What Happened to Closest Focus Priority?

Anyone that's attended one of my workshops knows that I like Group AF Area Mode (on the Nikon DSLRs). I use it often, though situationally. Group AF has one attribute to it that is incredibly important: closest subject priority (CSP).

CSP was a Nikon innovation back in the film era. Whoever came up with it needs to be knighted (or whatever they do for distinguished contributors in Japan). Why? Because it adds a predictability to the system upon which you rely to make decisions for you. 

Think about it for a second: which picture have you taken recently where the focus point shouldn't have been on the thing nearest to you (and under the focus sensors being used)? You're probably going to have a difficult time finding an example. That's not to say they don't exist. When shooting sports with free-ranging players (and referees—Scott Kelby once wrote an entire article on how to get referees in focus ;~), we often get someone moving in front of the thing we want in focus. Of course, that's why Focus Tracking with Lock On timing was introduced by Nikon back on the F5: if that overlap is short or temporary, maybe it should be ignored (i.e. set a longer Lock On time). 

dpreview just published some additional Z7 focus testing, and the thing that their results show—as do mine—is that Nikon isn't really using CSP any more. That's a huge mistake. Moreover, in the bicycle test scenario dpreview uses, it's an immensely huge mistake (the background isn't changing much, but the object in the foreground obviously is). What are the chances that the background is what the user wants in focus?

And remember that we have an AF-ON button and back button focus techniques on these sophisticated cameras. If the background were important and the thing in front not, I'd have focused on the background with AF-ON and then released the button to leave focus on that background. Instead, I'm holding down AF-ON hoping that the camera will eventually figure out that thing moving in front is what I want in focus.

The thing about phase detect is that the camera knows that there's something up front, and that it's moving. Phase detect, by definition, gives the camera near/far information. 

In examining my initial thousands of Z7 photos, when the camera missed focus, it generally missed it by placing it behind the subject. CSP would have fixed that.

So, note to Nikon: add Group AF and it's CSP nature back to the mix in a firmware update, ASAP. It'll fix so many of the out-of-focus complaints you're going to get that you'd be surprised. Frankly, I'm gob-smacked that Nikon thinks they don't need CSP in at least one AF Area Mode on the camera.

Update: Some users have pointed out to me that Wide Area (Small and Large) uses CSP. Well, probably. But I've got examples that indicate that this isn't always true, and moreover the big boxed areas aren't as useful as the smaller Group diamond in terms of the photographer controlling what the camera might focus on. I'll try to elaborate on that in my upcoming review, but having a large rectangular area doing some quasi-CSP is not the same as having a tight area doing for-sure CSP.

I've now done some further quick testing, as the number of folk trying to tell me I'm wrong because of what Brad Hill wrote is getting long. I can say with some certainty that Wide Area doesn't use CSP, at least not the way Group does on the DSLRs. That's because I see a great deal of hunting at times in Wide Area. If Wide Area were prioritizing CSP the way Group does, then it would have instant snap to the close point, period. What appears to be happening is that CSP is one of the things the camera considers, but it is also doing a check to see how much of the box is close/far and making some sort of judgement call. 

So, we're not really getting CSP, in particular the P part (priority). Distance has some level of priority, but not absolute priority. And that means that you can't really trust it. I shot a lot of images with the various modes in the last two weeks and have examined them closely. Wide Area was not terribly reliable, and I see plenty that did not focus on the most forward element in the box. Trying to make sense of why that is will take some time, and maybe a discussion with Nikon. 

My point remains, however. Group mode on the D5 generation DSLRs is an absolute. It might not work for you in some situations, but it is 100% predictable and very fast. The Z7, no, we don't have something that's 100% predictable and very fast. Instead, we have something that's sort of predictable and not as fast as CSP would suggest it should be. 

This gets to Nikon design philosophy. Those brilliant—and I do mean brilliant—Nikon engineers often make assumptions and design towards lowest common denominator with the automated features. That discounts the "thinking photographer." As I've noted many times, with the D5 generation cameras I have them programmed so that I have back button focus with different area modes on both the AF-On and thumbstick buttons. This was a great change by Nikon and highly welcome, because it allows me to use my brain in evaluating what's in front of me and picking the best AF Area Mode for the job in real time. You can't do that on the Z7. Moreover, even if you could, the lack of true predictability in some of the modes means that you can only guess at what the camera will do. 

Let me be clear: I don't want to be guessing about what a US$3400 camera will do. Maybe you don't mind that, but I certainly do. This is a "miss" by the Nikon engineering team, and needs to be cleaned up.

text and images © 2020 Thom Hogan
portions Copyright 1999-2019 Thom Hogan-- All Rights Reserved
Follow us on Twitter: @bythom, hashtags #bythom, #sansmirror