f*********n
发帖数: 11154 | 1 Apply coupon "DUT" for $5 Shipping over $125
http://www.brownells.com/rifle-parts/receiver-amp-action-parts/
Complete Top End Includes Barrel, Free-Float Handguard, Bolt & Carrier
Ready to install .308/7.62 NATO upper receiver comes fully assembled with
bolt/carrier, charging handle, free-float handguard, gas block, and barrel.
Lets you change your LR-308 from a sporter to a match rifle or long-range
varminter in just minutes—or build a completely new gun customized to your
exact needs Beefy, th... 阅读全帖 |
|
l**n
发帖数: 2405 | 2 I had only one 20-mile long so far at 10:00 pace.
Really want to have another 20-mile long run with
better pace (target 8:40), however given the fact
that CIM is only 2.5 weeks away and I have sour knees
and sour low-calves, I decided to give up the 2nd
20-mile long run today, hoping knees and calves
recover so that I can enter CIM in good shape.
I am very afraid that my knees won't have time to recover
if I do a 20-mile run this weekend.
After 10/3 San Jose RnR HM, my knees took 2-week to recov... 阅读全帖 |
|
f*******d
发帖数: 12693 | 3 ☆─────────────────────────────────────☆
lken (归零) 于 (Wed Nov 17 16:08:05 2010, 美东) 提到:
I had only one 20-mile long so far at 10:00 pace.
Really want to have another 20-mile long run with
better pace (target 8:40), however given the fact
that CIM is only 2.5 weeks away and I have sour knees
and sour low-calves, I decided to give up the 2nd
20-mile long run today, hoping knees and calves
recover so that I can enter CIM in good shape.
I am very afraid that my knees won't have time to recover
i... 阅读全帖 |
|
s*****2
发帖数: 472 | 4 haha, you may be disappointed since her skis would sink relentlessly in the
powder that should abound in all lower western resorts this weekend. I
decided skipping Utah and heading directly to home mountain. Will see you
next time!
The lesson of the trip is that super-computers track jet streams more
accurately above ocean than land. Once landing it starts dispersing wildly
in all three dimensions, making forecasting increasingly harder over distance. Tahoe is closer to the coast and making weat |
|
q*c
发帖数: 17993 | 5 REI的这篇文章挺好，针对滑雪Goggle的选择，我转贴过来：
http://www.rei.com/learn/expert-advice/goggles.html
Goggles for Skiing and Snowboard: How to Choose
/How%20to%20Choose%20Ski%20and%20Snowboard%20Goggles.jpg
Goggles offer you better eye protection than sunglasses do when you're
snowboarding or skiing for the day.
At first glance, it may not be apparent why goggles range so widely in price
—from $25 to over $200. Here's how to make sense of the technology and find
the right pair for your needs.
Why Wear Goggles?
Th... 阅读全帖 |
|
s*****2
发帖数: 3103 | 6 天妒英才啊？
Drifting volcano ash threatens Copa America
ASUNCION, Paraguay (AP)
The governing body of South American soccer says the arrival of teams
playing in the Copa America could be delayed because of the ash spewing from
Chile's erupting volcano that's disrupting flights across the southern
hemisphere.
Flights were grounded Monday in Argentina, which is host to the continental
championship. The tournament opens July 1 when Argentina faces Bolivia in La
Plata and ends July 24.
Francisco Figuered... 阅读全帖 |
|
w********0
发帖数: 1211 | 7 我又查了一下，找到这个去年的链接
http://www.tennis-x.com/xblog/2010-06-16/4443.php
里面说到
Seeds will be randomly dispersed by groupings:
5-8, 9-12 and 13-16; seeds 17-24 and 25-32.
