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发表于 2018-3-9 19:47 | 显示全部楼层

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微调放大曝光和对比度              优化打印
The old axiom for creating high-quality negatives is
‘expose for the shadows and develop for the highlights’.
When it comes to printing negatives in the darkroom,
this recommendation appropriately changes to ‘expose
for the highlights and control the shadows with con-
trast’. That is good advice, but as experienced printers
know, there often is a small difference between a
good and a mediocre print. So, when it comes to
fine-tuning exposure and contrast, how concerned
do we really need to be about the optimal settings?
How much deviation is acceptable, and how little is
recognizable? What are the smallest increments we
need to work with? How do we advance from casual
work to fine-tuned images without going completely
overboard? Exploring a sample print of the Castle
Acre Priory will provide some answers.
Castle Acre Priory is located just five miles north of
Swaffham in Norfolk, England. Its ruins span seven
centuries and include an elaborately decorated 12th-
century church, a 15th-century gate house and the prior’s
former living quarters, which are still fit to live in.
The picture on this page was taken inside of the
prior’s chapel in July of 1999. I used my Toyo 45AX
with a Nikkor-W 135 mm, f/5.6 on a tripod. This metal
field camera travels well, and is fast and easy to set up,
considering the large 4x5-inch format. The 135mm lens
was required, because the room is very small, and I
was not able to step back any farther. I measured the
scene with my Pentax Digital Spotmeter and placed
the dark interior wall on Zone III, in order to keep
the option of some detail. The bright vertical wall of
the window fell on Zone VII, but due to the bright
sunlight, the windowsill was clearly on Zone XI. To
pull the sill back onto Zone VIII, N-3 development
was needed. I changed the EI to 25, as is necessary
when dealing with a rather broad subject brightness

range such as this, in order to sufficiently expose
创造高质量底片的老原则是
为阴影曝光,为高光显影。当谈到在暗室放大底片时,
此建议适当更改为“公开”
对于高光和对比度控制阴影。这是个好建议,但正如经验丰富的打印机所知,好的和平庸的作品之间往往有一点差别。因此,在微调曝光和对比度时,我们真正需要关注的是最佳设置吗?
多少偏差是可以接受的,多少偏差是可以接受的可辨认?
我们如何随意的
在不太过分的情况下微调放大图像?
探索城堡的样图,阿克里修道院会提供一些答案。
城堡阿克里修道院位于北部五英里处
英格兰诺福克的斯瓦夫汉姆。它的废墟横跨七层
包括精心装饰的12世纪教堂,一座15世纪的门楼
以前的生活区,现在还适合居住。 1.jpg
这一页上的照片是在1999年7月的普利斯教堂。我用了我的Toyo 45斧头
有一架135毫米口径的尼克- W型飞机,f / 5.6在三脚架上。这金属
现场摄像机运行良好,安装快捷方便,考虑到大的4×5英寸格式。135毫米镜头之所以需要,是因为房间很小,而我
无法再后退一步。我量了一下使用我的Pentax数字聚光灯并放置场景
第三区的黑暗内壁,以保持一些细节的选择。明亮的垂直墙
窗户落在第七区,但由于阳光明媚阳光照射下,窗台上分明是Xi区。到
将门槛拉回到VIII区,N - 3开发区需要。必要时我把EI改为25
当处理相当宽的主题亮度时这样范围,以便充分暴露



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 楼主| 发表于 2018-3-9 19:59 | 显示全部楼层
had given enough exposure time to get at least good
tonality from the shadows, even though most of the
detail was lost. With this treatment, the image printed
well on grade-2 paper and only required minor burn-
ing down of the upper corners. I consider this print
to have a full tonal scale from Zone II to VIII, which
makes it a prime candidate to discuss optimized print
exposure and contrast.
Print Exposure
It makes little sense to print highlights lighter or
shadows darker than what the human eye is able to
discern under normal lighting conditions. Neither
does it make sense to worry about exposure differences
that are too small to see. With that in mind, some
questions need to be answered.
1. What are ‘normal’ lighting conditions?
The fi rst to answer this question was Henry Dryfuss
through extensive research conducted in the 1960s,
which is fully documented in his book The Measure
of Man. He established lighting conditions for coarse,
medium and fi ne manual work. His recommended
illumination levels were initially meant for manual
labor conducted over several hours, but they are also
adequate to view photographic prints. Subsequent
viewing standards, ANSI PH2.30-1989 and the cur-
rent version ISO 3664:2009, are based on his work.
Fig.1 shows Henry Dryfuss’s fi ndings, and I in-
cluded the conversion to EVs at ISO 100/21° so that
you can quantify illumination levels with your own
lightmeter. Consequently, EV 7 is the minimum il-
lumination at which a print should be displayed, and
there appears to be no benefi t to illuminate beyond
EV 11. This range seems to be reasonable, based on
the display lighting conditions in my own home and
those found in galleries. When lighting levels drop
below EV 7, previously well-detailed shadows get too
dark for good separation. At illuminations above EV
11, previously well-detailed highlights tend to bleach
out. This is the logic behind the recommendation to
print with the display conditions in mind, as advo-
cated in Ansel Adams’ book The Print. A picture to
be hung in the dark hallway of the local church must
be printed lighter than the same picture exhibited in
a well-lit photographic gallery. I recommend printing
for ‘normal’ lighting conditions of EV 8 to EV 10, if
the fi nal display conditions are not known.
已经给了足够的曝光时间来获得至少好的结果
色调来自阴影,尽管大多数
细节丢失了。通过这种处理,图像被放大
在二号纸上,只需要稍微烧掉上角。我认为这是作品
具有从区域II到区域VIII的全音阶,其
使其成为讨论优化放大的首选
曝光和对比度。
放大曝光
放大较亮或较亮的高光没有什么意义
阴影比人眼能看到的更暗
在正常照明条件下辨别。也不
担心暴露差异有意义吗
太小看不见。考虑到这一点,有些人
问题需要回答。
1 .什么是“正常”照明条件?
第一个回答这个问题的是亨利·德莱克斯
通过1960年代进行的广泛研究,
这在他的著作《衡量标准》中有充分的记载
人类。他为粗糙、粗糙,
中、细体力劳动。他推荐的
照明水平最初用于手动
劳动进行了好几个小时,但他们也
足以查看照片打印。随后的
查看标准,ANSI PH2.30 - 1989和cur -
租金版本ISO 7464 : 2009,都是基于他的工作。
图1显示了亨利·德莱克斯的发现
包括在ISO 100 / 21中转换为电动车辆,以便
您可以使用自己的照明级别进行量化
测光表。因此,ev7是最小的
应显示打印的照度,以及除此之外,似乎没有什么好处可言
11岁。这一范围似乎是合理的,依据是
我自己家里的显示照明条件和
画廊里的那些。当照明水平下降时
在ev7之下,以前非常详细阴影也会出现
暗为好分离。在高于以往光照下
11、先前精心制作的亮点往往会褪色
出去。这是建议背后的逻辑
按照Ansel Adams的《打印》一书中所倡导的那样,打印时应考虑显示条件。给…的照片
被挂在黑暗走廊上的地方教会必须
比中展示的相同图片要轻
灯光明亮的摄影画廊。我建议打印
对于ev8至ev10的“正常”照明条件,如果
最终显示条件未知。
图1还揭示了阴影更受影响
被昏暗的光线比被明亮的高光更受影响
光。因此,检查图像会更安全
在显示照明的较低阈值时
印刷。我在暗室里用塑料研究我的指纹
我水槽旁边的木板。它被照亮以读取ev6
将测光表设置为ISO 100 / 21。这确保了良好的
最终打印中的阴影细节。如果我能在ev6阴影下,我可以看到它们
正常照明条件也一样。但是,如果评价光线太亮了,有印出来的危险
在正常照明条件下太暗。作为其他优点,打印ev6阴影细节也

