Inaccurate autofocus with D5300 and 50mm 1.8G

[malin_ranwala]

<p>I having using a Nikon D5300 for over a year and I recently purchased a 50mm 1.8G lens for portraits. Great lens, but the only issue is that when I autofocus on a subject in a dimly lit area (eg - indoors), the focus appears fine in the viewfinder, but when I check out the final photo, the camera nearly always seems to have focused slightly behind the subject. I have tried this with stationary subjects and a tripod to make sure that the focus isn't changed by camera movement. <br>

I have tried shooting with the camera's inbuilt AF assist light as well as that of my speedlight, but even so this only slightly reduces the focus error instead of eliminating it. <br>

The unusual part is that this seems to occur only when shooting throught the viewfinder with phase detection AF (and the center focus point which is said to be the most sensitive). There appears to be no problem at all with contrast detection AF in Live view.<br>

Also, in the past I used an 18-55 lens and ran into this problem on a couple of occasions. However, the focus was not as off as with the 50mm, and for the most part, it focused perfectly.<br>

Any help would be much appreciated.</p>

[Sohaib Siddique]

<p>i have same problem with nikon d3200 and 50mm 1.8g but in my case thats very rare</p>

[alan_olander1664878205]

<p>The 50mm f/1.8 G lens that I use on my D7100 requires a +8 focus adjustment using the AF Fine Tune feature of the camera. Unfortunately, the D5300 does not have this feature. It's not uncommon to need to use AF Fine Tune.</p>

[ilkka_nissila]

<p>Focus fine tune is available to adjust the PDAF in higher end models (D7200, D750 etc.) so that the user can attempt to correct systematic back or front focusing themselves (but it may not in all cases solve the problem perfectly, depending on the case, usually it does help in my experience, but it can be a tricky process to come up with the optimal value to use). Since your camera doesn't have the autofocus fine tune feature, the only option is to take your camera and lens to Nikon authorized service for adjustment. It is normal that this only affects PDAF - the cause of the problem is the different optical paths to the autofocus sensor and main image sensor. In LV mode the actual image sensor data is used to focus (the AF sensor is not used) so you don't have this discrepancy between optical paths.</p>

[craig_shearman1]

<p>Before you make any adjustments or send the camera in, have you double checked your focus technique?<br /><br />If you are using the lens wide open at 1.8, there is very little depth of field and focusing becomes much more critical than with a slower lens. If you are using the center spot, are you using "focus and recompose"? That's where you put the center spot on your subject (typically the eyes if it's a person), squeeze the release button halfway down to lock focus, then keep it held down as you recompose the picture the way you like it, then squeeze the rest of the way to shoot. If you don't do that, the camera is focusing on something else -- focusing on a point behind the subject is a very common AF error if you're not doing focus and recompose.<br /><br />Low light situations are more challenging for AF than bright light, so all the more reason to be very careful with focus technique and even then to expect a certain percentage of frames to be off.<br /><br /></p>

[chip_chipowski]

<p>+1 Craig</p>

[LenMarriott]

<p>Malin, I've had similar experiences with a recently purchased 35mm f1.8 on my D5100. Live View is the way to go for accurate focusing wide open but that's not always very convenient. I mean, I bought the 35mm for low light photography and Live View is not my preferred shooting mode for most subjects. I believe the problem is minimized with kit lenses as they are f3.5 to f5.6 and have greater DOF when used at maximum aperture so this fact may mask some questionable focusing techniques. (try your 50mm at f5.6 and see if you still have the same problem) Still working on perfecting my own focusing technique. I find my subjects are sharper when the camera-subject axis is perpendicular to the subject. I sometimes get into focusing accuracy trouble with subjects that are shot on an angle, especially when shooting close ups. (keypad on a phone for example) If you find an easy solution please come back and enlighten those of us having the same concerns. Best, Len.</p>

[malin_ranwala]

<p>Thanks alot for your opinions everyone. Craig, I do use the 'focus and recompose" technique. I shall try changing my focusing style first and see. I however don't think shooting at a lower aperture will properly solve the problem (true, in the final photo, a larger depth of field means that focus errors are less noticeable) since the lens is always wide open when autofocusing with the viewfinder, and only stopped down just before the shutter releases.<br>

I shall carry out a series of tests and find out more.</p>