Focused?

<p>I promise last question. I know I have been posting a lot, but trying to figure this out.<br>

Is my son's face in focus? His face does not look focused when I zoom in. Taken with my D600+Sigma 35 1.4 lens @ISO400, 1/1000s, f/2.2. When previewing on the back of the camera - the red focus dot is clearly on his face. Used single point focus, aperture priority, and used focus point one above the center focus point. He was not moving at the time, and I was using AF-C.</p>

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<p>Depth of field is pretty narrow at F2.2. How does it work out with larger apertures?</p>

<p>I realize 2.2 is somewhat wide open, but I should still be able to focus properly at that aperture, right? When I view the other pictures in this set, when I used the center focus point, they were in focus - just not when I use anything other than the center.</p>

<p>Looking at the shirt, I`d say it is more or less in focus, maybe be a little front focus, but the image is certainly soft.</p>

<p>The light is flat, it does`t help, but looks like the teeth on the dinosaur are sharp but not right...there is a halo or double image around the seams. The knee looks to be closer to the focus plane.</p>

<p>The out of focus blur is harsh, double image type, it makes me think that the focus plane is slightly in front of the child, and the aperture may be not the best one.</p>

<p>I`d check focus on a tripod, over a static subject. I`d also check the optimal aperture on e.g., a newspaper. BTW, is yours the new Sigma "Art" lens?</p>

<p>Yup, I'd go front focus. The sharp bits improve from back to front, but are still not sharp on the eyes. </p>

<p>Try the same type of shot via tripod-mounted AF in Live-View, and if that's as 'out' as this shot, there's another problem brewing.</p>

<p>The focus point was clearly on his face - I even double checked on the back of the camera to make sure after I enlarged this on my computer. And it does appear that his shirt is in focus rather than my son's face. <br>

Yes, Jose, it is the new Sigma lens. What exactly do you mean about the blur? Honestly, I understand this is a pretty open aperture, but I don't feel as though it is impossible to get a decently focused shot with these settings. If I scroll through the images during this set, the only shots that are accurately in focus is when the focus point is set to the center one. That is why I feel as though there is a problem. All settings remain teh same.<br>

The thing is, I have the D700 right now, and I don't have this problem at all with the same lens, so I can definitely rule out anything wrong with the lens.</p>

<p>The reflections in the eyes look as sharp as anything else, so even at 1/1000 could there have been some camera movement, though the softness does not seem directional which suggests otherwise?</p>

<p>I tried sharpening the photo, as it was pretty soft as transmitted. It was clear that your son's eyes, as well as any other part of his face, were not in focus. His clothes were better, but far from what I would consider acceptable. I know you said the lens works on your other camera body, but I would personally test it out on a static subject two ways...one with a 45 degree focus chart to see if it was front or rear focusing in the AF mode and how much, and then try an AF and a manual focus test on a static subject about 10 ft from the camera to see if there is a difference...if there is, and as you say the lens works perfectly on your other body, you should probably have this body adjusted. Even at f/2.2 you should have sharper results with your lens.</p>

<p>Wow! 1/1000th, f/2.2, ISO 400 Aperture Priority.</p>

<p>I always shoot a test shot in Program mode to see how the camera meters and adjusts all settings due to the fact the camera manufacturer put a lot of work and research in coming up with the data they embedded in the lens in order for that data to be used to communicate to the camera's metering to come up with the camera's best exposure for that lens and light level.</p>

<p>I then zoom in on the back LCD preview to check sharpness and DOF quality. Most of the time my camera made the best decision except for maybe a darker or lighter result I wanted shooting Raw with my 18-55mm kit.</p>

<p>One thing that always screwed up the auto focus shooting in dim light was when I opened up the aperture instead of choosing to adjust shutter or ISO. For instance yesterday I rattled off a quick shot in my dimly lit apartment about two feet from the subject @ 45mm, 1/20th, f/6.3, ISO 800 and auto focus nailed it surprisingly. Decided I'ld increase exposure by opening up the aperture to f/5.6. Reshot and I kept getting soft results as I could hear the auto focus allocated to a separate button from shutter release constantly hunting with micro tweaks. Put the aperture back to f/6.3 and auto focus went back to nailing it.</p>

