D800 AF-ON focussing technique

<p>Anyone interested in knowing more about the AF-ON focussing technique can read about it here:<br>

<a href="http://apple-and-eve.co.za/2013/01/using-the-af-on-focussing-technique-with-the-nikon-d800/">http://apple-and-eve.co.za/2013/01/using-the-af-on-focussing-technique-with-the-nikon-d800/</a><br>

I hope you find it useful !</p>

<p>Very well written, Jacques.</p>

<p>You mentioned that you may add or amend; what are your thoughts about the oft-repeated lament (Thom Hogan, etc.) about the D800 and the changes making trap-focus unattainable? Many thanks!</p>

<p>(P.S., Shun, I hope I'm not being repetitive with this request; I know there are some threads specifically addressing it, so I'm asking Jacques to add it to his linked post. --Bill)</p>

<p>Bill, <br>

Thanks for your response. To my knowledge focus-trap is not supported anymore, I suspect the reason for that might be the fact that continuous focus (AF-C) kind of caters for the situations where focus trapping would've been used previously. The last time where I myself used trapping was when I was shooting with an old manual film SLR and no such thing as AF existed !<br>

Okay, I suppose that also tells you something about my age :-)</p>

 

<p>Jacques, <br>

I understand that AF on decouples the focus from shutter button. So one can do shooting and focussing separately and doesn't need to initiate focus each time the shutter button is pressed. <br>

Well, that much i understood, but beyond this, i couldn't. The settings argument...that one doesn't have to change settings with AF on....isn't that true with normal shooting also..? Maybe there's something i'm missing...? You write, "Notice that you can switch between shooting any of the example scenes above <em>without</em>having to change any focus settings? That’s the beauty of using this technique – no more fumbling with focus settings when you can least afford to!.." But i just can't seem to notice or get it...<br>

Focus recompose: this also is same in both techniques. In normal shooting, you focus lock and recompose. In AF on shooting, you do the same...</p>

 

<p>Anurag,<br>

You are correct in what you're saying that focus/recompose can be achieved in normal shooting equally well.<br>

The point I'm trying to bring across is this:<br>

If you're using the normal (default is perhaps a better term) way of shooting (AF-S, no AF-ON button) and you suddenly or unexpectedly want to shoot a moving subject, then you need to switch to AF-C to enable tracking a moving subject before you can shoot, else you might loose focus. When you want to revert back to the default way of shooting, you once again need to change settings (AF-C to AF-S) before continuing.<br>

Using the AF-ON technique frees you from <em>having</em> to change settings in between, you can accomplish everything for shooting both stationary and moving subjects <em>without</em> making any changes in between. This is really the benefit of using this technique.<br>

I agree if that you <em>always</em> shoot either stationary or <em>always shoot </em>moving subjects <em>only</em>, then you do not benefit much from this technique. However, if you switch between shooting stationary and moving subjects regularly (like wedding photographers do) then there is huge benefit in using this method.<br>

I hope this has cleared it up for you?<br>

Regards,<br>

Jacques</p>

<blockquote>

<p>the reason for that might be the fact that continuous focus (AF-C) kind of caters for the situations where focus trapping would've been used previously.</p>

</blockquote>

<p>Not so, focus trapping also allow you to set up your camera near a spot where you expect in a certain point in time that there will be someting "in Focus", by setting up a "focus trap" combined with a repeatedly triggering the shutter ( like by using a MC-36 remote with timer ), you are able to just fire the shutter when there is actually something to frame upon. This is a technique that i suse sometimes to shoot a bird on a spot where i expect it to be in a near future whithout me having to be close to operate the shutter while still having a picture with the bird in focus.. ( srry if this sounds fuzzy, but English is not my mother tongue..) .</p>

<p>This guy explains this better than i can .. :<br>

<a href="http://whatdoineed2do.blogspot.nl/2010/12/trap-focus-shutter-de-coupled-af-on-and.html">http://whatdoineed2do.blogspot.nl/2010/12/trap-focus-shutter-de-coupled-af-on-and.html</a></p>

<p>Jacques,<br>

Well written explanation of the advantages of using the AF-ON technique with AF-C. It is particularly pertinent to the D800 where one needs to use <strong>two hands </strong>to switch between AF-S and AF-C. <br>

I have always used this technique with Nikon DSLRs since it is suitable for moving as well as stationary subjects (allowing focus/lock/recompose, without requiring another button to lock focus). <br>

In short, using this method there was never any need to switch the camera to AF-S, EXCEPT when one wanted to use <strong>trap focus</strong> (on a D700 or any earlier model). And therein lies the nexus of my discontent. By crippling the use of the AF-ON button in AF-S mode (in the D800) and offering no advantage in return, Nikon has made a serious error.</p>