有助于补偿干燥效应。
2 .调性的反射密度限制是多少?
区域系统将音调限制定义为区域
VIII用于高光,而区域II用于阴影。
在精确思考方面没有达成普遍协议
等效打印区域的密度,但现有
纸特性曲线标准,ISO 6846,可
帮助定义近似值。图2示出了这如何
标准集中在纹理密度范围
特性曲线,通过忽略低对比度
脚趾和肩膀的区域,因为它们
对绘画摄影几乎没有实用价值。
标准将“第一可用密度”定义为
比纸的基本密度高0.04。最
精美的印刷纸,包括伊尔福德的多重商标
IV,具有约0.05反射密度的基础白色。
因此,我们将把第八区定在0.09左右
大多数纸张的反射密度。暖色调
纸,或有象牙底座的纸,可能有一个稍高的价值,因为他们有一个较小的事实
反射基地白色,但他们是少数。
当前的ISO标准定义了“最后可用
“密度”为最大密度的90 %,还
叫做Dmax。需要考虑的另一个因素是
人眼对阴影细节的敏感度限制。i
在“正常”照明条件下进行现场测试
在ev8附近。六个人被要求辨认
最暗的区域,30种不同的印刷品上仍有可见的细节。
180密度读数的平均值为1.88,标准偏差为0.09密度。今天的光泽还是珍珠
纸张的Dmax密度约为2.10,如果
色调。ISO标准的90 %规则指向a

这些纸张上的“最后可用密度”为1.89。
这两个数字几乎精确的相关性
是巧合。但是,这两个协议
方法,以及与研究的良好佐证
其他作者,包括黑白摄影的控制
通过理查德·亨利,似乎表明了这一价值
是“最后可用密度”的良好近似。
因此,我们将把第二区定在1.89左右
大多数纸张的反射密度。有少数人
无光泽表面纸或具有纺织品表面的纸,
其具有显著较低的Dmax值

这些论文采用90 %法则更适合计算“最后可用密度”。
3 .眼睛对反射的辨别能力如何
密度差异?
这个问题的答案将决定
我们需要关注放大曝光差异。
一些放大机采用的“经验法则”是
暴露量的20 %变化是显著的,10 %
变化不大,5 %的变化很小。在
常规的f / stop定时密切地对这些值进行项
分别与1 / 3、1 / 6和1 / 12停止相关。我又做了一个实验来找到答案。
将两步片剂暴露并加工。为
每张纸,我用一张5x 7英寸的纸打印
它上面有七个1英寸宽的条。一步片剂是
打印区域VIII周围目标密度为0.09
而另一个印刷密度约为1.89代表第二区。暴露程度不同



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 楼主| 发表于 2018-3-9 20:07 | 显示全部楼层
放大的对比度
The desired shadow detail is typically fine-tuned with
paper contrast after the highlight exposure has been
set. The recommended rule of thumb is to start with
a soft paper-grade estimate and then slowly move up
in contrast until the desired shadow detail has been
reached. The trial and error portion of this approach
can be minimized, if we realize that contrast can also
be referred to as the exposure of the shadows.
We can use fig.5 to determine the required expo-
sure for Zone II. Only the characteristic curves for
the paper contrast limits, grade 0 and 5, are shown. I
made sure that both papers were exposed so that the
highlights of Zone VIII were rendered with the same
reflection density. This allows us to measure the rela-
tive log exposure difference between the shadows of
these two paper grades. In other words, the highlights
were placed on top of each other to see how much
the shadow exposures differ from each other. The
shadows differ by about 1.0 log exposure.
A different method is shown in fig.6, and it leads
to the same conclusion. All standard paper grades
have a defined log exposure range to match differ-
ent negative density ranges. Soft papers have a low
grade number and a wider exposure range than hard
papers, which have a high grade number. Although
all grades have exposure ranges expressed within
the shown limits to accommodate manufacturing
tolerances, we need only to concern ourselves with
the average exposure ranges for this exercise. The
difference between the average exposure ranges of
grade 0 and 5 is, reading from the table, 1.55 - 0.58 =
0.97 log exposure. This is a very similar value to the
log exposure difference 1.0, which we already got
from fig.5 earlier.
Paper grades are often subdivided in 1/2-grade
increments to provide enough flexibility to fine-tune
image contrast. This provides ten increments between
grade 0 and 5, and we can assume, within a reasonably
small error, that the log exposure difference between
grade 0 and 5 is linear. Consequently, a log exposure
difference of about 1.0, between grade 0 and 5, divided
by ten increments results into a 0.1 log exposure dif-
ference between 1/2-grade increments. By definition,
a log exposure of 0.3 equals one stop of exposure dif-
ference, and therefore, in average, a 0.1 log exposure
difference makes for a 1/3-stop exposure difference
between 1/2-grade increments.

