The Darkroom Automation F-Stop Timer FAQ: F-Stop Printing with Darkroom Automation's f-Stop Timer and Precision Enlarging Meter
AN f-STOP TIMER FAQ

WHAT IS AN F-STOP TIMER?


An F-Stop timer lets you set the exposure time in stops and tenths. Each whole stop setting on the timer halves or doubles the exposure, just like the clicks on a camera's shutter speed dial. Burns and dodges are set in stops relative to the base exposure. Other features are automatic test strips, split filter variable contrast printing and memories for storing print exposure sequences.


WHY USE AN F-STOP TIMER?


  • You work like you think with f-stop timing: in print tones and not in seconds.
  • You get more work done with less effort: the timer does the drudge work.
  • Fewer wasted prints: No math errors, no forgotten steps, no forgetting to reset the timer before and after a burn.
  • Working in the darkroom is that much more pleasant.
  • ... All adding up to better prints.

HOW DOES F-STOP PRINTING WORK?


Print tones, such as 'skin', 'dark skin', and 'detailed shadows', are a constant number of exposure stops apart.

  • Changing the exposure by 0.5 stops with grade #2 paper results in a one tone lighter or darker print.
  • Burning or dodging by 0.5 stops darkens or lightens an area by one tone.

This relationship is linear:

  • A 1 stop change on grade #2 paper results in a two tone change, a 0.1 stop change results in a fifth of a tone, and so forth;
  • A one tone change in stops of exposure effects all print tones equally: 'veiled highlights' become 'detailed highlights', 'skin' becomes 'dark skin', 'detailed shadows' become 'dark shadows'.

The Zone system provides standard names and values for these tones.

The direct link between the timer's display and the tones on the print makes it easy to predict the outcome of a change in print exposure or the effect of a dodge or burn. The timer displays the exposure in stops: a display of 2.0 is one stop greater exposure than 1.0, as a result you always know just what you are doing with the exposure and how much correction you are applying.

The Darkroom Automation f-Stop Timer is the only timer that works entirely in stops.

In the darkroom the timer becomes a box that controls exposure, not seconds -- just as the aperture ring controls light intensity and not millimeters of aperture opening.

The F-Stop timer is calibrated so that stops of exposure correspond to seconds as:

Displayed
Stops
Seconds
0.0 1.0
1.0 2.0
2.0 4.0
3.0 8.0
3.1 8.6
3.2 9.2
3.3 9.9
... ...
9.9 954

The timer counts down seconds when it is making an exposure.

In addition to basic exposing the Darkroom Automation F-Stop timer has dedicated features for other enlarging tasks: test strips; dodging; burning; complex burning; exposure compensation; split filter printing; and memorizing and replaying the steps used in making each print.


HOW DOES IT AUTOMATE DODGING AND BURNING?


The Darkroom Automation f-Stop Timer has many unique and powerful dodging and burning features and is the only timer with a dedicated dodging feature.

Dodges and burns are set in stops relative to the base exposure. The dodge and burn settings do not need to be changed and produce exactly the same effect when you change the base exposure because of a different print size, paper, developer, toner or other reason.

Dodging

To dodge you enter the number of stops to dodge, insert the dodger and hit the expose key, it can't get any simpler. The timer will do any number of dodges and will automatically merge the dodges as needed -- as an example it is impossible to do a 1 stop dodge and a 2 stop dodge without merging the exposures.

Changing a dodge setting only changes the exposure for that particular dodge - there is no 'ripple effect' and other dodges, burns, and the base exposure are not affected.

Burning

Burning is as simple as dodging: set the number of stops to burn; insert the burning card; and hit the expose key or footswitch. Any number of burns can be made. Changing a burn exposure has no effect on dodges, the base exposure or other burns.

Burns within burns can be made with the Darkroom Automation f-Stop Timer's progressive burn feature. Each progressive burn builds on the burns before. If, after making a work print, an area inside a burn needs to be darker only the exposure needed to darken the area from what is seen in the work print to what is desired in the final print needs to be entered. Progressive burns can be made within progressive burns and multiple progressive burns can be made inside each base burn.

Waypoint memories can be set to allow branching burn sequences: burn in the sky; progressively burn in the top of the sky & set a waypoint; progressively burn in the first cloud in the top of the sky; return to the waypoint & progressively burn in the second cloud in the top of the sky.


HOW DOES IT AUTOMATE TEST STRIPS?


The timer generates the correct sequence of exposures to make a test print with any starting exposure, any number of strips and any increment between test strips -- expose the entire sheet at the starting exposure and enter the number of stops between strips. For each strip advance a card over the print and press the expose key.

Optionally, the timer can make a series of individual test prints that increase at the entered increment value.


DO I HAVE TO KEEP ENTERING BASE, BURN AND DODGE VALUES INTO THE TIMER?


