Theres been a large amount of debate about using the right ISO and how ISO works.
In a recent DPreview forum thread, the topic poster started with this somewhat evocative subject. Now for those who spend time on forums will know using capitals is seen as shouting, and is very rude and incenses a number of people. Theres even a section where I underlined a reply to highlight and emphasise the point I was making and that annoyed some individuals as well. I watched the entire comparison video that the original poster linked to with some interest. To me it seemed reasonably fair and as balanced as the reviewer was able to make it. This wasn’t a scientific review but rather a supposedly objective look at two cameras with an opinion as to which the reviewer thought was better in general, for his purposes. Click the link below and watch the video and then read through the forum posts. You can quickly see that it devolves into a discussion regarding ISO and that there are particular proponents who feel they have a superior view of how ISO works and what ISO is.
By and large the thread becomes totally off topic but serves as an interesting read as to how people interpret what ISO is and what makes it work, with a large emphasis on the notion that you really need to have the technical knowledge to really understand how ISO works so you can use it. You can see some of my replies to this as you read through.
It may also be of interest to you to see how Nikon, one of the worlds foremost camera makers views the subject of ISO, and without a huge technical spiel puts it into terms that for the average photographer makes a good deal of sense. Follow this link Nikon & ISO. To me at least it is a sensible description that should be readily understood by anyone who has used a digital camera. According to our resident authorities on the above mentioned forums Nikon is essentially accused of lying and the propagation of mis-truths. Fuji are essentially accused of cheating and lying to curry favour with the Fuji users. The assumption being that ISO is a strict international standard that everyone except Fuji is adhering to.
Tech-radar does a reasonable job of expanding upon the Nikon article and goes into a little more detail without becoming boring. What is ISO
Now as a lot of Fuji owners will attest to, Fuji cameras usually tend to underexpose a little bit and need to have the Ev adjusted accordingly. When comparing the Fuji to another makers product it seems as though the stated ISO value is off, Instead of both cameras for example using ISO 200 it appears that the Fuji is using ISO 160 and therefore Fuji is cheating and lying about their settings. However the Fuji cameras still doubles the “sensitivity” as you increase the setting to a higher ISO, and it may be that they are still a slight step out when compared to the opposition. This has everyone crying foul, but with a bit of detective work and Google its simple to see that there is in reality a number of methods that can be used for the calibration of a given sensors ISO performance. Here is an article describing the standards for testing ISO by manufacturers, Digital camera ISO speed and exposure index.
So is Fuji lying? I seriously doubt it.
Which camera is best? They all are, they all do exactly what they advertise and by and large do it well. The main difference come about from sensor size and design.
In the my next offering I’m going to outline my methods for using ISO in the real world, pertaining specifically to the XA2 and by extension other Fuji X cameras.