Starry Night at Laguna Meadows (3 photos)

Santa Ana weather is pretty annoying if you ask me – clear blue skies and hot, dry winds. Not exactly any photographer’s favorite I guess, but at night the winds die down, temperatures drop, and the dry air brings exceptionally clear skies that are pretty good for night time photography.

My friend Tracy and I drove up to Mount Laguna and hiked into the Laguna Meadows and to Big Laguna – the largest of the three bodies of water up there. It was nicely filled with water again after it was entirely dry last year. In the open meadow up there, it was quite cold, 4°C/36°F. That was particularly unpleasant on the hands, fiddling with tiny camera buttons, carrying ice cold tripod legs, and worst of all, just standing around waiting for the exposures and in-camera long exposure noise reduction to finish. :-}

At the lake, we didn’t notice anything unusual at first until Tracy turned on his powerful LED flashlight – a thin fog rose from the surface and wafted across the water, driven by the wind – it looked like dozens of fine, silky cloths dancing over the water. Absolutely beautiful! The LED flashlight was actually strong enough to illuminate these thin water vapors enough to capture them on camera (third photo). Unfortunately, it also illuminated the grasses in the lake in the foreground… a lot. :-)

Here are three photos. You can click on them to open a larger version, if you’re on a desktop/laptop with a bigger screen. Technical notes about night photography follow below the gallery.

Tech Notes

Night photography is the discipline where you really need to know your gear well. Below are some notes about what you need to keep in mind, and maybe prepare in advance.

Focus

Focusing is really critical with night photography. Since you’ll have to use the lens more or less wide open to get enough light in, you’re dealing with a reduced depth of field – tricky enough in daylight! Also, quite obviously, it’s dark, so the camera’s AF can’t really lock on to anything. You need to focus manually. Sounds easy enough, but the tricky part is that modern lenses with their built-in AF motor (Nikon calls them AF-S) and so-called “instant manual override” don’t have a hard stop at the infinity setting, but go a little bit further.

This means at the end of the focusing range you’re past the infinity setting. And at that position, everything will be just slightly out of focus – the stars turn into little rings or discs, instead of being solid dots. Such deficiencies probably don’t show at web resolutions, but in a printed full size file, it doesn’t look good.

For my 16-35/4 lens, I know exactly where I need to put the distance marker for correct focus at infinity. Test your lens(es) in daylight before you head out into the night: focus the lens at infinity in daylight – and remember where exactly on the distance scale that’s at. And if you’re using a zoom lens, you should check for different focal lengths as well.

Even better than using the infinity setting is of course to use the hyperfocal distance. How do you find out the hyperfocal distance easily? I’m using the online depth of field calculator from DOFMaster.

For my 16-35mm lens at f/4 (as wide open as it goes) and at 16mm, I’d need to focus on something ~7 feet away to get the hyperfocal distance – that way, everything from 3.5 feet to infinity will be in focus. That’s actually fairly close, and allows for some nice wide-angle compositions with a (carefully light painted) close foreground already.

The problem is of course that my lens doesn’t have a distance marker that indicates 7 feet – there’s a marker for 2 feet and then after a small gap of maybe 5mm there’s already the infinity symbol. Is 7 feet somewhere in between? I guess I could find out with a measuring tape! :-D

Exposure

Another critical thing is exposure – you need to use high ISO, which is more prone to noise in darker areas, so you want to get as much light as possible onto the sensor. But if you want to keep the stars from turning into streaks, you only have a limited amount of exposure time available.

I mentioned before that the old “600 rule” doesn’t apply anymore to modern high resolution sensors – I’d make it a “300 rule” to get nice star-dots, maybe a “400 rule”.

This rule means that the longest exposure time to keep the stars from streaking is “300 divided by your focal length” – and at 16mm, that’s only 20 seconds. With the lens that I was using (my 16-35/4) at 16mm, 20 seconds is a bit too dark at ISO 6400. Brightening the photos on the computer left me with more noise that I’d desire – and just like with a slightly imperfect focus, it’s another thing that doesn’t really show in a web-sized photo on screen, but the usability of the images for printing is more limited.

Consider this, and you understand that you need a “fast” lens – and a rather wide angle is definitely preferable, too.

Color

I like my night skies cool and blue. The camera, set to Auto White Balance, would suggest a color temperature that is way too warm for my taste, leaving the sky with a dark orange tone. That’s not a problem of course – unless you’re also light painting. I like to put an orange (“CTO”) gel on the flash to paint with warmer light – which then allows me to reduce the color temperature at home, rendering the sky nice and blue, and any light-painted areas in a more neutral color.

In hindsight, it would be been best to use the orange gel with Tracy’s LED flashlight, to paint the wafting fog with warmer tones. It would have made processing the third photo above much, much easier, and allowed for a more consistent rendition with the other two.

…and I wish I wouldn’t feel so totally hung over the day after a night photo outing… :-P

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2 Responses

  1. Good writeup. Focus is indeed most critical and hardest to get right in the field if you didn’t do your prepwork. At 16 mm I usually limit the exposure to 15 seconds for stars that need to be points. My lens goes to f/2.8 so that’s a bit easier than f/4. I generally end up around ISO 6400 but ISO doesn’t matter much anymore with the sensors in most recent cameras. You get the same result signal-to-noise wise by just dialing in exposure compensation in post. More important to not blow out the exposure on bright stars. Even at 15 seconds you can already see arcing of the stars on my 24 MP sensor. 30 seconds is definitely too long and you can even see arcs in smallish web sized images.

    1. You’re right – I do see some arcing but it’s more in the corners of the frame in these photos because I was either facing pretty much north, or south. I’m not sure if ISO doesn’t matter entirely anymore (ie. whether Nikon’s recent cameras are indeed ISO free) or if there’s still some “cut off”, I remember reading an article a while ago that talked about finding the best ISO for one’s camera. I’m just too lazy to waste my time with testing. :-P

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