Even though we ARE Nikon lovers,we are NOT affiliated with Nikon Corp. in any way.

English German French

Sign up Login
Home Forums Articles Galleries Recent Photos Contest Help Search News Workshops Shop Upgrade Membership Recommended
members
All members Wiki Contests Vouchers Apps Newsletter THE NIKONIAN™ Magazines Podcasts Fundraising

D800 and AF performance

ericbowles

Atlanta, US
10544 posts

Click to send email to this author Click to send private message to this author
ericbowles Moderator Awarded for his in-depth knowledge and high level skills in various areas, especially Landscape and Wildlife Photoghraphy Writer Ribbon awarded for for his article contributions to the community Donor Ribbon awarded for his very generous support to the Fundraising Campaign 2015 Nikonian since 25th Nov 2005
Sat 08-Jun-13 02:40 PM

Based on a thread in another forum, I've discovered some information that makes me rethink my AF choices.

The D800/800E uses the Multi-Cam 3500 FX focus module. With that module comes AF at f/8. But there is a big difference in AF across sensors. Keep in mind all this is based on lens or lens+teleconverter combinations wide open.

With a lens that is at f/5.6 wide open, the central 15 sensors are cross type sensors and all sensors will AF. The outer 18 sensors on each side operate as regular line sensors.

With a lens that is >f/5.6 but < f/8, the center sensor and the adjoining 8 sensors are cross sensors, and the central 3 sensors to the left and right of this group are line sensors. Others sensors will not reliably AF.

With a lens that is f/8, only the center sensor is a cross type sensor and the line sensors are the four sensors to the left and right, plus the one sensor above and below the center sensor.

http://imaging.nikon.com/lineup/dslr/d800/features03.htm

This has implications on the choice of sensors when you are using a lens with a variable aperture or a teleconverter.

If you are expecting to track a subject with AFC, you have some increased likelihood of losing focus as the subject moves through the frame. But there is nothing you can do.

The center sensor is the one that performs best and is a cross type sensor while using other sensors means you are more likely to miss AF, but it will depend on your lens. In any event the sensors outside of the center sensor are less reliable.

All of the diagrams for 11 point AF on current cameras show there are no cross type sensors - and the diagrams are next to diagrams of the 51 point AF which have highlighted cross sensors. I think this means that there are no cross sensors with 11 point AF but I don't have confirmation. I have previously chosen 11 points for speed in moving the cursor across the frame, and this will cause me to rethink that decision and choose 51 points.

The D600 has fewer sensors and fewer cross type sensors, but the conclusions are the same.
http://imaging.nikon.com/lineup/dslr/d600/features02.htm

The D4 has the same CAM 3500 FX system as the D800.
http://imaging.nikon.com/lineup/dslr/d4/features02.htm

And the D7100 has a different layout with only the center sensor performing above f/5.6 and it is a cross sensor.
http://imaging.nikon.com/lineup/dslr/d7100/features01.htm

All of these cameras are going to be less reliable with AF using regular line sensors than cross sensors. All may focus depending on the target and light levels but the distinctions are relevant.

Eric Bowles
Nikonians Team
My Gallery
Workshops

Nikonians membership — my most important photographic investment, after the camera

jamesvoortman

Durban, ZA
1468 posts

Click to send email to this author Click to send private message to this author

#1. "RE: D800 and AF performance" | In response to Reply # 0

jamesvoortman Silver Member Nikonian since 06th Sep 2004
Sat 08-Jun-13 01:43 PM

Thanks for the details Eric

I knew that 15 of the D800 sensors can work at f8 but thought they were all grouped together...and it seems they are not. So while AF at f8 might be possible using these 15, tracking is probably not going to be too effective because of the intervening sensors that are less sensitive.

Visit my Nikonians gallery.

Visit

rbsandor

Denver, US
1751 posts

Click to send email to this author Click to send private message to this author

#2. "RE: D800 and AF performance" | In response to Reply # 0

rbsandor Silver Member Nikonian since 29th Aug 2007
Sat 08-Jun-13 10:00 PM

Eric: thanks for the useful information. I had recently moved to 11 focus points for the ease of moving around the screen. What I didn't realize was that I was not taking advantage of all the cross sensors by doing so. Richard

walkerr

Colorado Springs, US
16920 posts

Click to send email to this author Click to send private message to this author

#3. "RE: D800 and AF performance" | In response to Reply # 0

walkerr Administrator Awarded for his con tributed articles published at the Resources Awarded for his in-depth knowledge in multiple areas Master Ribbon awarded as a member who has gone beyond technical knowledge to show mastery of the art and science of photography   Donor Ribbon awarded for his most generous support to the Fundraising Campaign 2015 Nikonian since 05th May 2002
Sat 08-Jun-13 10:08 PM

Great analysis, and it certainly makes sense. Thanks, Eric.

Rick Walker

My photos:

GeoVista Photography

RECONLEY

Marietta, US
572 posts

Click to send email to this author Click to send private message to this author

#4. "RE: D800 and AF performance" | In response to Reply # 3

RECONLEY Silver Member Nikonian since 18th Jun 2012
Sat 08-Jun-13 11:35 PM

Eric, when using the 11 af points (A7) you have all 51 available for use when in a dynamic area auto focus. You just do not have but 11 points available as the initial af point.

Also the center three stack at all cross hatched.