所需的阴影细节通常用高光曝光后的纸张对比度集合。
推荐的经验法则是一张软纸等级估计然后慢慢往上移动
相反直到期望的阴影细节被到达。这种方法的试错部分
可以最小化,如果我们意识到对比度也可以被称为阴影的曝光。
我们可以使用图5来确定肯定是二区所需的曝光量
。只有的特征曲线示出了纸张对比度极限(等级0和5 )。i
确保这两份文件都已曝光第八区的重点以同样的方式呈现
反射密度。这允许我们测量的阴影之间的相对对数曝光差异
这两个纸品等级。换句话说,亮点都放在彼此的上面看有多少
阴影曝光彼此不同。这
阴影相差约1.0 log曝光。
图6中示出了不同的方法
得出同样的结论。所有标准纸张等级
具有定义的对数曝光范围以匹配不同的负密度范围。软纸有低
等级号和比硬的更宽的曝光范围
论文,其中有一个高等级的数字。尽管
所有等级的暴露范围均在以下范围内表示
所示的限制以适应制造
容差,我们只需要关心自己
本练习的平均接触范围。这
的平均曝光范围之间的差异
等级0和5为,从表中读取,1.55 - 0.58 =
0.97日志暴露。这与
记录曝光差异1.0,我们已经得到
从图5中可以看出。
纸张等级通常细分为1 / 2等级
增量以提供足够的灵活性来微调
图像对比度。这提供了以下10个增量
0级和5级,我们可以假定,在一个合理的
误差小,说明日志曝光差异大
等级0和5是线性的。因此,日志暴露
差约1.0,在0级和5级之间,除
增加10个增量导致1 / 2级增量之间的0.1 log暴露差异。根据定义,
0.3的对数曝光等于曝光差的一次停止,因此,平均而言,0.1的对数曝光
差异导致1 / 3停止曝光差异
在1 / 2级增量之间。

.jpg 3.jpg
图7存在以下关系
停止曝光差异
阴影和纸张等级
偏差,如果高亮显示
曝光保持恒定。

图8a - c具有相同底座的测试条曝光,但不同曝光增量,可用于
确定所需阴影细节和对比。所有测试条都具有18秒的目标曝光,
f /停止增量为1 / 3时,1 / 6和1 / 12停止,下降
向左并增加到右边。纸张对比在2.5级保持恒定,
但是不同的暴露显示不同阴影细节,预测目标对比度
坡度(标在顶部),无任何附加测试。

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 楼主| 发表于 2018-3-9 20:10 | 显示全部楼层
本帖最后由 cndby 于 2018-3-9 20:15 编辑

