I'm tired of raising you, someone else's child. My delicacy may come to an end. Dreamer.. You need to go to the site of fiction lovers, not in the photo. You write a lot, even too much. but you don’t take photographs. I have met people who have developed creative potential, but a complete failure with intellectual potential. And education is lame. This cannot be said definitely about you yet, since you show a lack of intelligence, but no presence of creative potential.. 