Am I doing something wrong? (AF with prime lens)

[reza_rezazad]

<p>My first prime lens, a 35mm 1.8G Nikkor on a D5300. The pictures I take all seem to be out of focus. I don't know if it's because the aperture is wide (although I didn't shoot wide open) or is it an AF issue. Please see the attached image and also this one: (I applied the unsharp mask to the latter one.)</p>

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

[SCL]

<p>If your focus point was on the eyes of the man in the foreground, your picture is in focus just fine. If you mean that the background people aren't in focus it is because you don't have sufficient depth of field (your diaphragm needs to be substantially closed down because you need more light to get everybody in focus). You get more light by a variety of means: 1) increasing your sensitivity by raising your ISO (but it may result in grainier results), 2) using a flash, 3) lowering your shutter speed (but this will result in motion of your subjects - so not advised for this particular case. Indoor lighting is often insufficient for large depth of field shots unless the intensity is pretty high, this is where flash really helps.</p>

[Matt Laur]

<p>The attached image looks perfectly in focus, on the main subject's left sleeve (his left, not our left). If the aperture is relatively wide, you've got pretty shallow DoF in that situation. If you're not using single center spot focus in poor lighting conditions like that, it could be as simple as the camera's AF not being able to read your mind, and that's where it chose to focus because it found some nice contrast there to latch onto. In your second shot, you've chosen to focus on the back row of musicians, and are again looking at shallow depth of field. With that camera you can jack up ISO pretty high in order to buy yourself the ability to stop down for greater DoF.<br /><br />Need to know more about your AF mode and configuration to comment more intelligently. Mostly, stop down that lens for more DoF, and use a single center focus point for better control. Half-press the shutter, obtain focus, then recompose as needed for framing before taking the shot.</p>

[reza_rezazad]

<p>Thanks. AF was on automatic. So it seems I'd better use center spot focus when shooting with a wide aperture, at least when I don't have much time to recompose. It seems that the benefits of a wide aperture lens are pretty limited, mostly to portraiture? </p>

[Matt Laur]

<p>There are plenty of times when images like your attachment above would very much want the front subject in focus and the background less so. Environmental scenes with busy backgrounds are a perfect scenario for a fast lens used with the aperture wide. </p>

[reza_rezazad]

<p>Yeah the blurring of the background is something useful but it's a different thing when someone's left sleeve is in focus but his face is not. That's very narrow DoF. </p>

[Wouter Willemse]

<blockquote>

<p>Yeah the blurring of the background is something useful but it's a different thing when someone's left sleeve is in focus but his face is not.</p>

</blockquote>

<p>It's the same thing, really. Just a matter of degree. How shallow or deep you want your DoF to be is a choice. I think the biggest advantage of lenses with very wide apertures is the fact that you have that choice (a f/4 lens offers less creative choice in this sense). Having choice in my view always beats not having it. Especially with primes they can still be small and affordable, such as your 35mm - wide aperture zooms tend to be a lot bigger and more expensive. A last advantage is that these lenses are very sharp at medium apertures (f/4), where the normal variable aperture zooms (as the 18-55) are not yet near their optimum performance. So, there is a little bit more to it.<br /> If you feel that for your style of photography, a very wide aperture has little use, then you do indeed have limited gain. That doesn't mean "<em>the benefits of a wide aperture lens are pretty limited, mostly to portraiture</em>" - we all have a different style and approach. Wide apertures sure are not limited to portraits at all - or at least, I hardly shoot portraits, and I do shoot an awful lot at f/2 and below.</p>

[William Michael]

<blockquote>

<p>“Am I doing something wrong? (AF with prime lens) . . . My first prime lens, a 35mm 1.8G Nikkor on a D5300. The pictures I take all seem to be out of focus. I don't know if it's because the aperture is wide (although I didn't shoot wide open) or is it an AF issue.”</p>

</blockquote>

<p>Regarding the attached colour image: I suspect that <strong>you have neither an issue with Aperture nor Shallow DoF nor Auto Focus.</strong></p>

<p>The issue concerning the blurring of the Main Subject of that Portrait is that <strong>the shutter speed is too slow to arrest SUBJECT MOVEMENT.</strong></p>

<p>There are portions of the Man’s Left Shirt Sleeve which appear sharp, evidenced by the lines in the shirt fabric – most noticeable at the inside elbow, but his Left Hand and his watch band appear blurred by comparison.</p>