Fig.7 shows the relationship between the f/stop
exposure differences of the shadows and paper-grade
deviations, if the highlight exposure is kept constant.
This discovery has placed the value of test strips into a
completely different light for me. In the past, I looked
at test strips purely as a tool to determine accurate
highlight exposure. Moreover, I resisted looking
at the shadow detail in test strips, because I knew
how confusing it can be to determine exposure and
contrast at the same time. Only after the highlight
exposure was set did I modify the shadow detail by
slowly changing paper contrast. I still believe that
there is much value in this approach, and I would not
recommend anything else to a beginning or practicing
printer. However, I’m glad that Paul Butzi pointed out
to me that an advanced darkroom practitioner can get
valuable information about the desired paper contrast
by evaluating the shadow detail of the test strip.
Fig.8 shows three test strips, which differ only by
the exposure increments used. They have all been
printed at grade 2 1/2 and have the same base exposure
of 18 seconds in the center. The exposure decreases to
the left and increases to the right. Figures 8a-c, from
top to bottom, were prepared in 1/3, 1/6 and 1/12-stop
exposure increments, respectively. There is enough
information here to fine-tune the highlight exposure
securely down to 1/12 stop. Let’s assume, for this ex-
ample, an exposure of 18 seconds to be just right.
Now, we can take a look at the shadow detail
on the different test strips. Unfortunately, I cannot
predict how easy it will be to see a difference in the
final reproduction of these test strips. However, in
the originals, there are clear differences in the upper
left corner shadows of fig.8a, a modest difference in
fig.8b and a minute, but still visible, difference in
fig.8c. From fig.7, we know that 1/3, 1/6 and 1/12-stop
exposure differences are equivalent to 1/2, 1/4 and
1/8 grade, respectively.
Therefore, we can look at highlight and shadow
detail on different test strips and select one each to
our liking. We will then know immediately what
exposure time is required to retain highlight detail,
and what contrast change is required to achieve that
level of shadow detail. As an example, if we like the
highlight detail of the center strip in fig.8a, but we
prefer to have the shadow detail of the second strip
to the left, then the base exposure would remain at 18
seconds, but the contrast would have to be reduced by
图7示出了f /停止之间的关系
阴影与纸张等级的曝光差异偏差,如果高亮曝光保持恒定。
这一发现将测试条的值放入对我来说完全不同的光。过去,我看了看
在测试条上纯粹作为工具来确定准确突出曝光。而且,我拒绝看
在测试条的阴影细节,因为我知道确定暴露和同时对比。只有在亮点之后
曝光设置是否通过修改阴影细节慢慢改变纸张对比度。我仍然相信
这种方法很有价值,我不会这样做在开始或练习时推荐其他任何东西
打印机。不过,我很高兴保罗·布奇指出对我来说,一个高级暗房从业者可以得到
有关所需纸张对比度的有用信息通过评估测试条的阴影细节。
图8示出了三个测试条,其不同之处仅在于使用的曝光增量。他们都是
印刷等级为2 1 / 2,基本曝光率相同18秒的时间。接触减少到
向左并向右增加。图8a - c,来自
自上而下,分别制备了1 / 3、1 / 6和1 / 12 - stop曝光增量分别为。够了
此处的信息用于微调高光曝光
安全下降到1 / 12档。让我们假设,对于这个前充足,曝光18秒才算恰到好处。
现在,我们可以看一下阴影细节在不同的测试条上。不幸的是,我不能
预测在这些测试条的最终再现。然而,在
原件,上面有明显的区别图8a的左下角阴影中
图8b和一分钟,但仍然可见从图7中,我们知道1 / 3、1 / 6和1 / 12 -停止
暴露差异相当于1 / 2、1 / 4和分别为1 / 8级。
因此,我们可以看看亮点和阴影详细说明不同的测试条,并分别选择一个测试条
我们喜欢。我们会马上知道需要曝光时间来保持高亮显示细节,
以及实现这一点需要什么对比度变化阴影细节级别。举个例子,如果我们喜欢
突出显示图8a中的中心条的细节,但是我们更喜欢第二条的阴影细节
向左,则基本曝光将保持在18几秒钟,但对比度必须降低 4-1.jpg 4-2.jpg
1年级。图8b允许对比度选择下降到1 / 4
等级,因为曝光增量仅为1 / 6
停下。图8c允许我们选择对比度增量
低至1 / 8级。
应在此补充说明,根据使用的设备和材料,微小的接触变化
可能需要保持恒定高亮
更改纸张对比度时的曝光。我不相信
任何不断强调曝光的声明
测试并校准了我的所有工具以进行补偿
效果。详细的工作方法见
对比度变化的曝光补偿'。
4 .我们需要多精确地选择纸张对比度?
过滤镜器制造商似乎已经回答了这个问题
问我们问题。市场上所有的过滤器都进来了
1 / 2级增量,即使VC和二向色
彩色头允许更精细的增量。在上一节关于印刷曝光,我们得出结论
1 / 12光圈的曝光增量大约。理论上,这种说法是正确的
对于高光和阴影细节,如中所示
并在图7和8c中验证。似乎有然而,作为一个观众
照片能够辨别他或她是什么
愿意区别对待。眼睛是最重要的
吸引到图像的较亮区域。影子区域最终会引起观众的注意,但非常
黑暗或空洞的阴影对大多数人来说并不有趣观众。然而,对对比的欣赏
降低到一个等级的1 / 8是存在的,即使它们无可否认很难看到。
我认为1 / 4职等的加薪是足够的,但认为标准的1 / 2职等是足够的
增量太粗,无法进行精细工作。
图9a - e示出了从下部开始的区域序列
引线图片的左下角。调整曝光以具有一致的高光反射密度,
但纸张对比度从2级提高
在图9a至图9e中以1 / 4等级增量的等级3。
再次,影子的最终再现能力细节我不知道,但在原件上,一
可以清楚地看到差异而无需任何必要
更精细的增量。此外,我们可以在图8b中看到
期望的纸张对比度如何容易预测从一个简单的暴露测试。测试条提供了
关于曝光和对比度的形成。微调打印曝光和对比度是必不可少的
以获得最佳打印色调。理所当然,找到了
最适合在1 / 12光圈内高亮曝光
优化1 / 4等级内的阴影需要一些努力,
因为微调是通过传统试条的评价。一次性的
电子计量的方法不适用于边界条件的比较。然而
经验丰富的打印机,阅读曝光和对比度
提供相同的测试条是一个受欢迎的快捷方式,它
导致复杂的结果而不妥协。



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 楼主| 发表于 2018-3-9 20:19 | 显示全部楼层
Measuring Paper Contrast测量像纸对比度
After an appropriate print exposure time for the
significant highlights is found, shadow detail is
fine-tuned with print contrast. Without a doubt, the
universally agreed units to measure relatively short
durations, such as exposure time, are seconds and
minutes. However, when it comes to measuring paper
contrast, a variety of systems are commonly used.
Many photographers communicate paper contrast
in form of ‘paper grades’, others use ‘filter numbers’,
which are often confused with paper grades, and
some photographers, less concerned with numerical
systems and more interested in the final result, just
dial-in more soft or hard light when using their color-
or variable-contrast enlarger heads. Nevertheless, a
standard unit of paper-contrast measurement has the
benefit of being able to compare different equipment,
materials or techniques while rendering printing re-
cords less sensitive to any changes in the future.
The actual paper contrast depends on a variety of
variables, some more and some less significant, but it
can be precisely evaluated with the aid of a reflection
densitometer or at least adequately quantified with
inexpensive step tablets. In any case, it is beneficial
to apply the ANSI/ISO standards for monochrome
papers to measure the actual paper contrast.
Contrast Standards
Fig.1 shows a standard characteristic curve for pho-
tographic paper, including some of the terminology,
as defined in the current standard, ANSI PH2.2 as
well as ISO 6846. Absolute print reflection density
is plotted against relative log exposure. The paper
has a base reflection density and processing may
add a certain fog level, which together add up to a
minimum density called Dmin. The curve is con-
sidered to have three basic regions. Relatively small
exposure to light creates slowly increasing densities

5-1.jpg
在适当的打印曝光时间之后发现显著亮点,阴影细节为
通过打印对比度进行微调。毫无疑问普遍同意的计量单位相对较短
持续时间(例如曝光时间)为秒分钟。然而,在测量纸张时
相反,通常使用多种系统。许多摄影师交流纸张对比
以“纸张等级”的形式,其他使用“过滤器编号”,
其通常与纸张等级混淆有些摄影师不太关心数字
系统对最终结果更感兴趣,只是使用它们的颜色时,拨入更多的软或硬灯光-或可变对比度放大头。然而纸张对比度测量的标准单位为
能够比较不同设备的优点,材料或技术,同时再现印刷再现
软线对未来的任何变化都不太敏感。纸张的实际反差取决于多种
变量,有的多,有的少,但它可以借助于反射来精确地评估
密度计或至少用便宜的阶梯药片。无论如何,这是有益的
要将ANSI / ISO标准应用于单色,请执行以下操作
纸张测量实际纸张对比。
对比标准
图1示出了pho -的标准特性曲线
照相纸,包括一些术语,
如现行标准中所定义,ANSI PH2.2为
以及ISO 6846中的标准。绝对印刷反射密度
相对于相对日志暴露绘制。报纸
具有基本反射密度,并且处理可以
添加某个雾级别,这些雾级别加起来等于
最小密度称为Dmin。曲线是
被认为有三个基本区域。相对较小
暴露在光下产生缓慢增加的密度

