Filter Type

ND filters and How Many Stops You need

So when you consider a ND filter, there are mainly 2 purposes for it

  1. reduce incoming light, and be able at using f1.4 like lens wide open, when you already hit lowest ISO, like 100, and also hit highest shutter speed, like 1/1000sec, to achieve Corret Exposure
  2. reduce incoming light, and be able to use a extreme slow shutter speed like 10-20sec, after you already use f8 and ISO 100, to achieve Corret Exposure
  3. or combination of both

Case Study

  • Situation 1: Bright Day Light and Wide Open portrait shot, (Ambient Light: EV 15)
    • answer: at least 3 stop ND filter needed for this case.
    • extra answer: if you doing flash fill, and you stuck with 1/125 sync shutter speed,then you need additional 4 stop ND to bring 1/2000 sec to 1/125, that is total 7 stop ND filter.
    • extra extra answer: if you
case F Iso Shutter note
normal correct setting f16 ISO100 1/125 sec
max wide open setting with 4 stop Pshift f4 ISO100 1/2000 sec f16→f11→f8→f5.6→f4
1/125→1/250→1/500→1/1000→1/2000
max wide open with addition 3 stop ND f1.4 ISO100 1/2000 sec f4→f2.8→f2→f1.4
f2.8 ISO100 1/500 sec for f2.8 lens
stuck with 1/125 sync speed, means to use 7 stop ND f1.4 ISO100 1/125 sec f16→f1.4, 7 stops
make ambient 1 stop darker than flash, means 7+1=8 stop ND f1.4 ISO100 1/125 sec f16→f1.4, 7 stops + 1 stop flash fill
f2.8 ISO100 1/30 sec f2.8 lens
if also with motion trail of background people, like 8 sec,
then it need to turn 1/125 into 20“, means 8+10=18 stop ND
f1.4 ISO 100 8” 1/125→1/60→1/30→1/15
→1/8→1/4→1/2
→1“→2”→4“
→8”
if you able to stop down to f8, you just need 18-5=13 stops ND f8 ISO 100 8“ f1.4-f8, 5 stops
  • Situation 2: Night time (Ambient Light: EV 3)
    • answer: Night is like a built-in ND for the sky, means it is 15-3=12 stops cut from day light settings.
case F Iso Shutter note
normal correct setting f1.4 ISO100 1/4 sec f16→f1.4, 7 stops; 1/125→1/4, 5 stops
f8 landscape setting f8 ISO100 8” sec f16→f8, 2 stop, 1/125→8“, 10 stops
1/125 sync speed not affect slower shutter speed f8 ISO100 8” sec no change
flash has no impact on ambient,
flash ⇒ portrait, shutter ⇒ ambient
f8 ISO100 8“ sec 1 stop flash fill
for 20” or 60“, 3 stops ND is enough or just blend 3 shots of 8” f8 ISO 100 8“ 8” → 15“ → 30” → 60“

conclusion

  • for a f2.8 lens, you need 3 stop of ND is good enough for day and night use
  • for a f2.8 lens with fill flash, you need 6 stop of ND to overpower the sun flash at wide open.
  • for a f1.4 lens, you need at least 6 stop of ND for day time use, and 10 stop ND for overpower sun flash at wide open.
  • 3 stop of ND is good enough for any night shots
  • Haida Neutral Density Filters’ Factors:
Neutral Density Exposure Adjustment Light Transmission
ND0.3 (2x) 1 stop , reduces ISO by 1/2 50%
ND0.6 (4x) 2 stops, reduces ISO by 1/4 25%
ND0.9 (8x) 3 stops, reduces ISO by 1/8 12.5%
ND1.8 (64x) 6 stops, reduces ISO by 1/64 1.0%
ND2.7 (400x) 9 stops, reduces ISO by 1/500 0.25%
ND3.0 (1000x) 10 stops 0.1%
  • haida 6 stop and 10 stop ND
  • note about Haida海大 price
    • PROII级多层镀膜 vs normal (price increment factor)
    • 超薄 vs normal (price increment factor)
  • link
    • Haida海大超薄PROII级多层镀膜减光镜MC-ND1.8 (64x) 49mm (琪琪摄影俱乐部) 128 link
    • Haida海大超薄型 ND1.8 (64x) 49mm 中灰密度镜 减光镜 84 link