The rule of thumb is that once you want to capture truly powerful landscape and cityscapes pictures with your DSLR, all you need is to purchase the handy kit of Neutral Density filters. ND filters are dark filters lengthening your shutter speed so that you can blur moving clouds, smooth water surface, freeze waterfalls or blend waves crashing against the seaside rocks. Added to that you can also create silky waves streaks or disappearing objects on the street. Why does it happen? Neutral Density Filters are responsible for obstructing the light coming into your lens. Using longer shutter speed without filter during the daytime is simply impossible resulting in overexposed images. Conversely, stacking a proper neutral-density filter is the equivalent of stopping down one or more stops of light impacting motion blur effect.
ND number notation
|f-stop reduction||Optical Density||Fractional transmittance
Depending on the type of ND, it reduces the appropriate amount of light. For Instance, ND100 blocks the lights about 100 times what accounts for 1% of light transmittance. Compared to ND 1000 (also called ND 1024) which is definitely darker one transmitting only 0.1% of light respectively.
The first step you need to take into account when using ND is to use Manual Mode that gives you a full control on exposure settings (ISO, Shutter speed,Aperture) compared to custom modes, Tv or Av (If you are Canon shooter you are probably familiarized with the names.) Here are the next steps for you guys:
2. Enable DSLR mirror lock-up and RAW. You can do this simply by shutting off the options ”OFF” in your camera mirror lock-up section. It is essential to reduce the camera shake caused by mirror shock to get the maximum of sharpness on you shoots. As for RAW format gives you the full flexibility in later post-editing process either in Lightroom or any other photo processors where you can change WB, dynamic range, vignetting and so on. At times, I use RAW+JPG as well.
4. Use MF and block viewfinder with a tape. After getting the right focus without filter, switch camera to Bulb Mode. Your lens can fail to set the desired sharpness of image once dark ND filter is screwed on. As for viewfinder, it is told that unblocked viewfinder with tape or eyepiece can cause nasty light streaks damaging the photo.
5. Put the ND filter on your lens and do some math: After setting all options required, screw the filter on the lens mount or use ractangular filters systems. Then, the chances are that you will not see anything on the viewfinder and even on your camera LCD. So, calculating is a must. If do not want to get the unpredictable effect of overexposed or underexposed image, just count. The exact result is only achievable once you count how much light is obstructed by ND filter for based shutter speed. In general, you can do this by using specialized smartphone app for example ”Long Exposure Calculator ” ( very positive comments left on the Google Store). The app is to calculate the desired shutter speed for the given setting on your camera. It tolerates ND filters from the range of 1- 16 stops. The final result will be shown on the bottom of the screen with controllable timer. Another way is to use traditional long exposure charts. The last way is to use the math formula:T nd = T 0 x2 ND while ND =Stop value of ND Filter and 2. T 0 =Based shutter speed in seconds and T nd = Final exposure Time. Example = T nd (32s)= T(1/30s ) x 2(10ND)
6) Switch on the the Bulb. ”B” mode will let you shoot photos with longer shutter speed then 30 s (Minimum in almost all DSLR cameras). Don’t forget to change Aperture once you are on the B( The mode is not to remember the setting from the previously used modes).
7) Press the shutter button or Shutter Release Remote Control. Shutter Release Remote Control seems to make more sense once you want capture perfectly sharp photos. You can do a test pressing the shutter button with your finger and probably you will come down to the point that the process seems to be too tiring ( keeping shutter button on in 3 minutes 😛 ) as well as giving totally blurred photos. Instead, I recommend to use a good qualitremote control compared to these 3 $ devices available on the market ( they only blocks shutter speed not giving the chance of capturing time lapses and more).
8) Wait. Block Shutter Release Remote Control or keep it if you want. You can relax and drink a cup of hot tea from your vacuum bottle (if you have one). Timer can show the counted value and beep to help you control time.