The validity and reliability of visual based research.

Visual sociology is concerned primarily with the visual dimensions surrounding social life, and as such it's main focus on research is based on photography and  documentary filmaking which can raise questions concerning the validity and reliability of such research methods.
A key problem in the reliability of visual based research is, according to Uwe Flick is the possibility of heavily influencing or the manipulation of the subject or image (Flick;2009:p-245) either consciously, through asking the subject to pose, or even they are lit in the image, or unconsciously in that the researchers very presence can affect a subjects behaviour or the researcher being selective in allowing what the camera can see.
This can also affect the process of data collection, leading into more ethical dilemmas concerning either 'covert' photography in an effort to not influence behaviour and thus the subject or group unaware they are even being researched. 
The context of a shot can affect the validity of the data as we are only being shown a single frame or 'snapshot', frozen in time with little to no way of  factoring in an understanding of the external or internal factors that shaped this single frame.(Prosser:1998:p-125).



Reference

Flick,Uwe    An Introduction to Qualitative Research
                    Sage publications
                   2009

Prosser.Jon Image Based Research: A Sourcebook for Qualitative Researchers
                   Routledge
                   1998