Strange autofocus issue

[waynesview]

<p>Nikon D3, Nikon 28-70 2.8G ED. Family portrait session out on the beach at dusk. One SB800 on camera, on SB800 off camera, Pocketwizard transceivers. The entire session, from beginning to end, 100+ exposures. My focus point was either the subjects eyes or mouth (if I was a little bit farther away). Every shot is just a little bit out of focus at 100% (in the eyes) and a few are very much so - especially as the sun went down. The strange thing is, the grassy dunes in the background, or the waves behind them, were in perfect focus! In checking the back of my camera during the shoot, I have always checked for the meter values and exposure. Never had to worry about zooming in close to check focus before. I tested the same exact setup this evening and it was pin sharp, shot after shot. The only thing I can think of is that maybe my lens was not seated properly? or the humidity was effecting the camera/lens? It ruined a wonderful portrait opportunity for this family, and probably lost me their trust and future business.</p><div></div>

[rick_m.]

<p>Wow. That is too bad. It was shot at 1/200, F4, 70 mm with the 28-70 F-2.8 ISO-400. This is one of my favorite lenses and sure should not be soft at those settings. At first I thought it had focused on the blade of grass to the right of the girl. But you said that the dunes and ocean were in focus which really indicates that the camera was hitting an odd focus point. </p>

<p>An interesting thing though. I took the liberty of putting the shot into Paint Shop Pro because I like their sharpening algorithm and hit the generic 'sharpen more' and the shot virtually snapped into focus. And it looks like you are right that it was focused at least in the plane of her leading eye. I am not talking about the usual subtle sharpening but really much better. It is not perfect but I think it is useable. I am reluctant to ever post another photographer's shot much less mess with it but just for fun try hitting this shot with some major sharpening in your CS6 if you haven't already and see what you get. </p>

<p>I have never seen that profound a difference with a one-click solution. It makes me wonder whether there is something going weird in the math or between this shot and PS.</p>

<p>Very strange.</p>

 

[SCL]

<p>I tried the same thing in GIMP and the eyes popped into focus.</p>

[rodeo_joe1]

<p>I found the GIMP's plain sharpen filter did a better job on this size image than USM. Unfortunately it also brought the background into focus more as well.</p>

<p>My recommended rescue procedure would be to create a second layer (Layers>New from visible) and then sharpen the background layer. Switch to the top layer and use the eraser tool to rub through to the sharpened eyes, mouth, nostrils and parts of the hair. This will give the visual impression of a sharp shot while not risking edge outlines and other sharpening artefacts where they're not wanted. It'll also leave the background and skin tones nice and soft. I've taken the liberty of working on your picture by way of example Wayne - I hope you don't mind. The result is below, and obviously working on a full-size image will give better results than this little web version.</p>

<p>WRT to the original focusing problem - this one has me stumped. I don't think a partly unseated lens could be the answer, because (1) the AF module should have compensated for any distance mismatch and (2) it's unlikely that the electrical contact between lens and body would be reliable in those circumstances. The only thing I can think of is that the red AF illuminator from the SB-800 might have interfered with the camera's autofocus. Infrared has a much different focus from visible light with most lenses. Also, did you have continuous AF switched on by any chance Wayne? If so there might be a possibility that the AF switched focus between initial shutter press and full release.</p>

<p>PS. One more thought occurs. You said it was very humid: Any possibility that condensation on the lens gave you an inadvertent soft-focus filter?</p><div></div>

[Andrew Garrard]

<blockquote>PS. One more thought occurs. You said it was very humid: Any possibility that condensation on the lens gave you an inadvertent soft-focus filter?</blockquote>

 

<p>Not if other portions of the scene are in sharp focus...</p>

[jenkins]

<p>Not that this is going to help you if you don't have it, CC Photoshop "camera shake filter" Maybe someone you know has?</p>

<p> </p><div></div>

[mike_halliwell]

<blockquote>

<p>Nikon 28-70 2.8G ED<br>

</p>

</blockquote>

<p>Umm...I'm not sure this lens exists?</p>

[Palouse]

<p>24-70--it's in the EXIF.</p>

[rick_m.]

<p>Its not a G lens. I have one and it is a D lens. A really nice one that you can use to pound nails if you want to.</p>

[ellis_vener_photography]

What it sounds like to me is that you need need to use the AF micro-adjust tools built into the camera to fine tune this

specific lens and camera body combination for optimal performance. I use the LensAlign Mark II and FocusTune software

as a target and analytic toolset for this purpose but their are other more labor and time approaches to do the same work.

 

Sharpening an image only increases the contrast along edges. (What is an edge? A difference in tone or color.) it does

not fix focus issues. I am a strong believer in multi-stage sharpening: capture sharpening based on the camera and

subject + output sharpening based on size, resolution and output media characteristics and occasionally some

intermediate very localized sharpening (around lips and eyes, but not on the surrounding skin in a portrait is an example

of this).

 

The detail sharpener in Lightroom's Develop module and in ACR is a capture sharpener. In LR you can choose the

appropriate output sharpening level. There are also Photoshop plug-ins available as well. I think the best of them is

Photokit Sharpener 2.

[ShunCheung]

<blockquote>

<p>24-70--it's in the EXIF.</p>

</blockquote>

<p>As Nick points out, the EXIF data in the OP's original image shows that the lens is actually the 24-70mm/f2.8 AF-S G lens. The original typo is the "28mm" part (should be 24mm), not the G part.</p>

<p>But exactly which lens he used is kind of besides the point. The 24-70mm/f2.8 AF-S and 28-70mm/f2.8 AF-S are fairly similar lenses. The puzzle is why focusing was off for that particular photo session, but apparently it was fine the day before and after with that exact combo.</p>

<p>Just as somewhat a wild guess, I have unintentionally switched from AF-S to AF-C (continuous) with release priority (instead of focus priority). It affected AF accuracy for that occasion.</p>

<p>Additionally, I think it is prudent to bring a small laptop to these location shoots and check your results while there is still the opportunity to reshoot. It may help to view the results with the customers too.</p>

[agitater]

<p>I think that a fair-skinned subject with pale eyes and light blonde hair against a washed out sky with pale background details equals a really, really, really difficult target for the AF system to lock on. I'd say don't start messing with AF Fine Tune and focus target testing or anything of the kind. The camera's AF system is near flawless, but it looks like a combination of difficulties combined to fool the AF system just a bit. Still, as three other posters have shown, there's plenty of detail to sharpen things up reasonably well in pp.</p>

<p>Seems like an ideal shooting situation in which to check focus every few shots and then, if you're set up on a tripod, manually tweak focus just before taking the shot. That's another reason that the 24-70 AF-S lens is so great because you don't have to switch to MF - just grab the focus ring and touch things up.</p>