Focal length equivalents between formats

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Introduction

The table below lists the focal length equivalents between formats, keeping track of aspect ratios, such that every format can fit into any target format. In other words the equivalent format is strictly wider.

Focal lens equivalents

APS-C

APS-C
Focal length Horizontal FOV Vertical FOV APS-C 35mm Fuji GFX/Pentax 645 Hasselblad HxD-39/50 Hasselblad HxD-60/100 4x5 6x17 8x10
10mm 102.9 79.7 10 14 17 20 21 48 36 101
14mm 83.7 61.6 14 20 24 27 30 67 50 142
16mm 76.2 55.1 16 23 28 31 34 77 57 162
18mm 69.8 49.8 18 26 31 35 39 87 65 182
35mm 39.5 26.8 35 50 61 68 75 169 126 354
50mm 28.2 19.0 50 72 87 98 107 241 180 506
55mm 25.7 17.3 55 79 96 108 118 265 198 557
56mm 25.3 17.0 56 80 98 110 120 270 201 567
60mm 23.6 15.8 60 86 105 117 128 289 216 607
80mm 17.8 11.9 80 115 140 156 171 386 287 810
90mm 15.9 10.6 90 129 157 176 193 434 323 911
200mm 7.2 4.8 200 287 349 391 428 964 719 2024

35mm full frame

35mm full frame
Focal length Horizontal FOV Vertical FOV APS-C 35mm Fuji GFX/Pentax 645 Hasselblad HxD-39/50 Hasselblad HxD-60/100 4x5 6x17 8x10
14mm 104.3 81.2 10 14 17 19 21 47 35 99
16mm 96.7 73.7 11 16 19 22 24 54 40 113
17mm 93.3 70.4 12 17 21 23 25 57 42 120
19mm 86.9 64.6 13 19 23 26 28 64 48 134
20mm 84.0 61.9 14 20 24 27 30 67 50 141
24mm 73.7 53.1 17 24 29 33 36 81 60 169
28mm 65.5 46.4 19 28 34 38 42 94 70 198
35mm 54.4 37.8 24 35 43 48 52 118 88 247
45mm 43.6 29.9 31 45 55 61 67 151 112 318
50mm 39.6 27.0 35 50 61 68 75 168 125 353
85mm 23.9 16.1 59 85 103 116 127 286 212 600
105mm 19.5 13.0 73 105 128 143 157 353 262 741
120mm 17.1 11.4 84 120 146 164 179 403 300 847
200mm 10.3 6.9 139 200 243 273 298 672 500 1411

Fuji GFX

Fuji GFX
Focal length Horizontal FOV Vertical FOV APS-C 35mm Fuji GFX/Pentax 645 Hasselblad HxD-39/50 Hasselblad HxD-60/100 4x5 6x17 8x10
23mm 87.2 71.0 12 17 23 26 28 64 42 133
32mm 68.8 54.3 16 23 32 36 39 88 59 186
45mm 51.9 40.0 23 33 45 50 55 124 82 261
50mm 47.3 36.3 25 37 50 56 61 138 91 290
63mm 38.3 29.2 32 46 63 71 77 174 115 365
100mm 24.7 18.6 51 73 100 112 123 276 183 580
110mm 22.5 17.0 56 80 110 123 135 304 201 638
200mm 12.5 9.4 102 146 200 224 245 553 366 1160
250mm 10.0 7.5 127 183 250 280 306 691 457 1450
Hasselblad 24mm 84.8 68.7 12 18 24 27 29 66 44 139
Hasselblad 28mm 76.1 60.7 14 20 28 31 34 77 51 162
Hasselblad 35mm 64.1 50.2 18 26 35 39 43 97 64 203
Hasselblad 50mm 47.3 36.3 25 37 50 56 61 138 91 290
Hasselblad 80mm 30.6 23.2 41 59 80 90 98 221 146 464
Hasselblad 90mm 27.4 20.7 46 66 90 101 110 249 165 522
Hasselblad 110mm 22.5 17.0 56 80 110 123 135 304 201 638
Hasselblad 150mm 16.6 12.5 76 110 150 168 184 414 274 870
Hasselblad 210mm 11.9 8.9 107 154 210 235 257 580 384 1218
Hasselblad 300mm 8.4 6.3 153 220 300 336 368 829 549 1740
Hasselblad 24mm (1.5) 62.6 49.0 18 26 36 40 44 99 66 209
Hasselblad 28mm (1.5) 55.1 42.7 21 31 42 47 51 116 77 244
Hasselblad 35mm (1.5) 45.3 34.7 27 38 52 59 64 145 96 304
Hasselblad 50mm (1.5) 32.6 24.7 38 55 75 84 92 207 137 435
Hasselblad 80mm (1.5) 20.7 15.6 61 88 120 135 147 332 220 696
Hasselblad 90mm (1.5) 18.4 13.9 69 99 135 151 165 373 247 783
Hasselblad 110mm (1.5) 15.1 11.4 84 121 165 185 202 456 302 957
Hasselblad 150mm (1.5) 11.1 8.3 115 165 225 252 276 622 412 1305
Hasselblad 210mm (1.5) 8.0 6.0 160 230 315 353 386 870 576 1827
Hasselblad 300mm (1.5) 5.6 4.2 229 329 450 504 552 1243 823 2610

