Fujifilm X100F – Digital Teleconverter + High ISO


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.


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  2. Christopher Schmitt · November 7, 2017


    I really like to read your Website because I get a lot of ideas for using my Fuji x100F. I have one question: when you use the digital Telekonverter at 50mm, you have a factor of about 1.4 what is about equal to squaroote of 2. So you have a magnification of 1.4 horizontel and 1.4 vertical what gives you 1.4 x 1.4= 2. So you have about 12 Megapixel (not 16MP) and at the digitalzoom of 70 you have 24MP/4=8MP. What do you think?
    (sorry for my English)

    best regards

    • Ritchie Roesch · November 7, 2017

      Thanks, Christopher, for your kind words and insight. I’m not a mathematician by any stretch of the imagination. I could very much be wrong, and I freely admit that. The digital teleconverters work by cropping, and as far as I know it crops out 1/3 of the image to get a

      • Ritchie Roesch · November 7, 2017

        Sorry, trying to do this one-handed on my phone while feeding a bottle to my baby.

        The digital teleconverter crops 1/3 of the image out to get the 50mm option and 1/2 for the 75mm. It’s roughly a 1.5x magnification for the 50mm and then an additional 1.5x for the 75mm. If you divide 24 megapixels by 1.5 you get 16, then if you divide 16 by 1.5 you get 10.6. These aren’t exact measurements, but quick figures. And, again, I could be completely wrong.

  3. Christopher Schmitt · November 8, 2017

    Thank you for your response Richie.
    I try to demonstrat my question in other words. If you stand in front of a wall and take a picture at 35 mm FL. And then take a Picture from the same point of view with the 50 mm digital teleconverter, the length and highths of the wall that is in your Picture are both devided by about 1.428. So, the area of the wall is devided by 2 (covered by 12 MP of the sensor).
    By the way: it’s intersting that most fixed focal length have a ratio of squareroot of 2: 35, 50,75,100mm.
    But math is not so important. Inspiration is what I’m looking for and I likie especially your classic crome Pictures a lot.


    • Ritchie Roesch · November 8, 2017

      Thanks, Christopher! You sound very knowledgeable about this, more than I, and I have little doubt that you are completely correct. I appreciate you sharing.
      Also, thanks again for your kind words. They mean a lot to me.

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