What are “Stops”?

A “stop” is the colloquial term for a relative amount of light.  Adding a stop is to double the amount of light being exposed to the film, and subtracting a stop is to divide the amount of light by half. 

Most cameras have their available shutter and aperture settings dividedq into 1-stop increments, so each adjustment either doubles or halves the amount of light striking the film. 

The ISO film sensitivity system also follows this trend; every doubling of the ISO number requires only half the amount of light to expose the film the same amount.  Halving the ISO requires a doubling of the light to expose the film the same.

EV (Exposure Value)

Exposure Value is a common way of quantifying photographic light levels irrespective of a specific shutter speed or aperture size.  The EV scale is exponential and therefore matches the standard adjustments of doubling or halving the amount of light as seen by the film when adjusting either ISO, aperture or shutter speed.

A specific EV number correlates to a specific amount of light striking the film, and so can be achieved by an infinite combination of aperture and shutter speed selections.  In this way, it is effective at divorcing the exposure value from the camera itself.  Since the same amount of light will produce a different exposure on a different ISO film, the EV system has to take into account the film ISO to be accurate.

EV Display

If the user wishes for a more granular lighting readout, they can select the EV Display feature, which will briefly show the measured EV to 1 decimal place before displaying the calculated shutter/aperture.  This allows the user to see whether the metered value was rounded up or down in order to produce useable settings, and may influence their setting choice depending on their own interpretation of the lighting conditions.

• Press the Menu button to cycle through menu options.  Stop when the top line of the display shows “EV”.

• Press the Left or Right arrow button to cycle between “EN.” and “DIS.”  This will enable or disable the EV display feature.

When EV mode is enabled, the EV will be displayed continuously while the power/sample button is held. When released, shutter/aperture values will be calculated and displayed. EVs aren’t displayed when the meter is in continuous mode.

Setting film ISO (film sensitivity or “speed”)

To meter accurately, your Reveni Labs Light Meter must be set to match the ISO of the film currently inserted in your camera.  Be sure to change this setting whenever you switch rolls or use your meter with a different camera.

• Press the menu button to cycle through menu options.  Stop when the top line of the display shows “ISO”.

• Press the Left and Right buttons to adjust the ISO setting up or down to the desired value.  The full range of ISO settings available are:

  • ISO 1, 3, 6, 12, 25, 32, 50, 100, 125, 160, 200, 250, 320, 400, 800, 1600, 3200, 6400, 12800.

• Press the Power/Sample button to save your selection and take a new reading at the newly selected ISO.

• For unavailable ISO ranges, manipulation of the exposure offset feature can be used to achieve the correct exposure for in-between values.

Metering Mode

The Reveni Labs Light Meter can perform its calculations based on two modes; Aperture Priority and Shutter Priority.  In Aperture Priority mode, the user selects the aperture they wish to use and the meter will calculate the shutter speed required to get the correct exposure.  In Shutter Priority mode, the user selects the shutter speed and the meter calculates the aperture.  This offers control to the user depending on their desired depth of field (soft background, prominent bokeh, wide range of focus, etc.) and shutter speed (freezing motion, blurred motion, etc.) within permissible ranges.

• Press the Menu button to cycle through menu options.  Stop when the top line of the display shows “MODE”.

• Press the Left or Right button to switch between “A. PRI” (Aperture Priority) or “S.PRI” (Shutter Priority) Mode.

• Press the Power/Sample button to save this selection and take a new reading in this mode.

Exposure Compensation

The Reveni Labs Light Meter has an exposure compensation feature commonly found on digital cameras and cameras with automatic metering.  It allows the user to set an “offset” for the exposure, adjusting it up or down to account for environmental conditions.  For example, a bright snowy day will cause the meter to read high.  This will make the snow look grey instead of white, and most non-snow subject matter will become very dark.  One solution to this is to apply an exposure compensation to “correct” for the snow. 

A similar thing can happen when metering a dark scene with a brighter subject, such as a concert stage.  The general darkness of the scene will cause the meter to read low, and the better-lit subject will become overexposed.

How much exposure compensation is needed is subjective, and so often a photographer may choose to “bracket” their exposure; take the photo multiple times at different exposure levels.  Often a photograper will shoot 3 shots; 1 at the metered speed, one at 1 stop under, and one at 1 stop over.  This ensures the photographer has captured the scene with correct exposure, at the cost of two wasted shots.

• Press the Menu button to cycle through menu options.  Stop when the top line of the display shows “COMP”

• Press the Left and Right buttons to adjust the compensation value in 1/3 stop increments.  This will cause the meter to trend higher or lower, depending on actual lighting conditions.

• The exposure can be compensated up or down by 2 stops maximum.

• Return the value to 0 to remove the exposure compensation.

When compensation is enabled, to indicate as a reminder, an extra rectangle is placed behind the arrow as shown below: