Multi-CAM 20k AF system behavior (D5/D500)

[chambeshi]

There's a large thread going on at http://www.fredmiranda.com/forum/topic/1478115 about the difference in behaviour of the D5/D500 AF and the older Nikon's

Since posting above on my experience with the D500, I read several pages of this thread. Revealing and valuable. And good to see Steve Perry's inputs there. These posts by very experienced users confirms that Nikon's AF system is right in front, if not the industry leader, and the absolute evidence of its abilities is there to see in many photographs. Yet as many of us know at first hand AF remains complex and too often frustrating. In its own right, the roadmap alone for AF settings is riddled with gremlins as to which modes to use where and when.

Obviously, another deciding factor of practical success with AF is the skill of the photographer, especially experience. The other is repeated arguments by experienced users of the D4 that the D5/D500 system is not yet refined. A test report of the D5 in DSLR Photography late 2016 [by leading automotive photographer Dean Smith] found that, compared to the D4, the D5 AF under-performed tracking fast-moving cars. Test of an early released D5 perhaps? Has AF been upgraded since?

While some wildlife photographers find 3D tracking works with the D5 [see posts by Ann Shelbourne], I settled on Group Area mode with my D500 on flying birds (confirmed by Steve Perry with much more tests). Another factor might be undisclosed updates by Nikon of the AF system since release of the D5 and D500.... The obvious step is to check for the latest firmware :-)

Nikon has been cursory in explaining how the AF algorithm(s) are designed to function, especially in fast and furious action. The official manuals leave more unsaid than said. Not withstanding their most kind help to all of us, the reverse engineering by experienced photographers like Steve Perry can only unravel some of the parts of D5/D500 AF system. Being better informed would enable having a less confusing roadmap, especially as to how the different menu settings and controls interact etc in real time

To adapt one of the timeless quotes of Mr Churchill, how we use selected segments in the deeper innards of Nikon's AF is very much "... a riddle wrapped in a mystery inside an enigma"

[Ilkka Nissilä]

For me, the D5's single point and group area AF have been very reliable. These are the AF area modes I am used to, and the improvement compared to D810 is especially evident in low light, at distance, and with fast (f/2.8 to f/1.4) lenses, and the extended coverage of cross type points is very helpful for vertical shots of people. But my subjects move a lot slower than cars, so it is a very different situation.

The only thing I can think of regarding the approaching car focus problem mentioned in the review is that the small points are very precise but not very forgiving in terms of position.

The D5 firmware update 1.1 included some changes to the AF system including the 9-pt dynamic area mode, improvements to auto area AF and 3D Tracking. Perhaps the 9 point dynamic would help keep the car plate in focus.

The DSLR photography reviewer complained about the exposure mode button position; he didn't seem to be aware that the record button can be reprogrammed to MODE.

[MFloyd]

I like Sir Winston Churchill's quote 😊  My experience goes to relatively large subjects (people, cars, planes, boats); I have no experience with sub-sized subjects as birds etc.  But I can ascertain that the D5 has the most efficient AF I ever experienced - even better than the D4s - of the about 10k pictures I took last year in challenging AF conditions, I count the misfocused pictures in the tens.  What more can you ask ?

[Akira]

Maybe a timely post on dpreview.com:

https://www.dpreview.com/techniques/5004008634/subject-tracking-why-it-matters

[MFloyd]

Thank you Akira.  Interesting article. Please don't read the reader comments.

[Akira]

Thank you Akira.  Interesting article. Please don't read the reader comments.

Christian, don't worry.  I've never paid any attention to those comments.   

[chambeshi]

The only thing I can think of regarding the approaching car focus problem mentioned in the review is that the small points are very precise but not very forgiving in terms of position.
The D5 firmware update 1.1 included some changes to the AF system including the 9-pt dynamic area mode, improvements to auto area AF and 3D Tracking. Perhaps the 9 point dynamic would help keep the car plate in focus.
The DSLR photography reviewer complained about the exposure mode button position; he didn't seem to be aware that the record button can be reprogrammed to MODE.

Good points :-)  many users of photographic gear seek refinements and fixes, but I concur with many other happy Nikonians that the D500 is an absolutely superb instrument. Given the presssure on the industry leader in AutoFocus, we can assuredly look forward to refined AF in future top Nikon SLRs. If I could afford the cost, I would buy another D500 as a backup when shooting far from 'civilization'!
The DPreview is also interesting

I like Sir Winston Churchill's quote 😊 

Here's an anthology of many more churchillian quotes. They always reward revisits.
https://www.goodreads.com/author/quotes/14033.Winston_S_Churchill

As an aside, one of my 2 beloved cats is named Winston. A marmalade ginger, he honours his namesake's predilection for felids, especially of the ginger phenotype. And my cats are frequent subjects. In fact, with their erratic leaps and pounces, a pair of sparring cats provide excellent subjects to practice action photography, besides sitting for portraits
http://www.winstonchurchill.org/support?catid=0&id=837

[Ilkka Nissilä]

Now that I've better understood what dynamic AF area mode tries to do, I am having some degree of success using it with the D5.

Here is an example shot where 25-point dynamic was used and the selected focus point was over the ice in an area to the left of the skater which I intended to focus on. This happens very easily when the skaters move laterally. Now, with group area focus there is a tendency to focus with closest subject priority and if one wants to place the focus somewhere in the middle of the group, dynamic area AF seems appropriate (and recommended by Nikon).

Here it seems to have worked and kept the focus on the skater and did not focus on the ice. One just has to be very careful in not relying on it too much and make an effort to maintain the primary point's placement over the primary subject as closely as possible.  I still think the group area AF works more reliably and is easier to use, but I will now use dynamic in situations where I want to focus on somewhere in the middle of a group of subjects.

