How to test the out of focus of the Tenglong lens
Taking the Tenglong 35/1.4 lens as an example, the test of out-of-focus can be carried out according to the following steps: First, the shortest focusing distance of the lens must be determined (for example, the shortest focusing distance of the Tenglong 35/1.4 lens is 0.3 meters or 30 centimeters, which is the distance between the sensor and the subject). Use a tape measure to ensure that the distance between the center of the test card and the sensor is the shortest focusing distance to obtain an accurate test result. Then, adjust the lens aperture to the maximum and shoot at the center of the test card. Check the results to determine if the lens is out of focus and the amount of deviation (for example, the lens is shifted back by 8mm in the example). In addition, for other lenses of Tenglong, a similar method could also be used. For example, for lenses that were about 1.5 - 2 cm away from the focal length 17 and had a regular change in focal length, a similar test method could be used under different focal lengths. During the test, you should pay attention to the influence of different factors on the amount of out-of-focus.(For example, it is found that the out-of-focus of the lens does not matter whether the optical anti-shake switch is on or off, but the law changes when the aperture size changes). Read more exciting novels for free
Tenglong lens maintenance
For Tenglong lens maintenance, please refer to the following contents: 1. ** During inspection **: - If you want to disassemble the back cover of the Tamron single-lens reflex camera to check the lens, you need to gently remove the four small screws on the back cover. Pay attention to the possible cable on the cover. Do not break the cable when you open the cover. Then, he removed the three layers of pads under the lid. At this time, the back cover was connected by a circuit board. After removing the screws and wires used to fix the circuit board, the back cover could be removed to see the lens. 2. ** When cleaning the lens **: - Observe whether there is dust or mold inside the lens. If there is, use cotton cloth or good quality napkins to clean it. If possible, it is best to use a cleaning tool for the lens, and pay attention to avoid scratching the lens during the cleaning process. - When the connection between the camera and the lens failed, first check if the connection was accurate and if there were any obstacles. If there were no problems, you could use a cotton cloth to clean the contact points of the lens, because it might be a problem caused by mold. 3. ** When the lens is damaged **: - If the motor in the lens was damaged, they could go to the shop to get a motor of the same model and replace it. If the lens itself was damaged, the price might be more expensive. It could be matched with a lens of the same model in a professional shop, and then the damaged lens could be removed and replaced with a new lens. However, if the lens was damaged, it was best to repair it at a professional repair shop. 4. ** When the compact flash card fails **: - If he found that the compact flash card was faulty, he could remove the card and then re-install it. If that didn't work, he could only format the compact flash card. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Domestically-made Tenglong lens
Tenglong was a Japanese optical equipment manufacturer. It was not a China brand, so there was no domestic Tenglong lens. Tenglong mainly engaged in photography products, surveillance and FA lenses, as well as mobile and healthcare products. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Tenglong lens correction information
Some Tenglong lenses support the built-in lens correction function. For example, Tenglong's top APS-C frame micro-single lens is compatible with the built-in lens correction function of the body; Tenglong 28 - 200mm lens can be easily corrected with Tenglong's lens configuration file; Tenglong B070S 17 - 70mm F/2.8 Di III - A VCRXD lens includes lens correction in the body. In addition, the 70 - 180mm F2.8 Di III VXD lens part of Tenglong had insufficient performance of the floating mechanism used to correct the curvature of the imaging surface. The affected products could be identified through the official website by checking the serial number. Tenglong would provide recalibration or lens replacement services for the affected users. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Excellent landscape photography lens Tenglong
Teng Long had several lenses suitable for landscape photography. The Tenglong 20mm F/2.8 Di III was an ultra-wide-angle lens that was compatible with the full-frame micro-camera of the Sony-brand. It was worth recommending for scenery photography. It was light and small, easy to carry outdoors, and its focal length was suitable for shooting scenery and portraits. It had a good focusing feel, fine and smooth damp, simple sealing, and an all-metal lens body, suitable for a variety of shooting environments. Inside the lens were nine sets of 10 optical structures, including GM glass cast aspheric lenses and LD low-dispersion lenses, which could effectively suppress color aberrations and reduce distortion. The front lens has BBAR wide-band anti-reflective coating, which can avoid ghosts and glare in the sun. The effect of background blurring was good at the maximum F/2.8 aperture. The scenery shot at a reduced aperture of 2 stops was sharper and the colors were more natural and saturated. The quality of the image was maintained at a high level within the F/10 aperture range. It was no problem to shoot night scenes. Tenglong 50 - 400mm F4.5 - 6.3 E-mount lens. Although it lacked a wide angle, the overall image quality was good. It could be used for landscape photography, and could also be used as a tourist head or street sweeping lens. It weighed only 1155g and was relatively light. The Tenglong 28 - 200mm F2.8 - 5.6 E-mount lens had a wide focal length range and good image quality. The 28mm aperture at the wide-angle end reached F2.8, which was suitable for traveling and shooting outside to reduce the weight burden. The Tenglong 18 - 300mm F3.5 - 6.3 lens had excellent image quality and was light. It was a good street sweep for the users of the half-frame and Fuji cameras. It could also be used for landscape photography. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Tenglong lens inquiry old and new
