Today, actually as image for Monday, I have an image that I technically made on Monday, precisely at 1 am, having just arrived in Vienna. I don’t put this up for its artistic merits, today it is about image quality at higher ISOs.
The image has been taken at ISO 1600 and 1/8 s. That is what happens when the OM-D is on aperture priority, Auto-ISO, and using its defaults. Depending on the focal length of the lens the camera tries to maintain a certain minimum shutter speed (for the 14 mm lens this is 1/30 s, basically it’s always the old principle of one over the equivalent focal length). This goes on until the maximum ISO is reached (by default set to 1600), and from there the camera compensates by lowering shutter speed.
As I’ve already said, for my taste the Nikon method of allowing the user to set the crossover speed (instead of calculating it) is superior, but then, for me it works perfectly. On the E-P2 ISO 1600 was already a problem, especially at night, but look at the images: Stabilization does a great job, dynamic range is clearly there and noise is well contained. In fact, this is good enough that I can stop worrying about ISO at all. I don’t even have a function button assigned to ISO. The camera is always on Auto, with one exception and that is manual mode. For manual mode I’ve set it to ISO 200.
At ISO 1600 and a reliably holdable shutter speed of 1/8 s the camera already sees more than my eyes do, i.e. the resulting image is brighter and has more visible contrast than the scene in reality. As long as my goal is to show what I see, I have no reason to increase ISO further.
There may still be reasons to raise maximum ISO to a higher value, for instance if you need faster shutter speeds in low light or if you need more depth of field.
Here I have an ISO progression from 800 up to 6400. These are 100% crops of JPEGs right out of the camera. Only the ISO 6400 image was slightly rotated to better align with the other images. The lens is the Panasonic 20/1.7 at f2.2, shutter speed goes down to 1/5 s for ISO 800. In reality the scene was considerably darker.
I think it’s safe to say that ISO 6400 is visibly worse than the other three, and of course the fall-off in image quality is as expected. ISO 3200 is definitely usable, better than on the D300, and ISO 1600 is good enough for any kind of professional use. ISO 6400 is usable on the web and certainly for small prints. I think I should be able to squeeze out some more quality from the RAW as well. Remember: these are 800×800 crops from 3456×3456 images.
Apropos RAW and quality: I have tried to improve the ISO 6400 image by working from RAW, but at least my first attempt failed. What I got was visibly worse than the JPEG from the camera. I think this is remarkable and a testament to Olympus’ JPEG engine.