exposure - Is it true that the best images from all digital cameras can be obtained at ISO 200?

Recently a very professional photographer who shoots stunning pictures told me that the best images can be obtained from digital cameras at ISO 200. He also stated that this is what all the manufacturers (Nikon, Sony, Canon, ...) say.

He explained it something like this (I heavily paraphrase as my amateur brain does not remember the correct technical terms used): The light is taken in by the sensor as is at ISO 200. At higher values the signal is amplified (which I understand is correct). At lower values like 100 however, the signal is artificially diminished, which leads to bleeding(?) of the pixels. Therefore ISO lower than 200 is only to be used for extreme lighting situations like shooting a solar eclipse.

However, I could not find any information corroborating these claims. I also checked a couple manuals of high-end DSLRs. They did not contain any mention of such a manufacturer's recommendation. I also took some comparison shots with my own digital camera (Lumix) and found ISO 100 to produce better, lower-noise results.

Now I'm at a loss as what to make of that man's statement?

Answer

The information your friend gave you was essentially correct for most digital cameras, particularly compact digital cameras with very small sensors, made about 15-20 years ago. Digital imaging sensors were more primitive and noise reduction techniques were less sophisticated. By placing the native sensitivity of a sensor at one stop higher than what otherwise might be desired (typically ISO 100), the camera could have a wider 'usable' ISO range at very little detriment to the ISO setting one stop below the native sensitivity of the sensor. In exchange for a little less dynamic range at ISO 100 a sensor with a native sensitivity of ISO 200 could gain a stop of sensitivity on the higher end with regard to dynamic range versus the noise floor.

Such is not the case with most current dedicated cameras. There is more variety with regard to native ISO among current cameras, but most of them have a native sensitivity somewhere in the neighborhood of ISO 100. This is particularly the case with the current crop of APS-C and full frame cameras.

Once ingrained in a particular culture, such as professional photographers, some ideas are hard to modify when the current state of technology makes those ideas outdated and in need of modification if not outright obsolete.

Look, for example, at Image Stabilization. When the IS lenses for interchangeable lens SLR cameras first began appearing in the second half of the 1990s, there was an issue with vibration feedback loops when the camera and lens were mounted on a tripod. Vibration from the IS unit would cause the camera to vibrate, which would induce correction from the IS unit, which would cause vibration, which would induce correction from the IS unit, which would cause vibration... By the year 2000 pretty much every lens manufacturer had upgraded their IS technology to automatically turn off IS when the camera was detected to be mounted on a tripod. Some lenses have even appeared on the scene that have IS profiles specifically designed to be used with a tripod. Yet more pros than not will still tell you in 2017 to ALWAYS turn off IS when you are using a tripod.