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 楼主| 发表于 2018-3-10 21:45 | 显示全部楼层
and is represented in the flat toe section of the curve.
Increasing exposure levels create rapidly increasing
densities and are represented in the steep midsection
of the curve. Further exposure to light only adds
marginal density to the paper in the shoulder section,
where it finally reaches the maximum possible density
called Dmax. The extreme flat ends of the curve are
of little value to the practical photographer. In these
areas, relatively high exposure changes have to be
made in order to create even small density variations.
This results in severe compression of highlight and
shadow densities. Therefore, the designers of the
standard made an effort to define more practical
minimum and maximum densities, which are called
IDmin and IDmax. IDmin is defined as a density of
0.04 above base+fog, and IDmax is defined as 90%
of Dmax, which is the maximum density possible for
a particular paper/processing combination.
Please note that according to the ISO standard
IDmax is a relative measure. At the time the standard
was developed, the maximum possible density for any
particular paper/processing combination was around
2.1, which limited IDmax to a value of 1.89. This is a
reasonable density limitation, in order for the human
eye to comfortably detect shadow detail under normal
print illumination. Modern papers, on the other hand,
can easily reach Dmax values of 2.4 or more after
toning, in which case, a relatively determined IDmax
would allow shadows to become too dark for human
detection. Therefrom, a fixed IDmax value of 1.89 is
a more practical approach for modern papers than a
relative value based on Dmax.
While limiting ourselves to the textural log expo-
sure range between IDmin and IDmax, we can secure
quality highlight and shadow separation within the
paper’s density range. With the exception of very soft
grades, the textural density range is constant for each
paper and developer combination. However, the tex-
tural log exposure range will be wider with soft paper
grades and narrower with hard paper grades. It can
therefore be used as a direct quantifier for a standard
paper-grading system.
Prior to 1966, photographic papers were missing
a standard nomenclature for paper grades, because
each manufacturer had a different system. The first
standard concerned with paper grades was listed as
an appendix to ANSI PH2.2 from 1966 (fig.2a). It
divided the log exposure range from 0.50 to 1.70 into
six grades, which were given numbers from 0 through
5 and labels from ‘very soft’ to ‘extra hard’. Agfa, Ilford
and Kodak had used very similar systems up to that
time. A never-released draft of the standard from
1978 added the log exposure range from 0.35 to 0.50
as grade 6 without a label. In 1981, the standard was
revised, and the numbering and labeling system for
grades was replaced. In this ANSI standard as well
as the current ISO 6846 from 1992, different contrast
grades of photographic papers are expressed in terms
of textural log exposure ranges. In fig.1, we see that
the textural log exposure range is defined by H S - H T ,
which is determined from the points ‘S’ and ‘T’ on
the characteristic curve. In the standard, the textural
exposure ranges are grouped into segments referred
to as paper ranges, which are 0.1 log units wide and
expressed as values from ISO R40 to ISO R190 (see
fig.2c). In order to avoid decimal points in expressing
the ISO paper ranges, the differences in log exposure
values are multiplied by 100.
并且在曲线的平趾部分中表示。暴露水平的增加导致迅速增加
密度和表示在陡峭的中间部分曲线的。进一步暴露于光只会增加
纸在肩部的边缘密度,在那里它最终达到最大可能密度
叫做Dmax。曲线的最平坦端为对实用摄影师来说没什么价值。在这些
区域,相对较高的暴露变化必须以便产生甚至更小的密度变化。
这导致高光和阴影密度。因此,设计师们
标准努力定义更实际最小和最大密度,称为最大值和最小值。
IDmin定义为密度为高于基准+雾0.04,IDmax定义为90 %Dmax,这是可能的最大密度
特定的纸张/处理组合。请注意,根据国际标准化组织标准
IDmax是一个相对度量。当时的标准是被开发出来的,最大可能密度为
特定的纸/处理组合在周围2.1,将IDmax限制为1.89的值。这是一个
合理的密度限制,为人类眼睛在正常情况下舒适地检测阴影细节
打印照明。另一方面,现代报纸,可轻松达到Dmax值2.4或更高
调色,在这种情况下,相对确定的IDmax会让阴影变得对人类来说太暗
探测。由此,1.89的固定IDmax值是现代论文的一种实用方法
基于Dmax的相对值。同时把自己限制在纹理原木博览会
一定范围在IDmin和IDmax之间,我们可以确保中的高质量高光和阴影分离
纸张的密度范围。除了非常柔软等级,纹理密度范围对于每个等级是恒定的
纸张和显影剂组合。然而,特克斯软纸的自然对数曝光范围会更宽
等级和较窄的硬纸等级。它可以因此用作标准的直接量词
纸张分级系统。1966年以前,照片文件不见了纸张等级的标准命名法,
因为每个制造商都有不同的系统。第一个与纸张等级有关的标准列为
1966年ANSI PH2.2的附录(图2a )。它将对数暴露范围
从0.50到1.70划分为六个年级,从0到5和标签从“非常软”到“额外硬”。
伊尔福德·阿格法柯达在此之前也使用了非常类似的系统
时间。一份从未公布的标准草案1978年增加了0.35至0.50的对数暴露范围
没有标签的6级。1981年的标准是
修订后,编号和标签制度为等级被替换。在这个ANSI标准中也是如此
如现行ISO 6846从1992年起,不同对比相纸的等级用以下术语表示
纹理对数曝光范围。在图1中,我们看到纹理对数曝光范围由H . S - H . T定义,
其由点“S”和“T”确定特征曲线。在标准中,纹理
曝光范围被分组为参考段以作为纸张范围,宽度为0.1个日志单位
表示为从ISO R40到ISO R190的值(请参见图2c )。为了在表达中避免小数点
ISO文件的范围、日志曝光的差异值乘以100。
5-2.jpg 5-3.jpg

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 楼主| 发表于 2018-3-10 21:54 | 显示全部楼层
本帖最后由 cndby 于 2018-3-10 22:50 编辑

