M-series camera assembly

Leica treated us to a full tour of the assembly line for its M-series rangefinders. The sheer number of checks and calibrations that each and every camera is subjected to before it leaves the factory is very impressive indeed, and goes a long way towards explaining the digital M's heart-stopping price tag.

This is Leica's assembly room for the M-series and S2 digital cameras. High standards of cleanliness, coupled with a large quantity of computerized test equipment, give it more the feel of a laboratory than a factory.

Basic assembly

	The cameras arrive at the assembly line as a set of sub-assemblies; the main mechanical assembly, including the rangefinder & shutter mechanism affixed to the front plate; the rear plate holding the LCD and controls; the top plate with its controls and associated electronics; and the sensor and control boards. Unlike Caterham, Leica doesn't allow you to buy the kit to build at home.
	This is the M9's sensor board, showing that 18 Mp, full-frame 36 x 24mm chip, custom-made by Kodak. The sensor board arrives at Solms individually calibrated by Leica's electronics partner Jenoptik to its associated control board, with which is shares a serial number.
	This is the sensor board in place on the main mechanical assembly...
	...onto which it's screwed in place...
	...with tiny metal shims just 1/100mm thick being used at three mounting points, which allow the sensor to be precisely aligned such that is not tilted in either the vertical or horizontal dimension.
	The sensor alignment process makes use of computerized analysis of the point-spread function of a star-shaped test pattern, which can detect very small tilts of the sensor.
	The program tells the operator to add shims to the required overall thickness at each of the three fixing points (highlighted on the display in yellow). In this particular case, the camera is good and needs no further adjustment. The whole process typically takes 6 or 7 minutes.
	Following this, the main assembly is completed. Here's an M9 with the rear plate fixed in place, showing the rangefinder mechanism and top plate control electronics...
	..which are then fixed together by hand...
	... to give essentially the complete camera. However there's still lots more tests to come before it's actually finished.

Tests and calibrations

	In the first stage of calibration and testing, the camera's TTL light meter is checked using a standard illuminant, and adjusted as necessary. In principle all M8.2s or M9s should meter exactly the same when they leave the factory.
	Following this, the camera's flash sync operation is verified.
	Next the shutter is checked for accuracy at all speeds using a system of three lasers which track the travel of the shutter curtains at the top, middle and bottom of the frame. It's recalibrated if necessary.
	This screen shows that the particular camera under test returns an impressively accurate and consistent result.
	The camera’s white balance system is calibrated using two light sources – one simulating daylight, the other warmer incandescent lighting.
	Next the viewfinder framelines are checked for correct alignment at both near and close distances. Here we're looking at the close-range test; a video camera records the position of the framelines in the eyepiece, and this is compared to the image captured by the camera's sensor.
	This is the original version of the frame-line testing equipment - incredibly, this alignment instrument was commissioned in 1951 for the original M3, and is still in use today.
	The camera's rangefinder mechanism is then checked for focus accuracy. High resolution digital sensors impose greater demands on focusing accuracy than 35mm film, so Leica designed and built in-house this impressive rig specifically for testing the M8 (and now the M9). A series of six angled rulers at various distances are used to test for accurate focusing.
	Focusing is carried out with a laser beam dot projected onto the ruler as the target, using a video camera that looks into the camera eyepiece and provides a much-magnified viewfinder image to the operator for maximum accuracy.
	This is a closer view of the array of angled rulers, which are positioned to test focus at distances of 0.7m, 0.9m, 1.2m, 1.8m, 3.5m and 8m.
	This screen display summarizes the results - this camera falls within the tolerance bounds marked by the red and green lines, and has therefore passed the test.

As well as this set of checks and calibrations, the camera also goes through some further tests. The sensor is checked for defects such as dead pixels; if it does not meet Leica's specification, it is rejected. The camera also undergoes full electrical testing, and a continuous shooting / SD card write check.

Final Finishing

Once the camera has passed all of this testing and is considered within specification, the finishing touches are applied ready for it to be shipped.

	These are the leatherette coverings for the M9. The smoother of the two is used with the new, very handsome gun-metal finish; the coarser 'Vulcanite' finish is applied to black-painted cameras.
	Adhesive is carefully painted onto the camera's surfaces...
	...and the cover painstakingly applied by hand.
	The front controls - the lens release button and frameline selection lever - are then attached, making the camera functionally complete.
	At this stage the camera is almost ready for boxing up and shipping to the retailer or customer. Before that, though, the sensor is cleaned of any dust.
	One thing is still missing though - the Leica badge. Here are boxes of them, waiting to be fixed to the camera. In typical Leica fashion, even those badges which aren't absolutely perfect are rejected.
	Only when the camera has passed of all its tests is it considered complete and ready for sale. In recognition of this, the famous Leica dot is applied as the very last stage, as a symbolic act of final approval before boxing and shipping.