Digital camera meters question

[Abitconfused]

We know that digital camera meters respond to reflected light at a particular reflectance but is this something the meter is adjusted to during manufacture or hardwired to respond to a particular amount of light?

[xpatUSA]

We know that digital camera meters respond to reflected light at a particular reflectance but is this something the meter is adjusted to during manufacture or hardwired to respond to a particular amount of light?

The metering part of the camera is certainly not adjusted during manufacture - therefore you can indeed call it "hardwired".

May I ask what prompted the question?

[Mike Buckley]

I don't understand the question.

[Dave Humphries]

Hi Ed,

I could be a pedant and say that the meter will respond to whatever photons impact the metering sensor and while those are often reflected (outside the camera), that's not the case when photographing a light source itself; e.g. the sun (but not moon) or a light bulb.


I am inclined to agree with Ted, it is doubtful that each camera's meter is calibrated during manufacture, mass production will likely rely on good design and close tolerance electronic (and optical/mechanical) components used to build the camera.

That said, with computer interfaces and the electronic nature of the camera's 'brains', these days software implemented calibration during manufacture might be cheaper than buying close tolerance components.

HTH, Dave

PS
I'd also like to know what prompted the question?

[Abitconfused]

While considering metering, I had a vision of a worker turning a tiny screw inside a light meter while looking at a gray card. Can't be is suppose.

[xpatUSA]

I could be a pedant . . .

[Manfred M]

While considering metering, I had a vision of a worker turning a tiny screw inside a light meter while looking at a gray card. Can't be is suppose.

In the "old days" of built in mechanical (analogue) light meters, that was definitely the practice as the meter needle had to be matched to the neutral position.

A modern digital camera is really a computer that takes pictures. So long as the metering module is in spec, there is no need to fine tune the meter. I suspect there might be some additional testing / calibration on pro bodies, but these are unlikely done on amateur camera bodies.

[Stagecoach]

A modern digital camera is really a computer that takes pictures. So long as the metering module is in spec, there is no need to fine tune the meter. I suspect there might be some additional testing / calibration on pro bodies, but these are unlikely done on amateur camera bodies.

And if we think the metering module is out of spec (or not performing how we think it should) the manufacturer has given us the option on some cameras to 'fine tune' each individual metering mode through the menu system.

[pnodrog]

I would assume every camera is put on a test jig at some stage towards the end of it's assembly. This maybe the time when the current firmware is installed although it is possible the firmware is written to batches of memory devices before they are installed on the circuit boards. It is likely the test jig automatically runs through a series of tests including shutter timing, exposure detection, autofocus confirmation, image capture and any calibration required done and the values saved to the eeprom or whatever type of memory storage the camera uses. Some of the sub modules such as the autofocus, shutter mechanism or exposure units etc may have been jig tested prior to being assembled in the camera. No manufacture wants the the time wasted in disassembling to replace a faulty module that could have been tested before being assembled in the camera.

When I was involved in the manufacture of electronic controllers all units that left the production line were fully tested and calibrated as necessary. I doubt that it would be different for a DSLR camera.

Just about all testing will be fully automated once the camera is connected to the test jig. Unlikely anyone will be leaning over it with a screw driver to do a physical adjustment unless it is in the rework line.