AF Assist Lights??

[mike_halliwell]

<p>I notice that the AF Assist lamp built into the camera body is a white 'bulb' that illuminates the area to make any detail contrasty enough for the AF to grab onto. However, if it happens to be pretty featureless, it can still fail. I seem to remember it's a mini halogen bub <em>not</em> an LED, is that right?</p>

<p>However, the AF Assist built into Flashguns and particularly my SC-29 remote TTL cord projects a pattern of red stripes that gets the AF to quickly lock-on, almost without fail.</p>

<p>Why is there no Pattern Projector in the camera?</p>

[howard_m]

<p>my first thought is size. that feature in the flash unit seems to be moderately large (even if it is tucked behind a red filter). I dont think there's a lot of dead space in the camera body for something like that given how little it would be used.</p>

[MichaelChang]

<p>Probably because the AF assist light is usually side-mounted without much room to angle the light or make it direction, and the lens will get in the way of beam-spread over distance. Then there is the power requirement consideration. </p>

[frank_skomial]

<p>Effective range of auto focus suport light in a camera (whatever you have ?), is usually very short.<br>

SC29 could possibly provide longer usable range.</p>

[jcofer1]

<p>Minolta used to manage to shoehorn in a pattern-projecting focus assist in some of their models (700si and 800si for sure, probably others).</p>

[rodeo_joe1]

<p>Has nobody at Nikon noticed how small the head of a laser pointer is? Some of the cheaper ones even come with a 'fun pack' of diffraction gratings to project patterns like hearts, stars, Donald Duck, etc. So a few stripes should be no problem at all.</p>

[mike_halliwell]

<blockquote>

<p>Probably because the AF assist light is usually side-mounted without much room to angle the light or make it direction, and the lens will get in the way of beam-spread over distance. Then there is the power requirement consideration.</p>

 

</blockquote>

<p>Surely the same lens obstruction and angle problems apply to the current AF assist lamp? Just replace it with an LED laser diode with a pattern projector to say a 50cm square @ 2m. 20mA is more than enough to power it. I wonder how much current the current (sorry!) lamp uses? I suspect it's way more than that!</p>

<p>I have a D50 (IR Conversion), D80, D90, D5100, D300 and a D700!</p>

[mike_halliwell]

<p>RJ, got it one! My server is being kinda slow and I posted before yours arrived!</p>

[MichaelChang]

<p>I have a few Sony cameras with laser assisted focus that projects a cross-hatch pattern. Obstacle disruption isn't a problem on the DSC-F828 even with its long lens barrel but is completely obstructed when I install a wide-angle adapter.</p>

<p>The problem is you need a proportional projection over distance that is hopefully relatively centered; both are difficult to achieve when there is such a variety of lenses that can be user mounted in the case of a DSLR. </p>

<p>The Sony cameras are "dark optimized" because of their complementary built-in IR capability and laser focusing. Nikon obviously decided no on-camera solution can be optimized across their lens family, hence their optional off-camera solution. </p>

<p>Mike - "LED laser diode" is a misnomer. </p>

<p> </p>

[CvhKaar]

<p>Doesn't that white light also double as a "red eye reduction"light ?<br>

btw. You would not want to use a laser diode as an af-help light i guess, lasers are well known to xause possible eye damage, imagine taking a close-up of your kid, and forgetting to switch it off ....</p>

[mike_halliwell]

<p>Michael C, indeed it is! It was more a stream of typing... I combined 2 sentences without cutting enough out...:-(</p>

<p>What I don't get is what is the built-in light 'optimised' for?, that a laser projected pattern couldn't replace in an instant?</p>

<p> </p>

[mike_halliwell]

<p>CPM, you're absolutely right. That aspect was not in my original thought. I think they're supposed to be well below harmful level but ..I'm with you on that idea!!</p>

[MichaelChang]

<p>Mike, I suspect the built-in assist light is just a "good enough for rock n' roll" solution to say they've done something about it. I agree it's all but useless for the most part. </p>

<p>Lasers have their own problems, not the least is C.P.M.'s remark about safety. Sony used it for a few years on their high-end P/S cameras but never on their DSLRs, and they are no longer used as far as I know presumably due to safety/liability concerns. </p>

<p>C.P.M, I think red-eye reduction is done via pre-flash. </p>