Although there are widely used

zoom lens, composition convenience, a multi-purpose lens, etc., but there are many places is less than fixed-focus lens.For example: shooting strongly backlit scenes, as a result zoom lens has a complex structure, prone to reflection and glare; at close range photography, it will produce vignetting, edge of the screen brighter than the center at the end of such phenomena.If the lens quality and worse, the more obvious of these phenomena.Therefore, the choice should note the following:

1, smaller than the good

zoom magnification from the image quality and manufacturing cost considerations, zoom magnification should be as small as possible.Zoom zoom magnification is the focal length of a long side and short side ratio of focal length.Such as a 35-70mm lens, the zoom ratio is 2:1.For starting from the wide-angle zoom lens, its magnification is a little more is better.

if a buyer is less than 28mm focal length of the zoom lens, the greater should be carefully selected, because it more difficult to design and manufacture of the lens.The best choice for a smaller rate of change Jiaohao lens.

If you purchase more than 70mm focal length zoom lens, you can point to consider a larger zoom range.

not like this three times zoom lens, both for easy frame composition, but also to ensure the quality of the lens is our most worthy of consideration when matching the lens zoom magnification.

2, faster lens is better than slow

"fast - slow" means the maximum aperture size, zoom the sooner the better, that is, the bigger the better maximum aperture.

In general, the maximum aperture zoom lens should be able to achieve F4, of course, also can be F5.6, the present single-lens reflex cameras are aperture fully open the case of focus, soaperture larger the more bright viewfinder, but also easier focusing.At the same time the fire of the small maximum aperture the lens is the lens to reflect the level of an important indicator of manufacturing, even if the shot using the same F5.6 maximum aperture F2.8 lens certainly higher than the maximum aperture F5.6 lens imaging quality.

Nikon50mm lens with F1.8 maximum aperture shooting.F1.8 large aperture in the circumstances, the actual situation is very obvious contrast, beautiful.

3, simply better than the complex

compared with the same type of lens, a camera lens little as possible, the mirror group structure as simple as possible, its effect is more remarkable shooting.

a typical 35-70mm zoom lens of about 12, divided into 10 groups.Between groups for each piece each 2 "air a lens" contact surface, then, 10 groups had 20 surfaces, which form a 190 axial reflection - known as "ghosting."Only a group of nine lenses, 18 contact lens surface, the formation of the corresponding 152 "ghosting"; and 11 lenses in 22 groups lenses contact surface to form a 231 "ghosting."

In addition, if coupled with color filters, you can make "ghosting" the number has risen sharply.Thus, in theory, choose the structure of the lens as simple as possible.However, with the optical technology to improve the camera "ghosting" phenomenon has little of.

4, longer than the short-good

Nikon Macro lens photography

a weight of 560g, volume 75 × 1045mm lensbrought along a little bit heavy, but can a flower show is going so well, and then also the value of hard work!

If the pursuit of high image quality based, then the lens barrel or a longer and better.In order to ensure image quality, zoom lenses pre-and post-lens distance should be a long focal length 2 times the side, that is, a 35-70mm lens, its length of around 140mm is best.Unfortunately, this means that now these latest lightweight full-and middle-zoom lens aperture in use when the shooting results not as good as their "predecessors."Of course, this is important for whether or not also depends on the purpose of taking photographs.If just the photo printed postcard size, then these tiny lenses can make a person completely satisfied.If you want great pictures more freely, or will use photographs taken by fixed-focus lens and the use of zoom shot mix up to watch the slide, then, is to buy a tube length of the lens is better.

5, better than the last

if just from the image quality considerations, try not to buy can be close-focus zoom lens.Because make zoom in zoom process to maintain a clear focus, take a very complex mechanical structure.

recent focus distance of the lens should be at least 10 times as long focal length side.Thus, a 35-70mm zoom lens of the closest focusing distance can only be 0.7m.This time, things like the ratio is 1:8, if the past, it will create a noticeable decline in the clarity, so a lot of zoom lens has a 1:4 macro close-up capability, are in fact beyond the limits of optical quality,at the expense of the quality of the cost of the lens to get.

use the Canon Macro lens photography

a small drop on the morning grass, when shooting at close range, even become so beautiful.

Attachment: Lens appearance quality and performance testing

buy the lens, in addition to the camera, the image quality tests, but also test the lensappearance and performance, depends on whether it is supporting the use of the camera.Only through a comprehensive examination, in order to detect hidden faults and help to select the desirable lens.

1. The appearance of the mechanical system testing

lens mechanical systems are mainly: barrel, aperture blades, aperture adjustment ring, focus ring, zoom ring and the relevant regulatory agencies.

① lens surface

the outer surface of the lens should be smooth, no bump marks, no scratches, no wear, no rust, no Mildew; plating layer should be no yellowing,No rust, no peeling of the phenomenon; decorative leather should be smooth appearance, no tilt.Surface coating should be smooth, non-shedding and non-obvious phenomenon of uneven color.

