摄影技巧在物证拍摄中的应用

The application of the phtographic technics in the shooting of material evidence

在现场勘察中经常会遇到各种客体上附着的各种指纹,如汗液指纹等,这些指纹遗留条件较差,不易处理,通常的刷显方法很容易破坏检材,不利于物证的提取,因此,要采取拍照的方法加以固定。通常情况下,在犯罪现场留下的指纹印与背景反差小,拍照效果差,或者背景有图案干扰,这都会给指纹的处理增加难度。文章简要论述了汗液指纹的特性,并根据其特性,重点论述了这些指纹常见的配光方法、成像原理和拍摄技术,如暗视场照明法。指出对不同性质的检材,应使用不同的配光方法和拍摄技术,这样就会得到不同效果的照片,对这些照片加以比较,从而得出不同检材上的不同指纹拍摄的最佳方法。并有针对性地从原理到试验的剖析,初步分析、研究、解决汗液指纹在某些客体上的光学显现和拍照方法。

In the investigation of the scene, it is easily to encounter various objects which are attached with all kind of fingerprints, such as sweat fingerprints. Because the condition for these fingerprints to be remained is very poor and difficult to handle, and using the brush usually destruct samples and is not propitious to the extraction of material evidence. Therefore we need to adopt the method of photographing to make the evidence to be fixed. Usually the difficulty enhanced when the prints left in the crime scene have little contrast with the background, or with poor camera effects, or with background interference. This paper briefly discusses the characteristics of sweat fingerprint, and in accordance with their characteristics, it focuses on the common-method, principle of imaging technology and shooting when fingerprints photographing, such as dark-field illumination intense method. It also dissert that according to the different feature of the surface of the object, it must adopt different method of distribution and production of optical technology in order to get different samples of the evidences. Moreover, by comparison of these samples, we can get the best method of photographing. What＇s more, it preliminary analyses the method of the shooting and showing of the sweat fingerprint on some certain objects.