Visit my Nikonians gallery.

ericbowles

Atlanta, US
10544 posts

Click to send email to this author Click to send private message to this author

#5. "RE: D800 and AF performance" | In response to Reply # 4

ericbowles Moderator Awarded for his in-depth knowledge and high level skills in various areas, especially Landscape and Wildlife Photoghraphy Writer Ribbon awarded for for his article contributions to the community Donor Ribbon awarded for his very generous support to the Fundraising Campaign 2015 Nikonian since 25th Nov 2005
Sat 08-Jun-13 11:54 PM

I think the distinction is whether they operate as cross sensors. With 11 point, it's easy to end up with an AF sensor that is not a cross sensor. While that's okay for f/5.6 and lower, at greater than f/5.6 it can make a difference in AF performance and cause you to miss focus.

This is even more of an issue with an f/4 lens and teleconverters. If you use a 1.7 or 2.0 teleconverter, its easy to end up with an AF sensor that does not perform as well as the center sensor. The same issue applies to a variable aperture zoom. In both cases you need to be aware of the impact on AF from the narrower aperture - not just whether AF occurs but the accuracy of AF as well.

Eric Bowles
Nikonians Team
My Gallery
Workshops

Nikonians membership — my most important photographic investment, after the camera

gorji

Jamesville, US
311 posts

Click to send email to this author Click to send private message to this author

#6. "RE: D800 and AF performance" | In response to Reply # 0

gorji Registered since 07th Jan 2007
Sun 09-Jun-13 12:01 AM

Thank you very much for your information. Its very useful.
-------------
Please visit my galleries: Reza Gorji Photography

ajdooley

Waterloo, US
3330 posts

Click to send email to this author Click to send private message to this author

#7. "RE: D800 and AF performance" | In response to Reply # 0

ajdooley Gold Member Nikonian since 25th May 2006
Sun 09-Jun-13 03:44 PM

Eric - Thank you for sharing your insightful analysis. I have been chatting with a lady in Florida about AF issues on her D700, and there are multiple complexities there as well. I have cautioned her not to leave all the decisions to the camera, as doing so renders it an extremely expensive point-and-shoot machine and leaves her wondering why things did and didn't work.

I'll restate what an old boss at the US 7th Fleet used to have on a piece of paper taped to the front of his desk. In ballpoint pen, it stated simply: "Too many moving parts..."

Thanks again -- this is the kind of thoughtful examination of our cameras and how they work that marks you and our fellow Nikonians as somewhat of a different kind of photographers. I of course, mean that politely and positively!

Alan
Waterloo, IL, USA
www.proimagingmidamerica.com

Visit my Nikonians gallery.

Ned_L

Philadelphia, US
8049 posts

Click to send email to this author Click to send private message to this author

#8. "RE: D800 and AF performance" | In response to Reply # 0

Ned_L Moderator Awarded for his in-depth knowledge in various areas, especially Travel Photography Charter Member
Sun 09-Jun-13 08:21 PM

Super work Eric. Thanks.

Ned
A Nikonians Team Member

-----------------------------
Visit my Travel Photography Blog and my Galleries.

txstone12

Texas, US
599 posts

Click to send email to this author Click to send private message to this author

#9. "RE: D800 and AF performance" | In response to Reply # 0

txstone12 Gold Member Donor Ribbon awarded for his generous support to the Fundraising Campaign 2014 Nikonian since 12th Feb 2012
Mon 10-Jun-13 04:37 PM

On reading this topic, I was confused about the 11 point AF selection that I tend not to use.

Thom Hogan, Complete Guide to D800/E, pg 571 explains it this way. Select 11 points for one reason only, speed in selecting *initial* focus area. As Roy said, you still have all 51 sensors available for use in Dynamic Area AF. That's fairly difficult to figure out if you just look at the camera; you are still free to choose S, 9, 21, 51 pt dynamic areas, they are all still displayed in the VF, but when you select, only 11 sensors are available. They *are* still available for dynamic subject tracking though.

However, as Eric points out, you're reducing the number of cross sensors available. Or as Thom calls them 'cross-hatched' sensors. Thom indicates there are 3 cross sensors, the center column, when 11 point AF is selected.

It's a real trade when you are photographing rapidly moving small subjects, e.g., BIF. Why reduce the no. of cross sensors available? Initially, my thought was for tighter control. But I'm only able to control the initial focus point selected, and my penalty is a reduced cross sensor function set. This doesn't sound like a great trade for BIF, perhaps other application areas - other thoughts?

David

Visit my Nikonians gallery

ericbowles

Atlanta, US
10544 posts

Click to send email to this author Click to send private message to this author

#10. "RE: D800 and AF performance" | In response to Reply # 9

ericbowles Moderator Awarded for his in-depth knowledge and high level skills in various areas, especially Landscape and Wildlife Photoghraphy Writer Ribbon awarded for for his article contributions to the community Donor Ribbon awarded for his very generous support to the Fundraising Campaign 2015 Nikonian since 25th Nov 2005
Mon 10-Jun-13 05:18 PM

There were two ideas that I've picked up.

With 11 points, there are a maximum of 3 cross sensors available but with some lenses or teleconverters you might have just a single cross sensor. It depends on the most open aperture of your lens. for example with 11 points you have only 3 sensors that work at all at f/8, while with 51 points you would have 11 working sensors.

For birds in flight, unless you have a medium or fast lens (f/5.6 or faster) you pretty well need to stick with the center sensor. Even with a medium or faster lens, there are relatively few cross sensors. That does not mean the others won't work with good light - just that your misses are going to be more frequent.

I really wonder why Nikon does not allow a menu setting to use cross sensors only or to display cross sensors in a different color from regular line sensors. I'd also like to see the option to only use sensors that work with a given lens. If I used cross sensors only, AF accuracy should improve.

If you have a D600 or D7100, its much more important to be aware of these issues as the number of sensors is much more limited. The center sensor is always good, but other sensors can have more limitations.