<p>Jacques,<br>

Well written explanation of the advantages of using the AF-ON technique with AF-C. It is particularly pertinent to the D800 where one needs to use <strong>two hands </strong>to switch between AF-S and AF-C. <br>

I have always used this technique with Nikon DSLRs since it is suitable for moving as well as stationary subjects (allowing focus/lock/recompose, without requiring another button to lock focus). <br>

In short, using this method there was never any need to switch the camera to AF-S, EXCEPT when one wanted to use <strong>trap focus</strong> (on a D700 or any earlier model). And therein lies the nexus of my discontent. By crippling the use of the AF-ON button in AF-S mode (in the D800) and offering no advantage in return, Nikon has made a serious error.</p>

<p>Jacques, <br>

Why would i change to AFS when shooting normal?<br>

I can keep it to AFC no matter what i'm shooting, stationery or moving objects...right? Because everything moves anyway, if not the subject, then the photographer...so its a good idea to be on AFC anyway with this kind of camera...<br>

<strong>So this is the part i get and agree: </strong><br>

<strong>Decoupling the AF so one doesn't have to refocus each time a picture is clicked. </strong><br>

Sorry, i am trying to understand the damn thing...:)</p>

<p> </p>

<p>Jacques,<br>

As I have stated (inadvertently twice above) your description of the technique is well done. However there is one point that I must question:</p>

<blockquote>

<p>In the Autofocus custom setting menu, set AF-C priority selection (a1) to Release priority. Even though the D800 will fire (if AF-C priority is set to Focus priority) when recomposing to an out of focus area after the AF-ON button has been released (once focus was achieved), you might encounter some hesitation to fire if there was the slightest shift in focus distance.</p>

</blockquote>

<p>Once the AF-ON button has been released all autofocus operation ceases and focus remains unchanged (effectively locked). Thus even when AF-C Priority (a1) is set to Focus, the shutter will release instantly even when the recomposition causes a major shift in the focus distance of the object under the active focus point. This is the behavior I have observed with my D800.</p>

<blockquote>

<p><strong>Decoupling the AF so one doesn't have to refocus each time a picture is clicked. </strong><br />Sorry, i am trying to understand the damn thing...:)</p>

</blockquote>

<p>Anurag,<br>

The reason to decouple the AF (from the shutter release) is to ensure that one (the camera)<strong> is not forced to refocus each time a picture is clicked</strong>. This allows one to focus (using the AF-ON button and then release the button) then recompose the shot while having the focus remain unchanged from the initially chosen subject.</p>

<p>Normally on Nikon if you use the shutter to autofocus and have the camera in AF-C you can't focus and recompose. As you recompose you move the camera and it will then focus on something else.</p>

<p>And focus points never cover the entire frame, especially on full frame cameras, so focus and recompose is often needed when you shoot something where you don't fill the entire frame with the subject.</p>

 

<p>@Mike - Thanks Mike for pointing out my mistake, I have now updated the blog and hope it now explains point 3 correctly.<br>

The loss of focus-trap in the newer bodies appears to upset a lot of photographers, it's a pity that Nikon did not leave that as an option in the custom setting menu.<br>

@C.P.M. - you are quite correct in you explanation. My version of focus-trap is actually more a case of pre-focussing at some point, and then releasing the shutter once the subject has reached that point.<br>

@Anurag - You are starting to understand the concept and you are correct in saying that using this technique you don't have to alternate between AF-S and AF-C - just stick with AF-C. I think Mike has also answered your question about decoupling the AF better than I could.<br>

@Pete S - you are 100% correct !</p>

<p><em>"</em><em>Normally on Nikon if you use the shutter to autofocus and have the camera in AF-C you can't focus and recompose"</em> Of course you can... IF you use the focus lock button.</p>

<p><em>"Of course you can... IF you use the focus lock button."</em><br>

<em><br /></em>Elliot is correct, the AE-L/AF-L can lock focus (and exposure unless the button has been reconfigured to only lock focus), or some of the other buttons can be configured to lock focus in AF-C mode.</p>

<p>Mike,<br>

<em>The reason to decouple the AF (from the shutter release) is to ensure that one (the camera)<strong> is not forced to refocus each time a picture is clicked</strong>. This allows one to focus (using the AF-ON button and then release the button) then recompose the shot while having the focus remain unchanged from the initially chosen subject.</em><br>

But this can be done by half pressing the shutter and locking the focus also...</p>

<p>"<em>But this can be done by half pressing the shutter and locking the focus also..</em>."<br>

