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Lag correction circuit eliminates shutter lag variation in D1-series cameras  
Sunday, September 30, 2001 | by
LPA Design, makers of flash and camera triggering devices including the PocketWizard, has developed a modification for the Nikon D1/X/H that virtually eliminates the 10ms or so variance in the shutter lag that is a quirk of the company's line of pro digital SLR cameras.

The modification, which sees a tiny circuit board installed into the camera, should enable D1-series cameras to be reliably "equalized" alongside any other compatible camera in multiple camera and strobe setups triggered by the FlashWizard II. It does so by locking in the shutter lag at 75ms (with a maximum variation of 1.1ms, says LPA Design's Jim Clark, the engineer that developed the circuit), as compared to a stock D1-series camera, whose shutter lag jumps between about 70-80ms from frame to frame. This compares to about a 1.2ms variation for the Nikon F100, and 2.8ms for the F5, in my testing.

For the general user, the US$1000 modification will provide no perceptible performance benefit. For photographers from major sports publications that routinely rig up multiple cameras, including different models of cameras, the lag correction circuit should allow a Nikon D1-series camera to finally be properly utilized in such a setup.

Say Clark:

When Equalized with strobes and other cameras- a Nikon D1(x/h) can be used at 1/320 second with 99% of photos perfectly exposed. At 1/400 second, over 90% of the photos will be perfectly exposed, and the ones that are not are only 1/3 - 1/2 stop under exposed, but still very usable.

Without the modification, usable shutter speeds, and the proportion of frames recorded at the same time the strobes fire, drops precipitously, to a motion-blurring 1/125th or less typically.

The full benefit of the lag-stopping modification should be experienced by FlashWizard II users; those with original FlashWizards or the PocketWizard MultiMax may see a slightly lower percentage of fully strobe-lit photos. Because the D1/X/H exposure time is controlled electronically by the CCD, and not by the shutter, those frames that don't receive the full strobe blast will be slightly darker overall. This is unlike cameras in which the shutter does control exposure time, where a dark band appears across the bottom of the frame instead. With any triggering device, the camera must be kept awake to achieve consistent shutter lag times, even with the lag correction circuit in place.

About the Lag Correction Circuit

The lag correction circuit is installed by LPA Design at their facility in South Burlington, VT. The circuit slides into a small crevice inside the camera, near the PC sync outlet. Once installed, the change is invisible to the user; the exterior of the camera is not altered, and only some additional short runs of wire hint at the modification when the top of the camera is removed.

The view inside a Nikon D1X camera, prior to
the installation of the lag correction circuit

Once installed, only a few additional wires snaking across
the top of the inside of the camera hint at the circuit board
lurking inside a small crevice near the PC sync outlet

LPA Design provides a 6 month warranty for the modification, where the liability will be limited to repair or replacement of the lag correction circuit. The company also warrants the camera against damage during its installation; all cameras will be checked for proper function prior to work commencing. In addition, Clark indicates that the performance of the camera, except for the reduced shutter lag variance, should not be changed by the installation of the LPA circuit board, except for the number of frames per charge, which may drop by about 1%, estimates Clark.

Any remaining Nikon warranty, however, is voided by the lag correction circuit's installation, though Nikon service centres should still accept modified cameras for repair at the owner's cost. Clark cautions that cameras sent to Nikon for repair should include a note stating:

DO NOT REMOVE the lag correction circuit unless the repair requires replacement of attached circuits.

If the repair requires the removal of the camera circuit board that the LPA's board attaches to, then LPA will reinstall the lag correction circuit for US$200-300, assuming that an undamaged lag correction circuit is returned with the camera to LPA Design for refitting.

For more information, contact Jim Clark at

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