During the last few years of production, certain Iloca models began to incorporate built-in light meters. However, there were a great number of Iloca cameras that were sold without any form of in-built metering during the life of the company. Consequently, an accessory lightmeter is a very useful aid for any camera that does not have a built-in meter. There is a good range of suitable meters to choose from, either from the same era as the camera itself, or from later periods. Most older meters use selenium light cells to measure the light intensity. Unfortunately, these types of light cells have a finite life span and many of these old meters are no longer active. Once a cell has failed, it can't be rejuvinated.
Some lightmeters are capable of taking light readings using different methods; either Reflected or Incident readings. To take a reflected light reading, the meter is pointed towards the subject, and measures the amount of light reflected from the subject. This method works well enough for general scenes where the subject and the light conditions are close to average. However, if the subject is darker, or lighter, than average, then the readings will be inaccurate with this method. Strong light sources (eg shooting into the sun) can also interfere with reflected light readings. In these conditions, it is better to take an incident light reading if possible. An incident light reading measures the amount of light actually falling on the subject (and on the meter). To take this type of reading, the meter must have a light diffuser of some sort in order to measure the amount of light actually falling on the meter. You will need to stand beside your subject (or at an equivalent location) and point the meter towards the camera to get your reading.
In general, incident light readings tend to be more accurate, but you must be able to get close to the subject, or at least be able to take a reading where the light conditions being measured are equivalent to the light falling on the subject.
Some of the Gossen meters shown in the photo gallery have a plastic semi-opaque cover which serves as the diffuser for incident light readings. So, even though the very nice looking black and silver Gossen model (complete with its metal roller cover) looks the most elegant, it is not as practical because it is not capable of taking incident readings. Some models from other manufacturers have clip-on diffuser attachments which enable incident readings to be taken.