Pentax 645

Pentax 645
Focal length Horizontal FOV Vertical FOV APS-C 35mm Fuji GFX/Pentax 645 Hasselblad HxD-39/50 Hasselblad HxD-60/100 4x5 6x17 8x10
25mm 82.4 66.5 13 18 25 28 31 69 46 145
28mm 76.1 60.7 14 20 28 31 34 77 51 162
33mm 67.1 52.9 17 24 33 37 40 91 60 191
45mm 51.9 40.0 23 33 45 50 55 124 82 261
55mm 43.4 33.2 28 40 55 62 67 152 101 319
80mm 30.6 23.2 41 59 80 90 98 221 146 464
85mm 28.9 21.8 43 62 85 95 104 235 155 493
110mm 22.5 17.0 56 80 110 123 135 304 201 638
150mm 16.6 12.5 76 110 150 168 184 414 274 870
160mm 15.6 11.7 81 117 160 179 196 442 293 928
300mm 8.4 6.3 153 220 300 336 368 829 549 1740

Hasselblad H5D-60

Hasselblad H5D-60
Focal length Horizontal FOV Vertical FOV APS-C 35mm Fuji GFX/Pentax 645 Hasselblad HxD-39/50 Hasselblad HxD-60/100 4x5 6x17 8x10
24mm 96.4 79.9 10 14 20 22 24 54 36 114
28mm 87.6 71.3 12 17 23 26 28 63 42 132
35mm 75.0 59.7 15 21 29 32 35 79 52 166
50mm 56.5 43.8 21 30 41 46 50 113 75 236
80mm 37.1 28.2 33 48 65 73 80 180 119 378
90mm 33.2 25.2 37 54 73 82 90 203 134 426
110mm 27.4 20.7 46 66 90 101 110 248 164 520
150mm 20.3 15.3 62 90 122 137 150 338 224 709
210mm 14.6 10.9 87 125 171 192 210 473 313 993
300mm 10.2 7.7 125 179 245 274 300 676 448 1419
24mm (1.5) 73.4 58.4 15 21 29 33 36 81 54 170
28mm (1.5) 65.2 51.1 17 25 34 38 42 95 63 199
35mm (1.5) 54.2 41.9 22 31 43 48 52 118 78 248
50mm (1.5) 39.4 30.0 31 45 61 69 75 169 112 355
80mm (1.5) 25.2 19.0 50 72 98 110 120 270 179 568
90mm (1.5) 22.5 16.9 56 81 110 123 135 304 201 639
110mm (1.5) 18.5 13.9 69 99 135 151 165 372 246 780
150mm (1.5) 13.6 10.2 93 134 184 206 225 507 336 1064
210mm (1.5) 9.7 7.3 131 188 257 288 315 710 470 1490
300mm (1.5) 6.8 5.1 187 269 367 411 450 1014 672 2128

LF (4x5)

LF (4x5)
Focal length Horizontal FOV Vertical FOV APS-C 35mm Fuji GFX/Pentax 645 Hasselblad HxD-39/50 Hasselblad HxD-60/100 4x5 6x17 8x10
72mm 80.1 67.9 12 18 24 27 30 72 45 151
90mm 67.8 56.6 15 22 30 34 37 90 56 188
150mm 43.9 35.8 26 37 51 57 62 150 93 314
240mm 28.3 22.8 41 59 81 91 99 240 148 502
300mm 22.8 18.4 52 74 101 114 124 300 186 628