Taking the Tenglong 28 - 75mm lens as an example, the model A036 28 - 75mm F/2.8Di III RXD released in 2018 was the first generation product. In 2021, the second generation product 28 - 75mm F/2.8Di III VXD G2 (model A063) was developed on the basis of the first generation product. The second-generation product had improved in terms of image quality and resolution, close-up performance, design, AF-mode speed, and custom functions. In terms of image quality, the optical system was re-designed, and the image from the center of the picture to the edge of the full-focus segment was sharp. In terms of close-up performance, the nearest shooting distance at the wide-angle end was shortened from 0.19m to 0.18m, and the maximum photography ratio was increased from 1:2.9 to 1:2.7. In terms of appearance, metal parts were added inside the zoom ring and the focusing ring, and the outer surface was newly painted, which made it difficult to scratch and leave fingerprints. The handling performance and appearance texture were improved. The AF-speed was about twice that of the original product. The lens could also be customized with various functions through dedicated software. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Focus the lens
Theoretically speaking, lens focusing was to change the image distance (v), which was the distance between the lens 'optical center and the film plane. For a microscope, it was the process of adjusting the distance between the objective lens and the object to obtain a clear image of the object. In a camera, focusing (focusing, focusing) was to adjust the focus of the lens to the exact position of the subject to take a clear picture. Whether the subject was still or moving, accurate focusing could ensure that the subject was clear. Except for some low-end camera lenses that could not change the image distance because they did not have a focusing mechanism, other lenses, whether fixed-focus or zooming lenses, could change the image distance to get a clear image. In lens imaging, the image has the clearest position on the screen (camera film or sensor). Countless such points form the focal plane. Focusing is to change the front and back position of the focal point to satisfy the imaging formula 1/u + 1/v = 1/f (u is the object distance, v is the image distance, and f is the focal length), so as to form a clear image on the film. When shooting distant objects, the object distance was far greater than the focal length, and the image distance was close to the focal length and almost unchanged. At this time, the concept of "depth of field" was also involved to ensure the imaging effect. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
How to test the resolution of the lens
There were several ways to test the resolution of a camera: 1. [** Iso12233 Chart Test **: This is a common test method.] 2. **TV Chart Detection **: The Chart is in the shape of a fountain, which is more intuitive and can be judged by the human eye. However, the TV line test would cause the reading value to be unstable due to different people's reading and different states. Moreover, the line pair number read by the Iso12233 chart could only represent the reading position, especially the TV line in the center. It was difficult to reflect the resolution of the imaging system at different positions. Generally, the human eye can only read the approximate value of the line pair, but you can also use the line pair measurement software such as HyRes to measure the accurate value. 3. **MTF Chart Test (Modulated Transfer Function)**: Test using a line with the corresponding line width. The MTF value was a ratio between 0 and 1. This value was based on a given spatial frequency (black and white lines). It was a comprehensive evaluation of the sharpness, contrast, and resolution of the lens, reflecting the overall performance of the lens and chip. Testing MTF required special equipment. First, there must be a very small luminous object, which was used to image through the lens to be tested. Then, a suitable high-power objective lens was selected to magnify and image it on the device's CCD-or CMOS-camera. The image was transmitted to the computer and analyzed by special software. Finally, the MTF was calculated by the Fourier-transform. There are three types of light sources used to test MTF: point, slit, and edge. - Point light source: An ideal point light source can be regarded as an infinitely small object in the XY direction, and the energy distribution is expressed by a two-dimensional pulse function. An ideal point light source will form a diffuse spot after passing through an aberrated optical system. Its light intensity distribution is the impulse response (point spread function) of the optical system. - Slit light source: Because the energy of a point light source is weak and it is difficult to obtain an ideal point light source, slits are often used to produce a line light source. The multiple point light sources were arranged along the y direction at an infinitely small interval to form a one-dimensional light source. Each light emitting point was incoherent, and the equivalent slit was regarded as a constant in the y direction and a variable in the x direction. The light intensity distribution along the x-direction of the slit is the line spread function LTF. The slit had a higher measurement accuracy than the point light source. - Edge-edge light source: used when the energy provided by the slit is insufficient. The MTF is indirectly calculated by deriving the LTF from the edge spread function ESF. However, if the edge is differentiated more than the slit, the noise will increase. 4. ** FFR Chart Detection **: Use the slanted side chart, which is more abstract. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Soft focus artistic lens