也就是说，5-8的确像你说的可以是任何一个1/4区，
但9-12和13-16是不一样的；17-24和25-32也是不一样的。 |
|
b*********z
发帖数: 1817 | 8 我看了，是假，但是同一个主题下，有这篇比较updated的
http://skepticalteacher.wordpress.com/2011/03/15/japanese-nucle
13.internal contamination not external radiation is the danger said
April 28, 2011 at 11:42 pm
There is a difference between radiation and contamination. Also a difference
between getting a dose of radiation externally (like an xray) and ingesting
radioactive particles which then target specific tissues (eg thyroid, lung,
brain, bone marrow etc depending on the specific element).
Radiation levels from t... 阅读全帖 |
|
D**********e
发帖数: 147 | 9 Pisces Horoscope for November 2010
By Susan Miller
November's aspects can only be described as breathtakingly special and once-
in-a-lifetime rare. As Jupiter
and Uranus make their final run together through Pisces in your lifetime,
they will set up a fireworks display
to blaze the night sky, the likes of which you've never seen and may never
see again. This will truly be an
exciting month, and if you are wise and wait until November 18 to finalize
an exciting deal, then all the
potential you se... 阅读全帖 |
|
b******n
发帖数: 2328 | 10 Leo Horoscope for February 2011
By Susan Miller
You seem ready to join forces with someone special, and that's unusual for
you. Leo tends to like to be in charge and control the flow, but these days
a new spirit of "let's join forces" will be in the air, and suddenly you'll
be willing to form a partnership that is equal to you in every sense. You
seem excited by the possibilities of this "coming together" of you and one
special individual. Talks and plans will begin to shape up quickly this
mont... 阅读全帖 |
|
w**********t
发帖数: 19 | 11 Scorpio Horoscope for July 2011
By Susan Miller
You've just come through two major eclipses last month, a solar eclipse on
June 1, and a full moon lunar eclipse on June 15, and both almost forced you
to focus exclusively on money. Among the financial topics on your mind
include finding a way to appropriate funds more wisely, as well as another
pressing matter, how to find ways to earn a bigger salary. A source of
income is about to change dramatically, either immediately or within the
coming eig... 阅读全帖 |
|
t***y
发帖数: 182 | 12 英文原文对照：
Eclipse season is here, and surprising events are popping up everywhere. Fortunately, these solar and lunar events are due to be somewhat easier for you to experience than the ones that occurred last year. Eclipses bring new experiences, often right out of the blue, from events outside your control that you would never expect. They add a new twist to life, increase your experience, and evolve you into a more mature, seasoned person. Eclipse time often marks the truly big events of life, ... 阅读全帖 |
|
t***y
发帖数: 182 | 13 source:
http://astrologyzone.com/forecasts/monthly/capricorn_full.php
Most people think of January as the time for a fresh start, but for you, it'
s not only the New Year, but also birthday time, making this a doubly
exciting important time. Capricorns like to give their lives form, goals,
and structure, and you want to map out an outline of a plan, but over the
past two years, you've experienced so many twists and turns, partly due to
the eclipses in Cancer and Capricorn, that you aren't sure i... 阅读全帖 |
|
t***y
发帖数: 182 | 14 来自：susanmiller小组（http://www.douban.com/group/susanmiller/）
搬运排版： MQ-美棋 译者：幻觉
译文：
——————————————— ★★★正 文★★★ ——————————————
4月是个一分为二的月份，上半月，财务事宜占据了你的精力，之后的下半月，是有很
多娱乐、放松活动，还可能去旅行的时候了。要记住，下半月的时候将为你打造更好的
氛围，而这个月的前两周，你要忙于你的收入、支票簿、计算小票这些事情上。这种财
务上的忙碌是暂时的，所以也要为下半月会很好感觉高兴哦！
如果看看你的整体状况，你长期以来一直在处理困难的财务局面，也许这远从2009年10
月就开始了，土星从那时候起一直在天秤座行运，明显的限制了你的收入。看起来你一
直在应对预算紧缺的老板和客户，所以情况变得更加困难，并且换工作也没得到帮助—
—如果你曾去面试工作，也遇上的一样的情况。同时，你的开支也上升了，你肯定感觉
自己陷入财务困境。
等到今年10月份的时候，你紧缩的现金状况就会消除，那时土星将离开天秤座这个对你
来说较为艰难的位置。但这个月你还遇上4月6日的满... 阅读全帖 |
|
l*y
发帖数: 21010 | 15 【 以下文字转载自 Military 讨论区 】
发信人: inergas (大坏猪), 信区: Military
标 题: 东亚女胸小的原因找到了
发信站: BBS 未名空间站 (Fri Feb 15 09:21:19 2013, 美东)
http://www.nytimes.com/2013/02/15/science/studying-recent-human
East Asian Physical Traits Linked to 35,000-Year-Old Mutation
By NICHOLAS WADE
Published: February 14, 2013
Gaining a deep insight into human evolution, researchers have identified a
mutation in a critical human gene as the source of several distinctive
traits that make East Asians different from other races.... 阅读全帖 |
|
s*****g
发帖数: 73 | 16 I think name of this flowers also call GIANT MILK WEED
Family: Calotropis Procea
Beautiful small clusters of purple and white flowers, which often bloom as
other parts of the plant are producing large, (3 to 4 inches), green oval
seed pods.
