Tag Archives: digital

Hints for Night Photography

February 11, 2009 G Dan Mitchell 19 Comments

(Revisions: April 21, 2017; March 8, 2018; December 18, 2018 July; July 2019.)

A reader wrote and asked how I determine exposure times for night photography, and I decided my answer so that others can see it. Once I started writing, I decided to go ahead and share more basic techniques that can be very useful for night photography, too — including things like focus, etc. This isn’t a comprehensive coverage of the subject, but it does touch on a few key ideas.

First, for information about the techniques of nocturnal photography (and for some great examples of the photographic results and for workshop opportunities) I recommend a visit to the web site of The Nocturnes, the San Francisco Bay Area night photography group more or less run by Tim Baskerville. I’ve joined them on many night photography shoots, and the resources at their web site provide a ton of basic information that will save you many frustrating nights of trial and error. (I’m a member of a related group, Studio Nocturne SF, a collective of photographers who do night photography and exhibit as a group.)

Since so much of the basic information is available there, I’ll just add a few techniques and ideas that I find useful, especially for shooting with DSLRs. Here they are, in no particular order.

Consider using your camera’s long exposure noise reduction system — On my Canon DSLRs this setting causes the camera to make a second “dark frame” exposure following your “real” exposure. You might be tempted to forego this option since it doubles the time required for each exposure – your 60 second exposure will be followed by a 60 second dark frame exposure, while you stand there and twiddle your thumbs. (Or, do what I do – start composing your next shot.) DSLRs are subject to increased noise and “hot pixels” with very long exposures, but the dark frame provides the camera’s software with a reference that contains only the noise and hot pixels, and it can use this to map out (or subtract) the noise, etc from the image.

(Experiment with your own camera to discover the exposure lengths that benefit from the use of this setting. Modern digital cameras are less susceptible to noise issues than these cameras used to be. Some of the most recent digital cameras will not really need to use this feature much, if at all.)

Rely on your histogram to check exposure — do not rely on how the shot looks in the display. If the shot looks like what you see at night, in most cases it will be way underexposed — and, as a result, you’ll have a very noisy image and you may end up with artifacts like noise and banding. Instead, use an exposure that produces a balanced histogram curve — or, “expose to the right,” as many of us like to say. Your exposure may look brighter than the scene looks in person, but you can darken things in post and thus reduce visible noise even further. With many subjects, a well-exposed night photograph will look just as bright as one made in daylight.

Shoot wide open at high ISO to calculate basic exposure – If you have a f/1.4 lens and can set your camera to ISO 3200 or higher, do so. Let your camera make an automatic exposure and use that as a starting point. For example, if you get a decent (though noisy and otherwise awful looking) exposure at ISO3200, f/1.4, and 1 second you can work backwards from there to get a better exposure. Switching back to ISO 100 means that you need 5 stops more light, so your exposure time will go from 1 second to 32 seconds. (Count 1, 2, 4, 8, 16, 32.) Changing your aperture back to a more reasonable f/8 means another 5 stops or about a 17 minute (!) exposure – if my quick calculations are correct. (Update: I understand that if you can do this at ISO 6400 you can do a straight conversion from seconds to minutes – e.g. if the exposure at some aperture is 1 second at ISO 6400 the claim is that it will be 1 minute at ISO 100 at that same aperture.)

Apertures and ISOs that work in the daytime are good starting points for long exposure night photography — If f/8 at ISO 100 is your preference for daytime landscapes, then there is a good chance that these will be about right for night time landscapes as well. It just takes longer — sometimes a lot longer. If you are shooting a subject that would use larger apertures and smaller DOF in the daytime, you can probably use similar apertures at night. (This advice is mostly intended for those shooting from the tripod. When shooting handheld in very low light you may have no choice but to use a large aperture and a higher ISO. Fortunately today’s cameras are very good performer at higher ISO values, and some post-processing noise-reduction will usually produce a good image.)

Find something to focus on — Getting good focus stymies many night photographers. There are several approaches that you can try, and the right choice will vary depending on the shot.

