投白墙是否可以－以SONY-VW60为参考的验证性实拍-欢迎提出评价意见

calven1981

我就想问LZ，实际画面的黑位有这么沉么？颜色有这么艳么？
如果在浅色环境下都能得到这么棒的画面，那纯黑环境拿来干嘛。根据我对摄影的经验，LZ这个应该是相机的优化作用。

mugualee

答复: Calven 1981
一、你上一帖曾说：“可以保证LZ看到的实际画面和拍摄的画面是绝对不一样的，我才拿到VW60的时候试机也是直接投的白墙，但是那画面确实很一般，画面像蒙了纱，不太通透，颜色也一般，因为周围的衍射太严重了。但是我拍出来的画面就还不错，还是用手机拍的。sony的R1颜色是比较艳丽的，比较讨好一般的摄影爱好者”。
    本帖的意思可以理解为你已经拥有了VW60 （可别告诉我你又卖了啊，哈哈－）。

二、你在本帖中说：“我就想问LZ，实际画面的黑位有这么沉么？颜色有这么艳么？
    如果在浅色环境下都能得到这么棒的画面，那纯黑环境拿来干嘛。根据我对摄影的经验，LZ这个应该是相机的优化作用。”
    既然你有VW60，就应该知道并体会了VW60的35000：1对比度。


三、为证明你言之有据，希望能把你家里用的VW60实物帖张图出来。


四、答复你的话：
    1、实际画面的黑位就这么黑。当然，需要说明的是，由于摄影曝光的问题（照顾了明处难以顾全暗处），这次照的暗部偏黑了，但投影机完全可以做到更黑的。
    2、颜色没有用更艳丽的模式。原自动设定过艳了。不是相机的优化作用。对此，你也可以照啊。
    3、为什么要用“纯黑的环境”？我不是专家，我的理解是，由于以前的投影亮度底、对比度底，有了亮光就没法看了。如果亮度高了，同时对比度也高了，那完全可以在亮的地方看呀！我的证据是：你天天看的CRT或液晶电视不是开着灯和大白天都能看吗？所以，所谓的投影只能“黑环境”看实在是曲解。

mugualee

各位坛主高手：

    这次开帖的目的是为了联络各路高手来求证白墙到底能不能替代三五千块钱的幕布。

    我从没过开帖，因为不想误人之弟。本次采取的是实证主义的方法，即言必有据。

    平时逛坛子，发现那么多高手侃侃而谈、振振有词。本次，我也希望大家能踊跃参与，比如，有幕的网友可以帖出更好的图片，来证明幕是必要的。

    请大家帮助大家，帮助那些尚在困惑的网友。

mugualee

请卖幕多店家来指点一下。

     我开此帖的背景是基于以下逻辑推理：我想－－－

       幕多作用有以下：1）可以提供一个投影多平整平面；2）由于以前多投影亮度低，如三枪，波珠幕可以提高亮度；3）由于以前的投影对比度低，如以前的LCD，灰幕可以提高对比度。

     所以产生了白珠幕、灰幕、白朔幕等。有人撰文说：“白塑幕与灰幕的主要区别是白塑幕（1.1以上）的增益大于灰幕（0.8以下）；灰幕比白塑幕最大的优点就是提高色彩对比度、灰阶对比度，更适合一些家庭  影院中低流明的投影机和光线较低的环境使用；白塑幕适合与亮度较高的投影机配合使用”。

    我的主观感觉是白墙的增益大约在0.9－1.0之间，又平整。这符合白朔幕的特点，所以还是适合替代一般幕作投影用的。

    对于家庭来说，毕竟不是实验室， 如果一个投影的实际亮度在1000流明以上，实际对比度在15000以上，即亮度和对比度的问题都解决了，那是不是只需要一个平整的平面了.即白朔幕或白墙了？不知大家注意没有，北京万达影城的放映厅里并不是全黑的呀。

calven1981

原帖由 mugualee 于 2008-4-22 17:44 发表
答复: Calven 1981
一、你上一帖曾说：“可以保证LZ看到的实际画面和拍摄的画面是绝对不一样的，我才拿到VW60的时候试机也是直接投的白墙，但是那画面确实很一般，画面像蒙了纱，不太通透，颜色也一般，因为周围的 ...

