I talked about how the Digital Teleconverter on the Fujifilm X100F adds versatility, and I talked about how great the camera does at high-ISO photography, but I never talked about how these two things do together. I’ve noticed some things about using the Digital Teleconverter at high-ISOs that I’d like to discuss.
Does the Digital Teleconverter limit how high you can go on your ISO settings? The answer is simple: yes. But it’s actually a little bit more complicated than that, so let me dig a little deeper.
I’ve already discussed exactly what the Digital Teleconverter is, and I don’t want to spend much time rehashing that, but basically it’s a digital zoom (zoom-by-cropping) that receives some smart upscaling and sharpening to make the file appear to have more resolution than it actually does. It’s a software trick that allows you to print larger than you might otherwise be able to. You can do this yourself with software on your computer, or you can let the X100F do it for you (which is the Digital Teleconverter).
I’ve also discussed that the practical high-ISO limit on the Fujifilm X100F is 12800, which is very high. Yes, some cameras with larger sensors can go a stop or so higher, but ISO 12800 is way up there, much higher than I ever imagined ISOs going even just 10 years ago.
When using the 50mm Digital Teleconverter (16 megapixel crop) setting, ISO 12800 doesn’t look all that usable. If you want soft and grainy looking black-and-white images, you can get away with ISO 12800 using Acros and the 50mm option. I’ve produced acceptable results this way. However, for the most part, ISO 6400 seems like a more practical high-ISO limit for this situation.
When using the 75mm Digital Teleconverter (12 megapixel crop) setting, anything above ISO 6400 doesn’t look all that usable. ISO 6400 looks alright for soft and grainy looking black-and-white images using Acros. For the most part, ISO 3200 seems like a more practical high-ISO limit for the 75mm Digital Teleconverter.
You might have noticed a trend, and that’s a one stop loss for the 50mm option and a two stop loss for the 75mm option. It’s not that the camera is performing worse, it’s that you are looking much more closely at the exposure (because of the crop). You can more clearly see the degradation in image quality that happens at the higher ISOs. It’s kind of like pixel-peeping–you don’t notice certain things when viewing normally, but they become obvious when you zoom in.
If you use the Digital Teleconverter along with auto-ISO, pay careful attention to the ISO that the camera is selecting. You may need to set it yourself (very quickly and easily done via the knob on top of the camera). My recommendation is to go no higher than ISO 6400 with the 50mm setting and no more than ISO 3200 with the 75mm setting. You can get away with higher sometimes (especially if it’s only for web use), but for best results keep the ISO a little lower than you otherwise would.