Yes, in AF-S mode. In AF-C half pressing the shutter will not result in focus-lock, the camera will focus continuously. You can in fact perform focus-lock in AF-C mode by assigning the AE-L/AF-L button to "AF-lock" and pressing it once you want to lock focus while keeping the shutter-release half pressed.<br>

Anurag I suggest you set up your camera as I described and then play around with it, you will soon see how it all fits together and works. It does take some time to get one's head around this but once you get the hang of it you will most probably not want to shoot any other way.<br>

Keep asking questions if you get stuck !</p>

<blockquote>

 

<p><em>"Of course you can... IF you use the focus lock button."</em><br /><em><br /></em>Elliot is correct, the AE-L/AF-L can lock focus (and exposure unless the button has been reconfigured to only lock focus), or some of the other buttons can be configured to lock focus in AF-C mode.</p>

 

</blockquote>

 

<p>Well, but then you are using two buttons again :-) But instead of telling when you WANT to focus you're telling when you NOT WANT to focus. Might as well program af-on to af-lock to make the confusion complete.</p>

 

<p><em>"Well, but then you are using two buttons again :-)" </em><br>

Yes, and that is what I'm trying to avoid as much as possible. During a busy shoot there is enough going on to keep me very busy so I don't want anything extra to distract me. It is for this reason that I find the AF-ON technique so useful - it leaves me free to concentrate on the shoot instead of having to deal with camera settings in between.</p>

<p>Thanks for the great discussion.<br>

On my D700, I commonly set it to AF-C (Release/AF-ON) and then the AF-C Priority to focus and was always happy with the results.<br>

Using similar settings on the D800, I feel that the AF-C results are not quite as sharp as the AF-S settings. Just an impression. This is true with stationary objects. Wonder if other people feel the same way?</p>

 

<p>Thanks for posting this, Jacques. I played around with this technique this afternoon on my D800 and it works great. What a breakthrough! <br>

--Greg Embree</p>

<p>Thanks Steve & Greg.<br>

Steven, generally I get sharper images more consistently with AF-C on both D700 and D800. However with the D800 you need to be very careful using dynamic 9/21/51 points when shooting stationary subjects, it is far more eager than the D700 to switch focus to the neighbouring focus points without you realising it and that might result in softer images, whereas with the D700 that seldom happens.<br>

My suggestion is that you try single-point only focus with AF-C and see how that works for you, in my experience it works extremely well and I seldom get soft images this way.</p>

<p>Mike said:</p>

<blockquote>

<p>Once the AF-ON button has been released all autofocus operation ceases and focus remains unchanged (effectively locked). Thus even when AF-C Priority (a1) is set to Focus, the shutter will release instantly even when the recomposition causes a major shift in the focus distance of the object under the active focus point.</p>

</blockquote>

<p>And explained why:</p>

<blockquote>

<p>The reason to decouple the AF (from the shutter release) is to ensure that one (the camera)<strong> is not forced to refocus each time a picture is clicked</strong>. This allows one to focus (using the AF-ON button and then release the button) then recompose the shot while having the focus remain unchanged from the initially chosen subject.</p>

</blockquote>

<p>Anurag responded:</p>

<blockquote>

<p>But this can be done by half pressing the shutter and locking the focus also...</p>

</blockquote>

<p>I used the AF-ON button on my D200 for the same reason Mike described. However, there is another very important reason not mentioned.</p>

<p>I want to <strong>decouple the focusing point from the exposure metering point</strong>, like I do with my film bodies. It took me some time to figure out how to do this on the D200, and I know of no other way. Pressing and releasing the AF-ON button once allows me to focus at a point and lock it, WITHOUT locking the exposure. After locking the focus, I then turn the camera and recompose. Releasing the shutter will then meter the exposure for this composition and capture the image.</p>

<p>If instead of using the AF-ON button, I half press the shutter to lock focus as suggested by Anurag, I would lock the exposure metering as well. When I turn the camera, recompose and release the shutter, I may end up with an erroneous locked exposure metered from a different composition.</p>

<p>The reason and practice of decoupling focusing from metering is an important topic that is seldom discussed. Even Thom's guides don't touch upon it. On film bodies, that is easy. But with the dslrs, it can be a challenge to figure out all the settings correctly in order to accomplish this simple goal. (And can't be done at all on most p&s?) Every time I ask a sales staff at a camera store to demonstrate how to do this on a new body I'm interested in, he/she won't have a clue. </p>

<p>Robert K,<br>

Thanks for pointing out this additional advantage of using only the AF-ON button for focus. (It's sometimes referred to as "back button focus".) Those of us who have been using this method for a long while are so accustomed to this advantage that we don't give it a second thought. So even though Thom's guides do mention this method (I think he calls it the pro's approach to autofocus) he also fails to point out this benefit.<br>

Thanks again.</p>