Today happens to be 14 February. Happy Valentine’s Day for all my lady readers (if there are any)! Well, this post isn’t going to be romantic at all cos it’s about 10 stop ND filter once again. ;) As you may have read in my recent post, I just dismissed the idea of using 10 stop ND filter for cityscape photography at blue hour, but I’m back here to report my re-attempt with a different approach.
My previous two attempts taught me that exposing super long (for 10 minutes) towards the end of dusk won’t work well with cityscapes (as the digital noise caused by long exposure is too unbearable, especially affecting buildings badly), and starting the exposure earlier by halving the exposure time to 5+ minutes results in a photo that lacks “WOW” factor (as there are not many city lights lit up yet).
This time, once again I’m aiming to expose for 5 to 6 minutes (5 minutes and 41 seconds to be exact), which can be achieved by starting the exposure at 1/3 second of shutter speed, according to Long Exposure Calculator app . That said, if using a narrow aperture like f/13 or f/11 (my default choice), 1/3 second of shutter speed could be reached even before sunset, which is way too early to start the exposure. There will be no city lights, no blue hour sky to be captured. For this reason, I must wait until the light falls a bit more, allowing city lights to be lit up and the sky to start taking on a deep blue hue. But how?
5 minutes and 41 seconds of exposure (shutter speed) can be achieved by using a base shutter speed of 1/3 second, according to Long Exposure Calculator app.
Solution to Start Exposure as Close to Dusk as Possible
One solution is to use a wider aperture. For example, when the shutter speed indicates 1/3 second at f/11, opening up the aperture by “one stop” to f/8 doubles the shutter speed to 1/6 second, which gives me a few more minutes before shutter speed is reduced back to 1/3 second.
The question here is how much wider (from f/11 to f/8, f/5.6, f/4 until f/3.5 in case of my trusty Nikon 18-35mm lens) the aperture should go in this particular scenario, as many lenses aren’t very sharp at wide open, and the question of having enough depth of field is another concern when using a wide aperture.
Opening up Aperture to f/8, f/5.6, Then to f/4
So, I came back to Singapore CBD one sunny evening, trying to put all these plans into practice (sunset and dusk times on that day was 19:03 and 19:25 respectively).
At first, I set the aperture at f/8, but it was only at 19:07 (18 minuets before the end of dusk) when the shutter speed fell to 1/3 second. So I opened the aperture up to f/5.6 and waited for the shutter speed to come down to 1/3 second again, which happened at 19:11. Still having 14 minutes left until the end of dusk, I wondered whether to start this 5 minutes and 41 seconds exposure or not, but decided to open the aperture up to f/4 and wait for another few minutes.
In the end, it was 19:15 (10 minutes before the end of dusk) when the shutter speed fell back again to 1/3 second, and I finally started the exposure that runs 5 minutes and 41 seconds, and this is what I got.
You may be thinking what I’m thinking – what’s the difference from those shot with 6 stop ND filter used (below, shot with 162 seconds of exposure in the previous week)?
Well, nothing really. This experiment proves that 2 to 3 minutes of long exposure with 6 stop ND filter is sufficient to shoot waterfront cityscapes with silky smooth water effect. Whether the shutter speed goes for 5+ minutes (with 10 stop ND filter) or 2+ minutes (with 6 stop ND filter) doesn’t seem to make any significant difference.
Still, 10 Stop ND Filter Is Redundant for Me, at Least
I can now safely conclude that 10 stop ND filter is redundant for someone like me exclusively shooting waterfront cityscapes at blue hour. It’s probably best used when shooting long exposure photos at pre-dusk, golden hour or even in daylight (e.g. to shoot motion blur of waterfalls in bright sun, like the photo below found on Flickr [shot with 10 stop ND filter attached]).