LF (6x17)

LF (6x17)
Focal length Horizontal FOV Vertical FOV APS-C 35mm Fuji GFX/Pentax 645 Hasselblad HxD-39/50 Hasselblad HxD-60/100 4x5 6x17 8x10
72mm 99.5 45.2 11 15 19 21 23 51 72 108
90mm 86.7 36.9 13 19 23 26 28 64 90 134
150mm 59.1 22.6 22 32 39 43 47 107 150 224
240mm 39.0 14.3 35 51 62 69 76 171 240 359
300mm 31.6 11.4 44 64 77 87 95 214 300 448

LF (8x10)

LF (8x10)
Focal length Horizontal FOV Vertical FOV APS-C 35mm Fuji GFX/Pentax 645 Hasselblad HxD-39/50 Hasselblad HxD-60/100 4x5 6x17 8x10
150mm 80.5 68.2 12 18 24 27 30 71 44 150
240mm 55.8 45.8 20 28 39 44 48 114 71 240
300mm 45.9 37.4 25 35 48 54 59 143 89 300
450mm 31.5 25.4 37 53 73 82 89 214 133 450
600mm 23.9 19.2 49 71 97 109 119 286 177 600

Code

The table above was generated by the program below.

package main

import (
	"fmt"
	"math"
)

type Medium struct {
	h, v float64
	name string
}

func (m Medium) AspectRatio() float64 {
	return m.h/m.v
}

var (
	MediumAPSC  = Medium{25.1, 16.7, "APS-C"}
	MediumFF    = Medium{36, 24, "35mm"}
	MediumMFF   = Medium{43.8, 32.8, "GFX"}
	MediumMFH   = Medium{53.7, 40.2, "H5D"}
	MediumLF45  = Medium{121, 97, "4x5"}
	MediumLF617 = Medium{170, 60, "6x17"}
	MediumLF810 = Medium{254, 203, "8x10"}
)

var Mediums = []Medium {
	MediumAPSC,
	MediumFF,
	MediumMFF,
	MediumLF45,
	MediumLF617,
	MediumLF810,
}

type Lens struct {
	focal float64
	tc float64
	mfg string
}

func (l Lens) String() string {
	var s string
	if l.mfg != "" {
		s = l.mfg + " "
	}
	s += fmt.Sprintf("%.0fmm", l.focal)
	if l.tc == 1.0 {
		return s
	}
	return s + fmt.Sprintf(" (%.1f)", l.tc)
}

func (l Lens) Focal() float64 {
	return l.focal * l.tc
}

var LensesAPSC = []Lens {
	{10, 1.0, ""},
	{14, 1.0, ""},
	{16, 1.0, ""},
	{18, 1.0, ""},
	{35, 1.0, ""},
	{50, 1.0, ""},
	{55, 1.0, ""},
	{56, 1.0, ""},
	{60, 1.0, ""},
	{80, 1.0, ""},
	{90, 1.0, ""},
	{200, 1.0, ""},
}

var LensesFF = []Lens{
	{14, 1.0, ""},
	{16, 1.0, ""},
	{17, 1.0, ""},
	{19, 1.0, ""},
	{20, 1.0, ""},
	{24, 1.0, ""},
	{28, 1.0, ""},
	{35, 1.0, ""},
	{45, 1.0, ""},
	{50, 1.0, ""},
	{85, 1.0, ""},
	{105, 1.0, ""},
	{120, 1.0, ""},
	{200, 1.0, ""},
}

var LensesGFX = []Lens{
	{23, 1.0, ""},
	{32, 1.0, ""},
	{45, 1.0, ""},
	{50, 1.0, ""},
	{63, 1.0, ""},
	{100, 1.0, ""},
	{110, 1.0, ""},
	{200, 1.0, ""},
	{250, 1.0, ""},
}

var LensesPentax = []Lens {
	{25, 1.0, ""},
	{28, 1.0, ""},
	{33, 1.0, ""},
	{45, 1.0, ""},
	{55, 1.0, ""},
	{80, 1.0, ""},
	{85, 1.0, ""},
	{110, 1.0, ""},
	{150, 1.0, ""},
	{160, 1.0, ""},
	{300, 1.0, ""},
}

