Click any time value to set it as the new base time.
Timing Table
F-Stop
Time
Increment
Darkroom Tools
Enlarger Exposure
Magnification-based exposure correction
Configuration
Print Dimensions
Corrected Exposure
Initial magnification—
Target magnification—
Target exposure—sec
Formula
t₂ = t₁ × ((m₂ + 1) / (m₁ + 1))²
m = print width / negative width
Accounts for the inverse square law at different magnifications
Darkroom Tools
Print Placement
Calculate optimal print position on a mount
Units
Placement Mode
Optical centering places the print slightly above the geometric center to compensate for visual perception
Mount Dimensions
Print Dimensions
Positive moves up, negative moves down
Preview Image
Drag & drop an image onto the canvas
Display Options
Meopta
Opemus 5 Exposure Calculator
Nomogram correction for f = 50–80 mm lenses
Lens Selection
Enlarger Scale Positions
20
45
Test Print Exposure
Corrected Exposure
k coefficient3.75
Corrected time46.1sec+1.9 stops
Aperturef/32
At the same aperture. If the time is impractically long, open up the lens and halve the time per
stop.
⚠Thin negative + heavy filtration: This correction may underexpose by ~⅙ to ⅓ stop
due to wavelength-dependent scattering. Consider testing at the final position.
f-stop timer
Correction from test time+46/24
Rounded time46.3sec
Exact: 46.1s → Rounded: 46.3s (Δ +0.2s)
Nomogram — k vs. scale position (f = 75–80 mm)
Adjust the r parameter if your measured corrections differ from the calculator.
Defaults: r = 6.694 for 75–80 mm, r = 14.0 for 50–55 mm (derived from the manual nomograms).
A higher r shifts curves right; lower shifts left. Switching lenses resets r to the default.
Mathematical Model
k = ((r + s₂) / (r + s₁))²
where r = 6.694 for f=75–80 mm on
Opemus 5
Derived from the inverse square law adapted to the inclined column geometry
s₁ = test position · s₂ = print position · k = time multiplier
Darkroom Tools
Dilution Calculator
Weight-based mixing for darkroom chemistry
Chemical
Dilution
+
Parameters
1+501 part concentrate + 50 parts water
Results -- weigh on scale
Concentrate
11.1g
= 9.8 ml
Water
490.2g
= 490.2 ml
Total weight501.3 g
Tip: Tare your vessel, weigh the concentrate first, then add water to reach the total. Density varies by batch -- weigh a known volume to calibrate.
Darkroom Tools
Development Time
Push-pull & temperature compensation
Film & Developer
Base Development
Push / Pull
Fallback factor when no verified time exists. 33% from Rollei datasheet. Shown as "estimated" in results.
Actual Temperature
Adjusted Development Time
Base time8:00min
After push/pull8:00min
Final time8:00min
At reference temperature. No adjustment needed.
Formulas
t_push = t_base x (1 + f/100)^N
t_final = t_push x 2^((T_ref - T) / 10)
f = compensation factor per stop
N = push (+) or pull (-) stops
Temperature model: Q10 = 2 (rate doubles per 10 C)