w*********b
发帖数: 1111 | 1 我看肯大嘴的照片明显是f5.6的更sharp啊，为啥他说 Apertures of f/8 and smaller
blur the image due to diffraction.
万佛给讲讲 |
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t********y
发帖数: 21 | 3 曝光模式
P：（program AE）程序自动曝光
A：（aperture priority）光圈优先自动曝光
S：（shutter priority）快门速度优先自动曝光
M：（manual）手动曝光
测光模式
CW：（centre-weighted average）中央重点加权平均测光
SP：（spot metering）点测光
MS：（multi-segment）多分区测光
闪光模式
A： （auto flash）自动闪光
RE：（red-eye reduction）防红眼闪光
SL：（slow syn.flash）慢速同步
OF：（OFF）关闭
FI：（fill-in flash）填充式闪光
RF：（rear flash sync）后帘同步
WR：（wireless/remote flash）无线/遥控
E-TTL：（evaluated TTL）评估式TTL
取景器
镜头标识
AD:（anomalous dispersion）异常色散
AE：（auto exposure）自动曝光
AF：（autofocus）自动对焦
AF-I：（AF nikkor）尼康内置马达的镜头
AF-S... 阅读全帖 |
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p**p
发帖数: 3386 | 4 过去有个f64 group，包括安大师在内，但主要原因是当时的镜头不行
现在的大幅镜头，光圈太小反而受diffraction的很大影响，记得LFF上有些相关的讨论 |
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t****g
发帖数: 35582 | 5 你们这是生物的near-field定义？
near field imaging难道不是通过让objective靠近object到sub wavelength的距离，
然后把evanescent wave couple进来，beat diffraction limit么？
从这个角度上讲，当时收集了不能propagate的k vector了。 |
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s*n
发帖数: 2603 | 6 是因为加了水，diffraction limit提到 1.33 k_0
但是objective收集的已经不再是nearfield了 |
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t****g
发帖数: 35582 | 7 水浸，油浸，或者倒扣一个dome本质上还是beam不了diffraction limit的。所以你这
个nearfield只是靠的近而已。
真正的nearfiled是要把propagate不出来的evanescent wave都couple出来，然后beat
NA。 |
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t****g
发帖数: 35582 | 8 懒老师说near field能把不能propagte的K vector收集起来是没错的，但是前半句错了
，靠的不是大NA，再大的NA没有coupling也只能在
far field的diffraction limit里面呆着。 |
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b*******t
发帖数: 33714 | 9 那个有时也会叫成near/far field diffraction |
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t****g
发帖数: 35582 | 10 Nikon其实一直到F4都压过佳能。在手动时代直到自动时代的早期，Nikon是当之无愧的
王者
。这也是为啥国人一直捧Nikon。更早的时候，Pentax的销量曾经比Nikon高过几年，罗
口时代，但是从来技术旗舰的巅峰一直是Nikon的。
佳能当年被逼无奈只好换卡口（也不是被逼无奈，卡扣换了没有包袱正好迎接革命)。
EF的机器搞了几年，到EOS-1出来的时候，基本上赶上Nikon了。然后EOS-1n一出来，F5
立马
不行了。然后Canon储备的技术一样一样的出来，EOS-1v/EOS-3的45点对焦，Nikon差不
多15年后才搞出来类似的东西。然后是DO镜头，虽然技术还不那么成熟，但是减轻重量
和体积的效果是明显的，毕竟是Diffractive Optics首次在照相镜头上成功应用。
将来配合革命机，镜头必须小型化，走DO路线是唯一的路。
当然了，最近5年来，我也不知道Canon再干嘛。相机/CMOS感觉原地踏步，镜头不痛不
痒的换了几个新的，小修小改，算不上有重量级的东西出手。电视机搞了几年，样机还
没出来，
几十亿日元估计打水漂了。 |
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x5
发帖数: 27871 | 11 是啊，如果有SNR -> inf，连diffraction limit都没有了 |
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m*t
发帖数: 2464 | 12 注：这人当年关于观音镜头的书毒翻了多少人啊。
http://blog.sina.com.cn/s/blog_4710d3430100y098.html
尼康D800和佳能5D3都发布了，如大家预先所料，现在网络上开始进行3600万像素对
2200万像素的画质大战。这是一个非常有趣的现象，遥想当年，5D2以2110万像素带来
的优异画质遥遥领先1200万像素级别的D700，受制于CMOS原件的制造能力，尼康只能在