Eric Bowles
Nikonians Team
My Gallery
Workshops

Nikonians membership — my most important photographic investment, after the camera

RWSTARRETT

Gardnerville, US
145 posts

Click to send email to this author Click to send private message to this author

#11. "RE: D800 and AF performance" | In response to Reply # 10

RWSTARRETT Gold Member Nikonian since 03rd Feb 2009
Mon 10-Jun-13 06:47 PM

This little discussion, in and of itself, is quite sufficient reason to be a paying member or Nikonians.org! Thank you all

Visit my Nikonians gallery.

Ned_L

Philadelphia, US
8049 posts

Click to send email to this author Click to send private message to this author

#12. "RE: D800 and AF performance" | In response to Reply # 10

Ned_L Moderator Awarded for his in-depth knowledge in various areas, especially Travel Photography Charter Member
Mon 10-Jun-13 08:26 PM

Eric this has been great stuff. I had never looked at the Global site to read what you linked for us before. Since your original post I've thought about my AF results in light of the information, and it would seem to me that it confirms it.

All of my lenses max out as f/5.6 lenses unless I have a teleconverter on the lens. And at this point I only use a teleconverter on my 70-200mm f/2.8 which with a 2X only raises it to f/5.6, and my 500mm f/4 on which I normally don't use more than an 1.4X which raises it to f/5.6, though every once in a while I'll use a 2X which raises it to f/8.

There is no doubt in my mind that my AF results really fall down if I'm using AF-C on the 500mm f/4 with the 2X teleconverter and try to track a flying bird, for example, even a large flying bird such as a great blue heron, or great egret, or bald eagle. The number of frames out of focus is at least 50% higher with the 2X teleconverter on (no degradation with the 1.4X). The lens is on a tripod, and this isn't blur, it's focus.

>For birds in flight, unless you have a medium or fast lens
>(f/5.6 or faster) you pretty well need to stick with the
>center sensor. Even with a medium or faster lens, there are
>relatively few cross sensors. That does not mean the others
>won't work with good light - just that your misses are going
>to be more frequent.

I quickly found on my own, with the 500mm f/4 and the 2X teleconverter that I had little trouble using single point (center) AF-S if shooting stationary birds, but that when flying, and switching to AF-C, any time the bird was on other sensors than the center sensor, AF was slow and inaccurate.

>I really wonder why Nikon does not allow a menu setting to use
>cross sensors only or to display cross sensors in a different
>color from regular line sensors. I'd also like to see the
>option to only use sensors that work with a given lens. If I
>used cross sensors only, AF accuracy should improve.

That would be great. The next time I talk with the Nikon Professional Services people, I'll suggest that. I do get the impression they listen to their NPS members.

Ned
A Nikonians Team Member

-----------------------------
Visit my Travel Photography Blog and my Galleries.

ScottChapin

Powder Springs/ATL, US
9045 posts

Click to send email to this author Click to send private message to this author

#13. "RE: D800 and AF performance" | In response to Reply # 0

ScottChapin Moderator Awarded for his high level skills in various areas, including Aviation and Birds Photography Charter Member
Mon 10-Jun-13 09:24 PM

I need to print the screen shots out and study them to remember the patterns. My glass is all f/2.8 or faster and f/5.6 with a tele. That's a real small window between f/5.6 and f/8. You're not likely to realize you're in it when you are, let alone remember the pattern for it as you're concentrating on a BIF.

Scott Chapin
Powder Springs, GA, USA

Nikonians Team Member

Ned_L

Philadelphia, US
8049 posts

Click to send email to this author Click to send private message to this author

#14. "RE: D800 and AF performance" | In response to Reply # 13

Ned_L Moderator Awarded for his in-depth knowledge in various areas, especially Travel Photography Charter Member
Mon 10-Jun-13 10:10 PM

Scott, if I understand your post, you're saying that if you use the lens at a setting of f/8, say on an f/2.8 lens, that's the same as a lens with a base aperture of f/8, in the way the AF works. As I've been grappling with this, that's what I thought initially.

I can be very wrong, about both your post and the way this works, as I'm just learning these facts about how the D4 and the D800 work, but it's my understanding that it has to do only with the base (max) aperture. I'm counting on the others to correct me, if I'm wrong, or confirm my understanding, if I'm right.

With AF and AF-S lenses, it's my understanding that basically, the aperture is wide open to the maximum aperture when focusing, and stays that way until the shutter release is pressed all the way down. At that time, the aperture stops down to the chosen aperture, until the exposure is complete, then opens up to the max aperture again.

Therefore, my understanding is what the lens is set to when the image is made doesn't count with regard to how AF is working. It's base (max) aperture is what controls the way the AF system works.

Ned
A Nikonians Team Member

-----------------------------
Visit my Travel Photography Blog and my Galleries.

ScottChapin

Powder Springs/ATL, US
9045 posts

Click to send email to this author Click to send private message to this author

#15. "RE: D800 and AF performance" | In response to Reply # 14

ScottChapin Moderator Awarded for his high level skills in various areas, including Aviation and Birds Photography Charter Member
Mon 10-Jun-13 10:34 PM

Ned,

I should have been more clear. My lenses shouldn't have issues as they are all fast enough even with a teleconverter. Their minimum maximum aperture is f/5.6 with a tele.

My thought was that there are three scenarios; one where the aperture is <= f/5.6, one where the the aperture is > f/5.6 but < f/8.0, and one where the aperture is >= f/8. That second window is very small and you would have to be on your toes to know your lens is in that range, and to have a visualization in your mind as to the sensors that are active in that case.