No. The timer has seperate working values for the base, dodge, burn, progressive burn and test strip interval exposures. The timer sequences through these exposure steps with each press of the mode key. For more complex prints with more than just a few dodges and burns you may want to use the timer's memories.


WHAT DO THE MEMORIES DO?


The timer has 300 steps of non-volatile memory to hold the sequences of exposures used for making your prints. The memory feature is useful for: making multiple identical prints, designing the dodge and burn sequence for a print, storing the exposures for stock prints that are made often, and split filter variable contrast printing.

Making Multiple Identical Prints

The timer automatically plays back all the exposure steps used to make a print. With each exposure step the timer advances to the next step, and at the conculsion of the print returns to the base exposure. The only actions you need to make are changing the paper, waving dodgers and burning cards and tapping the footswitch or expose key. By using the timer's memory you don't miss dodging or burning steps or make errors in setting the timer to each of the exposure steps. Instead you can concentrate on dodging and burning technique and don't have to shift your attention to setting the timer. The timer prompts you for each dodge and burn so you know where you are in the sequence.

Designing a Print

Using the memories you can design your prints one step at a time. The timer will play back progress to date and you then formulate the next step exposure and add it to the memory.

The timer memory can be edited at any time, even in the middle of making a print -- exposure settings can be changed and steps inserted or deleted as needed.

Storing Exposures for Stock Prints

The memory is large enough so that you can program the exposure data for your popular prints in the timer and leave them there. The data has a power-off retention life of 100 years.

Split Filter Printing

The memory holds the exposures for the two channels that make up the total exposure for one print. Split filter printing is discussed below.


300 EXPOSURE STEPS - HOW DO I FIND MY WAY AROUND?


The timer's memory is organized in 15 banks of 20 exposure steps each. Each bank can hold more than one print - you can tell the timer where one print ends and the next begins. You can then note that the print "Moon Over Patterson" is in bank 12 at step 9.


HOW DO I KNOW WHERE I AM IN A COMPLEX EXPOSURE?


The timer's display shows the number of the step to be exposed, what sort of exposure it is and how many stops.

Display Step Exposure type Stops
4E3. 4 Base 3.
7b.5 7 Burn .5
9L2. 9 Base exposure for
the low contrast
channel
2.

The display shows a rounded value for the exposure to aid in identifying the step while printing - when entering, changing or displaying the value the display shows the complete value.


HOW DOES THE TIMER DO SPLIT FILTER VARIABLE CONTRAST PRINTING?


The timer has high H and low L channels for variable contrast printing. The exposure sequence - base, dodge and burn exposures - for each channel is entered into the timer. There can be multiple dodge, burn and progressive burn sequences in each channel. The dodges and burns track the base exposure of only their own channel.

The timer provides two methods of split filter printing:

  • Independent control of exposure and contrast. The first channel determines the base exposure for the whole print. The second channel controls the contrast and is set in stops +/- relative to the first channel. In this way the contrast stays constant when the base exposure is changed.
  • Seperate high and low contrast exposures. The channels do not track. This method may be prefered by traditional split-filter printers who make two test strip prints: one for the high contrast exposure and one for the low.

The timer prompts for the high or low contrast filter and then exposes the base, dodge and burn exposures, advancing through the channel as it goes. When it reaches the end of a chanel it prompts for the next filter and exposes the steps for the second channel. At the end of the second channel it returns to the beginning of the print's exposure sequence, ready for the next print.

Burns can be made with fixed grade filters. The timer can be programmed to prompt for the corrected grade of filter. These fixed grade burns can track either the high contrast or low contrast base exposure.

Contrasts for the burns and dodges remain constant when the base exposure changes because the burns dodges track their respective channel's base exposure.


WHAT ABOUT A FOOTSWITCH?


The footswitch provides complete control:

  • Tapping the switch starts an exposure
  • Tapping the switch during an exposure pauses the exposure
  • Tapping the switch again resumes a paused exposure
  • Holding the switch down during an exposure or pause cancels the exposure
  • Holding the switch down when the timer is idle puts the timer in focus mode and turns the enlarger on
  • Tapping the switch when focusing turns the enlarger back off

Dodging and burning are made easier because both hands are free to place the dodgers and burners with the enlarger on (and red filter in place) and then to start the exposure without moving your hands.

Darkroom Automation sells a footswitch that works with the timer.

Any momentary action signal-level footswitch with a 1/8" Walkman-style plug will work.


ANY OTHER FEATURES?


  • The timer can control exposure in seconds for those rare occasions where this may be needed.
  • The timer has a focus-timeout that can be set from 1 to 99 minutes or defeated.
  • Optional drydown compensation can be set 0 to 30%.
  • Optional paper speed compensation can be set +/- 3.0 stops.
  • Optional lamp turn-on/ramp-up time compensation can be set from 0 to 990 milliseconds in 10 millisecond increments.

FOR MORE INFORMATION PLEASE SEE THE MEMORY f-STOP TIMER'S INSTRUCTION MANUAL.