我没这么无聊，家里没有vw60来这里乱喷.....

calven1981

vw60才到家的时候，我马上就拿出来投家里的白墙了，左右墙，天花都是白色乳胶漆，地面都是浅黄色的玻化砖，所以整个房间的光衍射很厉害。你不会衍射都不知道吧。试机时当画面亮度比较高时，整个屋里像白天一样，很亮堂，这就是周围的环境反射光，然后叠加到画面上就造成了画面发灰，对比不足。不管是DLP，LCoS，3LCD，在这种环境下都不可能发挥的很好，除非你是用的火星技术的投影- -b
所以新家的视听室在装修的时候吸取了教训，搞的全黑装修。为什么要全黑的装修，你还没反应过来吗，避免周围环境的衍射......另外告诉你液晶电视,CRT内部光路也是全黑的，密封的.....

[ 本帖最后由 calven1981 于 2008-4-22 23:36 编辑 ]

sun_ce

照片拍的不错，不知道是否是原图调整大小而已，还是经过ps了

sleepyday

其实幕的最重要作用主要是用 减少视角 换 减少环境光干扰。平整平面是次要作用。

白墙是漫反射面，幕反射的角度要小的多。所以有更多的光进入眼睛（亮度提高），上下左右墙壁的反光及大部分环境光不会再通过幕反射到眼睛里来（对比度提高），眼睛的宽容度主要通过环境光才能控制，幕只能通过涂黑边略微改善。

亮度可以通过提高投影机亮度解决，对比度可以通过环境遮光，暗环境避免反光来解决。宽容度问题主要通过控制环境光来解决。

幕主要是用来减少系统对环境的要求。要是可以完美控制环境，幕的作用就大大降低了。

wubin8210

不管是否效果会进一步提升，反正ae2000头白墙的效果我已经很满意了。不想多折腾。

jackalwan

只能说楼主的屏摄水准太牛了。一看就中毒。

mugualee

To:
calven1981, sun-ce, sleepyday, wunbin8210, jackealwan, jixiao


感谢你们在百忙之中抽出宝贵的时间参与讨论。



sun-ce, sleepyday, wunbin8210, jackealwan, jixiao 兄的观点十分客观、公正，我表示赞同。

mugualee

To: calven1981: 阁下上一个回复的观点跟我的观点是吻合的，赞同。

      但是，似乎你又提出了一个新的分论点：即：即使用VW60这么高达1000流明亮度和35000：1 对比度的投影机，也不仅必须用幕，而且得把墙涂成黑色的。 (原文：“所以新家的视听室在装修的时候吸取了教训，搞的全黑装修。为什么要全黑的装修，你还没反应过来吗，避免周围环境的衍射......”)

      由于calven兄的观点和实际做法跟我本来提出的命题正好相反(我提出希望大家论证的是：是不是可以直接用白墙而用不着幕里)，我感觉很有意思，也很想看看把家里的四墙涂成黑色的感觉（以前只在专门的投影室看见过）。不知是否可以劳烦calven兄把你家的视听室（或客厅）环境拍张照片帖上来，我等也见识一下，最好也拍几张投影画面等效果来。
        你前边贴子里等VW60投白墙的照片我感觉很奇怪，虽然照的取景和构图挺专业的，但是画面的效果只象普通29寸电视在480i 下的分辨率。恕我直言，不象VW60的显示效果。

mugualee

关于VW60的话：

     我也注意到了Projectorcentral 上到那篇评测VW60的文章，我在日本店里的经历也比较赞同他的观点，但是，其实他的文章有个问题，即缺乏测试数据。
其实，投机机评测还有一个更有名的杂志叫《Ultimate AV》，它不仅有评价，最后都附有测试数据。大家可以搜索一下。
下边是我摘录都它关于VW60，SANYOZ2000，EPSON等等测试数据部分，大家不难发现，其实VW60的实际数据还是很高的。我的感觉是就对比度来说，JVC HD1 HD100最高，EPSON 2000次之，再者就是VW60。

Sony VPL-VW60 SXRD Video Projector
By Thomas J. Norton   •   February, 2008

Contrast and Overscan
In the Auto1 Advanced Iris setting, I measured a superb peak dynamic contrast ratio of 14,200:1 (!) (14.2 foot-Lamberts peak white, 0.001fL video black). In practice, this may be somewhat less, since 0.001 is the lowest specified sensitivity of our recently calibrated Minolta LS-100 light meter. I took at least a dozen readings and the meter did read 0.002 several times, but 0.001 predominated.