<p>My lighting conditions were far worse than yours going by your exposure results so you might want to find the best aperture for that particular lighting situation and adjust accordingly.</p>

<p>Nope, you missed the face. He was moving out of the plane of focus (or you were) or you had some camera shake, the AF was off, or (more likely) focused on the wrong thing</p>

<p>And as a side note, this is just the most recent example. I could show you plenty of others in much better lighting conditions with similar results. I've had focusing issues for quite some time now. </p>

<p>A static test on a tripod would be in order here, if you've not already done so. If you can find a target that's big enough to offer contrast for focusing and allow you to select individual points, you should be able to narrow it down. <br>

<br />Not sure how much more time you'd like to spend on it. </p>

<p>I'm assuming the D600 does not offer any sort of AF Microadjustment? </p>

<p>Personally, if you're getting good results with the center focus point, and you're not shooting professionally, stick with that and work on your focus-and-recompose technique. Does the Sigma offer full-time MF override? Adjust for your recompose direction and you'll probably be a lot happier. :) Good luck. </p>

<p>I wasn't focused on the wrong thing Robin - the focus point selected is highlighted on his face on the back of the camera. Can't argue with that.</p>

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<p>I wasn't focused on the wrong thing Robin - the focus point selected is highlighted on his face on the back of the camera. Can't argue with that.</p>

 

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<p>I guess you're missing the point. You might have the cross-hairs where you want it. BUT you're using Phase Detect AF, where the body tells the lens where<em><strong> it thinks</strong></em> the best point of focus is. That can be wrong, that's why cameras have AF fine tune.... to correct for these inherent errors. Live View uses Contrast AF, where it 'knows' by trial and error where best focus is. It's slower but much more accurate.</p>

 

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<p>I'm assuming the D600 does not offer any sort of AF Microadjustment?</p>

 

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<p>It does. Learn how to use it.</p>

<p>...and more importantly this is lens + camera specific. It might be perfect on your D700 but not your D600.</p>

<p>Thanks, Mike, for clearing that up. I did miss her point.<br>

This isn't a problem with this particular lens and camera. I have this problem with my Nikon 50 1.4g on this body as well. <br>

I will set this up on a tripod and do the af testing again. I've already had to do this months ago, which resulted in an autofocus repair at Nikon. I just assumed after I used the D700, and had great success with achieving focus, that is has to be something with the camera. I could very well be wrong, and that is why I post here. I may not know as much as I could about photography and how to use my camera, but I learn something new everyday and appreciate everyone's input. </p>

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<p>I wasn't focused on the wrong thing Robin - the focus point selected is highlighted on his face on the back of the camera. Can't argue with that.</p>

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<p>I get the highlight focus point signal too and still get soft results. Have you seen how a camera's auto focus phase detection system works? Good lord! With all the mirrors used to bounce the incoming light after making it past all the lens elements, down to a tiny meter just below the sensor it's a miracle anything comes in tack sharp.</p>

<p>If you're shooting at f/2.2 making DOF a small sliver of area that's sharp and contrasty enough as well as not moving especially in focus/recompose for the phase detection metering to actually nail a spot and adjust the focus ring under all that diffused over cast light, I would say you might want to try a different aperture.</p>

<p>Or do the test Rob suggests to rule out faulty lens and/or autofocus metering. I can tell you I've never had the opportunity to shoot with a lens that could go to f/2.2 and beyond without getting soft results. I even manually focused with no improvements to sharpness.</p>

<p>What was the point you focused on in that scene, the face? or the clothes?</p>

<p>I have and it is very complicated Tim - way over my head! <br>

Yes, the focus was on the eye nearest the camera.</p>

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<p>Decided I'ld increase exposure by opening up the aperture to f/5.6. Reshot and I kept getting soft results as I could hear the auto focus allocated to a separate button from shutter release constantly hunting with micro tweaks. Put the aperture back to f/6.3 and auto focus went back to nailing it.</p>

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<p>That's a really strange observation. While autofocusing, and until the shutter is released, the lens aperture is always set wide open. So the choice of aperture should have no effect on the autofocus accuracy. </p>