Drought-resistant, very salt-tolerant, and through its wind and animal
dispersed seeds, it quickly becomes established as a weed along degraded
roadsides, and in overgrazed native pastures. Has a preference for and is
often dominant in areas of abandoned cul |
|
g*******a
发帖数: 903 | 17 這是大部份老中(或老韓老印)父母的想法。讀好書是個保險，先讀好書後想幹幹嘛再去
幹嘛。所以老中第二第三代的素質整齊，但很少聽到有什麼石破天驚之舉。
老美比較不興萬般皆下品，所以素質高低的Dispersion很大，但比較常聽到Jobs，
Zuckerberger這種發跡史。 |
|
j****z
发帖数: 1402 | 18 有一天，不知怎么把蚂蚁带进了屋，过了几天切开的西瓜放桌上后，蚂蚁分两路大军浩
浩荡荡地爬上了桌，看见后浑身起JPGD，然后去home depot买了杀蚂蚁的药，听说蚂蚁
不喜醋，于是用醋擦桌，后来蚂蚁没再进来过。
不过后院蚂蚁很多，时不时地有叶子被吃，不知道是蚂蚁的过错还是别的虫子。打算开
荒种菜，把草皮翻了堆在了一起，有天翻了翻堆土，里面几百个蚂蚁，就用醋对水浇了
下去，不得了，蚂蚁慌慌张张集体搬家，来来回回的忙个不停，我就看热闹，用相机拍
照片，拍不下来，只好用摄像，但见每只蚂蚁都背个小小的白色的蚂蚁卵，这是baby吧
，几小时候后蚂蚁的家搬完了，堆土里一只蚂蚁也不见了。真干净。
看来蚂蚁不喜欢醋，但醋不杀蚂蚁，我不知道蚂蚁该不该杀，古狗后看了更糊涂，好像
有的蚂蚁不碍事，有的蚂蚁也害庄稼。
下面是古狗来的。
Ants live in soil, and some ants live in wood or plant cavities. The ant is
hunted by many species including lizards, spiders, toads, assa... 阅读全帖 |
|
S***n
发帖数: 2932 | 19 哇！你看过很多书阿！仰慕！
pat pat。。。不要太悲观。
文汇读书周报上蛮多顾准之类的文革8g，红都见闻录（苏联清洗的事情），贺龙之流的
书我中学看过一咪咪。。。更小的时候看到屈原投江苏武牧羊之类。。。
但是明清痛史我到现在还没办法看。
哈哈，烦人的扯这么多无非想斗胆讲一句，或许你的心情我勉强能体会。
但是另一方面，或许不必太绝望。特别不要太小看同侪们和80，90后小朋友们。
古文是一个障碍，但是这障碍有多大呢？
他们小的时候看起来有点傻，或许真的很傻，但是一旦开窍，有的事情非常快。。。
哈哈，作为工科文盲我稍微有一点点个人体会，我本人已经十分闭塞，但仍看到比我小
的很多很多牛人。。。斗胆将自己也算进去的，希望你不要定论中华文化后继无人。
最后送一段我引用过好几次的：
For, in truth, there is no sure way of holding other than by destroying, and
whoever becomes master of a City accustomed to live in freedom and does not
destro... 阅读全帖 |
|
w***r
发帖数: 7173 | 20 原文在这里:
http://www.mitbbs.com/article_t/Translation/31133701.html
Ju Hua Tai(菊花台) Jay Chou (周杰伦)
你的泪光 柔弱中带伤
惨白的月儿弯弯 勾住过往
夜太漫长 凝结成了霜
是谁在阁楼上 冰冷地绝望
Your glistening tears, soft and delicate, carry a hint of sadness
The pale crescent moon curves, hooking onto the past
The night is so long it crystallizes into frost
Who stands in the attic, frozen with despair?
