Exif
Photograph, reveal your secrets
It stands for Exchangeable image file format, but basically it is a standard way of capturing parameters and adding to images.
EXIF is a standardized way of capturing information about a variety of files, but it is particularly relevant for photographs and images. Most computer programs will be able to make use of this information and display additional information about the photograph, when, and how it was taken and include additional technical information. This can be very useful for you to understand and reason about what you could change the next time you see a particular problem.
See for example the images used for the article in falloff. You visually see that there are darker corners in the initial picture and this disappears in the second one. Comparing the EXIF, you can see that the aperture in the first one was f/1.8 and the second one f/4.5. You can see that the difference in speed was compensated by the exposure time.
However, like anything else in a computer file, the content of EXIF can be manipulated, or even completely removed. As far as possible all images in this Wiki retain their original EXIF data, and I made no attempts to conceal anything. However, all images are also scaled (and sometimes cropped) for the Wiki as well, so there was at least some processing.
For older lenses parts of the information about the image is not transmitted (as they do not have the electronics to communicate this to the camera). In these cases, if the user puts some effort into it, the information can be added manually. See for example this example where the camera has the correct Manual Lens no CPU information that stored. However, for another one like this one the information is misleading as the initial manual setting was not correct (a mistake on my part).
There is quite a bit of information in the EXIF files, some of which (location, make/model of camera/lenses, time, number of images taken) so it is understandable that someone may like to remove (at least parts of) it. The Exiftool by Phil Harvey is probably one of the best references (as well as EXIF tools) available and is highly recommended if you are interested to know more.
Here is an example image where we can see what EXIF can show you.
You can go to the page of the image on this Wiki, and at the bottom you will see Metadata that you can extend. The following is the first part of the information corresponding to the image above.
You will see that, Nikon D90 was used for the photograph, exposure time was 1/30s, the aperture f/6.3 and the ISO at 1'250. There is much more information about the picture in the EXIF.
These pages are for Amateur Photographers and not really for seasoned photographers and professionals. I have no affiliation or commercial interest with any brand/make. I write from my own experience. I ended up using mainly Nikon, so I am more familiar with this brand than others. See price for notes on pricing as well as photography related links.