Off the top of my head though, I cannot think of any lens with a minimum aperture between f/5.6 and f/8. It would have to be a non-constant aperture zoom, perhaps with a tele? It would be very tricky to be shooting and know that your minimum aperture just went from below f/5.6 to just above it!

Scott Chapin
Powder Springs, GA, USA

Nikonians Team Member

Ned_L

Philadelphia, US
8049 posts

Click to send email to this author Click to send private message to this author

#16. "RE: D800 and AF performance" | In response to Reply # 15

Ned_L Moderator Awarded for his in-depth knowledge in various areas, especially Travel Photography Charter Member
Mon 10-Jun-13 11:25 PM

"Off the top of my head though, I cannot think of any lens with a minimum aperture between f/5.6 and f/8. It would have to be a non-constant aperture zoom, perhaps with a tele? It would be very tricky to be shooting and know that your minimum aperture just went from below f/5.6 to just above it!"

The Sigma Bigma and the Sigma 150-500mm are f/4.5-6.3 and f/5-6.3 respectively. They're the only ones above f/5.6 that I can think of, off the top of my head.

We get above f/5.6 with the use of teleconverters. So, for example the 500mm f/4, becomes f/5.6 with a 1x, and f/8 with the 2x. The Sigma Bigma becomes ~f/9 with a 1x, if it would even work, at 500mm. So for those using teleconverters, you've got to keep that in mind.

If you have, for example, the Nikkor AF 80-400mm f/4.5-5.6D ED VR, you know ahead of time you're safe as at its worst it's f/5.6, unless you use a teleconverter with it, which I don't. I have that lens, and I'll just think of it as f/5.6 for AF.

Ned
A Nikonians Team Member

-----------------------------
Visit my Travel Photography Blog and my Galleries.

ericbowles

Atlanta, US
10544 posts

Click to send email to this author Click to send private message to this author

#17. "RE: D800 and AF performance" | In response to Reply # 15

ericbowles Moderator Awarded for his in-depth knowledge and high level skills in various areas, especially Landscape and Wildlife Photoghraphy Writer Ribbon awarded for for his article contributions to the community Donor Ribbon awarded for his very generous support to the Fundraising Campaign 2015 Nikonian since 25th Nov 2005
Tue 11-Jun-13 12:00 AM

The Nikon 80-400 f/4.5-5.6 is exactly the kind of lens that runs into this with a 1.4 teleconverter. At most of the outer end it would be f/5 plus a lost stop with the teleconverter. That puts it at around f/7.1 - so it will AF with the f/8 sensors, and maybe with the middle ground sensors.

The Sigma 150-500 and the Sigma 50-500 are both f/6.3 at the outer end of the zoom. These lenses on the D600 and D7100 are where the problem really comes up. You probably have to use the center AF point on those bodies to have reliable AF - or at least limit your efforts to a few sensors that work beyond f/5.6.


Eric Bowles
Nikonians Team
My Gallery
Workshops

Nikonians membership — my most important photographic investment, after the camera

Ned_L

Philadelphia, US
8049 posts

Click to send email to this author Click to send private message to this author

#18. "RE: D800 and AF performance" | In response to Reply # 17

Ned_L Moderator Awarded for his in-depth knowledge in various areas, especially Travel Photography Charter Member
Tue 11-Jun-13 12:14 AM

Thanks Eric. That confirms my understanding of all this.

Ned
A Nikonians Team Member

-----------------------------
Visit my Travel Photography Blog and my Galleries.

ScottChapin

Powder Springs/ATL, US
9045 posts

Click to send email to this author Click to send private message to this author

#19. "RE: D800 and AF performance" | In response to Reply # 18

ScottChapin Moderator Awarded for his high level skills in various areas, including Aviation and Birds Photography Charter Member
Tue 11-Jun-13 07:40 AM | edited Tue 11-Jun-13 09:20 AM by ScottChapin

Ned and Eric,

That's my point. It's such a limited range of F nos. that it would be problematic with a lens that can operate on either side of it.

Scott Chapin
Powder Springs, GA, USA

Nikonians Team Member

Ned_L

Philadelphia, US
8049 posts

Click to send email to this author Click to send private message to this author

#20. "RE: D800 and AF performance" | In response to Reply # 19

Ned_L Moderator Awarded for his in-depth knowledge in various areas, especially Travel Photography Charter Member
Tue 11-Jun-13 11:34 AM

Scott, that's certainly true. I agree that a photographer will have to keep different scenarios in mind, but I was thinking, just how tricky is knowing where we stand from a practical standpoint, and how many lenses will any of us have to worry about.

For this exercise, I'm only going to look at FX lenses since this is the D800 forum.

We can eliminate lenses with max apertures of f/2.8 or greater, and I'll also eliminate lenses which aren't at least 200mm since it's unlikely anyone would use a teleconverter on them. That leaves us 12 FX lenses in the Nikon stable.

We can take out 6 of those lenses if we only use a 1.4X teleconverter, as their max aperture is f/4.

So for 6 lenses, and perhaps 12, in the Nikon stable, one would have to worry about the 3 scenarios, but for all practical purposes I think you really have to worry about the f/5.6 and f/8 scenarios and most of the time it will be the f/5.6 scenario.

Without using a teleconverter all the current Nikon lenses will use the f/5.6 scenario at all focal lengths.

If the lens is a prime, the teleconverter magnification will directly dictate the scenario, as will be the case with a fixed max aperture zoom lens, but if you're using a zoom lens with a variable max aperture it could become a complicated mix of scenarios.

