70-200mm lens knowledge. .
We used a stage photography lens is 70-200mmf2. .8.. following that say it:.
Section 70-200 of this focal length lens has been the various critical battleground, the one is the focal length of the segment is very popular, second only to be sold as a standard focal length lens of 28-80 segments, success or failure solidarity on the life and death. Furthermore, the development of this section of the lens has been a long time, the optical structure has been well established, and in order to maximize the image quality of the lens to achieve a considerable level, virtually every family and the generous application of the image in the lens inside the focus, low dispersion high cost of technical glass, etc., a constant aperture so that the product is destined to become the high price of goods. .
However, the original manufacturer, there is no doubt their optical technologies is a leading, in order to meet the demanding professional user satisfaction, and their products in the mechanical and optical on the best level for a lens like this optical products, their most critical is to constitute the lens glass lenses. It is a well-known fact that a good German lens comes mainly from the use of short glass factory of optical glass, made the world's best optics products.
The camera no matter how hard the Japanese are still not a small gap, which is the power of the glass. Now for the original and the Deputy factory lens, also has such a claim. Lens Plant in Japan like Nikon, Canon, Pentax has its own glass so the lenses of the formulation and production process are highly confidential. In the deputy factory to produce the highest level of optical glass is Tokina, it's ED glass is used in many well-known manufacturers specified.But do not know why, tuli itself rarely use this upscale expensive material, but the production of large-diameter ED glass production, the top three in the world, like the single with a diameter of 300 mm price on 70000 yen or more, huh, huh. The world can have several of such capacity.
Another is the design capacity. In the optical, the Japanese design is undoubtedly the strongest ability to Canon's optical research and development center, especially in the last few years, Canon's pioneering work in optics are many, although not established with Chase than the classic structure of achievement, but applications is indeed leading the factory of 5-10 years. Very important in electron optics technology Canon has in many key patents with decisive force, like ultrasonic motor technology, the start of each plant patent Xian Yu, spent a lot of time in an attempt to develop a kind and The counter technology.Results in less than 5 years, including Nikon, Minolta AF these have the capacity to provide the camera manufacturers are already close to ultrasonic technology and comprehensive. (Until now, this trend is also being constantly being shown).
In Japan, there is a design and a strong reverse-engineering capabilities of the manufacturers - Sigma. This is a short history of professional lens factory, started a design center that came to rely on. Their strength lies in the capacity of the reverse design is very strong feeling that we should be, no matter what original introduction of new technology, he was always the first follow-up.The company's weakness is due to the history of production and management experience, they shot at an early stage are not durable, or poor-quality machinery, which is compared to the Dragon and sturdy, tuli really helpless; now there must be improved, but the impression of incidents, it can be reversed, not to mention today shima lens processing quality is still not and N, c, and so companies compete.
The quality of the lens lies in the low dispersion glass:. .
To emphasize low dispersion glass quality. Now the camera often said how much they use low dispersion glass block, however, the manufacturers of low dispersion glass is a high level lower.
Start with fluorite glass, which is now the best natural low dispersion of optical materials, the main component is calcium fluoride, which is a high chemical stability of chemical substances, acid and alkali, it is not easily dissolved in water . Because of this, very little natural crystal, artificial crystal is difficult, the biggest drawback is the fragile, difficult process, anti-vibration capability poor, so the military is the use of magnesium fluoride to replace him to produce infrared missile hood. The use of fluorite in the camera lens to produce lenses that only Zeiss, Leica and Canon.Other manufacturers are mixed with special low dispersion glass to achieve, on the one hand, the purpose of this is to minimize dispersion, another aspect is to avoid the use of calcium fluoride glass, so that the camera's ability to withstand harsh environments to reduce.
Since most manufacturers are using a mix of glass, the plant's products will inevitably bring about differences. In the mixed glass, Canon's Super UD is the best, it has close to the optical properties of fluorite, but there are ordinary optical glass processing performance and reduce production costs significantly. However, the application of the lens is not much, but with Canon's new products look like or can not replace the fluorite position. But relatively speaking, since the use of fluorite products may be less and less, should be replaced is the Super UD. .