Fig.2c shows a comparison of the variable-contrast
filter numbers used by Agfa, Ilford and Kodak, with
the two standards. It is easy to see that there is only
a vague relationship between filter numbers and the
old standards. Manufacturer dependent variable-
contrast (VC) filter numbers should not be confused
with standard paper grades. They should always be
referred to as ‘filters’ or ‘filter numbers’, to eliminate
any possible misunderstanding.
In this book, we use both the paper-grading system
of the old ANSI appendix and the standard ISO paper
ranges, to measure and specify paper contrast, for
several reasons. Manufacturers do not use their own
grading systems anymore, but they have not switched
completely to the new standard either. Graded papers
are still available in grades from 0 to 5, even though
standard paper ranges are typically also given for
graded and variable-contrast papers. In addition,
photographers seem to be much more comfortable
communicating paper grades than paper ranges,
and the confusion between filter numbers and paper
grades has not helped to speed up the acceptance of
standard paper ranges. Consequently, we continue
to use the old paper-grading system, and we take
the liberty of incorrectly referring to paper contrast,
measured according to this once proposed standard,
as ‘standard ISO paper grades’.
Variable-Contrast (VC) Paper
The advantages of variable-contrast paper over graded
paper have made it the prime choice for many pho-
tographers today. The ability to get all paper grades
from one box of paper, and even one sheet, has reduced
darkroom complexity and provided creative controls
not available with graded papers.
Variable-contrast (VC) papers are coated with a
mixture of separate emulsions. All components of
the mixed emulsion are sensitive to blue light but
vary in sensitivity to green light. When the paper
is exposed to blue light, all components react and
contribute similarly to the final image. This creates
a high-contrast image because of the immediate
additive density effect produced by the different
components (see fig.3). On the other hand, when the
paper is exposed to green light, only the highly green-
sensitive component reacts initially, while the other
components contribute with increasing green-light
intensity. This creates a low-contrast image because
of the delayed additive density effect produced by
the different components (see fig.4). By varying the
proportion of blue to green light exposure, any inter-
mediate paper contrast can be achieved.
There are several options to generate the proper
blend of light required to achieve a specific paper con-
trast. The **st way of controlling the color of the
5-4.jpg
图2c示出了可变对比度的比较
Agfa、Ilford和柯达使用的过滤器编号,带有
这两个标准。很容易看出,只有一种模糊关系
旧标准。制造商相关变量-对比度( VC )过滤器编号不应混淆
具有标准纸张等级。他们应该永远是称为“过滤器”或“过滤器编号”,以消除
任何可能的误解。在这本书里,我们同时使用了纸张分级系统
旧的ANSI附录和标准的ISO文件用于测量和指定纸张对比度的范围
有几个原因。制造商不使用自己的产品分级系统已经不存在了,但它们还没有转换完全符合新标准。分级试卷仍然可以从0到5年级使用,尽管
标准纸张范围通常还用于分级和可变对比度的纸张。此外,
摄影师似乎舒服多了传达比纸张范围更高的纸张等级,
和纸张之间的混淆成绩没有帮助加快接受
标准纸张范围。因此,我们继续使用旧的纸张分级系统,我们采取
错误引用纸张对比度的自由,根据这个曾经提出的标准测量,
作为'标准ISO纸张等级'。可变对比度纸变对比纸优于分级纸的优点
纸已经成为许多摄影师的首选。获得所有影调成绩的能力
从一盒纸,甚至一张纸,减少了暗室的复杂性和提供创造性的控制
可变对比度( VC )纸涂有
分离乳液混合物。的所有组成部分混合乳液对蓝光敏感
对绿光的敏感度不同。当纸暴露在蓝光下,所有组分反应并
对最终图像的贡献类似。这就产生了高对比度的图像
加性密度效应产生的不同部件(见图3 )。另一方面,当
纸张暴露在绿光下,只有高度绿色——敏感组分最初起反应,而另一组分
组件有助于增加绿灯强度。这将创建低对比度图像,因为
的延迟相加密度效应不同的部件(见图4 )。通过改变
蓝光照射与绿光照射的比例可以实现中间纸对比度。
有几个选项可以生成正确的获得特定纸张所需的混合光
查斯特。控件的颜色的最简单方法