提高D700的AF性能和操控性上痛下苦功。当然，后来的市场反应来看，“1200万像素够
用论”显然不敌5D2的高性价比攻势，被打的一败涂地。
而突然之间，攻守之势异也，现在尼康的D800以3600万像素遥遥领先，佳能5D3开始大
打“AF性能”大幅提升牌，这实在是件有趣的事情。
有能力造成山河易势的力量实际是背后的索尼。目前看来，全画幅传统CMOS的设计生产
能力已经形成索尼和佳能两家独大的局面，差别只在于佳能的CMOS只给自己使用，索尼
则可以提供给其他厂家，和两三年前的战略不同，索尼现在愿意把高像素技术和其他厂
家共享，包括全画幅，也包括非全画幅。大家开始纷纷和索尼合作“制... 阅读全帖 |
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a*********a
发帖数: 3656 | 13 因为衍射是镜头的特性，用胶片，一样受衍射影响。
就算10亿像素，能分辨出衍射斑的n个次级，不考虑高感，缩到12M像素，细节不会比原始12M采集的差。用低分辨率的Sensor，衍射影响不明显，因为整个系统从头到尾都是Sensor Limited，根本没有看到镜头最佳光圈的潜力。用了高像素，有可能f8时是Sensor Limited，f22时是diffraction Limited，f1.2时是Abberation Limited。最终目标当然是全程Opitcs Limited，最佳光圈是Sensor 仍然充分 out resolve lens. |
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a***e
发帖数: 27968 | 14 也不会比12MP的好到哪里去，是更好一些。
只有lens比sensor牛，你才会觉得sharp,否则都是肉乎乎
原始12M采集的差。用低分辨率的Sensor，衍射影响不明显，因为整个系统从头到尾都
是Sensor Limited，根本没有看到镜头最佳光圈的潜力。用了高像素，有可能f8时是
Sensor Limited，f22时是diffraction Limited，f1.2时是Abberation Limited。最终
目标当然是全程Opitcs Limited，最佳光圈是Sensor 仍然充分 out resolve lens. |
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G**Y
发帖数: 33224 | 15 这里还有一段：
Stopping aperture down increases depth of fi eld, making the
foreground and background sharper. Stop aperture down
too far, however, and diff raction will actually cause the image
to lose defi nition. The eff ects of diff raction are partly infl uenced
by the size of the pixels in the camera image sensor,
but with the D800/D800E’s high resolution the eff ects generally
become noticeable around f/11. When you need more
depth of fi eld, don’t just immediately stop the lens all the way
down... 阅读全帖 |
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G**Y
发帖数: 33224 | 17 看来，未来就是F/8-11的了。广角够了，长焦和微距怎么办呢？ |
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h*******e
发帖数: 8370 | 19 DO是什么？diffractive optics？
C的两只DO镜都是失败作品。正如我跟别人聊过的，我很少对某只镜头有恶感，最多就
是不喜欢。但是我确实对三只（或四只）镜头十分不齿：50 1.0、70-300 DO、400 DO
。
如果是四只就加一个50 1.2。四倍的价格，光圈大了半档，其他各项素质除了色彩没有
本质提高还有focus shift的毛病…… |
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f**s
发帖数: 968 | 20 链接在此：
http://www.kenrockwell.com/tech/8mm-f35.htm
8mm f/3.5 Fisheye
Pro-Optic, Samyang, Rokinon, Bower &c. (2009-)
© 2010 KenRockwell.com. All rights reserved.
Intro Specs Performance Compared Recommendations
8mm f/3.5 Fisheye, Pro-Optic Nikon AI-s version. enlarge. ($290, Korean, no
filters, 13.8 oz./391g). This one came from this link to it at Adorama (also
specifically in Nikon, Canon EOS, Pentax/Samsung and Minolta Maxxum/Sony
mounts). It also comes branded as Bower, also specif... 阅读全帖 |
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d****n
发帖数: 12461 | 21 You think Olympus camera is cool? Not at all as advertized.
f2.0 zoom lens sounds fast? No thank you. You get diffraction as early as f/
8.