[Ilkka Nissilä]

Auto-area AF can now easily keep up with figure skating, which is pretty nice. It works great for pairs and ice dancing. D5, 300mm f/4E PF, 1/1250s, f/4, ISO 4000. I don't think I got a single misfocused shot when photographing this pair's program. The relatively homogeneous ice makes skaters a good subject for auto area AF, it seems, but also it worked when the subjects were far away and a part of the audience was in the frame - even in that case, it focused on the skaters and not on the background.

I think when shooting at wider apertures, some disadvantages of auto area AF would show up, mainly the fact that you don't really know which skater it will decide to focus on (it does show active focus points in the viewfinder, but you have no control over the choice). Also ViewNX-i shows the points that the automatic mode had used, so it's interesting to see.

In a more complex situation such as in synchronized skating, it becomes more important to select the skater to be focused on, as auto will no doubt cause surprises in that context.

[MFloyd]

These two type of pictures are very easily handled with the 3D setting; on top, with the D5 you can give a priority to the face. 

[Ilkka Nissilä]

The problem with 3D tracking in ice dancers or pairs is that the subject that one chooses to track can be facing any side of the rink at any given time and may be occluded by the partner frequently, furthermore when they are not facing the camera, I would prefer to switch to the other skater's face. I think slipping from the main subject is inevitable when using 3D tracking in this situation (but haven't yet confirmed with 3D tracking area set to NORM; will test this soon). Auto area AF seems to handle the situation well but it offers less precise control.

These are with auto-area AF, with 200/2 at f/2 (Finlandia Trophy 2016):

https://www.flickr.com/photos/ilkka_nissila/30262372941/in/dateposted-public/
https://www.flickr.com/photos/ilkka_nissila/30051630580/in/dateposted-public/
https://www.flickr.com/photos/ilkka_nissila/30262372661/in/dateposted-public/

In these shots, focus is correctly on the person or face which is facing the camera. I will try to investigate if the camera is actually using face detection to achieve this. I've noticed auto area AF to have a tendency to switch to the more active member of the pair, so if one of the skaters starts to spin vigorously, auto area AF appears likely to catch onto that skater. Nikon doesn't provide too much detail on how it works but it seems to be a good choice for pairs and ice dancers as recommended.

I think the 3D Tracking is better suited for situations where the same person is facing or approximately facing the camera.  When the pair are spinning around each other there is little chance that 3D tracking would be able to follow the same person all the way through, and because of facial visibility issues this is not what I want (I don't want the person who is facing away to be focused on at that time).

Anyway later this week I will be shooting singles so it is a different situation. Nikon's recommendation for singles is 25-point dynamic or auto area AF, for distant subject group area AF.

[Ilkka Nissilä]

I had a lot of fun shooting figure skating at the world championships in Helsinki last week.

I did some additional testing of 3D tracking this time with the watch area set to NORM and face detection ON. I was shooting ice dance. In some cases I was able to have the system track the subject for up to 5-10 seconds but in many cases it would lose the subject much earlier than that (even in 2-3 s), and given the fast spinning of the subject it was very difficult to specify the subject area to track correctly in the first place. I would say it simply doesn't work for this type of subject. I went back to auto area AF for ice dance and group area AF for singles and was happy with those choices. The speed of the skaters at this level of sport is such that I really need the extra area of the group to maintain focus on the subject, instead of using single point. For ice dance I didn't use group because I wanted to give the camera a chance to choose the face which was open to the camera at any given time, however, this didn't always work. Nikon says about Auto Area AF:  "The camera automatically detects the subject and selects the focus point. Priority is given to the faces of any portrait subjects detected." I think I am getting good results using it but it's not 100% of the time that the more open face is in focus; this could be because the camera can't decide which subject to focus on or because the subjects are moving so fast the camera didn't have time to refocus for the more visible face. Either way I am quite happy with what I got.

The lighting at the arena was about 2/3-1 stops dimmer than my local arena (which has newer LED lighting); interestingly some skaters felt the arena was really bright. I was at f/4, 1/1600s, ISO 6400 most of the time, with the 300 PF. I think this level of lighting starts to already show the disadvantage that an f/4 lens has compared to f/2.8 or f/2 in autofocus, but nevertheless I got very few out of focus shots in total.

Two shots from the short dance.

[MFloyd]

Never photographed ice skating.  But seems to work. Nice pictures !

[chambeshi]

SECRETS TO THE NIKON AUTOFOCUS SYSTEM

Steve Perry's 450+ page ebook is on line:
http://backcountrygallery.com/secrets-nikon-autofocus-system/

He covers Nikon D5, D4, D4s
Nikon D800, D810, D750, D600, D610
Nikon D500, D7200, D7100
Nikon D5xxx series, D3xxx series
I looked over a friend's copy. This is a must have and not only for action photography. What I picked up in a few minutes skimming the explanations of how AF actually works and how the Modes differ finally conferred long sought enlightenment. Steve P more than closes gaps left open in manuals. And I see a ray of light here beyond the labyrinth cul de sacs mined out in so many of the n++ posts on discussion groups about AF settings (e.g. the  recent thread on FredMiranda is very long and confusing, which obscures the nuggets of sound advice!). Among several, two strengths of this new book is its simpler access with logical, readable layout...Looks like a bargain

[Andrea B.]

Thank you for this reccie. I'm definitely getting this to make sure I haven't missed anything. (I'll bet I have!!) And to remind myself of things I forget over the long winter when I don't shoot too often.

I was a little daunted at the thought of 450 pages.
But why not......I don't have to read it all in one day. 

I got a chuckle from the Chapter 13 section title: The importance of realistic expectations
It's been my opinion for some time that folks expect too much from auto-focus. Don't you think so??