var LensesHasselblad = []Lens {
	{24, 1.0, ""},
	{28, 1.0, ""},
	{35, 1.0, ""},
	{50, 1.0, ""},
	{80, 1.0, ""},
	{90, 1.0, ""},
	{110, 1.0, ""},
	{150, 1.0, ""},
	{210, 1.0, ""},
	{300, 1.0, ""},
}

func init() {
	for _, v := range LensesHasselblad {
		v1 := v
		v1.tc = 1.5
		LensesHasselblad = append(LensesHasselblad, v1)
	}
}

func init() {
	for _, v := range LensesHasselblad {
		v1 := v
		v1.mfg = "Hasselblad"
		LensesGFX = append(LensesGFX, v1)
	}
}

var LensesLF = []Lens {
	{72, 1.0, ""},
	{90, 1.0, ""},
	{150, 1.0, ""},
	{240, 1.0, ""},
	{300, 1.0, ""},
}

var LensesLF810 = []Lens {
	{150, 1.0, ""},
	{240, 1.0, ""},
	{300, 1.0, ""},
	{450, 1.0, ""},
	{600, 1.0, ""},
}

type System struct {
	Medium
	Lenses *[]Lens
	Name string
}

var (
	SystemAPSC = System{MediumAPSC, &LensesAPSC, "APS-C"}
	SystemFF = System{MediumFF, &LensesFF, "35mm full frame"}
	SystemGFX = System{MediumMFF, &LensesGFX, "Fuji GFX"}
	SystemPentax = System{MediumMFF, &LensesPentax, "Pentax 645"}
	SystemHasselblad = System{MediumMFH, &LensesHasselblad, "Hasselblad H5D-60"}
	SystemLF45 = System{MediumLF45, &LensesLF, "LF (4x5)"}
	SystemLF617 = System{MediumLF617, &LensesLF, "LF (6x17)"}
	SystemLF810 = System{MediumLF810, &LensesLF810, "LF (8x10)"}
)

var Systems = []System {
	SystemAPSC,
	SystemFF,
	SystemGFX,
	SystemPentax,
	SystemHasselblad,
	SystemLF45,
	SystemLF617,
	SystemLF810,
}

func fov(ssize, focal float64) float64 {
	return 2 * math.Atan(ssize/(2*focal)) * 180 / math.Pi
}

type LensAll struct {
	Lens
	HFoV float64
	VFoV float64
	Eq map[Medium]float64
}

func (la LensAll) String() string {
	var s string
	s = fmt.Sprintf("|%v\n|%.1f\n|%.1f", la.Lens, la.HFoV, la.VFoV)
	for _, m := range Mediums {
		s += fmt.Sprintf("\n|%.0f", la.Eq[m])
	}
	return s
}

func Equivalent(l Lens, m Medium, mtarg Medium) float64 {
	if m.AspectRatio() <= mtarg.AspectRatio() {
		return l.Focal() * mtarg.v/m.v
	}
	return l.Focal() * mtarg.h/m.h
}

type SystemEquiv struct {
	System
	Lenses []LensAll
}

func (se SystemEquiv) String() string {
	s := fmt.Sprintf("=== %s ===\n", se.Name)

	s += `{| class="wikitable"` + "\n"
 	s += "|+"+se.Name + "\n"

	s += fmt.Sprintf("|-\n")
	s += fmt.Sprintf("|Focal length\n")
	s += fmt.Sprintf("|Horizontal FOV\n")
	s += fmt.Sprintf("|Vertical FOV\n")
 	for _, m := range Mediums {
 		s += fmt.Sprintf("|%s\n", m.name)
 	}
 	for _, l := range se.Lenses {
 		s += fmt.Sprintf("|-\n%s\n", l)
 	}
 
 	s += "|}"
 
	return s
}

func main() {
	for _, system := range Systems {
		se := SystemEquiv{system, nil}
		lenses := []LensAll{}
		for _, lens := range *system.Lenses {
			la := LensAll{Lens: lens}
			la.HFoV = fov(system.Medium.h, lens.Focal())
			la.VFoV = fov(system.Medium.v, lens.Focal())

			la.Eq = make(map [Medium]float64)
			for _, m := range Mediums {
				la.Eq[m] = Equivalent(lens, system.Medium, m)
			}

			lenses = append(lenses, la)
		}
		se.Lenses = lenses
		fmt.Println(se)
	}
}