Because of that 2x crop factor you get DOF similar to high-end P&S. You
shoot the picture at f/2.8 and it looks like a picture from a FF body at f/5
.0. Great for macro but terrible for everything else.
Because of the tiny sensor, noise is always one stop or two stops worse than
the current crop factor consumer DSLRs, not mentioning prosumer FF ones.
All of ... 阅读全帖 |
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e**n
发帖数: 5876 | 22 RX100和其他DC芯片大小的比例关系大致相对于FF和APS的关系. 就拿FF和APS做个比较.
在光学充足的时候, 现在的芯片技术可以做到FF和APS的成像画质相似. FF的优势有2
个, 一个是光线不足的时候画质好, 另一个是景深控制能力强. 但这两个优势都建立在
有相应大光圈镜头的前提. 假设APS用个35f1.4的头. FF只有一个50mmf3.5的头. FF还
有画质和景深的优势嘛?
RX100等DC和FF,APS之类的另一个区别是衍射极限. 前几天有童鞋说到4/3在f8就开
始到衍射极限了. 那么象RX100这样芯片面积只有43一半, 像素总数还更多的, 那f4多
一点就开始有diffraction了. 所以光圈也没有什么好缩的了 |
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h******i
发帖数: 1941 | 23 d800E在f5.6以前比d800sharp，但是同时受moire影响很大。在f8以后成像质量受
diffraction影响，不如d800.
因为moire，作为录像机的话philip bloom（用5d2摄像的pioneer）建议买d800，不建
议用d800E。 |
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h******g
发帖数: 11250 | 24 ☆─────────────────────────────────────☆
egon (schiele) 于 (Wed Dec 26 12:41:49 2012, 美东) 提到:
最近RX100的hype很多, RX100的sensor面积是别的DC的2.6倍多, 又有f1.8的大光圈,
体积又小, 看起来确实很美. 很美的东西我就忍不住多看了几眼...
但看之前要插2句废话:
#废话warning
比较光线充足的条件下的base iso的画质是一件很无聊的事情. 在光学充足的时候,
现在的芯片技术可以做到FF和APS在同样base iso时成像画质差别不大. RX100和其他DC
芯片大小的比例关系大致相对于FF和APS的关系. 再考虑到LX7 的base iso是 80,
RX100是125, 在同样面积, 光学充足的情况下, LX7能容纳比RX100多60%左右的photon.
RX100的面积比LX7大个160%左右, 那么photon saturation总量RX100只比LX7多60%左
右. photon总量决定画质. 这个photon总量的差别比FF和... 阅读全帖 |
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w****e
发帖数: 2210 | 25 Here’s a complete list of all 68 improvements the X100S has over the X100.
Most of these changes were as a result of the fantastic feedback provided by
X100 users.
1. 16-megapixel sensor, up from 12-megapixel
2. X-Trans CMOS II sensor eliminates need for Optical Low Pass Filter
2. The resolution has improved to match Full Frame domain sensors
3. The Signal to Noise ratio improved to be on a par with Full Frame domain
sensors
4. Phase detection pixels allow 0.07 sec Auto focus
6. 1080p 60fps full... 阅读全帖 |
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w****e
发帖数: 2210 | 26 Take a look at the list of ALL 51 improvements the X20 has over the X10,
1. 2/3-inch X-Trans CMOS II sensor without optical low pass filters improves
resolution to as much as a 4/3″ sensor.
2. S/N ratio improved to level similar to Full frame sensors.
3. Phase detection AF allows for AF speeds as low as 0.04secs (compared to
X10 0.16secs).
4. 1080p HD video @ 60fps (X10 1080p HD video @ 30fps).
5. Phase detection Autofocus also works during movie recording.
6. Face detection works during movie r... 阅读全帖 |
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w**7
发帖数: 5258 | 28 Has the bubble burst? Is that why camera sales in N. America are down by 43%?
http://visualsciencelab.blogspot.com.au/2013/08/has-bubble-burs
DSLR sales are down this year, worldwide, by 18.5% according to CIPA. The
total decline in the entire dedicated camera market is closer to 43.5% and
mirrorless cameras are seeing about the same year to year decline as
traditional DSLRs. Why?
I think there are two reasons driving this incredible decline. Two bubble
bursting phenomena occurring on top of eac... 阅读全帖 |
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x****y
发帖数: 1853 | 29 Not true. But don't want to argue any more.