<p>Focus distance: 1.3m; DOF: 17cm - almost equally before and after the plane of focus. Nothing in the image is sharp, so you missed by at least some 9-10cm. If you can, get the same shot again, but move back a little so that the boy is fully in the frame with some foreground to spare - you should then be able to see the DOF zone. My guess is that you the boy is just about outside since his sweater appears a bit sharper than the face.</p>

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<p>The focus point was clearly on his face</p>

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<p>You keep repeating this without telling just what part of the boys face was focussed on.<br>

<br /> 2 remarks<br>

<br /> - In general (on FX) for portraits for which you want the head " sharp" from front to back you need mostly to shot the diaphragm from F3.3 on ,any wider does not give you enough DOF for this.<br>

<br /> - If your single focus point is on, lets say'the cheek , there is in general not enough contrast for the AF to work with securely, you need the focus point to be on something with more contrast than flat skin. it is a very often made mistake to focus on a clean part of skin where there is not enough contrast to work on.<br /> So you might want to check the exact location of the focussing area by showing it in ViewNX2 or CaptureNX2 ..<br /> -</p>

<p>I apologize - I thought I said the focus point was over his eye nearest the camera. <br>

I have the exact same shot, with the center point selected over his eyes with good results.<br>

I will work on my focusing skills - obviously I have a lot to learn.<br>

Thank you for your help.</p>

<p>I agree there is a real problem here. The boy's face is clearly out of focus. The shutter speed used should have produced a sharp image, other things being done right. The camera/lens may be back focusing as others have pointed out. You need to reshoot this using a tripod, same lens, same camera and a subject that is not moving. Make sure the camera is not set to Auto A which is easy to set on the D 600. Set it to S and AF C or AF-S. Use a cable release to trigger the shutter. If you do not have one, use the self timer. Use Live View to check the focus. If you need to adjust AF fine tune for this lens, see how to do it on page 259 of your D 600 manual. It is AF Fine tune under the Set Up section of your menu. Assuming all was done right and you still get these poor focused images, repeat with a different lens. If you get the same results with a different lens, I would send the camera and lenses in to Nikon for repair or take it to a local repair shop if that is available to you. I do not blame you for being upset. I would be too. Joe Smith</p>

<p>A vicious sharpening regime goes improve things a bit.</p>

<p>Sharpened Version</p><div></div>

<p>The issue is <em>front</em> focusing, not rear. Parts of the face closer to the camera as well as the boy's clothing are more clearly focused than those further away, but the focus is still missing his eyes.</p>

<p>I've said this many times before, and I'm gonna repeat it now. AF systems and the human eye alike have problems with wide aperture lenses. Residual spherical aberration, which almost all wide aperture lenses exhibit, produces a spread of the point of focus. The plane of best contrast isn't the same as the plane of finest resolution, and so AF systems - phase detect especially - become confused and give a false positive.</p>

<p>You can easily verify that this is the case by looking at the many tests of wide aperture lenses on Photozone.de. Nearly every single wide aperture lens shows a noticeable shift of focus on stopping down. Scroll down to the (weirdly titled) 'Bokeh Fringing' section of <a href="http://www.photozone.de/nikon--nikkor-aps-c-lens-tests/793-sigma3514dgdx?start=1">this page </a>and mouse over the aperture options. You can easily see the forward shift of focus on stopping down with this Sigma 35mm lens. (Why the guys at Photozone call it Bokeh Fringing I have no idea, when the effect they're intending to show is simply caused by longitudinal chromatic aberration, and LoCA would be a sufficient and more accurate heading.)</p>

<p>Fine-tuning the AF may well help, but can only be absolutely accurate for one aperture setting. The way I usually get around it is to use MF and make an allowance for back or forward focus by using the confirmation dot. I know with some lenses that I have to have the dot just lit by approaching it from near focus to far. With other lenses it's the reverse and I have to focus from infinity to near. OK it's slow and doesn't suit all subjects, but with many wide aperture lenses it's either that or Live View if you want your focus bang on at wider apertures. Once you're working below f/4 you can usually let depth-of-field take care of things.</p>

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