Night and Day Long Exposures

We always like when we see a picture with clouds motion in the sky and the blur effect due to long exposure times. This gives a surrealistic touch to the images. But the question for common people is how a photographer gets this effect.

The approach depends on the time hour, if it is near night or if we are in the midday or not near to dawn or after twilight.

During the day, to increase the exposure time it is necessary to decrease ISO (but this can be only done in some professional cameras and only 1 step, from ISO 100 to ISO 50). Or another solution it is to use small apertures (around f/22). But it is usual that although the diaphragm is very close, the estimated time for the exposure was not sufficiently long. So the solution is to use what photographers call Neutral Density filters (ND).

The ND filters rise the time exposure by several stops ( a stop is the halving or doubling of the amount of light availables and means double exposure or as consequence double time for exposure). So it is usual to select one depending on the time requested or effect in the sky (if for example there is so few wind, we will need a ND with more stops). The usual filters and their stops increase are:

· ND2 (or ND0.3) : 1 stop
· ND4 (or ND0.6): 2 stops
· ND8 (or ND0.9): 3 stops
· ND400 : 8 2/3 stops
· ND1000 : 10 stops

So that means that when you use a NDx filter, x is equal to time multiplier ( that is 2 ^ stop), the time for the exposure will be the exposure reads by camera meter without filter multiply by x. It is usual to measure exposure without filter, due to 3 reasons:

– The use of ND filters produces warm or cold hues and changes your White Balance. So if you want to use the appropriate WB, you need the camera metering without filter to set it later in your RAW editor. Although, you sometimes prefer the colors created with the filter.

– As the filter is so dark ( e.g ND400, ND1000) the camera has not light to calculate an exposure time. So in Bulb mode, you manually select the time.

– Due to the same problem, the camera can’t focus automatically.

How you are seeing, for long exposures (time > 30 s), you need to set you camera as follow:

– Set Bulb Mode ( because you time is > 30 s and other modes don’t support this).
– Use low ISO to avoid noise due to long exposure.
– Use a remote control to release the shot in order to avoid camera shake.
– Pre-focus without filter or use manual focus.
– And of course, to use a tripod or put the camera in a fixed surface.

Clouds Vanishing On Arganzuela Footbridge

Manzanares riverside, Madrid (Spain).

Canon EOS 5D Mark III | Canon EF 17-40mm f/4L USM + Hoya ND400 @ 19 mm | f/22, 33 s, ISO 100. BW from 1 exposures on a tripod

But during the night they are more problems to get a correct exposure. Then, You don’t need the use of ND filters but you should take into account:

– As it is so dark, the camera again has problems to focus, but now you can’t usually focus automatically (or pre-focus) as during the day. So you can use Live View Mode to select manually the focus distance, with the help of a lantern e.g. or use what it is called hyperfocal distance ( in a short-hand, it is the distance to focus for the best sharpness, widest deep-of-field, DOF). The hyperfocal distance depends on your DSRL type sensor (Full-Frame or APS-C), lens focal length and aperture. You can get tables to calculate it.

– And again, due to you have so few light, you need to set manually your time exposure. But now, the solution to calculate the time is to increase ISO and/or increase aperture (decrease f-stop number) and to take the time measure with AV mode and later adapt it for the aperture and ISO that you want or need to select with the Bulb mode. So each increment in ISO ( for example ISO 100, 200, 400) means double time. And each f-stop decrement (for example f/11, f/8, f/5.6, f/4 …) does the same.

Moonlit At Juan Carlos I Park

North Pond, Juan Carlos I Park, Madrid (Spain).

Canon EOS 450D | Sigma 10-20mm f4-5.6 DC EX HSM @ 11 mm | f8, 26s, ISO 100. HDR/DRI from 3 exposures on a stable surface @ [-2 EV .. 0 .. +2 EV ]

Now, you are thinking, this is more to calculate, I am not a mathematics … what I do to simplify this ? I am going to get you several tips:

• When I used my Canon EOS 450D (APS-C) and Sigma 10-20mm lens @ 10mm, I adapted the hyperfocal distance to a visible mark in the focus ring (usually 3 fts), so then my aperture was conditioned to f/4 or f/5.6 , I don’t remember exactly. So you can do similarly in you workflow.

• To use Photopills or a similar software with calculators for your mobile. With Photopills you have hyperfocals calculator, Exposures calculator (for ND filters) and more, but this will be a topic for another post.

Hyperfocal Distance Calculator

Exposure Calculator

3-in-1

In this case, I framed the 3 towers: ‘Torre Caja Madrid’, ‘Torre Sacyr-Vallehermoso’ and ‘Torre de Cristal’ at CTBA with the structure of the ‘Torre Espacio’.

I used a 9-stops neutral density filter, Hoya ND400, to increase the clouds motion sensation. I had a Lee Big Stopper (10-stops filter), but I broke it. That was more versatil because it has a square 100 mm format and can be used with any lens, you only need to change your ring adaptor for your filter holder. But I think that Lee needs to improve the frame with some harder stuff.

If you check my pictures, you will see that I usually shoot with ND filters. I love them, ‘cos you get more light quality and they usually warm the colour of your images ( this is fantastic for the time around dawn or dusk). I bought a Lee Filter holder for wide angle lens and 3 HiTech ND kits at Teamwork Digital, and I am very happy with the quality and the price. Although I have 2 graduated neutral density (GND) kits – 1, 2, 3 stops – with ‘hard’ and ‘soft’ transitions, I really don’t use due to that I often shot architecture and it is difficult to have a rectilineal horizon. So if you use them in this case, you will have some buildings or other elements darker than what you eye see as consequence of the black part of the filters. This is a reason to avoid GNDs and use multiexposures techniques like HDR or DRI for architectural photography, but the textures and details can be other ones.

Cuatro Torres Business Area, Madrid (Spain)

Canon EOS 450D | Sigma 10-20mm f4-5.6 DC EX HSM + Hoya ND400 filter @ 10 mm | f11, 2s, ISO 100. HDR from 3 exposures @ [-2 EV .. 0 ..+2 EV]

Symmetry Of Clouds

After breaking my Lee Big Stopper filter ( 10 stops ND filter) during a session at AZCA, Madrid, I decided to buy a Hoya ND400 77mm for my lens. The day was cloudy and there was some wind, so I decide to try the filter and shoot the clouds motion and their reflection on the water. I had to set my camera on a support of a barrier, because several minutes ago I was stopped by security staff saying that trippod were not permitted on the park, as they are considered for pro use. And professional photographers need to ask for a permit before shooting. What do you think about this, taking into account that this is a supposed public park.

North Pond, Juan Carlos I Park , Madrid (Spain)

Canon EOS 450D | Sigma 10-20mm f4-5.6 DC EX HSM @ 10 mm + Hoya ND400 | f16, 5s, ISO 100.  HDR /DRI from 3 exposures @ [-2 EV .. 0 .. +2 EV ]