By the way, diffraction is not really quantum mechanics. It has
been known in classic optics 2-3 hundreds years before QM. |
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m********l
发帖数: 6748 | 31 值得一看，他自己是用D800E和E-M1的，各种对比也很实在。 如果要对比A7R的AF的话
，和E-M1比较，那么按1-10 scale来说：
对焦速度：Oly 10， A7R 6
对焦精度：Oly 9， A7R 6
追焦： Oly 7， A7R 5
acquisition time: Oly 10, A7R 7
blog.mingthein.com/2014/01/08/sony-a7r-review/
其他的summary：
Vs Nikon D800E: Here, it all boils down to the system of lenses and flashes:
if you need any special purpose gear at all, or longer lenses, then the
balance tips heavily in favor of the D800E. I think the shooting envelope is
a bit wider, too – given the much better shutter mechanis... 阅读全帖 |
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J*********n
发帖数: 6974 | 32 24.3 megapixel APS-C CMOS sensor
Bionz X image processor
Hybrid AF system with 25 contrast-detect and 179 phase-detect points
Built-in flash + Multi-Interface Shoe
11 fps continuous shooting with subject-tracking
3-inch tilting LCD with 921,600 dots
OLED electronic viewfinder with 1.44M dots
Diffraction correction, area-specific noise reduction, and detail
reproduction technology
Full HD video recording at 1080/60p and 24p; clean HDMI output
Wi-Fi with NFC capability and downloadable apps |
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j****c
发帖数: 19908 | 33 PS上去的
我用的是APO镜子，里面没有支架，所以不会有衍射条纹 diffraction spikes。如果是
用反射镜，里面的secondary mirror是用支架的，那个支架会弄出spikes出来
我打算下次在APO镜筒外面拉两根十字丝，这样亮星就会出星芒了。 |
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j****c
发帖数: 19908 | 34 第一张的diffraction spikes是我后期加的 |
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j****c
发帖数: 19908 | 35 P出来的
如果是反射镜能拍出这种spikes。我用的是折射镜，里面没有支架，可以在镜头上拉一
个十字丝也能搞出diffraction spikes出来 |
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o**s
发帖数: 3412 | 36 New techniques that have enabled light microscopy to achieve resolution
beyond the diffraction limit. Three of the major contributors to the this
field were awarded the Nobel Prize in Chemistry this morning:
http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2014
Someone at my school said
"A couple of additional people who have also made major contributions to
this field... Xiaowei Zhuang, who probably should have been one of this year
's prize recipients, IMHO. "
庄小威1972年出生于江苏省如皋市，1987年... 阅读全帖 |
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s******3
发帖数: 1767 | 37 你要有photo-switchable fluorescence dye才行，每次就随机点亮几个，根据光点的
轮廓，算出每个光点的中心位置，从而超越 diffraction limit，最后在把成千上万的
frame叠加起来，形成super resolution image。本人做过STORM和PALM，都挺麻烦，
sample还不能有shift，不然就糊了。 |
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G**Y
发帖数: 33224 | 38 F/11, F/16?
感觉近处的鸟，F/8不够呀。 |
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k**L
发帖数: 3630 | 39 你知道怎么托吗? 就好比电影里看到的卖大力丸的.
1. 先让你相信他的权威,就是自吹自擂一番比如
"我认为这个坛子里面比我老镜头玩的多的朋友应该不多" ="我祖上13代密传朝廷专供,
水泊梁山指定产品"
2.专家引用.反正随便说个托词,你查不到也说不出哪不对劲就是了.
在老镜头镀膜不成熟的年代里，玻璃的透光率也就90%左右(我无从查证，这个数字是
nikon的工程师闲聊告诉我的）=具某某国际国家权威机构鉴定,联合国大力丸组织鉴定
验证.
3.等转你到差不多了,让你知道你现在用的多不好啦,你用这个会完蛋啦.就开始说了,"
那你怎么办呢?!!"
当然是用我推荐这个.
怎么看出是托呢?以下几个我的疑点,当然我不是权威,只是我的怀疑,也许说得不对,欢
迎指正.
1. 怎么算才是算玩得多,玩得多就等于有权威吗?