Practically speaking, when you're using a teleconverter, with a zoom lens, you're generally using the lens at or close to it's max zoom. Yes I know there are exceptions, but I presume not many. Therefore it will rarely be at any max aperture except it's least open max aperture. So, with an f/5.6 max aperture for the lens itself, you'll jump right to f/8, and its scenario. You'll rarely, if ever, worry about an in between scenario.

Note, I'm discounting above f/8, for practical purposes.

From my personal experience with my AF VR Zoom-Nikkor 80-400mm f/4.5-5.6D ED and the new AF-S version which I tested, with a 1.4X teleconverter taking the lens to f/8, AF is significantly degraded even on a D800 or D4. I found that's true on my AF-S 500mm f/4 with a 2X teleconverter. I find that most of the time with that combination, I'm manually focusing. When the max aperture is just f/8 the amount of light those AF sensors get is mighty small, so they don't work very well at that point, but at f/9.5 or f/11, AF, for all practical purposes comes to a screeching halt.

Therefore I'm going to suggest that in the practical world we need generally only remember 2 scenarios and we'll make out well, and we'll only have to worry about that with a few lenses in our camera bags.

Ned
A Nikonians Team Member

-----------------------------
Visit my Travel Photography Blog and my Galleries.

DrJay32

Colorado Springs, US
3377 posts

Click to send email to this author Click to send private message to this author

#21. "RE: D800 and AF performance" | In response to Reply # 1

DrJay32 Gold Member Awarded for his multiple written contributions for the Resources and eZine Nikonian since 12th Mar 2003
Tue 11-Jun-13 01:38 PM

Good post, Eric!

Looking at the diagrams, it's clear that you'd get only 3 cross-type sensors (the center vertical line) at f/5.6 in 11-point mode, and only the center point above f/5.6.

Thanks for pointing this out!

-Jason

Jason P. Odell
Colorado Nikonian
Author, The Photographer's Guide series of eBooks
Capture NX, Nik Silver Efex Pro, Digital Landscapes


www.luminescentphoto.com

JECoutre

Concord, US
375 posts

Click to send email to this author Click to send private message to this author

#22. "RE: D800 and AF performance" | In response to Reply # 20

JECoutre Gold Member Nikonian since 02nd Jan 2008
Tue 11-Jun-13 06:59 PM

Nice assessment rationale and thanks for putting it into usable perspective Ned.
JIm

Ned_L

Philadelphia, US
8049 posts

Click to send email to this author Click to send private message to this author

#23. "RE: D800 and AF performance" | In response to Reply # 22

Ned_L Moderator Awarded for his in-depth knowledge in various areas, especially Travel Photography Charter Member
Tue 11-Jun-13 11:48 PM

My pleasure. Thanks Jim.

Ned
A Nikonians Team Member

-----------------------------
Visit my Travel Photography Blog and my Galleries.

largebore

Clarks Summit, US
678 posts

Click to send email to this author Click to send private message to this author

#24. "RE: D800 and AF performance" | In response to Reply # 23

largebore Silver Member Nikonian since 17th Jan 2011
Wed 12-Jun-13 09:01 AM

Ok I give ...

What are the differences betwween "cross sensors" and " line sensors" ?

Visit my Nikonians gallery.

Visit my Nikonians gallery.

Visit my Nikonians gallery.

Ned_L

Philadelphia, US
8049 posts

Click to send email to this author Click to send private message to this author

#25. "RE: D800 and AF performance" | In response to Reply # 24

Ned_L Moderator Awarded for his in-depth knowledge in various areas, especially Travel Photography Charter Member
Wed 12-Jun-13 10:20 AM

The D800 utilizes the Nikon Multi-CAM 3500FX autofocus sensor module with TTL phase detection.

Phase-detect autofocus sensors are essentially tiny rangefinders. The light from then lens is split into two paths, and the two paths are projected onto small linear sensors. The difference between the pattern of light and dark is analyzed, and the amount of front or back focus instantly calculated and the camera then translates that into lens focus movement so the lens then autofocuses to be in focus, as long as the lens is at a distance where focus can be achieved.

Actually, all AF sensors are linear sensors (line), but at some sensor locations, the camera manufacturers, like Nikon, pair the sensors and orient them 90° from each other giving us the cross-sensor. The pair work together to determine focus.

The cross-sensor is superior to the regular linear sensor because it can analyze light patterns with both vertical and horizontal patterns while the linear sensor, according to its orientation can only analyze light patterns in either a vertical or horizontal pattern. Focusing via a cross-sensor focus point will be both faster and more accurate than via a linear focus point.

In the D800 and the D4 (both have the same autofocus system) of the 51 AF sensors the central core of 15 sensors, 5 vertically by 3 across, (camera in landscape orientation) are all cross-sensors, and the other 36 sensors are all linear sensors.

In our discussion in this thread, we are discussing how the base or maximum aperture of a lens effects which sensors are available to the photographer, and which cross-sensors retain their cross analyzation ability. It turns out that when the lens is f/5.6 or faster, all the cross-sensors are in play as cross-sensors. This would mean that for all Nikon lenses currently being sold, since all are always f/5.6 or faster, all the cross-sensors can be used and all remain cross-sensors, however, if you use a teleconverter on a lens, and it raises the base or maximum aperture above f/5.6 then fewer cross-sensors are available for use, and some may then only be used as linear sensors.

This is important, as an understanding of the differences and changes according to the base or maximum aperture will help the photographer better utilize the camera's autofocus system.