I checked several other combinations of the lamp and iris settings. The worst case was with the iris on manual, fully open, and the lamp on High: a peak contrast ratio of 2476:1 (19.81fL peak white, 0.008fL video black). Note that this peak light output is roughly the same as the best I obtained from Sony's $15,000 VPL-VW200! (The Black Pearl had just under 200 hours on the lamp when these readings were taken.)

With the Overscan control set to Off, overscan via both component and HDMI was 1.5% or less on each side in 480i and 480p, and 0% on all sides in 720p and 1080i.

Addendum for Sony VPL-VW60 Measurements

After the measurements were completed and the review was turned in for editing and posting, I took a second look at the calibration settings. They produced a good grayscale, but they also involved a considerable reduction in the green color-temperature controls, particularly Green Gain (the high end of the brightness range). Since the eye is most sensitive to green, I wondered if I could wring a bit more brightness from the projector by increasing these green settings and adjusting the other controls as needed to maintain an accurate grayscale.

So I attacked the calibration once again, beginning with all the custom color-temperature controls set to zero. Sure enough, the new calibration produced a higher light output. My new settings were:

Contrast: 95
Brightness: 47
White Balance
Gain: Red +19, Green -9, Blue -22
Bias: Red +5, Green 0, Blue -6

Most of the other settings remained the same, though I needed to decrease the Color control slightly and increase the Hue a few clicks toward green for the most natural skin tones.

Following these changes, I took a number of new peak contrast readings with different Advanced Iris and Lamp Control settings (all of them, as before, on my Studiotek 130 screen).

1. My preferred setup:
Iris: Auto1
Lamp Control: Low
Peak white: 16.74fL
Black level: 0.002fL
Peak contrast ratio: 8370:1

2. If you prefer a fixed iris:
Iris: Manual-Max
Lamp Control: Low
Peak white: 15.70fL
Black level: 0.007fL
Peak contrast ratio: 2243:1

3. If you need more output for a larger screen:
Iris: Auto1
Lamp Control: High
Peak white: 25.75fL
Black level: 0.003fL
Peak contrast ratio: 8583:1

4. As in 3, but with a fixed iris
Iris: Manual-Max
Lamp Control: High
Peak white: 24.34fL
Black level: 0.010fL
Peak contrast ratio: 2434:1

The new post-calibration grayscale curves are not shown here, since there were no dramatic changes. The new color temperature did measure slightly higher than 6500K across much of the brightness range, but on average, it was as near to the D65 standard as before.

The main subjective change on real program material was increased light output. The extra 2.5fL in the Low lamp setting was clearly visible. It did mean a slight sacrifice in black level and peak contrast—the change in black from 0.001fL to 0.002fL with the iris at Auto1 is visually marginal, but it does cut the measured contrast ratio roughly in half. Some viewers might prefer the earlier setup, but the new one added significant punch.

In any event, on a larger screen than mine, the added brightness should be welcome. I can also now say, with some confidence, that the Black Pearl is brighter than the Pearl.

Sanyo PLV-Z2000 1080p LCD Projector
By David Vaughn   •   January, 2008

Contrast and Overscan
In the Normal iris setting, Iris range at -30, I measured a peak contrast ratio of 3138:1 (12.55 foot-Lamberts peak full-field white, 0.004fL video black. Interesingly, however, changing the Iris range to zero did not affect the black level reading at all but increased the peak full-field white output to 14.1 for a peak contrast reading of 3503:1

Overscan in both HDMI was zero across the board, and only increased to 1.5% in component 480i/p at the left and right sides of the image.—Thomas J. Norton

Epson PowerLite Home Cinema 1080 LCD Projector
By John Higgins   •   July, 2007

Projected 1080p for the masses has arrived.

