ISO 12800 is not the name of a new sci-fi film directed by George Lucas like his first movie THX 1138. In fact, THX was the name of a new generation surround sound, developed by a George Lucas company, that nowadays we all hear in the cinemas. And if you don’t know, maybe we make HDR due to another product developed by a George Lucas Co, ILM. Industrial Light & Magic (ILM) is an American Academy Award-winning motion picture visual effects company that was founded on May 1975. And in 2000, ILM created the OpenEXR format for High Dynamic Range Imaging. This is the 32-bit file format that I use to save my HDR files before tonemapping.
Coming back to the post title, when we talk in photography about ISO, we are referring to one of the 3 exposure parameters (Exposure Triangle): aperture, time and ISO. This means that we can get the same exposure, changing these parameters. As an example, the combinations: aperture f/11, time 1/15s, ISO 12800 ; f/8, 1/30s, ISO 12800 or f/11 1/30s ISO 6400 produce the same exposure but not the same image. And you are wondering why ?
Each change of one of these parameters need a change for 2 other ones. But each parameter has its effect on the image:
– ISO: In traditional film photography, ISO was the indication of how sensitive a film was to light. In Digital Photography, ISO measures the sensitivity of the image sensor. The same principles apply as in film photography – the lower the number the less sensitive your camera is to light and less grainy.
– Aperture: It is measure with diaphragm diagonal with f-stop number. High f-stop numbers mean narrow aperture and as consequence less light. The aperture is basically the parameter that change the Depth Of Field (DOF).
–Time: It is measure in seconds or fractions of. It is basically used to control the sense of motion in the pictures.
But why 12800 ? Because it’s a high ISO number. And Higher ISO settings are generally used in darker situations to get faster shutter speeds and avoid camera shake. This is one of the reasons to change to a Full-Frame camera like Canon EOS 5D mark III. There are sites like the cathedral in this post image where tripods are not permitted, so the only possibility to get images sharp is to increase ISO. But High ISO means so much noise. About that, I can say that I am very happy with the behaviour of the 5D mark III at high ISOs. The images are fully usable for large prints at ISO 3200 and they are useful for middle-res at ISO 12800. In fact, if you check for reviews and comparisons of this camera with Nikon D800, you will see that 5D mark III wins D800 quality and sharpness, when ISO is higher than 800.
Catedral de la Almudena, Madrid (Spain).
Canon EOS 5D Mark III | Canon EF 17-40mm f/4L USM @ 17 mm | f/11, 1/15s, ISO 12800.HDR/DRI from 3 handheld exposures @ [-2 EV .. 0 .. +2 EV ]