<p>HOWEVER: there are areas of the shirt at the Man’s Right Hand Side Girth, where the shirt’s fabric pattern appears to be quite sharp and this area is substantially in front of the area of the Inside Left Elbow.</p>

<p>YET: at the man’s Girth, along the line of the shirt’s buttons, the fabric pattern is blurred: note this area of the line of buttons is located in-between the Right Hand Side Girth and the Inside Left Elbow.</p>

<p>This evidence leads me to an initial premise that the Image’s Blurring (of this man) is not a result of a shallow DoF but rather it is Subject Movement Blur which has not adequately arrested by using an appropriately fast Shutter Speed.</p>

<p>There is other evidence which corroborates, such as, but not limited to:<br>

> trailing edge blur in the Left Hand, specifically the index and middle fingers;<br>

> trailing edge blur at the top of the Right Shirt Sleeve; apparent edge blur in both irises (edge of the coloured portion of eyes);<br>

> if the image is a full frame crop and the man is average height, then the Subject Distance is about the range of 10~12 ft, using a Nikon APS-C Camera (D5300)and 35mm Lens at Aperture F/2.8, the resultant DoF would be about 3ft. If the image is a crop from the full frame image, then the DoF would be greater than 3ft </p>

<p>Therefore the assessment is: <br /> > the man is breathing: hence the line of row of short buttons is moving<br /> > the man is moving his left and right hand and also his right forearm is moving<br /> > the man is moving his head<br /> > 1/125^th second was not a fast enough SHUTTER SPEED to arrest this Subject Movement which results in a perceivable Blur in parts of the portrait when the image is interrogated at high magnification.</p>

<p>*</p>

<p>The Black and White Image appears to have a reasonable deep DoF, seemingly there is acceptably sharp focus from about the main Subject to near the Rear Doors, (evidenced by consistent detail in the floor boards). However parts of the Main Subject appear blurred (e.g. Right Hand) and also parts of the other Minor Subjects are blurred (e.g. head of female horn player, though her shoulders are much sharper by contrast).</p>

<p>The blur in various body parts of various Subjects is n-most likely attributed to insufficiently fast enough Shutter Speed to arrest Subject Motion, though, a conclusive statement of opinion requires full EXIF details of the image.</p>

<p>***</p>

<blockquote>

<p>"It seems that the benefits of a wide aperture lens are pretty limited, mostly to portraiture?”</p>

</blockquote>

<p>Firstly, the two images you posted are “portraiture” – but I believe that I understand what you mean: you mean a specific type of Portraiture, more controlled and probably portraiture of tight framing, like an “Head Shot”.</p>

<p>Secondly, the benefits of having a very fast Maximum Aperture Prime Lens are not <em>‘pretty limited’</em>: there are many benefits including, but not limited to:<br /> > the availability to use a very shallow DoF<br /> > perhaps/probably better and faster AF performance<br /> > perhaps/probably more accurate manual focusing<br /> > more likely to accept a Tele-Extender and maintain AF<br /> > ability to leverage a faster Shutter Speed at a lower ISO to arrest Subject Movement</p>

<p>As one example: your very fast 35mm Prime Lens could have allowed you to make that (colour) shot at F/2.8 or even F/2 and that Aperture would have providing an adequate DoF to have the Main Subject in acceptable focus and also the background and also the background Subjects nicely blurred (Bokeh).</p>

<p>To achieve that, instead of you pulling the shot at: F/2.8 @ 1/125^th @ ISO320 @ EV = -0.3.<br /> You could have used <strong>F/2.8 @ 1/500^th @ ISO1000 @ EV = 0</strong>.</p>

<p>1/400 ~ 1/500^th second is a very safe Shutter Speed to arrest the movement of breathing; head wobbles; and gesticulating hands for Portraiture at that Subject Distance.</p>

<p>WW</p>

[reza_rezazad]

<p>Thank you. In the DPreview of the lens the sharpest aperture was mentioned to be 2.8 (ad far as I remember).<br>

Good to know about 1/400-1/500 speed. I thought a speed of 1/125 would be enough to freeze small movements of the subject.<br>

