D7000

<p>Hi<br>

I had occasion to use my D7000 two nights ago with the lowest SB flash - it was a dinner function. Disconcertingly, on several occasions, the autofocus would 'hunt', finally settle down, but the camera would not then fire. I turned it off, then back on, and mostly, it would then work. The lens was an Nikkor 18-200. Camera set to P. Is this a problem? Thanks for any advice<br>

Arthur (Apiarist1)</p>

<p>Dim light, slow lens, D7000- the perfect situation for AF to fail.<br>

Dont know what flash is "lowest SB flash", but newer Nikon flashes are able to send focus light, if camera is set to AF-S and center focus sensor is activated.</p>

<p>Let me guess, the 18-200 hunted more at the long end.</p>

<p>That lens will do that indoors in dim light. Any slow lens will.</p>

<p>A higher end speedlight with the IR focus assist would have helped in my experience.</p>

<p>Get an SB700, which has an AF assist lamp, which will solve all your problems. If you want to help your camera even more, ditch the 18-200mm for something faster, but I had many good years with the 18-200mm despite its sometimes-mediocre image quality, and besides, I traded it for a 16-85mm, which isn't any faster of a lens.</p>

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<p>A higher end speedlight with the <strong>IR focus </strong>assist would have helped in my experience.</p>

 

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<p>I guess you mean <em>Red</em>? 21st century DSLR sensors are so<strong><em> Infra </em></strong><em>Red</em> shielded, you'd need a 20W LED to get through it from 5ft.... that and the fact I can actually <em>see</em> my SB-800 stripes and I'm mostly human!</p>

<p>The D7000 will hunt and not fire at some settings when you are closer that the nearest focus range. The 2 button reset should get you back on track. My D7000 will autofocus in near total darkness with just the built in focus assist light. If you have an 18-55, an 18-70, or an 18-105 they would be a better choice for a dinner function. Did you have a back up camera available?</p>

<p>Mike, the D7000 doesn't use the sensor to focus, it uses a phase detect autofocus system. The sensor isn't exposed to the scene until exposure in regular operation of the camera.</p>

It isn't really pure IR, but that doesn't matter. What the OP needs is either an AF assist light or, better yet, a faster lens -

an f/2.8 zoom or something like the 35mm f/1.8 DX.

<p>Ariel, unless something really hinkie is going on, the AF module will NOT SEE IR! If it did, the resulting AF solution will be<em><strong> wrong</strong></em> for visible light.</p>

<p>I didn't say that the AF module will see IR. I said that the <strong>sensor</strong> being infrared shielded doesn't have anything to do with the autofocus, since the <strong>sensor</strong> is hidden away behind a mirror and shutter during autofocus.</p>

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<p>Mike, the D7000 doesn't use the sensor to focus, it uses a phase detect autofocus system</p>

<p>I said that the sensor being infrared shielded doesn't have anything to do with the autofocus, since the sensor is hidden away behind a mirror and shutter during autofocus.</p>

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<p>But NOT if the OP was in Live View...;-) In which case AF is pretty poor in dim conditions anyway.<br /> <br /> OK, so the lamp emits light of a wavelength (IR) that neither the sensor nor the AF module can see.....Really??. Not sure the term '<em>Assist'</em> applies here!! It emits <strong>RED</strong> light.....any IR present is because of the inefficiencies of an incandescent bulb! I'm not taking my SB-800 or SC-29 apart, but would think they should be LED based which are almost monochromatic.<br /> <br /> Oddly, the camera mounted 'white' AF assist illuminator is still a small bulb.<br /> <br /> The red cross-stripe pattern projected by the AF assist lamps on the flash body or the off-camera cord SC-29 is very effective at assisting the camera AF. Nikon give the effective range as 1 > 10m whilst fitted with a 50mm f1.8. However, that's going to be severely reduced with a max f5.6 lens too. Another good reason to buy faster glass!<br /> <br /> I suppose being deep red, as opposed to the bright white in-camera lamp, it won't dazzle people quite so much and make them squint. The flash might blind them, but not the AF assist illuminator!<br /> <br /> <br /> </p>