Example Data Table
| Format |
Frame size |
Lens |
Approximate 35mm equivalent |
Typical use |
| 645 film |
56 x 42 mm |
80 mm |
49 mm |
General shooting |
| 6x6 film |
56 x 56 mm |
80 mm |
44 mm |
Square portraits |
| 6x7 film |
56 x 70 mm |
105 mm |
51 mm |
Natural perspective |
| 44 x 33 digital |
44 x 33 mm |
63 mm |
50 mm |
Digital standard lens |
Formula Used
The calculator compares the selected frame against a 36 x 24 mm reference frame.
Frame diagonal = square root of width squared plus height squared.
Crop factor = 35mm diagonal divided by medium format diagonal.
Equivalent focal length = actual focal length multiplied by crop factor.
Equivalent aperture = actual f-number multiplied by crop factor.
Angle of view = 2 x arctangent of frame dimension divided by 2 x focal length.
Subject coverage = subject distance multiplied by frame dimension divided by focal length.
Hyperfocal distance = focal length squared divided by aperture and circle of confusion, then plus focal length.
How to Use This Calculator
- Select a medium format preset or choose a custom frame.
- Enter the lens focal length marked on the lens.
- Enter the real aperture used for the shot.
- Add subject distance for coverage and depth estimates.
- Choose diagonal, horizontal, or vertical matching.
- Press calculate to show results above the form.
- Use CSV or PDF buttons to save the result.
Medium Format to 35mm Conversion Guide
Photographers often compare medium format lenses with 35mm lenses because the smaller reference frame is widely known. This calculator turns large frame dimensions into familiar equivalent numbers. It helps when you choose a lens, plan a portrait, or match a look across different cameras.
Why the Conversion Matters
An 80 mm lens is normal on many 6x6 cameras. It feels much longer on a 35mm frame. The difference comes from frame size, not from the lens changing. A larger frame records a wider view with the same focal length. The crop factor shows that relationship.
What the Results Mean
The diagonal equivalent focal length is the main comparison. It tells which 35mm lens gives a similar diagonal angle of view. Horizontal and vertical equivalents are also shown. They help when formats have different aspect ratios. A square frame and a 3:2 frame can match diagonally, yet crop differently on each side.
The equivalent aperture is not an exposure setting. Your meter still uses the real f-number. The equivalent value compares depth of field and total light gathered for the same framing. It is useful when comparing blur, background separation, and format character.
Planning Better Shoots
The field of view values show the scene angle captured by the chosen lens. The subject coverage estimates the width and height framed at your selected distance. These numbers are helpful for studio sets, product tables, landscapes, and film tests.
Use presets for common film and digital sizes. Select custom when your scanned frame, camera back, or crop differs from standard dimensions. Enter an accurate focal length and aperture. Add a realistic subject distance for coverage and depth estimates. Then compare results before packing lenses.
Practical Tips
Think of the output as a planning guide. Real photographs also depend on focusing, lens design, bellows extension, scan crop, and final print size. Still, the calculator gives a quick bridge between medium format language and the familiar 35mm reference system. It makes lens choices easier and helps you explain framing decisions clearly.
Keep notes from each test. Small changes in crop, lens breathing, or masking can alter the final match. Consistent records make comparisons faster during editing later and sharing.
FAQs
What does this calculator convert?
It converts a medium format lens and frame size into 35mm equivalent focal length, aperture comparison, angle of view, and subject coverage values.
Is equivalent aperture used for exposure?
No. Exposure uses the actual f-number on your lens. Equivalent aperture only helps compare depth of field and format look.
Why are horizontal and vertical equivalents different?
Medium format frames often have different aspect ratios than 35mm. Matching width, height, or diagonal can give different equivalent focal lengths.
Which equivalent focal length should I use?
Use diagonal equivalence for general lens comparison. Use horizontal or vertical equivalence when matching a specific composition edge matters more.
Can I enter a digital medium format sensor?
Yes. Use a preset such as 44 x 33 mm or enter custom width and height for another sensor or cropped scan.
Does the lens focal length really change?
No. The actual focal length stays the same. The equivalent value only describes how the field of view compares with 35mm framing.
Why include subject distance?
Subject distance lets the calculator estimate framed width, framed height, hyperfocal distance, and depth of field limits.
Can I save my calculation?
Yes. After calculating, use the CSV button for spreadsheet data or the PDF button for a simple saved report.