玩过20个算多吗?还是100个?品牌广泛吗?就算是用过,有科学的比较过吗?就是玩过"很
多"说的话就自动牛B吗?这就好像说我走的路多,所以我对走路是专家一样.如他自己说
的,基本上是废话.
2.透光率90%概念是多少? 这里有讲coating的,说的是泛玻璃镜头,没分新旧,而言
Ordi... 阅读全帖 |
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e**n
发帖数: 5876 | 40 GX8有对衍射做特别的补偿. 不知道效果怎么样
The GX8 also has diffraction compensation processing, which will help
counteract the image softening effects from shooting at small apertures. |
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y*b
发帖数: 3190 | 41 http://www.canonwatch.com/canon-eos-1d-x-mark-ii-specification-
EDIT: Digicame-Info posted an updated and more detailed EOS-1D X Mark II
spec list.:
20.2MP CMOS sensor. Dynamic range improvement
Dual pixel CMOS AF
Dual DIGIC6 + processor
ISO100-51200 (expanded in 409600)
Continuous shooting of 14 frames / sec. 16 frames / second in the live view
mode
New mirror drive system that enables high-speed continuous shooting
Continuous shooting The number of storable RAW at 170 frames (at 16 frames /
se... 阅读全帖 |
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y*b
发帖数: 3190 | 42 "Dpreview compared the new Sony RX10III against the Panasonic FZ100 and the
Canon G3X. The Panasonic is as good as the Sony but does only go as far as
400mm. So the real contender seems to be the Canon:
The real reason people consider bridge cameras is for the reach, and Sony
extended the RX10 III’s reach by a full 400mm over the RX10 II. That means
it now offers the same amount of reach as the G3 X’s 600mm equivalent
maximum focal length. The RX10 III’s lens is clearly sharper, but it has
anoth... 阅读全帖 |
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d******d
发帖数: 2210 | 43 EOS 5D Mark IV DSLR Camera Specifications:
New 30.4 Megapixel full-frame CMOS sensor for versatile shooting in nearly
any light, with ISO range 100–32,000; expandable up to 50–102,400.4K
Motion JPEG video (DCI cinema-type 4096 x 2160) at 30p or 24p; in-camera
still frame grab* of 4K 8.8-Megapixel images; multiple video options include
Full HD up to 60p, and HD up to 120p.Superb Dual Pixel CMOS AF for
responsive and smooth AF during video or Live View shooting; LCD monitor has
full touch-screen i... 阅读全帖 |
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b*****e
发帖数: 5133 | 44 24-70离完美应该还有不少距离，适马新出的就搞砸了。不管哪家24，70两头总有一头
是短板。
佳能在搞的diffractive optical super telephoto出来的话算黑科技了，份量体积大
减了大家就不用抗大炮出门了 |
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b*****e
发帖数: 5133 | 45 24-70离完美应该还有不少距离，适马新出的就搞砸了。不管哪家24，70两头总有一头
是短板。
佳能在搞的diffractive optical super telephoto出来的话算黑科技了，份量体积大
减了大家就不用抗大炮出门了 |
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q***3
发帖数: 5088 | 46 Augustin-Jean Fresnel Diffraction
中文译作 单缝衍射 |
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d****o
发帖数: 32610 | 48 bacterial mineral excretion
也不是很好玩
http://jss.ecsdl.org/content/6/3/N3113.full
Sodium Tungstate and Sodium Molybdate Hollow Microspheres
Abstract
This study is to present sodium tungstate and sodium molybdate hollow
microspheres–microspheres with three length-to-diameter ratios of 1:1, 3:1,
and 10:1. They were excreted by two strains of aquaculture probiotic Gram-
negative bacterium, Shewanella sp. and Pandoraea sp. Their morphology is of
hollow spherical shape, which was captured via the scanni... 阅读全帖 |
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d********a
发帖数: 3698 | 49 谁有比较好的书或网站介绍晶体学.Crystallography，点群，空间群，结构符号的
这学期选了门DIFFRACTION OF Materials 的课，
老师一口老印英语基本听不懂啊，而且飞快，一天一章。
下周就要交作业 |
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c***r
发帖数: 4631 | 50 I am working on polymer physics now.
Kind of Nanoblahblah, self-assembly blah blah...
Anyway, still TEM and X-Ray diffraction. |
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