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I've been using my Nikon Df every day for 2 years now, and I still can't figure out focusing, especially in low light.

Focusing in low light is slow, and sometimes does not work. Sometimes focus will pan and search while I need to take a street photo. I also have a D600 body, and that one also does not focus as fast as I'd like.

Are there better camera bodies when it comes to focusing? For example, I noticed that Leica Q seems to be better at figuring out where to focus. I am guessing the Df focus system is pretty old.

I know focusing is mostly about lens quality, but I suspect the focus system plays a big role too.

I just want faster/better focus on whatever subject I'm pointing the camera at. Will upgrading the camera body would make a significant difference?

Alternatively, would switching to a different camera system make a bigger difference? This would be harder because I have already collected all the lenses I want.

Cameras:

  • Nikon Df
  • Nikon D600

Lenses:

  • 50mm 1.8 (stock)
  • 85mm 1.4
  • 105mm 2
  • Er, what Leica are you referring to? – mattdm Jul 19 '18 at 15:46
  • Leica Q but i would bet all of them (maybe aside from old models) have similar auto focusing capability – Sonic Soul Jul 19 '18 at 16:42
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    I'll take that bet — Leica's most famous "M" line doesn't even have any autofocus at all. And, as I understand it, the autofocus module in the Q actually comes from (and is essentially the same as) that found in Panasonic's mirrorless cameras. While that can be quite quick at single AF, it's probably not up to your Nikons for continuous AF. There may be some "the grass is always greener" going on here. – mattdm Jul 19 '18 at 17:57
  • @mattdm thanks that helps to put things in perspective. – Sonic Soul Jul 19 '18 at 18:08
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Both the D600 and the Df use Nikon's Multi-CAM 4800 AF module so focusing performance should be similar (differences in processors can effect the speed even between cameras with the same AF module).

Those lenses are nice and fast - which should help but the bottom line is the AF system needs contrast to acquire focus. You can help by keeping to using only the 9 cross type sensors in low light and looking for contrast edges in the image and using them to focus on. Things such as door or window edges, the edge between bags and other things people might be carrying, belts, shirt neck line etc.

According to this: https://imaging.nikon.com/lineup/dslr/d600/features02.htm there are only 9 cross type sensors not 15. I must have mixed the numbers up in my head while I was reading about various AF modules (answer corrected). That article has a diagram showing which sensors are cross type and which are single.

The difference between cross type and single type sensors is in about how they detect the contrast that they focus on. The basic building block of these AF modules is a sensor that can detect contract along a certain direction. Consider a window frame if you line up the AF sensor so that its ability to detect contrast crosses the frame - in other words the sensor can see part of the wall and part of the frame it will be able to detect that change in contrast and focus on that frame / wall edge. If you tilt your camera so that that AF sensor now runs parallel with that frame there is no contrast to detect: the AF sensor sees entirely the smooth wall or entirely the smooth frame and therefore sees nothing to focus on. Obviously the sensors are not laid out straight up and down or we would hit this frequently with geometric things. With non geometric thins like people you can hit this problem from time to time. In the AF module this problem is tackled by having some sensor points actually have two AF sensors oriented as a cross. Those sensors cannot be fooled the same way because there is no orientation that they cannot see contrast. These sensors also tend to perform better in low light situations. I don't know if it is because they typically are better sensors or the fact that there are two of them working together helps with low light situations.

As for better the D5, D850 and D500 share the Multi-CAM 20K which is supposed to be a significant step up in AF performance. While the D750 and D7500 share the Nikon Advanced Multi-CAM 3500 II which despite less sensors is also supposed to be better than the previous generation.

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    thanks!! how can i use only 15 cross type sensors? also, does the multi-cam 20k do anything for multi focus point / face / person recognition?? i found that super helpful while using a Leica – Sonic Soul Jul 19 '18 at 16:41
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    hmm according to this table D600 has it too nikonrumors.com/2016/12/30/… – Sonic Soul Jul 19 '18 at 16:54
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    Just as a comment for now - but would this be worth raising as a new question? What's a 'cross-point' in Nikon terms? I've seen pictures of Canons where they're a visible reference, but my 5500 theoretically has 9 of them[according to the above link]... which I've never seen... all the points seem to have the same graphic representation in the viewfinder. – Tetsujin Jul 19 '18 at 18:20
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    @Tetsujin You can raise the question, but Nikon is so dang secretive (probably because, for years, they lagged behind Canon in this department) about how their AF systems work that it might be hard to get a definitive answer. Canon, on the other hand, publishes reams of material on the exact capability of each focus "point" in their cameras. This helps their users understand how to best utilize those capabilities. – Michael C Jul 19 '18 at 22:02
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    I doubt that Nikon ever visually marked different types of AF points in the viewfinder, but they're clear enough about which ones are cross type - imaging.nikon.com/lineup/dslr/d600/features02.htm I'm mostly sure that it's in the manuals of the mentioned two and the D7000/D610 (since the D600/D610/Df all use the same or very similar AF module to the one in the D7000). – K. Minkov Jul 20 '18 at 13:50

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