Matematiği istediniz, işte gidiyor:
Kameranızın CoC'sini bilmeniz gerekir , Canon APS-C boyutlu sensörler bu sayı 0.018'dir, Nikon APS-C 0.019 için tam çerçeve sensörleri ve 35mm film için sayı 0.029'dur.
Formül bütünlük içindir:
CoC (mm) = viewing distance (cm) / desired final-image resolution (lp/mm) for a 25 cm viewing distance / enlargement / 25
Bunu yapmanın yolu Zeiss formülüdür :
c = d/1730
Burada d sensörün diyagonal boyutu ve c kabul edilebilir maksimum CoC'dir. Bu biraz farklı sayılar verir.
Lensiniz ve kameranız için önce hiperfokal mesafeyi hesaplamanız gerekir (bu formül, odak uzunluğuna yakın mesafelerle, örneğin aşırı makro ile yanlıştır):
HyperFocal[mm] = (FocalLength * FocalLength) / (Aperture * CoC)
Örneğin:
50mm lens @ f/1.4 on a full frame: 61576mm (201.7 feet)
50mm lens @ f/2.8 on a full frame: 30788mm (101 feet)
50mm lens @ f/1.4 on a Canon APS frame: 99206mm (325.4 feet)
50mm lens @ f/2.8 on a Canon APS frame: 49600mm (162.7 feet)
Ardından, kamera ve konu arasındaki mesafe göz önüne alındığında, odaklanacak en yakın mesafe olan yakın noktayı hesaplamanız gerekir:
NearPoint[mm] = (HyperFocal * distance) / (HyperFocal + (distance – focal))
Örneğin:
50mm lens @ f/1.4 on a full frame with a subject at 1m distance: 0.984m (~16mm in front of target)
50mm lens @ f/1.4 on a full frame with a subject at 3m distance: 2.862m (~137mm in front of target)
50mm lens @ f/2.8 on a full frame with a subject at 1m distance: 0.970m (~30mm in front of target)
50mm lens @ f/2.8 on a full frame with a subject at 3m distance: 2.737m (~263mm in front of target)
50mm lens @ f/1.4 on a Canon APS frame with a subject at 1m distance: 0.990m (~10mm in front of target)
50mm lens @ f/1.4 on a Canon APS frame with a subject at 3m distance: 2.913m (~86mm in front of target)
50mm lens @ f/2.8 on a Canon APS frame with a subject at 1m distance: 0.981m (~19mm in front of target)
50mm lens @ f/2.8 on a Canon APS frame with a subject at 3m distance: 2.831m (~168mm in front of target)
Ardından, kamera ile konu arasındaki mesafe göz önüne alındığında, odaklanacak en uzak mesafe olan uzak noktayı hesaplamanız gerekir:
FarPoint[mm] = (HyperFocal * distance) / (HyperFocal – (distance – focal))
Örneğin:
50mm lens @ f/1.4 on a full frame with a subject at 1m distance: 1.015m (~15mm behind of target)
50mm lens @ f/1.4 on a full frame with a subject at 3m distance: 3.150m (~150mm behind of target)
50mm lens @ f/2.8 on a full frame with a subject at 1m distance: 1.031m (~31mm behind of target)
50mm lens @ f/2.8 on a full frame with a subject at 3m distance: 3.317m (~317mm behind of target)
50mm lens @ f/1.4 on a Canon APS frame with a subject at 1m distance: 1.009m (~9mm behind of target)
50mm lens @ f/1.4 on a Canon APS frame with a subject at 3m distance: 3.091m (~91mm behind of target)
50mm lens @ f/2.8 on a Canon APS frame with a subject at 1m distance: 1.019m (~19mm behind of target)
50mm lens @ f/2.8 on a Canon APS frame with a subject at 3m distance: 3.189m (~189mm behind of target)
Artık toplam odak mesafesini hesaplayabilirsiniz:
TotalDoF = FarPoint - NearPoint
Örneğin:
50mm lens @ f/1.4 on a full frame with a subject at 1m distance: 31mm
50mm lens @ f/1.4 on a full frame with a subject at 3m distance: 228mm
50mm lens @ f/2.8 on a full frame with a subject at 1m distance: 61mm
50mm lens @ f/2.8 on a full frame with a subject at 3m distance: 580mm
50mm lens @ f/1.4 on a Canon APS frame with a subject at 1m distance: 19mm
50mm lens @ f/1.4 on a Canon APS frame with a subject at 3m distance: 178mm
50mm lens @ f/2.8 on a Canon APS frame with a subject at 1m distance: 38mm
50mm lens @ f/2.8 on a Canon APS frame with a subject at 3m distance: 358mm
Böylece CoC ve HyperFocal ile formülün tamamı önceden hesaplandı:
TotalDoF[mm] = ((HyperFocal * distance) / (HyperFocal – (distance – focal))) -(HyperFocal * distance) / (HyperFocal + (distance – focal))
Veya basitleştirilmiş:
TotalDoF[mm] = (2 * HyperFocal * distance * (distance - focal)) / (( HyperFocal + distance - focal) * (HyperFocal + focal - distance))
Önceden ayarlanmış CoC ile: Aşağıdaki denklemlerle aşağıdaki denklemleri basitleştirmeye çalıştım: a = izleme mesafesi (cm) b = 25 cm izleme mesafesi için istenen son görüntü çözünürlüğü (lp / mm) c = büyütme d = Odak Uzaklığı e = Diyafram f = mesafe X = CoC
TotalDoF = ((((d * d) / (e * X)) * f) / (((d * d) / (e * X)) – (f – d))) - ((((d * d) / (e * X)) * f) / (((d * d) / (e * X)) + (f – d)))
Basitleştirilmiş:
TotalDoF = (2*X*d^2*f*e(d-f))/((d^2 - X*d*e + X*f*e)*(d^2 + X*d*e - X*f*e))
WolframAlpha ile daha da basitleştirildi:
TotalDoF = (2 * d^2 * e * (d - f) * f * X)/(d^4 - e^2 * (d - f)^2 * X^2)
Ya da hiçbir şey önceden hesaplanmazsa, kullanılamaz olan bu canavarı elde edersiniz:
TotalDoF = ((FocalLength * FocalLength) / (Aperture * (viewing distance (cm) / desired final-image resolution (lp/mm) for a 25 cm viewing distance / enlargement / 25)) * distance) / ((FocalLength * FocalLength) / (Aperture * (viewing distance (cm) / desired final-image resolution (lp/mm) for a 25 cm viewing distance / enlargement / 25)) – (distance – focal)) - ((FocalLength * FocalLength) / (Aperture * (viewing distance (cm) / desired final-image resolution (lp/mm) for a 25 cm viewing distance / enlargement / 25)) * distance) / ((FocalLength * FocalLength) / (Aperture * (viewing distance (cm) / desired final-image resolution (lp/mm) for a 25 cm viewing distance / enlargement / 25)) + (distance – focal))
Basitleştirilmiş:
(50*a*b*c*d^2*f*e*(d-f))/((25*b*c*d^2 - a*d*e + a*f*e)*(25*b*c*d^2 + a*d*e - a*f*e)
Temel olarak yeniden hesaplanmış CoC ve HyperFocal kullanın :)