雨轻轻叹 朱红色的窗
我一生在纸上 被风吹乱
梦在远方 化成一缕香
随风飘散 你的模样
The rain taps softly against the vermillion window
All my life lies wri... 阅读全帖 |
|
b*s
发帖数: 82482 | 21 Julian Niccolini is a New York City restaurateur who co-owns The Four
Seasons Restaurant.[1][2][3] A Native of Italy's Tuscany region, Niccolini
has lived in New York since 1973 and became a US citizen in 2002.
Described as the "madcap maitre d' of America's most powerful lunchroom" by
GQ magazine, Niccolini is known for charming his patrons with a surprising
mix of innate hospitality and irreverence for the captains of industry who
patronize The Four Seasons daily.
A media darling who is often ... 阅读全帖 |
|
z*i
发帖数: 58873 | 22 不是，
What does it mean when we say that “the network” verifies transactions and
reconciles the ledger? And how exactly are new bitcoins created and
introduced into the money supply? As we have already seen, because Bitcoin
is a peer-to-peer network, there is no central authority charged with either
creating currency units or verifying transactions. This network depends on
users who provide their computing power to do the logging and
reconciling of transactions. These users are called “miners” bec... 阅读全帖 |
|
f**k
发帖数: 906 | 23 整理操袭如下:
主流观点是,成像质量和镜头直接有关. 牛机狗头--图象也狗.
以下每一个都能写一论文．我只写于菜鸟关心的结果吧．
1. 前对焦 (FRONT ＦＯＣＵＳ）
前对焦的镜头前组在对焦时旋转．会造成POROLIZER和GRADUATED FILTER等方向性的东东
难于控制．后对焦和内对焦就没有这个问题．
２．Low Dispersion的镜头提高清晰度和对比度．标识有：ED,LD, UD, ELD, SLD, SED.
一码事．
３．对数码优化（光线垂直射入sensor), 标识有： DI...
４．ASPHERICAL提高成像质量和减少镜头体积．
５．手动／自动对焦．不用多说了．提一下全时手动－－就是在自动对焦时，可以手动微
调．某些情况非常有用．Ｃ＋的就看有没有(FULL TIME MANUAL FOCUS)．好象ring type
USM都可以．只有一个不是ring type的全时手动（５０／１．４）？．
６．恒定最大光圈．大家都知道大光圈好处多．非恒定最大光圈镜头，变焦时最大光圈会
变化．恒定的好处加上，变焦后：Ａ在手动测光时，不用当心暴光数值．Ｂ．手动对焦时
不要 |
|
M*****l
发帖数: 4478 | 24 According to the pre-order information on amazon, it is $1699...Sigma not
only adds OS but also uses better low dispersion pieces. But it seems not
very wise because despite they use good parts, most buyers would go for
nikon VRII at that price range... |
|
i***f
发帖数: 10682 | 25 不能光看价钱，仔细比一下，一分钱一分货，不说能到120mm, 光那个5 Stop VR就不是
一个量级的，还有Nano coating，两片ED。。。
Canon EF 24-105mm f/4 L IS USM - $1,058.98
IS 3 stops
1 Super UD glass element
Nikon 24-120mm f/4G ED VR AF-S - $1,299.00
Nikon VR II - 5 stops
Nano Coating
2 Extra-low Dispersion (ED) Elements |
|
d******a
发帖数: 32122 | 26 1) The new M.Zuiko ED 75-300mm f/4.8-6.7 (equivalent of 150-600mm in 35mm)
It is the world smallest 600mm zoom lens. It weights 430 grams and has a
diameter of 7cm and 11.6cm length.