Canon has a UD glass, and Nikon, Pan Pacific Comox, Olympus with ED glass is the same type of thing, this is far the most mature production technology products. But the fact that several of the optical properties of or not all the same, on the whole, can only say basically the same. Adoption of such quantity of glass, the comparability with sibling can be regarded as having the same efficiency.
For each deputy factory, their position and the right economic performance of the value, Shita Men's materials in the precious Zhezhongxiangdui Shiyong Shangyouliaoxie tone: Shouxian yes Tuliliyong Zijiqiangda of raw material production capacity and develop a one kind of Chengbengengwei low, with low dispersion material and widely used. However, such materials are also divided into several types: SD, SHD, etc.. .
Tenglong more cost that: their LD lens is not a generally low dispersion lens, only a low dispersion in..
For Sigma, the lens it also has several now widely used and also similar to the Tokina Tamron, but slightly higher than they, and the original, but still a considerable gap compared to. Sigma is also an ideal low dispersion ED glass is roughly equivalent to the glass, but only as far as I know it's 180 / 3. .5 Use of a macro lens, but The lens becomes very high prices, and the lost and the original products price competitive. .
The difference between low dispersion glass, including the pros and cons of the camera can also be seen from the structure: low dispersion glass should be used in the camera's most thick lenses. If this is not the case, and low dispersion lens use rarely, for example, only one piece, that is, just like the Nikon 70-300ED, it can be said to be lulled into a false sense of "gimmick" consumer behavior.
Moreover, such lenses as fluorite and other lenses generally can not glue, can be used independently, low dispersion lens is so good. Functional performance for the same lens design, lens The more outstanding, largely reduce the processing of each piece of a single lens difficult, more accurately correct all the aberrations, but it has the factory coating on the level of serious test. .
Lens for vacuum coating:.
Test run in Japan, now the world's production of various lens coating plant to Canon, Fuji, Rollei three best, they can easily produce more than 9 or more multi-layer coating. The remaining Pentax's SMC 7 layers, Chase T * 6-layer, Nikon mc, etc. are all very good. .
Vice factory lens coating is the highest level of the Dragon, it has certain than the original manufacturer of coating technology. But like Ricoh these manufacturers, including its award-winning GR1-28/2. .8 lens is 3 ~ 5 layer only. In much of the three lenses, Vice factory, shima. It's many film through efficiency slightly lower than other manufacturers, the trouble is, it's solid performance coating in high humidity areas has always been a lack of praise, such as Japan, Hong Kong, Chengdu, and so on. This is also why it's the lens with the ages, the performance degradation was an important reason. In the secondary market, Sigma's lens is often the most inexpensive and not that important. .
In telephoto zoom lens variety, choice a lot, but for really suitable and practical not imagine that much. For whatever it is for the amateur or professional, this choice is mostly on the distance should be 70 (80)-200 (210), or 100-300. Now all the 75-300, 28-200 zoom lens, the image quality, there is still a big problem, the Eagle both belong to a class of things.
The most promising is that everyone is 70-200/2. .8 Such a "big guy." Such lenses are now the best zoom lens inside the lens. Caliber, high image quality, but also the most commonly used and slightly sub-level of f / 4 product is the bottom line is acceptable. .
The common brand lens for simple evaluation:.
Following some hasty comments on several products, but his words will inevitably be too subjective, we would have a brick fly CAREFUL IN THE SUMMER. .
1. First of all say that Nikon, Nikon 80-200 this focal length segment launched a total of 5 generations, the earliest Ai-S very rare, the price performance has a mysterious, but according to the first generation of AF to guess should be comparable. AF version generation, second generation optical structure exactly, just to improve the mechanical design problems are two different products, they are mainly the position of the lens hood. Overall, this lens is very successful, in spite of the problems in the mechanical, Imaging is not responsible for the Nikon on down for many years. Things that are unique at that time, in addition to slightly behind the year's EF 80-200/2. .8 L, the back is also worthy of the name is Swordsman. .