Ned
A Nikonians Team Member

-----------------------------
Visit my Travel Photography Blog and my Galleries.

ericbowles

Atlanta, US
10544 posts

Click to send email to this author Click to send private message to this author

#26. "RE: D800 and AF performance" | In response to Reply # 25

ericbowles Moderator Awarded for his in-depth knowledge and high level skills in various areas, especially Landscape and Wildlife Photoghraphy Writer Ribbon awarded for for his article contributions to the community Donor Ribbon awarded for his very generous support to the Fundraising Campaign 2015 Nikonian since 25th Nov 2005
Wed 12-Jun-13 10:51 AM

Great description of line and cross sensors, Ned.

For those of us that have the D600 or D7100, the number of cross sensors and line sensors at higher apertures drops a lot faster than the top of the line D800 and D4. So while the D7100 has the Multi-Cam 3500 focus system, it is the DX version. On the D7100 that means above f/5.6 you only have a single sensor that operates fully - and it operates as a cross sensor as well. Yes it's true that the D7100 has 51 point AF and AF to f/8, but it's just one sensor and not the same as the D800 or D4 which have a lot more sensors at f/8.

The good news is we are seeing this openly communicated. Earlier cameras had a similar design, but did not communicate as clearly the difference across the sensors at higher apertures.

Eric Bowles
Nikonians Team
My Gallery
Workshops

Nikonians membership — my most important photographic investment, after the camera

Ned_L

Philadelphia, US
8049 posts

Click to send email to this author Click to send private message to this author

#27. "RE: D800 and AF performance" | In response to Reply # 26

Ned_L Moderator Awarded for his in-depth knowledge in various areas, especially Travel Photography Charter Member
Wed 12-Jun-13 01:51 PM

Thanks Eric.

The good news about the D7100 is that unless you're using Nikon lenses with a teleconverter you have use of the full Multi-Cam system on the camera, as all the Nikon lenses top out at f/5.6 themselves.

Ned
A Nikonians Team Member

-----------------------------
Visit my Travel Photography Blog and my Galleries.

DaddySS

Woodcliff Lake NJ, US
1021 posts

Click to send email to this author Click to send private message to this author

#28. "RE: D800 and AF performance" | In response to Reply # 0

DaddySS Gold Member Donor Ribbon awarded for his generous support to the Fundraising Campaign 2014 Donor Ribbon awarded for his generous support to the Fundraising Campaign 2015 Nikonian since 26th Dec 2006
Thu 13-Jun-13 05:22 AM

Thanks for pointing this out - good to know.

Richard

Visit my Nikonians gallery.

emi_fiend

Poway, US
301 posts

Click to send email to this author Click to send private message to this author

#29. "RE: D800 and AF performance" | In response to Reply # 0

emi_fiend Gold Member Donor Ribbon. Awarded for his very generous support to the Fundraising Campaign 2014 Nikonian since 28th Jan 2006
Mon 15-Jul-13 07:23 PM

Eric,

I am little tardy in reading this thread, but I must congratulate you on a great post and a launching a great topic.

The upshot for me is that when my wife uses her D7100 with the 80-400VR and a 1.4TC, then the safest focus point to for her to use is the center point.

This is good to understand.

Jim

a San Diego Nikonian

ericbowles

Atlanta, US
10544 posts

Click to send email to this author Click to send private message to this author

#30. "RE: D800 and AF performance" | In response to Reply # 29

ericbowles Moderator Awarded for his in-depth knowledge and high level skills in various areas, especially Landscape and Wildlife Photoghraphy Writer Ribbon awarded for for his article contributions to the community Donor Ribbon awarded for his very generous support to the Fundraising Campaign 2015 Nikonian since 25th Nov 2005
Mon 15-Jul-13 07:37 PM

Thanks, Jim - great to hear from you.

That's exactly right. On the D7100 any sensor works without the TC, but if you add the teleconverter it's only the center sensor that works reliably.

Eric Bowles
Nikonians Team
My Gallery
Fall Workshops - Golf Photography at the Tour Championship and Fall Color in the Smokies

Nikonians membership — my most important photographic investment, after the camera

JonK

New York, US
6330 posts

Click to send email to this author Click to send private message to this author

#31. "RE: D800 and AF performance" | In response to Reply # 0

JonK Moderator Awarded for his high level skills and in-depth knowledge in various areas, such as Wildlife, Landscape and Stage Photography Donor Ribbon awarded for his very generous support to the Fundraising Campaign 2015 Nikonian since 03rd Jul 2004
Mon 15-Jul-13 09:54 PM

I'm late to the thread, and it makes a great read at a single sitting.

Outstanding analysis by Eric and the rest of you!

Jon Kandel
A New York City Nikonian and Team Member
Please visit my website and critique the images!

Dadorian

Johannesburg, ZA
83 posts

Click to send email to this author Click to send private message to this author

#32. "RE: D800 and AF performance" | In response to Reply # 25

Dadorian Gold Member Nikonian since 17th Jul 2011
Thu 18-Jul-13 01:47 PM

Many thanks for this explanation Ned, i was struggling to follow the threads until I got to this post and now I understand the debate. I appreciate the time you took to explain it.

Cheers

Ian

Visit my Nikonians gallery.

richardd300

Dyserth, UK
4509 posts

Click to send email to this author Click to send private message to this author

#33. "RE: D800 and AF performance" | In response to Reply # 30

richardd300 Silver Member Nikonian since 19th Apr 2009
Thu 18-Jul-13 07:45 PM | edited Thu 18-Jul-13 07:47 PM by richardd300

<<That's exactly right. On the D7100 any sensor works without the TC, but if you add the teleconverter it's only the center sensor that works reliably.>>

I'm late to this thread to, so it may help if Nikon themselves explained the short falls of using a TC with certain lenses, a bit like explaining when and when not to use VR. Thank goodness for Nikonians and commentators like Eric and many more here who can make sense of the can do and cannot do of equipment.