It allows nearly silent HD movie recording.
The new lenses are made with ED (extra-low dispersion)
It will be available in December 2010 for $899.99
2) the new M.Zuiko ED 40-150mm f/4.0-5.6 equivalent of 80-300mm in 35mm)
It weights 190 grams.
It will be available in November 2010 for $299.99 |
|
b****1
发帖数: 3685 | 27 嗯。乳摸网站上说了
1) The new M.Zuiko ED 75-300mm f/4.8-6.7 (equivalent of 150-600mm in 35mm)
It is the world smallest 600mm zoom lens. It weights 430 grams and has a
diameter of 7cm and 11.6cm length.
It allows nearly silent HD movie recording.
The new lenses are made with ED (extra-low dispersion)
It will be available in December 2010 for $899.99 |
|
L*****y
发帖数: 4290 | 28 中间不是写了么
Ultra-low Dispersion (UD)
ft. It is at bottom of the page and UD is not listed as a stand alone term.
thanks. |
|
x5
发帖数: 27871 | 29 呵呵，是我想叉了，正在看一个dispersion relation，那个横轴是波矢
结果就串到这个mtf上了 |
|
x*******3
发帖数: 8342 | 30 35L f/1.4 LII
Canon files patent for EF 35 f/1.4L II
Patent Publication No. US 7,944,625
Published 2011.5.17
Filled 2009.8.5
Specifications
Focal Distance: 34.59
Fno: 1.45
Half angle of view: 32.02
Image Height: 21.64
Lens Length (mm): 126.93
Back Focus (mm): 37.98
50 1.4, why not mark II?????
Canon patent for EF 50 f/1.4 USM
Patent Publication No. 2011-70032
Published 2011.4.7
Filled 2009.9.25
Specifications
Focal Distance: 51.70
Fno: 1.30
Half angle of view: 22.79
Image Height: 21.64
Lens Leng... 阅读全帖 |
|
e****t
发帖数: 17914 | 31 尼康镜头标识说明：
3 楼
DX镜头：专门为尼康DSLR生产的镜头，成像圈仅覆盖APS-C尺寸的传感器，由于使用在
一般35mm规格的相机上会有成像圈的产生且镜身可能在近端时压碰到底片或感光板造成
损坏，因此并不适合使用于35mm规格的相机上。
ED镜片：超低色散镜片（Extra-low Dispersion glass）, 是加工了有着为了减少在长
焦距使用时所产生光的色散，而降低分散光的波长的特性的特殊玻璃，而制成的镜头所
赋予的称号。
Nano：纳米结晶镀膜，最大的作用是防止镜片反光，增加透过性。
AF: 自动对焦（Auto focus)。
AF-S: 低噪音引擎镜头, 搭载了SWM超声波马达（Silent Wave Motor）, 对焦更加快速
且准确。类似于佳能的USM，即超音波马达技术（Ultrasonic Motor technology）。
VR减震系统：采用了防手震技术的镜头（Vibration Reduction）。使用该镜头有助于
纠正和减少镜头摇晃或运动过程中产生的照片模糊。部分VR镜头支持筛选模式（
panning shot mode），便于检测镜头的水平运动... 阅读全帖 |
|
f*******y
发帖数: 2368 | 32 没有评测。
只有canon anonounced时说的：
enhanced exterior design， inclusion of an Ultra-low
Dispersion (UD) lens element， Canon’s Super Spectra Coatings。 |
|
G********d
发帖数: 10250 | 33 当时以为是老黑打砸抢
今天查了wiki，警方说是有组织的无政府主义者。。。
On July 8, 2010, following the verdict, protests began peacefully,[146] and
officials commended both the protestors and the police for their
demonstrated restraint.[147] As night fell, vandals engaged in opportunistic
looting of local businesses, such as The Foot Locker, a bank, and a jewelry
store.[148] Oakland's police chief was quoted as saying that the people
doing violence did not primarily seem to be Oakland residents protesting the
verdict, but instea... 阅读全帖 |
|
v***a