PowerLite Home Cinema 1080 LCD Projector, $3,000

Full-On/Full-Off Contrast Ratio—6,852:1; ANSI Contrast Ratio—211:1

Measured Resolution with the Leader LT-446:
480: 480(per picture height)
720p: 720 (pph)
1080i: 1,080 (pph)

DC Restoration (poor, average, good, excellent): Excellent

Color Decoder (poor, average, good, excellent): Excellent

Measured Color Points:
Red Color Point: x=0.665, y=0.330
Green Color Point: x=0.261, y=0.659
Blue Color Point: x=0.150, y=0.048

Measured Color Points After Calibration:
Red Color Point: x=0.640, y=0.329
Green Color Point: x=0.300, y=0.624
Blue Color Point: x=0.152, y=0.059

The top chart shows the PowerLite Home Cinema's gray scale relative to its color temperature at various levels of intensity, or brightness (20 IRE is dark gray; 100 IRE is bright white). The gray scale as set by the factory, in the 6,500 K color-temperature mode, measures very warm with dark images and less warm with brighter images. After making adjustments using the Photo Research PR-650, the gray scale measures very close to D6500, the accurate color temperature, across the entire range.

The bottom chart shows the gray scale (or color temperature) relative to the color points of the display's red, green, and blue liquid-crystal panels. These are fairly off those specified by SMPTE. Red is somewhat oversaturated. Green is very oversaturated and somewhat bluish-green. Blue is very slightly undersaturated and very slightly purplish-blue. Some color-point adjustment is possible. After calibration, green is only slightly oversaturated, red is pretty much spot-on, and blue is ever so slightly undersaturated.

After calibration, and using a full-field 100-IRE white (6.852 foot-lamberts) and a full-field 0-IRE black (0.001 ft-L), the contrast ratio was 6,852:1. Using a 16-box checkerboard pattern (ANSI contrast), the contrast ratio was 211:1. The best contrast ratio was achieved with the Brightness Control (the lamp) set to Low and the auto iris set to On. The brightest image was achieved with the Brightness Control set to High and the auto iris set to On. This mode produced 8.993 ft-L with a 100-IRE field and 0.002 ft-L on a 0-IRE field for a contrast ratio of 4,497:1 (on an 87-inch-wide, 1.0-gain Da-Lite Da-Mat screen).—GM

calven1981

原帖由 mugualee 于 2008-4-23 14:47 发表
To: calven1981: 阁下上一个回复的观点跟我的观点是吻合的，赞同。

      但是，似乎你又提出了一个新的分论点：即：即使用VW60这么高达1000流明亮度和35000：1 对比度的投影机，也不仅必须用幕，而且得把墙涂成 ...

貌似我和你的观点没吻合吧，我一直的观点都是目前的投影技术在光线控制不好的房间，或四周是浅色装修的房间投白墙效果会大打折扣。 你不用叉开话题、节外生枝，我并没提出什么新论点，我说的把视听室处理成全黑，是为了避免房间的衍射，而达到vw60的最佳效果。而且vw60在优化画面过后亮度肯定会降低，请参考K版的评测，我实际使用中也是这个感觉，所以处理成全黑，亮度对比度才足够，你有看见哪一家电影院是浅色装修的吗？
我已经告诉你了，我是用iphone拍的，效果一般，但是都比实际看到的画面的黑色要沉一些，相机因为宽容度不够，为了让高光不过爆，让本来有点灰的黑色变得更黑，这就是相机的优化作用。再来有的相机内置程序从raw处理到jpg是会做一些ps处理，各个厂商不一样，sony的风格就比较艳丽，canon比较均衡，nikon的锐度高，白平衡偏蓝一点，这些特性都会造成屏射的二次失真。

calven1981

全黑环境最大的好处就是感觉是在黑暗的环境中看一个大的平板电视，投入感满点~画面绝对不会发灰，因为没有环境衍射光的影响，黑位也沉，不发灰了。
不过iphone拍我不能控制光圈快门，比较麻烦，基本上不能反应实际画面的效果。过段时间把家里收拾好，音箱装好，我拿20D好好的屏射一下。