I did a quick test of the lens with a focus chart (using a tripod and a remote shutter release) and the results are attached. The wide open shoot looks a bit blurry but the one with f2.5 looks good to me.</p><div></div>

[reza_rezazad]

<p>Wide open shot.</p><div></div>

[glen_h]

<p>I haven't had so much of a problem with f/2 lenses over the years, auto or manual focus.</p>

<p>I suppose everyone has at least one picture where AF found the background between the main subjects, such as two people.</p>

<p>To get the best use of depth of field, you want to focus between the front and back of parts you want in focus. That isn't always so easy with AF. </p>

<p>Prime lenses often have, zoom not so often, depth of field scales on the focus scale, which indicate the range of distances one should expect in focus. </p>

[William Michael]

<p>Very small Subject Movements are often mistaken for a Focusing error of a DoF miscalculation.</p>

<p>***</p>

 

<blockquote>

<p>“I did a quick test of the lens with a focus chart (using a tripod and a remote shutter release) and the results are attached. The wide open shoot looks a bit blurry but the one with f2.5 looks good to me.”</p>

</blockquote>

<p>I haven’t used Nikon for several years. Your results for your 35/1.8 seem to be appropriate for that type of lens, that’s what is generally expected from those medium-priced, fast Prime Lenses. Even many of the very expensive lenses are not super sharp wide open.</p>

<p>WW </p>

[reza_rezazad]

<p>"To get the best use of depth of field, you want to focus between the front and back of parts you want in focus. That isn't always so easy with AF."<br /> Good point. My lens has a focus ring on it but it has nothing written on it and I don't know how to get precise manual or M/A focus for a 24MP sensor using the view finder. It seems that using the live view gives better AF as someone else mentioned on <a href="http://www.dpreview.com/forums/thread/3585452">DPReview</a>. Here is the only sharp photo I've been able to take with this lens so far and I used LV.</p><div></div>

[Matthew Currie]

<p>If you're getting consistently better focus with LV than viewfinder, you might want to check whether either the lens or the camera is off. Higher models allow focus fine tuning, which unfortunately yours does not, as far as I know. But it's a problem sometimes, especially when the depth of field is shallow. If I were in this situation, I think I'd look up some resources for testing focus accuracy, and see, if possible, whether the camera needs adjustment. If you have another lens, I'd try that too. </p>

<p>A viewfinder magnifier can help. I use the DK-21M on mine. It is not a radical improvement, but it is noticeable. Eyepoint is changed, so you have to stuff your eye right in to get a full view, but that's liveable. Also, remember that there is a focus confirmation dot, which should be fairly accurate if you're using a single point. There's also a rangefinder option in the menu that will replace the exposure reading in the viewfinder with a rangefinder. If the auto focus is accurate in the first place, this will be too. </p>

<p>It varies. My D3200, fortunately, is right on the money, it seems, in fact so much so that in poor light the viewfinder focus is more likely to be right than the Live View (Live view being less exact despite its overall accuracy), much to the consternation of some who contend that this is not ever possible. Just lucky, I guess. </p>

<p>But remember also that Live View focusing uses different starting points, too. I would not jump to any conclusion if you're using Auto Area in the viewfinder. </p>

[reza_rezazad]

<p>I use center point focus and yes I've been consistently getting sharper images when using the live view. In the DPRevew thread that I linked before the OP sent his camera to Nikon for adjustment but my camera warranty is expired.</p>

[William Michael]

<p>The image made with <em>"live view"</em> which is the <em>"only sharp photo I've been able to take with this lens so far"</em> does not necessarily mean that there is a problem with the Camera or the Lens's Auto Focus System.</p>

<p>The photo of an inanimate vegetable at with 1/200th sec shutter is an entirely different shooting scenario to making Candid Portraiture of moving people using 1/125th sec shutter.</p>

<p>It is <strong>not</strong> really very difficult to use Auto Focus in any Portrait setting,: there is usually always something on which AF can be locked.</p>

<p><strong>Centre Point AF Focus > Lock Focus > Recompose</strong> is an invaluable technique to master and one which will be very useful and accurate for more than the majority of Portraiture shooting.</p>

<p>On the other hand, for Candid Portraiture (which is the Genre of Photography the original samples depicted), I don’t think Live-view and Manual Focusing would be really all that easy at all.</p>

<p>WW</p>

[reza_rezazad]