发帖数: 23651 | 34 Ben Polak is a Professor of Economics and Management in the Department of Ec
onomics and the School of Management at Yale University. He received his B.A
. from Trinity College, Cambridge University, his M.A. from Northwestern Uni
versity, and his Ph.D. from Harvard University. A specialist in microeconomi
c theory and economic history, he has published in Economic Letters, Journal
of Economic Theory, Journal of Economic History, Journal of Legal Studies,
Journal of Theoretical and Institutional... 阅读全帖 |
|
o******w
发帖数: 842 | 35 镜头具体资料：
1, 41MP像素CMOS，1／1.2寸。（记住，尼康1才1／1.2寸）ISO 50起跳。
2, 卡尔蔡司镜头，26mm(16:9), 28mm(4:3), F2.4, 5片1组，全为非球面,
3, 一片high-index, low-dispersion模铸玻璃镜片。
4, 对焦距离：15cm---无穷
5, 机械快门
6, 内置中灰滤镜
7, 提供8MP，5MP，2MP输出选择。
8， 1080P录像 |
|
d*****0
发帖数: 68029 | 36 【 以下文字转载自 Military 讨论区 】
发信人: laodou (别拿豆包不当干粮), 信区: Military
标 题: 武汉大学80后美女袁荃教授走红
发信站: BBS 未名空间站 (Wed Feb 29 14:21:37 2012, 美东)
姓 名： 袁 荃 Yuan _ Quan
出生年月：1982年2月
学历： 博士， 教授
专业方向：分析化学
电 话：
Email：y*********[email protected]
教育与研究经历
2000年9月– 2004年7月：武汉大学化学学士学位
2004年9月– 2009年7月：北京大学无机化学博士学位导师：严纯华院士
2009年9月-2011年12月：佛罗里达大学化学系博士后谭蔚泓教授课题组
2011年12月-现在：武汉大学化学学院教授
代表性成果
1.Quan Yuan, Yun-Fei Zhang, Ruo-Wen Wang, Chao-Lin Du, Emir Yasun, Yan Chen,
and Wei-Hong Tan* “Using Silver Nanowire Antennas to Enhance th... 阅读全帖 |
|
e****t
发帖数: 17914 | 37 this is called price dispersion. |
|
g*******n
发帖数: 1188 | 38 。。。还以为看得出dispersion呢。。。lol |
|
k****t
发帖数: 12697 | 39 明显能看出REFRACTIVE INDEX 大不需要看DISPERSION. 理科生马上会去GOOGLE 出一堆
高折射的材料来证明这完全可能不是铅玻璃. 但是市场上蜡烛台不外就是三种, 绿兮兮
含二价铁的钠玻璃, 脱色钠玻璃, 铅玻璃. 用CROWN 不MAKE SENSE 没人做. |
|
g*******n
发帖数: 1188 | 40 我是想说normal/anomalous dispersion... |
|
j****c
发帖数: 19908 | 41 velocity dispersion
gravitational lensing
hot gas in galaxy cluster |
|
e****t
发帖数: 17914 | 42 Does not include ED, Extra-low Dispersion Glass. The gold band is deceptive,
and in this case, used only to support the elevated price. It does not mean
ED glass. |
|
z*******5
发帖数: 2990 | 43 55-200是焦距
f/4是55端最大光圈
5.6是200端最大光圈
G头在镜身上没有光圈调节环
ED : Extra-low Dispersion超低色散镜片 |
|
i***f
发帖数: 10682 | 44 小黄不要走，宾德要出手。
Patent filing date: October 3, 2010
Zoom ratio: 2.82
Aperture: 2.9 - 3.0
Focal length: 70.21 - 198.32mm
Image height: 21.64mm
Lens length: 296.16mm
17 images lens group
configuration
14 4 ED elements
2 low-dispersion elements
Internal zoom and f focusing |
|
l*x
发帖数: 396 | 45 比较了一下，期望不高啊。估计就是个便宜L头。
24-105:
18 elements in 13 groups including three aspherical elements (two replica,
one glass molded) plus one S-UD (super ultra-low dispersion) element
24-70 f/4L:
15 elements in 12 groups, two aspherical lens, lens configuration sheet
2 UD lens |
|
w******o
发帖数: 119 | 46 Amazon上说有75-300mm,One Super ED (extra-low dispersion) lens and 2 ED
lenses.好像panasonic这方面说明少些.
