D700

[jonas_mccord]

<p>I just upgraded from a Nikon 40dx to a D700. I always used a telephoto on my 40dx and never had focus problems. I tried an 85mm 1.8 on the D700 and had a lot of focus problems. I set the d700 to S single servo auto focus, single point AF, and matrix metering. When I did this on close up's half the face was out of focus. Or the face was in focus, but the person's shirt wasn't. I also tried spot metering. Nothing seemed to work all the time. I'm wondering if it's because I used an 85mm 1.8. I never had this focus problem with my 40dx and telephoto lens. I tried Aperture priority and P (automatic), and still had problems. What am I doing wrong? Help!! </p>

[hans_janssen]

<p>What was your aperture on the pics? Use the DOF calculator to calculate the more shallow DOF of a FX camera and compare it with the DX DOF.</p>

[edchambers]

<p>Jonas,<br /> First of all welcome to Photo.net. You say in your post that part of the face is in focus and the shirt is not. This sounds like an aperture choice available to you by using the 1.8 85mm. (nice lens BTW) May I suggest that possibly your old telephoto, (not mentioned in your post by actual name) did not offer such a low aperture, shallow depth of field 'DOF,' there fore you could not have had the choice of shallow DOF before such as 1.8. (short distance in focus, a lot out of focus). Try A priority of 5.6 and try again. Note to look into the view finder to observe what the settings are as you take the shot, or alternatively look at the settings of the shot you just took and observe what you did. Or P mode and modify the shutter speed to obtain the desired aperture. Does this help?</p>

[frank_skomial]

<p>The D40 camera or D40X, both have the automated shooting/exposure modes, like the green icon Auto, Portrait, Landscape, Sport, etc... These modes are not available in the D700 camera so you get no immediate help. You are expected to know how to set your camera parameters with D700, since this camera is more oriented for professional photographers.</p>

<p>I suggest you inspect EXIF data in pictures taken before with your D40 camera and see how parameters were set for you. Once you know that, you set those parameters on the D700, and chances are that you will get at least as good, or more likely better pictures.</p>

[edchambers]

<p>Frank, Excellent answer!</p>

[vcakic]

<p>Jonas, you say you have a focus problem, but then you are trying to adjust it with metering (matrix and spot). Also aperture priority and P will set your exposure, not the focus.<br>

Maybe I'm wrong, I think you have selected largest aperture (1.8) and that's why you get very shallow depth of field. Try this: set aperture priority metering and then set smaller aperture (5.6 or smaler). That should give you greater depth.</p>

[SolaresLarrave]

You probably shot your D40 in P mode and the camera closed down the lens. As Frank said above, you need to find out

the aperture used in your "good" D40 shots, and use it in the D700. I'm guessing that the camera must have used f5.6

consistently, to give you enough DOF so that face and shirt would be in focus.

 

Don't fiddle with the spot meter. As Vanja said, the meter only regulates the exposure, not the focusing.

 

Take care!

[nishnishant]

<p>Side question : Will an 85 mm lens at 1.8 aperture give a shallower depth of field on a FX camera compared to a DX camera for the same camera-subject distance?</p>

<p>If so, perhaps that's his problem here. He's got to move further back with the FX camera maybe (other settings remaining the same)</p>

[nishnishant]

<p>Though when I read what I just posted, it seems to me that it should be the reverse. From the same distance from the subject, the FX camera should actually give deeper DOF.</p>

[ryan_long]

<p>Nish,</p>

<p>My understanding, from going from 35mm to 67 format is that the wider the capture area, the shallower the depth of field. So, yes, the transition from DX to FX would provide a shallower depth of field using the same lens, and noticeably so with the 85mm f/1.8 in question.</p>

[ryan_long]

<p>Nish,</p>

<p>My understanding, from going from 35mm to 67 format is that the wider the capture area, the shallower the depth of field. So, yes, the transition from DX to FX would provide a shallower depth of field using the same lens, and noticeably so with the 85mm f/1.8 in question.</p>

[nishnishant]

<p>Cool - so that must be it then.</p>

<p>Considering he's shooting in wider aperture with the FX lens than with the DX lens, the effect must be multiplied. So he's simply got to move further back from his subject.</p>

[frank_skomial]

<p>One could use a DOF calculator, but simpler method is possible to prove or reject your claim as below:</p>

<p>"is that the wider the capture area, the shallower the depth of field" </p>

<p>- if you have some older lenses that the depth of field scale is engraved, you can confirm or reject your statement by simly looking at those DOF scales.</p>

<p>Let set a wide angle lens at distance of e.g. 10 meters, and a F stop and observe the engraved DOF. </p>

<p>Do the same for a normal or telephoto lens, set it at the same aperture and focus distance as with the wide lens. This will capture much less area than the wide lens, and again observe the DOF. Now compare DOF obtained for the wide lens test to the DOF for the normalor tele lens. What would be your conclusion ? </p>

<p>Even simpler test can be done with a zoom lens that has engraved DOF scale, like the Vivitar Series 1:</p>

<p><a href="http://techtheman.blogspot.com/2008/09/vivitar-series-1-70-210mm-f35-tokina-v2.html">http://techtheman.blogspot.com/2008/09/vivitar-series-1-70-210mm-f35-tokina-v2.html</a></p>

<p>Scroll down a bit and you can see a red color curve describing DOF scale, that at 70mm it catches wider field than at 210mm setting, but at 70 mm DOF is much wider, and at 210 mm is very shallow. </p>

<p> </p>

[frank_skomial]

<p>DOF is property of the lens and not the sensor the lens will be used on.<br>

If a lens is installed on a DX sensor, in has the same DOF as on the FX sensor in the same common small area of the frame. In both cases you will get the same DOF in the picture. If you see larger picture area form FX sensor you would get more field of view and more details outside of of the central area, but it does not change the DOF in the picture.</p>

<p>This was explained in a book "Optical Illusions" - I cannot remeber the author.</p>

[tom_luongo1]

<p>If I were shooting with an FX body instead of a DX body and the same lens, I'd move closer to the subject to make up for the difference in "crop factor".</p>

<p>Since the lens is now closer to the subject, the depth of field is therefore reduced, given the same aperture.</p>

<p>Jonas - especially if you are using a wide aperture, try continuous servo single point AF, with selecting an AF point on the eye. If you are using single servo, it's possible you are locking focus then moving forward or backward before taking the picture. (It may also help to change the continuous servo AF priority setting from release priority to shutter priority.)</p>

<p>Post a couple of examples and we'll be better able to help.</p>

<p> </p>