If there is a relatively bright spot in your composition – perhaps a light bulb, a reflection, the moon, etc. — place an autofocus point right on top of it and see if it will acquire focus. Then switch AF off and recompose the shot if necessary.
Sometimes there is nothing in the scene that will provide enough light/contrast for autofocus to work. Look around for something outside of your composition that is about the same distance away — focus on that, switch AF off, and recompose.
Temporarily place a light in the scene — a bright flashlight or your smartphone will work — and focus on it.
You may be able to create a usable focus point by shining a laser pointer beam into the scene and focusing on it. Sometimes a bright enough handheld light or flashlight will be enough.
If you have one “must work” shot to make and plenty of time, you could set up the shot and determine focus during the daylight and leave the camera in position for your night exposure. (A potential focus shift due to temperature changes is real but likely inconsequential.)
Manual focus may be a possibility – either by trying to get a point light source such as a bright star (or your laser pointer, or a light placed in the scene, etc.) to focus manually through the viewfinder or by relying on the distance scale on the lens barrel.
Since perfect focus may be more elusive at night you have another reason to consider smaller apertures with their greater depth of field — they are a bit more forgiving of less-than-absolutely-perfect focus.
If your camera has a “live view” feature, you may be able to manually focus in light light levels at which neither AF nor traditional manual focusing will work – highly recommend for night photography work! See the exposure simulation feature on your camera.

With very long exposures, precise exposure time is less critical than you think — When shooting in the daytime very small changes in absolute exposure time make a bit difference. If you shoot at 1/100 second, increasing the exposure time to 1/50 second doubles the exposure. But at night things are a bit looser. If you are making a 6 minute exposure, you’d have to be off by six minutes to double the exposure or by three minutes to cut it in half. With that in mind, a few seconds hardly matter at all. I don’t bother with automated timers. I just count seconds (or chimpanzees, or hippopotamuses, or whatever…) or use my watch. That said, if you do have a timer you can probably let your mind wander a bit more while you enjoy your nighttime surroundings during the long exposure.

Daytime exposure tricks often work just as well at night — When photographing high dynamic range scenes during the day I may make two exposures — one for shadows and one for highlights — and use masks to combine them in post. The same situation often arises at night, especially if you have a shot that includes dark areas and bright artificial light sources. You may need to make one exposure that gets some detail from the shadows and a second that avoids blowing out the bright light sources.

Lens hoods are extra important with night photography — That may seem completely counter-intuitive, but when shooting at night you often have light coming from many more directions than when you shoot in sunlight, and the potential for flare increases. (You also may be a bit more likely to bump your lens into something, and the hood offers some physical protection.)

Asian Styles — People in front of a San Francisco storefront at night

Try shooting handheld — While most night photography is going to require a tripod, modern digital cameras often work effectively enough at high ISOs that you can shoot many subjects without a tripod. For example, I now do almost all of my urban night photography handheld, shooting with relatively large aperture prime lens at ISO1600-6400 or even higher.

Try a small mirrorless camera — For some kinds of night photography, such as my night street photography, a small digital camera can be ideal. For one thing, the small cameras are often unobtrusive and less likely to draw attention to you. Many of them work very well at high ISO settings, and all ow you to shoot handheld in typical urban environments. Their electronic displays can often give you a usable view of your scene even in extremely low light.

That’s a quick list. Hope you find it useful! Have a question or something to add? Leave a comment below!

(By the way some of my night photography is found here and other posts related to night photography are on this web site.)

Text, photographs, and other media are © Copyright G Dan Mitchell (or others when indicated) and are not in the public domain and may not be used on websites, blogs, or in other media without advance permission from G Dan Mitchell.