Really perfect is Nikon's third generation AF80-200 lens, this generation of the original unreliable single ring structure into a ring structure, joined the (false) focusing, internal zooming, this is a mature product, which is now commonly known as "little Cannon fans (XGP)", the lens than the previous two generations on the image quality has been greatly improved, there are 3 block ED glass help, imaging, Nikon taste, in the sales price is also not use expensive policies, moderate price attractive, even a lot of uncertainty in NC-fans go, extraordinary charm.
XGP's fly in the ointment is the 200mm focal length large aperture the image quality degradation, as well as its focus outside under a large aperture imaging results less impressive, resulting in a lot of criticism. .
Later, in Canon's powerful offensive, Nikon introduced a new generation of again AF-S 80-200, but you can see that this is a very mature product, although the application up to 5 block ED glass, optical performance but very limited in many ways and last generation products. Although the focus faster silent ultrasonic motor, but the volume and weight are enormous, while holding on "brilliant!!", but the feeling to be able to carry a balance of only F5.
Seriously, this is indeed the standard of some of the optical lens to improve, particularly on behalf of people make up the focal length of section 200 has been criticized for the performance gap. But will you win some and lose some in the 80 than previous generations of anti-a, and this generation of imaging more and more to go soft line, "Nikon taste" less and less, many N home home unhappy. .
Therefore, before the launch of the VR Nikkor70-200mmf2 .8G AF-S., given the price and brand loyalty, the N first or will have AF 80-200/2. .8D ED New and should not be lower than the other climbing. Because the Nikon Nikon is, no, unique in the world.
Then talk about Nikon's "Life and Death enemy" - Canon. .
Canon after entering the AF times suddenly made by virtue of excellent optical technology to seize innovative technology leadership. Many of the scenes are pioneers of expertise, offers a range of very good L lens. But unfortunately Canon l lens L is luxury, open flame gun like stealing money;.
Amateur-level camera, even though many have much to surprise, but many a dilemma of a dog's head. .
Canon's earliest 80-200/2. lens is supporting the then .8L Professional machine EOS-1 introduced, although the price of expensive (at that time the most expensive, really deserves the name L), but the image is very good, AF speed is now the standard is also faster. Soon as Canon in preparing professional photography piece to spit has been bad gas suppression of Nikon.
In the ultrasonic motor technology mature, re-launched its peak Canon 70-200 lens, and later added another anti-shake technology, IS lens, these two lenses both from the point of view, are very good. So far, no person can match his, worthy of the title of Emperor mirror. If not, then the introduction of innovative technology, beyond the first can only be empty talk. .
No wonder so many years, the factory the lens prices changes very little, but also on the secondary market, which saw Sanchia of certainty.
But these two aspects of the lens in the resolution seems better than the 80-200 to be the weak point, but clearly there is not a small increase sharpness, so much higher overall performance, especially in the 200mm focal length side, to focus can be comparable level. .
Canon also the mid-price lens market development, known as the "little white" 70-200/4L is such a representative, this lens pricing in half white, strapped the photographer has a very strong attractiveness.
Many people seen this lens uses fluorite and Super UD lens, The lens will be better than that white is good, in fact, they have overlooked a very important issue: the lens resolution and the maximum effective diameter, bore more large amount of light through the larger, the more information collected, a corresponding resolution will be. Although due to some other optical problems, such laws are not proportional, but still relatively clear. .
Canon will be applied to the fixed lens "after group af" institutions into the "inner group af-" (the only move in the middle of the lens unit), and in 70-200L on high-rate variable coking and lightweight. According to Canon Lens Work description, group AF type has the following advantages:.
1. . Because the move only lighter lens group, so very fast autofocus, manual focus is also very light;. .
2. The length of the lens does not change because of autofocus;.
3. . To achieve the overall lightweight camera system;. .
4. Filter box does spins;.
5. . Focus when the focus ring does not move back and forth. .