<p>I understand what you are saying William but here are two images taken at high shutter speed and medium open aperture.</p><div></div>

[reza_rezazad]

<p>And here using viewfinder. You see a clear difference if you zoom to 100% and I get this kind of difference consistently between viewfinder and live view shots.</p><div></div>

[William Michael]

<p>Those shots of a dim wall light in a dark room is potentially difficult for any AF system to nail. The AF might wander (that is termed "hunting") trying ot find focus - that is a lighting scenario where, if you have the time, using Manual Focus and Live view would be a good procedure to use.</p>

<p>If you want make a DIY <strong>test of the accuracy of the AF</strong> - then you really need to do that in good light and on a subject with a clean contrast edge and at a reasonably fast shutter speed, preferably with the camera on a tripod.</p>

<p>The Auto Focus on your gear might be inaccurate - I don't know: but you do need to restrict other possible inaccuracies to give a clearer indication of what is happening with the Auto Focus. </p>

<p>WW</p>

[reza_rezazad]

<p>The shutter speed in those two shots was 1/500 and the camera was focused on the head of the dragon which I think had good contrast with the lit background. I'll test again with a well light object again. The problem with using the LV with D5300 is that you can't change the aperture (so you have to switch to VF change aperture and move back). It also has a shutter lag of 2-3 seconds when using LV.<br>

<br /> I'm thinking of swapping my D5300 with a D7100. The only reason I've not done so already is the extra weight of the latter.</p>

[William Michael]

<p>The head of the dragon does NOT appear to me to be: "<strong>in good light</strong> and <strong>a subject with a clean contrast edge</strong>".</p>

<p>The edge of the face of this watch and the hands against the watch face are both <strong>"</strong><strong>a clean contrast edge</strong>" and the window display (and thus the watch's face) is <strong><em>illuminated</em></strong> <em><strong>by</strong></em> "<strong>good light"</strong>:</p>

<p><img src="http://d6d2h4gfvy8t8.cloudfront.net/18131930-lg.jpg" alt="" width="990" height="1350" /><br /> <br /> <strong><br /></strong>WW</p>

[Matthew Currie]

<p>A note about changing aperture on the D5200 and its ilk: You can indeed change the aperture, and it will take the picture at the aperture you choose. It is only the view in the viewfinder that does not change. The viewfinder view will use the last aperture chosen before it is initiated, and once you have taken a picture, the view will change to the aperture you just used. I think this is the same on the D7100, and on many others. It constitutes a kind of poor man's DOF preview if you shuttle back and forth.</p>

<p>If you can afford a D7100, you might be happier with it. It's a nice camera with a better viewfinder, and a few other features, including AF fine tuning. One I sorely miss on the D3200 is a control lock on the back. It's very easy to move the focus point off center by accident, and on mine, though the AF is accurate, it's easy to forget when in a hurry and focus on the wrong thing. </p>

[William Michael]

<p>Reza,<br>

I can across this conversation which you began in 2014.<br>

<a href="/beginner-photography-questions-forum/00d1mg">http://www.photo.net/beginner-photography-questions-forum/00d1mg</a><br>

I note this stipulation: <strong><em>“The main reason I want a DSLR is to be able to take tack sharp photos in suboptimal light” </em></strong><br>

<strong><em> </em></strong><br>

To make tack sharp pictures in suboptimal light takes practice, experience and skill, no matter what camera is being used.</p>

<p>I think the first issue you need to put to bed is to determine if the AF is accurate or not: to do that you need take some test images of a Contrasty Subject illuminated by good hard light. </p>

<p>Also understand that AF has limitations – in poor light there will be occasions where the AF cannot latch on to the Subject: one technique to use in these cases is to illuminate the area with a touch (flashlight) to make AF latch and then lock AF; another technique is to choose a portion of the Subject that does have an hard contrast edge and lock focus and recompose – I use the latter technique often for Portraiture in low light, I’ll drop the centre-point AF to the clothing line between the jacket and shirt or shirt and tie or for a woman the edge of the top section of her dress or blouse on her chest or a necklace etc.</p>

<p>In the other thread you asked a question and cited a seascape image, I have addressed that question in that thread.</p>

<p>WW </p>

[r_montad]

<p>The camera auto-focused on the man's left sleeve. Note the detail in the fabric, which actually has a blue stripe in it.</p>