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 楼主| 发表于 2018-3-10 21:59 | 显示全部楼层
light is the use of filters, for example a mixture of blue
and green filtered light using a Wratten 47b (deep blue)
and a Wratten 58 (green) filter. However, inexpensive
filter sets, optimized for VC papers and numbered
from 0 to 5 in increments of 1/2, are more practical
and available from most paper manufacturers. They
can be used in condenser or diffusion enlargers, either
below the enlarger lens or in a filter drawer above the
negative. The numbers on these filters correspond
only approximately to paper grades, because of a
missing standard between manufacturers (see fig.2c),
and because contrast differs from paper to paper and
according to the type of light source used.
Finer contrast control of up to 1/10-grade incre-
ments is available with dedicated VC heads. They
come with their own light source at a modest price,
but are typically only calibrated for the more popular
paper brands on the market. Their light source con-
sists of either two cold cathode bulbs or two filtered
halogen bulbs, both providing independent intensity
controls, to alter paper contrast. With some of these
products, a full contrast range may not be achievable,
and contrast is unlikely to be evenly spaced.
Another popular option is a standard color enlarger,
which can also be very useful to control contrast in
monochrome printing. A color enlarger is typically
equipped with a dichroic filter head, containing yel-
low and magenta filtration. The yellow filter absorbs
blue and transmits green light, and the magenta filter
absorbs green and transmits blue light. These filters
successfully alter the contrast in VC papers, and no
additional investment is required. Even minute but
precise contrast changes are ** with this setup.
The maximum contrast will be slightly lower than
that achievable with filter sets optimized for variable-
contrast paper. However, this is of little practical
consequence, since full magenta filtration typically
achieves a maximum standard ISO grade. Manu-
facturers of enlargers and papers often include tables
with yellow and magenta filter recommendations to
approximate the paper contrast.
To the down-to-earth monochrome printer, it is
commonly of little importance which paper grade
was required to fine-tune the final image as long as
it helped to achieved the desired effect. However,
to the discerning printer, it seems reasonable after
a long darkroom session, to spend a few moments,
scribbling down filter numbers or filtration settings
needed to render image detail appropriately. This
gives the satisfaction to pick up a negative, and start
printing where you left off several months or years
ago. Nevertheless, a dependable method to measure
5-5.jpg
光是使用滤光器,例如蓝色的混合物和使用Wratten 47b (深蓝)的绿色过滤光和
Wratten 58 (绿色)滤波器。是不贵的过滤片,
针对VC纸张进行优化并编号以1 / 2的增量从0到5是更实际的
并且可以从大多数造纸厂获得。她们也可用于冷凝器或扩散放大器
放大镜头下方或上方的滤镜抽屉中否定。这些过滤器上的数字对应
只有大约到纸的等级,因为一制造商之间缺少标准(见图2c ),
并且因为纸与纸之间的对比度不同根据所使用的光源的类型来选择。
更精细的对比度控制高达1 / 10级增量设备配备有专门的风险投资主管。她们
以适中价格配备他们自己的光源,但通常仅针对更受欢迎的对象进行校准
市场上的纸品品牌。他们的光源由两个冷阴极灯泡或两个过滤灯泡组成
卤素灯泡,两者提供独立的强度控件,以更改纸张对比度。其中一些
产品,可能无法实现全对比度范围,并且对比度不太可能均匀地间隔。
另一种流行的选择是标准颜色放大器,这对于控制中对比度也非常有用
单色打印。彩色放大器通常配有二向色滤头,内含Yel -
低过滤和品红过滤。黄色过滤器吸收蓝色和透射绿光,以及品红色滤光器
吸收绿色并透射蓝色光。这些过滤器成功地改变了风险投资论文中的对比
需要额外投资。哪怕只是一分钟使用此设置,精确的对比度更改非常简单。
最大对比度将略低于这可以通过针对变量优化的滤波器组来实现
对比纸。然而,这几乎没有什么实际意义结果,由于全品红色过滤通常
达到最高标准ISO等级。宏利-放大器和纸张的制造商通常包括桌子
使用黄色和洋红色滤镜建议近似纸张对比度。对于脚踏实地的单色打印机,它是
一般不太重要的是哪种纸的等级需要对最终图像进行微调,只要
它有助于达到预期的效果。然而,对挑剔的打印机来说,这似乎是合理的
一个漫长的暗室会议,花几分钟,草草记下过滤器编号或过滤设置
需要适当地渲染图像细节。这给满意的人拿起否定的,然后开始
打印您中断几个月或几年的位置前。然而,一种可靠的测量方法

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 楼主| 发表于 2018-3-10 22:09 | 显示全部楼层
standard paper contrast is needed in order to com-
pensate for equipment and materials changes reliably,
while rendering printing records less sensitive to any
changes in the future.
Equipment and Test Procedure
The equipment required to measure standard paper
contrast includes a transmission step tablet, a reflec-
tion densitometer or a reflection step tablet, some
graph paper and the typical darkroom equipment to
expose and process photographic paper. Fig.5 shows
the photographic scales supplied by Stouffer Graphic
Arts. The transmission tablet on the left is used to
generate the required density data. Precise measure-
ments rely on a densitometer, but in the absence of
such equipment, the reflection scale on the right,
can be used as a visual aid to quantify paper contrast
adequately. References to this alternative method are
made at the end of this chapter.
需要标准纸张对比度,以便设备和材料更换可靠补偿,
同时使打印记录对任何记录不太敏感未来的变化。
设备和试验程序测量标准纸张所需的设备
对比度包括透射阶梯片、反射片光密度计或反射阶梯片,一些
图文纸和典型暗房设备曝光和处理相纸。图5显示
Stouffer图形提供的摄影标尺艺术。左侧的传输片用于
生成所需的密度数据。精确测量仪器依赖密度计,但在没有密度计的情况下
这样的设备,右边的反射标尺,可以用作视觉辅助来量化纸张对比度
足够。对该替代方法的引用是在本章末尾制作。
5-6.jpg
There are many possible variables controlling
the paper contrast. Fig.6 shows how the variables
can be separated into their level of significance and
my suggested control method for them. In this test
procedure, we concentrate solely on the variables of
high significance. Variables with low significance are
either assumed to be fixed or are ignored. The goal
of this test procedure is to determine the standard
paper-contrast grades achieved with your favorite
filtration method and materials. Other variables,
which influence contrast significantly, need to be
closely controlled and are therefore assumed to be
fixed. In addition, some significant variables are
considered undesirable but avoidable, and therefore,
they are ignored as well. Be aware that conditions in
your darkroom may change over time, necessitating
an occasional control test.
For the sample test described here, the following
significant variables were fixed, tested or ignored. The
light source was an Omega D2V variable condenser
enlarger with filter drawer. I used Kodak’s Polymax
VC filters, and Polymax II RC-E paper was tested. The
developer used was Kodak’s Dektol at a dilution of
1+2 and at a temperature of 20°C (68°F). The agitation
was accomplished by constantly rocking the tray for
1.5 minutes, followed by normal processing without
toning. The paper was air dried after washing.
Generating Your Data
Select the paper and paper su**ce you would like to
test, and have it available in a practical size, so that the
transmission scale from fig.5 can be printed onto it. I
always have a box of 5x7-inch paper for these types of
tests in stock. Project the transmission scale, so that it
fits comfortably on the paper, with some room to spare.
Start with the softest filtration to produce the lowest
grade possible. Expose the paper such that the whole
tonal range fits on the paper. The highlight area should
have several paper white wedges and the shadow area
should have several maximum black wedges before
any tonality is visible. Record the filtration and the
exposure time on the back of the print. Then, pro-
cess the paper normally, keeping development time,
temperature and agitation constant. For RC papers,
the development time can be fixed to 1.5 minutes, but
for FB papers, the total development time should be
about four to eight times (6x is normal) the ‘emerging
time’ of the mid-tones. Ansel Adams referred to this
有许多可能的变量控制纸张对比。图6示出了变量如何
可以分为它们的重要程度和我为他们建议的控制方法。在这个测试中
过程中,我们只关注变量意义重大。低显著性变量为
假定为固定的或忽略的。目标本试验程序的目的是确定标准
用你最喜欢的纸做对比过滤方法和材料。其他变量,
其显著地影响对比度并因此被假定为
固定的。此外,一些重要变量包括被认为是不希望的但可以避免的,因此,
他们也被忽视了。请注意你的暗室可能会随着时间的推移而改变,这就需要
偶尔的控制测试。对于此处描述的样本测试,请执行以下操作
重要变量被固定、测试或忽略。这光源是ωD2V可变聚光器
带过滤抽屉的放大器。我用柯达的聚斧
测试了聚甲基丙烯酸甲酯( VC )过滤器和聚甲基丙烯酸甲酯( Polymax II )复写纸。这
使用的显影剂是柯达的Dektol,稀释度为1 + 2,温度为20℃( 68°F )。搅动
是通过不断摇动托盘来完成的1.5分钟,然后正常处理
调色。纸洗涤后风干。生成数据选择要使用的纸张和纸张表面
测试,并以实际尺寸提供,以便可以将来自图5的透射比例打印到其上。i
对于这些类型的纸张,始终要有一盒5x 7英寸的纸张库存测试。投影传输规模,以便
适合舒适地放在纸上,并留有一些空间。从最软的过滤开始,以产生最低的过滤
可能的成绩。暴露纸张,使整个色调范围适合纸张。突出显示区域应
有几个纸白色的楔形和阴影区域应该有几个最大的黑色楔形之前
任何音调都是可见的。记录过滤和放大背面的曝光时间。那么,亲
正常处理纸张,保持显影时间,温度和搅拌常数。对于驻地协调员文件,
开发时间可以固定为1.5分钟,但是对于FB论文,总开发时间应为
大约4到8倍( 6倍是正常的)新兴市场中间音调的时间。安塞尔亚当斯提到了这一点
图6多个变量负责
为最后的论文对比。怎么它们在测试期间被控制
取决于有多重要它们影响对比度。