Soft focus artistic lens was a kind of lens that could produce soft focus effects. For example, the Daguerretype Achromat 2.9/64 Daguerretype soft-focus art lens had a focal length of 64mm and an aperture of f/2.9 - f/16. It used the Waterhouse aperture system, with Canon EF mount, Nikon F mount, etc., which could be used with a variety of cameras. It could shoot different effects through different apertures. For example, if you used the f/2.9 aperture, you could shoot a transparent soft focus image. If you switched to the f/5.6 aperture, you could get a sharp and clear image. In addition, there were also special aperture films, such as the Lumière aperture film, which allowed the image to be surrounded by natural soft light, and the Aquarele aperture film, which could produce the effect of oil painting strokes. Soft focus artistic lens could be used for portraits, scenery, and other photography. It could make the subject's focus clear, soft, and beautiful, and take photos with unique artistic effects, such as increasing the softness and haziness of the image, adjusting the tone, and reducing the contrast. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Nikon 7200 manual focus lens
There were some key points when using a manual focus lens on the Nikon D7200. Some manual focus lenses may not have the integrated Nikon manual lens focus prompt function. On the Nikon D7200, although the 50mmF1.8D lens did not have a body focusing motor, it could use the D7200's body motor to drive the lens focusing component to achieve autofocus. When the D7200 could not autofocus, the possible reasons included the focus distance exceeding the closest focus distance of the lens, the camera was set to manual focus mode, the focus point of the telephoto lens was not suitable, there was no obvious light and dark boundary near the focus point, the light was too weak, the focus screen was shifted, the focus screen was blocked by dust, the camera was seriously out of focus, the focus unit was damaged, and so on. In terms of manual focus, for example, when shooting star trajectories, the focus mode can choose single-point focus.(landscape, portrait, or building, etc.), adjust the camera shooting mode, choose the lighting angle, use the raw format to balance the light sense to achieve the best effect, and pay attention to the image quality. During the focusing process, gently press the shutter and wait for the focus to be completed before completely pressing the shutter to shoot; You can also turn the mode dial to M, turn the main command dial to select the shutter speed B (bulb), turn the auxiliary command dial to select the aperture, press the shutter button to start the exposure after focusing, and press the shutter button again to end the exposure. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Testing standard for lens test card
The following are the test standards for some lens test cards: - Clarity Test Card: - ** Used to evaluate the camera definition **: The definition test card is a standard sample. It can provide auxiliary tests such as vertical resolution and horizontal resolution to evaluate the camera definition under various illumination conditions. - ** Requirements for relevant parameters **: The test card used should be close to the standard of the photographic resolution of the 135 camera used in China through the photographic film. Generally, the reflection density of the black line of the target plate should be greater than or equal to 1.60, and the reflection density of the white line should be less than or equal to 0.10. The density difference between the black and white lines should be greater than or equal to 1.50, and the contrast should be 1:20. - ** Horizontal definition calculation **: If the horizontal definition is expressed by Rh1, the vertical height of the picture is expressed by V, the horizontal length is expressed by H, and the horizontal length is expressed by m, then the horizontal definition Rh1 = V×m/H (Usually, the ratio of V to H is 3/4, which is 0.75). - ** Iso12233 resolution test target **: Comply with the standard of Iso12233,"Photograpy-Electrophotographic Image-Measuring Method". It is an essential tool for camera lens quality testing. It is the most authoritative measurement method for testing lens resolution, but the testing conditions are more demanding, such as color temperature, temperature, and illumination. If you want to print it yourself, it is recommended to print it on A3 paper, the highest precision and good printing paper (generally 80G printer printing paper is fine), because the ink on the general printing paper may be slightly melted. - ** Color reproduction test standard color card (used for lens color reproduction test)**: - ** Test environment setting **: Place the color card under uniform lighting to ensure that the lighting conditions are stable and consistent. Then use the lens to shoot the color card to ensure accurate focusing. - ** Comparing method **: Comparing the photo with the color card to check whether the colors are accurately restored. You can also choose a colorful scene to shoot, such as flowers, scenery, or artwork. Then compare the photo with the actual scene to observe the accuracy of the color restoration. When shooting, try to use the standard color temperature (such as sunlight) to shoot. You can also test different white balance settings (such as automatic white balance, sunlight, cloudy day, tungsten lamp, etc.), shoot the same scene under different lighting conditions (such as sunlight, cloudy day, indoor lighting), and compare the photos to observe the color reproduction performance of the lens under various lighting conditions. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>