Richard

Visit my Nikonians gallery

Visit my website www.pixels4u.co.uk
The important thing is not to stop questioning. Curiosity has its own reason for existing. Einstein

KnightPhoto

Alberta, CA
4954 posts

Click to send email to this author Click to send private message to this author

#34. "RE: D800 and AF performance" | In response to Reply # 31

KnightPhoto Gold Member Nikonian since 18th Dec 2006
Sat 20-Jul-13 04:46 AM

Also just reading this now and thanks. I'm in that transition zone at f/6.7 all the time as my 500 f/4 VR and TC17E is glued on to my D800E pretty much permanently. It's a sharp combo as you see on this Olive-sided Flycatcher and Solitary Sandpiper. I love the 1.7 for that little bit of edge over the 1.4 on reach and yet still razor sharp. I am not convinced the 2.0 would be this sharp and I wonder if f/8 AF would be responsive enough for my needs. I usually only have seconds to get these shots so responsiveness is part of the total package. My experience the the TC17 is perhaps slightly contrary to reputation, but I have had great success with the TC17 over the years on at least 4 different cameras now (D300, D7000, D4, and now D800E).

I use AF exclusively but it does explain why I have to be careful sometimes that the rig does not just completly miss and unable to focus at all (at which point I MF it close enough to the ball park and then re-press the shutter to get the proper AF).

Likewise I don't like the 1.7 combo on a flying bird, prefer the TC14 then, which would be explained by the above


Best regards, SteveK

'A camera is an instrument that teaches people how to see without a camera.' -- Dorothea Lange
My Nikonians gallery
My Nikonians Blog

Click on image to view larger version



Click on image to view larger version

Attachment#1 (jpg file)
Attachment#2 (jpg file)

richardd300

Dyserth, UK
4509 posts

Click to send email to this author Click to send private message to this author

#35. "RE: D800 and AF performance" | In response to Reply # 34

richardd300 Silver Member Nikonian since 19th Apr 2009
Sat 20-Jul-13 05:38 AM

<<I use AF exclusively but it does explain why I have to be careful sometimes that the rig does not just completly miss and unable to focus at all (at which point I MF it close enough to the ball park and then re-press the shutter to get the proper AF).>>

That's my method too. Stunning images by the way

Richard

Visit my Nikonians gallery

Visit my website www.pixels4u.co.uk
The important thing is not to stop questioning. Curiosity has its own reason for existing. Einstein

Crisol

Barcelona, ES
37 posts

Click to send email to this author Click to send private message to this author

#36. "RE: D800 and AF performance" | In response to Reply # 35

Crisol Registered since 15th Apr 2013
Thu 31-Oct-13 05:54 PM

Thanks for the information, that explain some issues I dindn't undertand on some lenses (without teleconverter).

robsb

San Jose, US
14848 posts

Click to send email to this author Click to send private message to this authorClick to send message via AOL IM

#37. "RE: D800 and AF performance" | In response to Reply # 20

robsb Platinum Member Fellow Ribbon awarded for his expertise in CNX2 and his always amicable and continuous efforts to help members Laureate Ribbon awarded for winning in the Best of Nikonians 2013 images Photo Contest Donor Ribbon awarded for his enthusiastic and repeated support to the Fundraising Campaign 2014 Donor Ribbon awarded for his generous support to the Fundraising Campaign 2015 Nikonian since 23rd Aug 2006
Sun 23-Nov-14 11:53 PM

" I'll also eliminate lenses which aren't at least 200mm since it's unlikely anyone would use a teleconverter on them"

Because when I travel I like to haul as few lenses as possible, I am afraid I am the outlier in your comment. I have used a Kenko 1.4 TC with my 35-70 f/2.8 - no problem with max aperture and also with my 85 mm f/1.4, also no aperture problem. My 300 f/4 is the only lens that ventures into f/8 territory if my mount my Nikon 2x TC II on it. Except for my 300 mm f/4 all of my AF glass is f/2.8 or wider. Even all of my manual lenses except for a 35-105 f/3.5 to 4.5 is f/2.8. One of the reasons I have decided to purchase a D810 is to gain the improved AF when at 5.6 and above as if I mount my old Nikon TC 2.0II on my 300 mm f/4 is will not reliably auto focus at all on my D700.

Bob Baldassano
My Nikonians Gallery

"Nikonians membership - My most important photographic investment, after the
camera"

Retirement is a gift of time - Don't waste it!
Old age is a special gift that very few receive. Be thankful if you get it.

robsb

San Jose, US
14848 posts

Click to send email to this author Click to send private message to this authorClick to send message via AOL IM

#38. "RE: D800 and AF performance" | In response to Reply # 0

robsb Platinum Member Fellow Ribbon awarded for his expertise in CNX2 and his always amicable and continuous efforts to help members Laureate Ribbon awarded for winning in the Best of Nikonians 2013 images Photo Contest Donor Ribbon awarded for his enthusiastic and repeated support to the Fundraising Campaign 2014 Donor Ribbon awarded for his generous support to the Fundraising Campaign 2015 Nikonian since 23rd Aug 2006
Mon 24-Nov-14 12:01 AM

Eric thanks for this very interesting post. I have learned a lot in this thread.

Bob Baldassano
My Nikonians Gallery

"Nikonians membership - My most important photographic investment, after the
camera"

Retirement is a gift of time - Don't waste it!
Old age is a special gift that very few receive. Be thankful if you get it.