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 楼主| 发表于 2018-3-10 22:16 | 显示全部楼层
as the Factorial Development. Repeat the process for
all remaining filters or significant filtrations. Be sure
to keep all other variables constant, including the
exposure. This will allow us to create an exposure com-
pensation table, as discussed in the chapter ‘Exposure
Compensation for Contrast Change’.
With the help of a reflection densitometer, all step
wedges can be read and charted as shown in fig.7. The
x-axis shows the relative log exposure values, which
have equivalent log densities in the transmission tablet
of fig.5. Just remember, that step number 1 has a rela-
tive transmission density of 0.0 and that number 31 has
a density of 3.0. To convert the step-tablet values into
paper exposures, take a step number, subtract 1, divide
by (-10) and add 3.0. The result is the relative paper
log exposure value of that step. The y-axis indicates
the reflection densities as read with the densitometer.
Use a copy of the blank record sheet from ‘Tables and
Templates’ to collect and chart the paper density data.
The result, in fig.7, shows the paper characteristic
curve of our test with filter number 2.
Measuring Contrast
Now, we are interested in the textural log exposure
range. From fig.1, we remember that it is the delta
between the first usable density and the last usable
density, or also referred to as IDmin and IDmax,
respectively. The ISO standard defines these two
densities in relative terms, but we need absolute values
for a quantitative **ysis. I have chosen a reflection
density of 0.09 for IDmin and 1.89 for IDmax for
reasons that are explained in more detail in ‘Fine-
Tuning Print Exposure and Contrast’. We will use the
log exposure range between 0.09 and 1.89 reflection
density for the rest of this sample test.
The chapter ‘Tables and Templates’ includes an
overlay called ‘Paper Range and Grade Meter’, which
is a handy measuring tool based on the ANSI/ISO
standard. The use of the meter overlay is shown in
fig.8, as it is applied to the sample test data. The curve
has been highlighted for clarity. The overlay is placed
on top of the graph so the ‘base+fog density’ line is
parallel to the grid, but tangent to the toe of the curve.
The overlay is then moved horizontally until the verti-
cal origin and IDmin (0.09) intersect with the curve
in point 1. At the same time, IDmax (1.89) intersects
with the curve in point 2. A vertical line drawn down
from point 2 allows for the measurement of ISO grade
6-1.jpg 6-2.jpg
作为阶乘发展。重复以下过程所有剩余过滤器或有效过滤器。确信
保持所有其他变量不变,包括曝光。这将允许我们创建一个
补偿表,如“暴露”一章所述对比度变化补偿'。
借助于反射密度计,所有步骤楔块可以如图7所示读取和绘制
x轴显示相对日志曝光值,该值在传输平板中具有等效的对数密度
请记住,步骤1具有一个rela -有效透射密度为0.0且数字31具有
密度为3.0。要将步进板值转换为纸张曝光,取步数,减1,除
乘( - 10 )加3.0。结果是相关的论文记录步骤曝光值。y轴表示
用密度计读取的反射密度。使用表和中的空白记录表副本
'模板'以收集和绘制纸张密度数据。图7中的结果示出了纸张特性
2号过滤器的试验曲线。测量对比度现在,我们对纹理日志曝光感兴趣
范围。从图1中,我们记得它是δ在第一可用密度和最后可用密度之间
密度,或者也称为IDmin和IDmax,分别。ISO标准定义了这两个方面
相对密度,但我们需要绝对值用于定量**。我选择了反思
IDmin的密度为0.09,IDmax的密度为1.89“罚款”中更详细解释的原因
“调整打印曝光和对比度”。我们将使用对数曝光范围在0.09和1.89反射之间
本样本测试其余部分的密度。“表和模板”一章包括
叠加称为'纸张范围和坡度计',它是一种基于ANSI / ISO的便捷测量工具
标准。仪表覆盖层的使用如所示图8是应用于样品测试数据时的示意图。曲线
为了清楚起见已经被强调。覆盖层被放置在图的顶部,因此“基本+雾密度”线为
平行于网格,但与曲线的坡脚相切。然后将覆盖层水平移动直到垂直
cal原点和IDmin ( 0.09 )与曲线相交在第1点。同时,IDmax ( 1.89 )相交
曲线在点2。向下画的垂直线从第2点开始,允许测量ISO等级

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