Calculate exposure time from bellows extension and additional filter stops.
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Calculate exposure time from bellows extension and additional filter stops.
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Inputs are processed on this page and are never sent to a server.
For large-format product photography: enter focal length and total extension in mm, metered seconds and filter stops. Extension squared divided by focal length squared is the bellows factor. Multiply time by this and by two to the filter-stop power. For conventional lenses with a calibrated measurement; excludes telephoto optics and film reciprocity failure.
B = (Total bellows extension ÷ Focal length)²; Corrected exposure = Metered exposure × B × 2^(Filter compensation (stops))
2 s
B = (Total bellows extension ÷ Focal length)²; Corrected exposure = Metered exposure × B × 2^(Filter compensation (stops))
2 s
No, not if the meter already includes bellows or filter loss. Avoid counting the same correction twice.
Calculations run on your device. Form inputs are not sent to a server.
The initial choice follows your browser region. Your choice is remembered on this device. Gallons are US gallons. Switching units keeps your numbers unchanged and interprets them in the new unit.
Numbers stay unchanged. Check the new unit and enter the intended measurement, or select an example for that system.
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: 0.1 · Maximum: 5000 mm
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: 0.1 · Maximum: 10000 mm
Enter a numerical value for this quantity. Use the unit shown beside this field. s
Minimum: 0.000001 · Maximum: 86400 s
Enter a numerical value for this quantity.
Minimum: 0 · Maximum: 20
For large-format product photography: enter focal length and total extension in mm, metered seconds and filter stops. Extension squared divided by focal length squared is the bellows factor. Multiply time by this and by two to the filter-stop power. For conventional lenses with a calibrated measurement; excludes telephoto optics and film reciprocity failure.
Calculated from your entries using the method below.
Extension squared divided by focal length squared is the bellows factor.
Calculated from your entries using the method below.
For large-format product photography: enter focal length and total extension in mm, metered seconds and filter stops.
Calculated from your entries using the method below.
For large-format product photography: enter focal length and total extension in mm, metered seconds and filter stops. Extension squared divided by focal length squared is the bellows factor. Multiply time by this and by two to the filter-stop power. For conventional lenses with a calibrated measurement; excludes telephoto optics and film reciprocity failure.
Calculated from your entries using the method below.
Extension squared divided by focal length squared is the bellows factor.
Calculated from your entries using the method below.
Mistake: Changing units and assuming the entered numbers were converted.
Fix: Numbers stay unchanged. Check the new unit and enter the intended measurement, or select an example for that system.
Mistake: Treating a result as valid outside the described scope.
Fix: No, not if the meter already includes bellows or filter loss. Avoid counting the same correction twice.
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