Giltic

SI
274 posts

Click to send email to this author Click to send private message to this author

#39. "RE: D800 and AF performance" | In response to Reply # 38

Giltic Registered since 11th Nov 2013
Mon 24-Nov-14 05:43 AM

Since I have bought D7100 I'm wondering, why Nikon can't make all the sensors cross-type. Physically it can apparently be done because Canon cameras have all the sensors cross-type.

stenstro

Los Angeles, US
13 posts

Click to send email to this author Click to send private message to this author

#40. "RE: D800 and AF performance" | In response to Reply # 39

stenstro Silver Member Nikonian since 24th Feb 2013
Fri 27-Feb-15 06:22 AM

I've read this thread more or less in one setting. I've learned a lot. I almost always use just one central sensor but maybe now that I understand more I will experiment.

I have another question and it relates to teleconverters. I have the TC-14E and TC-20E along with the 300mm F2.8 AF-I and 600mm F4 AF-I lenses. The 14E works fine with the 300 and 600mm lenses. The 20E works fine with the 300mm lens. When I use the 20E with the 600mm lens, the effective F stop becomes F8, and I did not expect the D800 to autofocus. The problem is that the camera just shuts down when I mount the combination.

I can mount the 20E to the D800 and it will stay one. When I mount the 600mm lens it powers off. If I mount the 20E to the lens first, then mount the combo to the D800, it powers off.

I was hoping that I would just loose autofocus with the 600 and the 20E, but be able to shoot with manual focus.

Does anyone have any wisdom here?

I should add that I read a lot of speculation on the AF-I lenses and focusing speed. When I purchased the 300mm, I evaluated the 300 AF and the 300 AF-I. The AF-I lense was much much faster in focusing, as well as having an improved optical formula.

The 600 focuses very fast too, but there was never a 600 AF to compare it to, and I have not had the opportunity to compare it to the AF-S version.

My 300 AF-I focuses at similar speed to an AF-S lens. I think it would take a detailed experiment to detect a difference in speed. The AF-S is quieter, of course.

Thanks very much in advance for your comments.

MK Stenstrom

Visit my Nikonians gallery.

Visit my Nikonians gallery.

ericbowles

Atlanta, US
10544 posts

Click to send email to this author Click to send private message to this author

#41. "RE: D800 and AF performance" | In response to Reply # 40

ericbowles Moderator Awarded for his in-depth knowledge and high level skills in various areas, especially Landscape and Wildlife Photoghraphy Writer Ribbon awarded for for his article contributions to the community Donor Ribbon awarded for his very generous support to the Fundraising Campaign 2015 Nikonian since 25th Nov 2005
Fri 27-Feb-15 12:42 PM

I have the 600 f/4 AFS VR and the D800E. AF at f/8 is fine with that combination using the center AF sensor. Light levels matter, and image quality does have a drop off - but it does AF.

I think your problem is the connection between the camera and teleconverter or teleconverter and AI lens. I'm not sure why it would shut down unless there is an electrical issue creating a short.


Eric Bowles
Nikonians Team
My Gallery
Workshops and Private Instruction

Nikonians membership — my most important photographic investment, after the camera

TonyJ

Boulder, US
1467 posts

Click to send email to this author Click to send private message to this author

#42. "RE: D800 and AF performance" | In response to Reply # 0

TonyJ Silver Member Nikonian since 14th Sep 2004
Fri 27-Feb-15 01:25 PM

Just thought I'd add that this discussion pertains to the maximum effective speed of the lens/teleconverter. All metering and focus is done wide open. How you set the lenses fstop doesn't matter. A 2.8 lens that's manually set to f11 will still meter and focus at 2.8.

This might not be obvious to folks who are newer to the game.

Great discussion, BTW.

D800e l D500 l D600 l D700 l Nikon 1 V1 l N90s l AF-S 16-35 f4 l AF-S 24-85 f3.5-f4.5G VR l AF-S 70-200 f2.8G VRII l AF-S 50 f1.8G l AF-S 300 f4 l 200-500 f/5.6 l TC-14EII l TC-20EIII l 2x SB600 l Autometer IIIF.
http://tonyjohnsonphotos.com
https://www.facebook.com/tony.johnson.photography
My Nikonians Gallery

Visit my Nikonians gallery.

stenstro

Los Angeles, US
13 posts

Click to send email to this author Click to send private message to this author

#43. "RE: D800 and AF performance" | In response to Reply # 41

stenstro Silver Member Nikonian since 24th Feb 2013
Sun 08-Mar-15 07:58 PM

Thanks for the thoughts. I don't see a short, at least not from the contacts. They all seem firm, nothing loose or out of place.


The TC 20E works fine on the D800 with the 300/2.8 AF-I and the TC-14E works fine with D800 and both the 300 and 600 AF-I lenses. So I am still puzzled.

When the TC 20E and the 600 are mounted to the D800, all power is off. It does not even show the number of pics remaining, which it usually shows even with the camera switched to off.

I am able to use the TC201 (AIS manual 2x teleconverter for short lenses) on both the 300 and 600 lenses and the images look good although I have not made a detailed comparison with enlargements. I have a TC-301 converter (the AIS manual 2x converter for long lenses. The front converter element extends into the back of the lens). Both converters mount without difficulty and nothing has broken! With the 301, I loose infinity focus. I find that odd because the 301 was designed to work with the 300, 400 and 600 AIS tele's and the 600 AF-I is only a little different optically, one extra element.

I am wondering if anyone has had any experience with the TC-301 and newer lenses. At one point, in the manual focusing era, the TC-301 was the only one to use on the long lenses. It was quite expensive and now is usually around $75 on eBay.

mks


Thanks.

mks

Visit my Nikonians gallery.

Visit my Nikonians gallery.

G