Enlarger Configuration#

Enlarger List#

Enlarger Settings#

Relay Control#

The simplest and most traditional method of controlling a photographic enlarger is via relay control. This method simply switches power to the “Enlarger” outlet on the rear of the Printalyzer Enlarging Timer. Some enlargers use this as a direct power source for their lamp, while others use it as a control signal for their own power supplies.

The only additional setting in this mode is the “Contrast filters” setting. If set to “Regular,” then it is assumed that you will be using standard numbered contrast filters in the light path. If it is set to one of the other options, recommended equivalent settings for each contrast grade will also be shown on the device as a reference. This is especially useful when using the dichroic filter adjustments on a color enlarger in lieu of separate contrast filters.

DMX Control#

For enlargers with non-traditional control mechanisms, a DMX512-compatible expansion port is provided by the Printalyzer Enlarging Timer. This allows interfacing to off-the-shelf DMX controlled LED drivers, as well as DMX controlled adapters that can be user provided for interfacing with a wide variety of manufactured and DIY enlargers.

The specific settings for this feature are still under development, especially in areas of value mapping and presets for contrast control and color printing. The options available here will be expanded over time alongside user needs and requests.

Parameter	Description
DMX channel set	White - Single white light channel RGB - Separate red, green, and blue channels RGB+W - Separate red, green, blue, and white channels
DMX resolution	8-bit - Single channel ID per light color, giving a value range of 0-255 16-bit - Two adjacent channel IDs per light color, giving a value range of 0-65535 Note: 16-bit control is highly recommended, if your hardware can support it, as it allows for much finer adjustments with contrast control and color printing.
Channel IDs	The DMX channel IDs corresponding to each light color
Contrast control	None - Printing will always use white (or white-equivalent) light, expecting contrast to be controlled via external filters Green+Blue - Printing will use a configurable mixture of green and blue light colors to achieve each contrast grade
Focus brightness	Brightness value used for the white (or white-equivalent) light when in focus mode
Safe (Red) brightness	Brightness value used for the red light when the enlarger is on but not exposing paper (This feature is only shown if your enlarger has a red light source, and is intended to be used as a convenience feature in-between test strip and burn/dodge exposures.)
Exposure brightness	Brightness value used to comprise the white (or white-equivalent) light used for print exposure without internal contrast control (This feature is only shown with the “White” channel set or the “None” contrast control setting)
Contrast grades	Red/Green brightness values used for each contrast grade (This feature is only shown if the channel set includes green and blue, and contrast control is set to “Green+Blue”)

Timing Calibration#

Photographic enlargers are not instantaneous sources of light. They always take some amount of time to turn on and off. The amount of time can vary dramatically depending on what sort of lamp the enlarger uses, and how that lamp is controlled. Some enlargers respond very quickly, while others do not.

The Printalyzer Enlarging Timer has the ability to characterize and compensate for this behavior. By taking this extra step, accuracy and repeatability of exposures can be dramatically improved. The impact of this is especially noticeable on short exposures, such as with incremental test strips and burn/dodge adjustments.

The following graph illustrates the events that occur during an exposure, thus illustrating the problem:

	Turn On Event The enlarger is commanded to turn on, by either toggling the control relay or via a DMX signal
	Brightness Rising The enlarger light begins turning on
	Full Brightness The enlarger light has reached full intensity
	Turn Off Event The enlarger is commanded to turn off, by either toggling the control relay or via a DMX signal
	Brightness Falling The enlarger light begins turning off
	Enlarger Completely Off The enlarger is completely dark

To characterize this behavior for better exposures, several parameters are measured and stored as a “timing profile” within the enlarger’s configuration. These parameters are as follows:

Parameter	Description
Turn on delay	The time from when the enlarger is commanded to turn on until the light level starts to rise
Rise time	The time from when the light level starts to rise until it reaches full brightness
Rise time equivalent	The duration of full brightness enlarger light that would produce an equivalent exposure to the rise period
Turn off delay	The time from when the enlarger is commanded to turn off until the light level starts to fall
Fall time	The time from when the light level starts to fall until the enlarger is completely off
Fall time equivalent	The duration of full brightness enlarger light that would produce an equivalent exposure to the fall period

While these parameters can be set manually, they are typically set via the enlarger timing calibration process. To perform the timing calibration, do as follows:

Adjust the enlarger head to maximize brightness
- Select the “Test Enlarger” menu option on the enlarger configuration screen and turn on the enlarger
- Lower the head to a height similar to what you would use for a 5x7” print
- Fully open the lens aperture
- Roughly focus the enlarger
- Turn off the enlarger
Make sure the Meter Probe is connected and place its sensor in the middle of the frame
Select “Calibrate Timing” and follow the prompts

This process will then run the enlarger through a series of automated on/off cycles while measuring its light output, and calculate the timing profile.

Enlarger Configuration

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