想在轻一点的里面找个最能数毛的, |
|
d******k
发帖数: 447 | 47 FLD (“F” Low Dispersion) glass offers superior optical performance, equal
to flourite, at an affordable price.
So I guess this is us poor man 's flourite. |
|
l*x
发帖数: 396 | 48 FLD不是萤石。我同事的朋友在国内开厂长萤石晶体，出口到日本。
"New lenses coming out of Sigma will be a little bit different than the
company's other offerings. All of their new high end lenses will be
switching from traditional glass to new F Low Dispersion (FLD) glass. It's
got the same performance as fluorite glass but it's much cheaper." |
|
k**o
发帖数: 3006 | 49 ☆─────────────────────────────────────☆
suddl (suddl) 于 (Mon Apr 29 11:08:18 2013, 美东) 提到:
什么时候出的啊，看版上不是说死马今年打鸡血了，出了几个好头，这个算么？用丐帮
残福如何？
☆─────────────────────────────────────☆
mlwei (南瓜乙) 于 (Mon Apr 29 11:13:28 2013, 美东) 提到:
24-70 f2.0?
☆─────────────────────────────────────☆
ShiyiJin (金似衣；今世遗) 于 (Mon Apr 29 11:14:45 2013, 美东) 提到:
很好
N+
C+也是比Tarmron和原厂的稍差
☆─────────────────────────────────────☆
ShiyiJin (金似衣；今世遗) 于 (Mon Apr 29 11:19:29 2013, 美东) 提到:
第一，死马的文艺头都打鸡血了。
其次，就是死马偷的... 阅读全帖 |
|
x****y
发帖数: 1853 | 50 这个问题如果这样问会更好回答些： 镜头的性能都是怎么测量，怎么从设计的角度去
改进的？之所以把分辨率改成性能，是因为镜头的性能得综合的评测，包括分辨率（最
大光圈，最优光圈）,对比度，畸变，色偏等。之所以要综合评测，是因为这些性能很
多都互相制衡，比如分辨率提高了，对比度会下降。中心分辨率提高了，边角的色偏会
严重。而且不同焦段的镜头设计的策略很不一样。
镜头光学设计很专业，可以写一本书。我把我知道的（很肤浅) 简单列一下，说错了大
牛请轻拍:
镜头的分辨率主要由球差，色差和衍射决定。一般光圈大时受球色差限制，光圈小时受
衍射影响。所以一般中间光圈分辨率最好。但不同焦距设计者重视的元素不一样。
标准焦距：这个焦距的主要用来拍人文，强调色彩，对比度，中间锐度。色差是这个焦
段比较重要。消除色差主要通过玻璃材料的选择。现在很多都用low dispersion的材料
，意思是不同的光被折射的程度差不多来减少色差。玻璃和空气之间的gap也会增加色
差，得尽量避免。另外，也可以通过折射系数不同的凹凸透镜配对来消除色差.
广角: 这个焦距光以大角度进入镜头，所以中心锐度主要受球差影响。减少球差主要... 阅读全帖 |
|