Equipment

Canon EOS 5D

July 28, 2008 G Dan Mitchell 1 Comment

Having used my Canon EOS 5D extensively for about two years, I figure it is about time for me to write up something about my experiences with and impressions of this camera. Rather than try to compete with the existing camera review sites and post a bunch of technical specifications and test results, I’m going to focus on aspects of the camera that may give a better general idea of its strengths and weaknesses and of situations for which it is best adapted. Continue reading Canon EOS 5D →

Commentary, Equipment, Popular, Technique

DSLR Sensor Cleaning – My Approach

October 20, 2007 G Dan Mitchell 14 Comments

Update: June 14, 2023 — I just returned to this article after not reading it for quite some time, perhaps years. I still think it contains useful information, and the steps I describe still represent more or less what I would do today. However, things really have improved when it comes to the dust issue. Back when I had a Canon 5D, dealing with sensor dust was a major issue that required frequent cleanings (often with wet cleaners) AND a lot of spot removal in post. But today that is hardly ever the case. It is actually pretty rare to encounter visible spots, and when they do show up the cameras dust reduction system often takes care of them and they disappear a few frames later. I still firmly believe in tolerating a tiny bit of dust and dealing with it when necessary by using the least intrusive methods first.

When I got my first DSLR (1) I was very upset if I got any sensor dust in a shot. I was also very paranoid about cleaning the sensor (2), having read too many posts about how one can damage the sensor during cleaning. Now that I’ve used digital cameras for quite some time I’ve gotten over it and life is much, much easier.

Here is a summary of my approach (3) to dealing with sensor junk…

Rule #1: Modern cameras typically include dust-reduction systems that vibrate the sensor to dislodge dust particles. I set mine to operate automatically each time the camera is turned on or off. In addition to ensuring that the process runs regularly, this automatically runs it after every lens change, the time when you are most likely to pick up dust. You can also manually trigger a dust-reduction system cycle from the control menus, and I do this if I notice a dust spot while shooting. (If you have ever shot for a day or a few days without checking, only to realize that you had picked up a big dust bunny on day one and that it appears in all of your several hundred or more photographs, you will adopt this practice!)

Rule #2: I don’t worry too much about a small amount of dust in my images. I rarely can get a sensor clean enough to get perfect, dust-free shots at smaller apertures, and when I do the dust will soon return. Rather than obsess about dust-free perfection I quickly fix most small spots in post-processing. I can usually deal with most dust spots in a matter of a few seconds in Adobe Camera Raw (ACR) or Photoshop. (My preference is to do this in ACR during the raw conversion process. This fits better with my workflow which relies on the use of smart layers in Photoshop.)

Rule #3: When the dust gets to the point that dealing with it in post is no longer efficient, I try the easiest thing first. I use a blower to try to clean out the worst of the stuff. More often than not this is enough and I can go back to relying on rule #2. Point the tip of a good blower bulb into the chamber but keep the tip itself just outside. As you blow a few dozen puffs into the chamber and toward the sensor, change the angle of the bulb to ensure that you get full coverage. It is probably best to hold the camera with the open chamber facing down. (Don’t overdo it, since the blower can move some dust onto the focus screen of some cameras, leaving annoying bits of dust that do no real harm and will not affect your photographs but which are very difficult to remove.)

Rule #4: Sometimes rules #1-#3 aren’t enough and a more direct cleaning of the sensor itself becomes necessary. At this point I used to try a static charged sensor brush, being very careful to avoid letting the brush touch anything but the sensor* glass itself. Yes, the brush can pick up other stuff in the chamber, and I have learned from experience to avoid this. I still occasionally use the brush, but with the availability of the sensor gel products (4), these days I’m more likely to try them before I try a brush, though the brush can still be useful sometimes for stuff caught right up against the edges/corners of the sensor.

Rule #5: On rare occasions rule #4 fails, too. If the contamination is adhering too firmly to the sensor surface I resort to wet cleaning with Eclipse fluid and PecPads. I can rarely get it right in one attempt, so I plan on having to work at this a bit, but eventually I get a reasonably clean sensor with no streaks. Be very cautious to not use pressure, to not “scrub” the sensor glass, and to not use too much liquid. Let the fluid loosen and/or dissolve the material and gently wipe it off with the pad attached to the “spatula” tool. Read the instructions for this cleaning method very carefully before attempting it. It isn’t terribly difficult but there are a few ways you could go wrong including: pressing too hard and damaging the coating on the sensor glass, transferring lubricants to the sensor from other parts of the camera chamber, leaving streaks on the sensor.