② Lens Internal

the surface of the lens within the mechanical system should be black, matt, black lacquer layer should be no fall off the surface of the screw thread and the lens ring and some other pressure should be intact,No traces of the demolition.

③ aperture blades

repeatedly rotating aperture ring, so that a small aperture close to open big, check the aperture blades before and after the surface whether there is oil, and rust.

oil will make the activities of aperture blades not working, and even sticky death, but also affect the flow of light through the lens, so that the photographer fell as the resolution, which is due to the lens assembly when the fuel excessive overflowcaused by the leaves.

In addition, when the aperture receive the most hours, but also look at whether the rules of light through holes.The rules of light through-hole or not is a reflection of the level of manufacturing process.

④ tube and adjust the ring

tubes, and adjust a variety of ring gauge lines, numbers and letters.They are either directly printed on tubes, and adjust the ring, and some showed depression-like, whatever the process, gauge lines, numbers and letters should be clear and beautiful.

Also, gently shake the hand lens, should be no strange noise.If "karaoke, karaoke," the sound, we should note that it is due to the lens pressure ring loose, causing the collision sent the lens movement of sound.Lens movement may cause the lens can not be co-axial, resulting in significantly increased aberration, lens imaging quality (eg, focus the lens clarity) was significantly decreased and so on.

2.the appearance of optical system testing

lens optical system including: lenses, mirrors, built-in color filter.

① transmitted light test

open the lens aperture to the largest, so that the light from the lens front or rear of Objects Launched into the lens, and from the other side of the lens to observe the internal optical groupspieces, each lens should meet the following conditions: clean, no cracks, no collapsed edges, no open glue, no mildew, no bubbles, no scratches, no oil, no fingerprints, no debris.

② reflected light test

the lens front and back slightly biased Well-Lighted Place, and from observation of the lens lateral surface of the lens reflected light to examine parts of the lens reflectorThe coating layer micro-scratch marks whether the phenomenon of choice lens usually pay attention to the following questions:

  • cracks are usually due to the lens by Shuaidie, collisions, etc. caused by violent shaking.
  • collapsing edge is the edge of a broken piece lens.
  • open gum is a result of collisions or by the severe shock caused by sudden changes in temperature.
  • moldy is the irregular shape of the surface of a lens material of cotton wool.Mildew is often because the storage environment, humid, the heat, lack of ventilation caused by lens surface, the breeding ground for mold.
  • bubble is the lack of quality optical glass itself.There should be bubbles on the lens, especially the center of the lens should not have a clear bubble.
  • scratch the lens when cleaning is often caused by improper methods.
  • oil is the assembly parts to the mechanical friction caused by excess fuel, lubricating oil overflow into the lens surface stains.
  • fingerprints fingers touch the lens directly after James left the scene.
  • debris is attached to the lens surface of the villi, paint chip debris, dust, and left in the lens inside the metal debris and other debris is due to dirty assembly shop, assembly process is not strictmaking.

certain focal lengths or a distance of problems: Testing zoom lens and internal focusing lens, should turn the lens focal length zoom to a different segment to a different focus from the detailed examination.People often find the whole lens is very good, but the focus in a paragraph or a focus distance of Shique problems, so the selection must be very careful when you zoom.

3, the appearance of optical system testing

① Focus ring, zoom ring adjustment ring.

adjust the lens focus ring and zoom ring, the damping of the handle size should be moderate, and always smooth, uniform, neither dead point, Shibuya point, not too flexible, and more without loose rock, the reverse should be no air conditioning back feel.

automatically zoom zoom, when the positive and reverse the direction of automatic zoom, the zoom ring speed should be smooth, uniform, should not be suddenly fast suddenly slow phenomenon.

lens aperture ring and shutter adjustment ring positioning device should be accurate and reliable, neither too tight nor loose.The adjustment ring is not on their own shift, such as push-pull zoom lens and macro lens when shooting in the pitch, its zoom ring and macro adjustment ring would not have emerged due to self-gravity displacement phenomenon.

② aperture

aperture blades formed by the light-hole must be presented by regular polygons, non-shedding phenomenon.Rod under the control of aperture and open aperture contraction should be flexible and comfortable, the aperture adjustment ring transferred to F16 (or F22), the hand repeatedly Qingbo lens aperture shrinkage under the back-end auto, aperture after each contraction of light-hole shapeand size should be the same.If the lenses have depth of field predicted rod, toggle the rod when the lens aperture of the reduction should be flexible and comfortable Zhang, light-hole size should be very accurate.

③ the lens and body connection

lens should be closely connected with the body, reliable, locking device shall be locked in prison, there should not be wrong while loading and unloading due to size too tight,too loose, or pretend not to, the lock is not strong phenomenon.Seat tube and the body co-ordination of the lens should be close, no cracks, no wear, no loose, no shaking.The lens should be simple and quick loading and unloading.No loose tube between the various parts.

④ lens shutter

with a mirror between the lens shutter, the shutter between the lens should be accurate and reliable work, the blocking shutter speed should be very accurate, the shutter blades should be no oil.


This articlesource:Design and Material (http://www.q60.org),detailed reference to the above website.