Perceptions of the visible world were greatly altered by the invention of photography in the middle of the nineteenth century. In particular, and quite logically, the art of painting was forever changed, though not always in the ways one might have expected. The realistic and naturalistic painters of the mid-and late-nineteenth century were all intently aware of photography -- as a thing to use, to learn from, and react to.

Unlike most major inventions, photography had been long and impatiently awaited. The images produced by the camera obscura, a boxlike device that used a pinhole or lens to throw an image onto a ground-glass screen or a piece of white paper, were already familiar—the device had been much employed by topographical artists like the Italian painter Canaletto in his detailed views of the city of Venice. What was lacking was a way of giving such images permanent form. This was finally achieved by Louis Daguerre (1787-1851), who perfected a way of fixing them on a silvered copper plate. His discovery, the "daguerreotype," was announced in 1839.

A second and very different process was patented by the British inventor William Henry Talbot (1800-1877) in 1841. Talbot's "calotype" was the first negative-to-positive process and the direct ancestor of the modern photograph. The calotype was revolutionary in its use of chemically treated paper in which areas hit by light became dark in tone, producing a negative image. This "negative," as Talbot called it, could then be used to print multiple positive images on another piece of treated paper.

The two processes produced very different results. The daguerreotype was a unique image that reproduced what was in front of the camera lens in minute, unselective detail and could not be duplicated. The calotype could be made in series, and was thus the equivalent of an etching or an engraving. Its general effect was soft edged and tonal.

One of the things that most impressed the original audience for photography was the idea of authenticity. Nature now seemed able to speak for itself, with a minimum of interference. The title Talbot chose for his book, The Pencil of Nature (the first part of which was published in 1844), reflected this feeling. Artists were fascinated by photography because it offered a way of examining the world in much greater detail. They were also afraid of it, because it seemed likely to make their own efforts unnecessary.

Photography did indeed make certain kinds of painting obsolete—the daguerreotype virtually did away with the portrait miniature. It also made the whole business of making and owning images democratic. Portraiture, once a luxury for the privileged few, was suddenly well within the reach of many more people.

In the long term, photography's impact on the visual arts was far from simple. Because the medium was so prolific, in the sense that it was possible to produce a multitude of images very cheaply, it was soon treated as the poor relation of fine art, rather than its destined successor. Even those artists who were most dependent on photography became reluctant to admit that they made use of it, in case this compromised their professional standing.

The rapid technical development of photography—the introduction of lighter and simpler equipment, and of new emulsions that coated photographic plates, film, and paper and enabled images to be made at much faster speeds—had some unanticipated consequences. Scientific experiments made by photographers such as Eadweard Muybridge (1830-1904) and Etienne-Jules Marey (1830-1904) demonstrated that the movements of both humans and animals differed widely from the way they had been traditionally represented in art. Artists, often reluctantly, were forced to accept the evidence provided by the camera. The new candid photography—unposed pictures that were made when the subjects were unaware that their pictures were being taken—confirmed these scientific results, and at the same time, thanks to the radical cropping (trimming) of images that the camera often imposed, suggested new compositional formats. The accidental effects obtained by candid photographers were soon being copied by artists such as the French painter Degas.

十九世纪中叶，摄影术的发明极大地改变了人们对可视世界的认知。尤其是它自然而然地使绘画艺术发生了永久性的改变，虽然并不总是以我们预期的方式。十九世纪中期与后期的现实主义和自然主义画家都高度关注摄影术，将其当做一门可以使用、借鉴而且要适应的技术。 与其他重要的发明不同，摄影术姗姗来迟。其实当时针孔照相机已经为大家所熟识，它是一种使用小孔或透镜将影像投射到毛玻璃屏或一张白纸上的盒状设备，这种设备已经为很多地貌风景画家所用，像意大利画家卡纳莱托就用它详细记录了威尼斯城。真正缺少的是永久保存这些图像的方法。路易斯•达盖尔（1787-1851）最终做到了这点，他完善了将影像固定到镀银铜板上的方法。他发明的“达盖尔照相法”在1839年公诸于世。 英国发明家威廉姆•亨利•塔尔博特（1800-1877）于1841年申请了另一种截然不同的照相法的专利。塔尔博特的“卡罗式摄影法”是第一种用负片洗印正片的方法，这种方法是现代照片的直接鼻祖。卡罗式摄影法革命性地使用了化学处理的纸片，纸片上受到光照射的区域的色调会变暗于是产生了负像。这种被塔尔博特称之为“负片”的东西随后会被用于在另一张化学处理的纸片上洗印多张正像。 这两种方法产生了极为不同的结果。达盖尔照相法是复制照相机镜头前端微小的、非选择性的细节得到唯一一张影像，不可以加印。而卡罗式摄影法可以洗出多张照片，因此相当于蚀刻术或雕刻术。其整体的效果是轮廓和色调模糊。 摄影术给最初接触它的观众留下的最深刻的印象之一是想法的真实性。现在大自然可以受到最小的干扰自己表达自己了。塔尔博特为他的书所选的书名《自然的画笔》（该书的第一部分发表于1844年）就体现了这种感触。艺术家沉醉于摄影，因为摄影为他们提供了一种可以更加细致地审视这个世界的方法。他们也很害怕摄影，因为摄影仿佛让他们的努力变得没有必要了。 摄影术的确使某些绘画种类变得过时了，达盖尔照相法几乎把迷你肖像画逼到绝路。它还使得整个制造业和拥有图像的产业变得平民化。肖像这个一度只是少数权贵的奢侈品，突然就变得触手可及了。 从长远角度看，摄影术对视觉艺术的影响远远不是那么简单。因为媒介很多，从这种意义上来说就有可能很廉价地生产一堆影像，因此摄影术很快就被当成是艺术品廉价的替代物，而不是注定的继任者。即使是那些对摄影术最为依赖的艺术家也不愿意承认他们使用过摄影术，害怕这会影响到他们的专业地位。 摄影技术上的迅速发展——包括使用更轻便简单的仪器，在照相底片、胶卷和相纸上涂以新型感光乳剂以及加快成像速度——产生了一些意想不到的结果。摄影师，例如爱德华德•麦布里奇（1830-1904）及艾蒂安•朱尔•马雷（1830-1904）进行的科学实验证明人类和动物的运动与我们通常在艺术品中表现的有巨大差异。艺术家往往是勉强地被强迫接受相机所提供的证据。新出现的堪的派摄影（即拍摄对象不知情时抓拍的照片）证实了这些科学成果，同时，由于相机对影像进行的彻底裁剪（修剪），这些图像暗示了新的创作版式。堪的派摄影师们获得的这种意外效果很快被一些艺术家比如法国画家德加给学去了。