Rule #6: On very rare occasions a combination of methods is required. Often the wet cleaning works well for me but leaves a few spots of dust on the sensor. For this reason I frequently follow the wet cleaning with a quick once-over with the static charged brush and/or the sensor gel stick.

From all of this, it might sound like I’m sensor-obsessed. I’m not. Remember rule #1 is the one I follow most. I usually go many months between real sensor cleaning sessions, and it is very rare for me to have to resort to a wet cleaning.

In my opinion, it is not necessary to fear the sensor cleaning operation as long as you are reasonably careful. Once you do it a few times it becomes quite quick and easy. Taking your camera to the shop or sending it to the repair facility is going to cost you a significant sum, take considerable time, and probably not result in a cleaner sensor in the end.

However, one photographer pointed out that he has a service plan that includes six free sensor cleanings per year. A few years ago, I would have counseled against relying on this – since early cameras without sensor cleaning systems often needed to be cleaned frequently and on short notice. However, the newer cameras rarely need a serious sensor cleaning – and in this case I can see how simply sending the darn thing in (while you keep shooting with your backup camera) could make sense for some people. (I still feel that you should be able to clean the thing in the field if necessary.)

Notes

(1) Interchangeable lens mirrorless cameras have become widely available since I first wrote this article about sensor cleaning. I use one along with my DSLR system, and both need occasional sensor cleaning — to the techniques described here are also broadly applicable to mirrorless cameras, too.

(2) I’ll anticipate that someone might feel obligated to write, “You aren’t really cleaning the SENSOR! You are cleaning the glass cover over the sensor, you nitwit!” Yes, I know that. It is just easier to refer to the whole assembly as “the sensor.” :-)

(3) Disclaimer: This report describes what I do, but I am not any sort of certified expert on these things – as I wrote, this is “my approach.” I strongly urge you to seek out and learn from other official sources of information on sensor cleaning and related issues. The inside of your camera contains fragile and sensitive electronic and mechanical components and it is possible to cause damage while working there. You should read and carefully consider warnings from the manufacturer of your camera and any accessories and tools you use on it. If you are not convinced that you are competent to do this work on your camera, you can always take it to a professional. I do not claim that my methods are the best or most appropriate, nor that they meet the standards of the manufacturers of the camera equipment nor do I recommend that you use my methods in place of manufacturers’ official recommendations.

(4) The Sensor Gel product (available here) is a cube of a sticky gel attached to the end of a plastic “wand.” The gel cube is placed in contact with the surface of sensor’s glass cover, and the dust adheres to it. Since the cube is smaller than the sensor, this process is repeated across the sensor surface. Press the cube against a supplied sheet of “sticky paper,” to clean it. I tried the Sensor Gel Stick partially out of desperation, as my aging Canon 5DII had picked up a ridiculous number of dust specks that were resistant to other methods of cleaning. After the first cleaning there were no noticeable spots left on the sensor. I continued to use it during a four-day shoot in Death Valley, a location known for dust—and, again, the result was impressive. The product is not cheap, costing about $50 for the gel stick and the sticky papers. Frankly, I think it is overpriced—but because it works so well I was willing to pay the price. I have recently seen similar products online from other distributors at lower prices, though I cannot vouch for their quality. I understand that two versions are currently available. One is the “blue” version that I have. The other “pink” version is apparently designed for certain camera brands, particularly for some Sony cameras. Check the product descriptions and make sure you get the right version for your camera.

(Most recent update: June 2023)

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Tag Archives: digital

Hints for Night Photography

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Canon EOS 5D

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DSLR Sensor Cleaning – My Approach

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Photographer and visual opportunist. Daily photos since 2005, plus articles, reviews, news, and ideas.

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Photographer and visual opportunist. Daily photos since 2005, plus articles, reviews, news, and ideas.