Nikon's 50mm 1.4G AF-S and autofocus/DOF issues

I recently purchased a Nikkor 50mm F/1.4G AF-S lens to go with my D700 to supplement my 70-200/2.8 and 14-24/2.8 instead of buying the 24-70mm/2.8. Call me crazy, but I don't have a problem moving 3 feet forward or backward to frame a shot, and that 24-70 is ridiculously overpriced (if it had VR...maybe).

I don't have any experience with lenses at 1.4/1.8 aperture. I normally shoot with 2.8+ zooms.

That being said, I'm running into focusing issues when doing portraits with the 50mm shot at 1.4/1.8 and I don't know whether I have a defective lens, or 1.4 depth of field is just too shallow to get the full face in focus.

As an example, I was shooting my girlfriend in front of a pier late at night and while bokeh was great - I couldn't get her in focus. Autofocus indicators showed all of her in focus, but the actual shot "looks" blurry when you see it.

Is this something I can check with Nikon, i.e. - at a local repair facility against my camera, or is 1.4 simply too shallow of a depth of field for a portrait taken at 3-5 feet from the subject?

I've had some trouble with this same lens but on a D40. After sending some test shots to Nikon, they concluded there was a problem, and the camera/lens are now being repaired. Testing this lens requires a tripod or other support to ensure nothing moves.

So, have you looked at the focus test chart available at the following address?

http://www.focustestchart.com/focus21.pdf

You can use this to see if the lens is operating properly. Print the chart, set it flat, use AF-S "single" focus point mode with the center focus point, line it up, and take a few pictures.

I almost never shoot at 1.4 - especially doing portraits. Just because your lens will open this far doesn't mean that it's only effective when wide open. The bokeh of your lens will still be very good if you stop it down a bit and you'll gain sharpness as well. So, why have a 1.4 and shoot it at f2.8 or even f8? You can see the difference in your background - even when stopped down and if you try using manual focus, the fast glass will help you see what you want to be sharp. I personally don't like portraits with one eye out of focus and one that's sharp. You can be much more precise when you turn the knob yourself.
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http://www.jhstudio.zenfolio.com

I'll give these instructions a try and report back. Will be interesting to see the result.

In this latest instance, I was shooting at night so 1.4 seemed the logical choice to let in the most light.

If you're going to shoot at 2.8 because the subject is out of focus, why not use the 24-70 then? If you can't use 1.4 most of the time, what's the point of having it?

If you use the Depth of Field (DOF) caluculator at the Nikonian.org website -

http://www.nikonians.org/html/resources/guides/dof/hyperfocal2.html

you will see that using the D700 with a 50mm lens set at f/1.4 and the subject being 4ft from the camera, you get a depth of field from 3.93 feet to 4.07 feet, which is less than an inch in front and behind the point that the camera used as the focal point. Depending on exactly what the camera locked on (such as her nose or her ear) most of her face and body could be out of focus. It would be even worse if you included the upper half of her body in the photo and the camera locks on her arm or shoulder which was not parallel to her face and not the exact same distance as her face from your camera.

Secondly, if you haven't fine turned the AF using the camera's memu and the camera and/or lens is just barely off perfect focusing, you would get a similar problem with using f/1.4 at a close distance to the subject.

Lastly, once the camera locks on focus if you are using AFS (single auto focus versus continueous auto focus AFC) and you move your body or the camera or she moves her body as small of an amount as 1 inch, again you will have focus problems.

Try shooting at your lowest ISO for a portrait in the shade. Do a series at f1.4, f2 and f2.8 settings. Once you get the hang of it in good light, then try it in a low light environment. Here is a recent shot with my 50 at f1.4, ISO 560 on my D80 -

Shooting wide open yields very poor IQ. Shooting at smaller apertures negates the need for this lens. I haven't used it since buying the 24-70 and the 35 f/1.8, both of which are beyond sharp...

I have the 50G and have compared it to a sigma recently, Also have a zeiss makro 50mm and honestly, while the Nikkor 50G's bokeh can't compare to the sigma, its not that bad a lens.

I personally feel that this lens is getting much more flak than it deserves. but perhaps its because of its price tag.

For what it's worth, I have great results from my 50G wide open. Less contrast of course but still quite sharp. even pixelpeeping eyelashes at 100%, i'm quite pleased. at f2 its still less sharp (but much sharper nonetheless) than the zeiss makro wide open but not by a large margin. I find upping contrast helps.

Focus shift with most 50mm lenses would make most of them difficult to shoot from a distance of 4-5 feet away at f1.4 I personally feel. especially when focusing on such a small area (an eye).

Just my take on things. its about knowing how to use the lens perhaps?

I was looking for a fast prime that wasn't too heavy and would be good nuff for every snapshot use but not compromise on IQ. I found that compromise with the 50G, and i don't hesistate to shoot at f1.4 if needed. though i feel for portraits DOF is just way too small to work with.

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Joe
http://www.pbase.com/joed
Photography simple is'nt it??

The way the 50mm G lens performs... it should be $199 ....

i returned it for the Sigma and am very pleased... the Sigma feels more like it is worth $450 + than the Nikkor... I was bummed... i really wanted to like the Nikkor...

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'Procrastinate now, don't put it off.'

'Vista is the ME of our generation.' - John C. Dvorak

fudgebrown said:

The way the 50mm G lens performs... it should be $199 ....

i returned it for the Sigma and am very pleased... the Sigma feels more like it is worth $450 + than the Nikkor... I was bummed... i really wanted to like the Nikkor...

Click to expand...

Does your Sigma have the focus problem?

I got one last Saturday but I returned it to the seller 2 days later as the images shot from F2.8 to F8 have back focus problems.

Regards,
Edmond