Category Archives: Lens

Photographing Aurorae with a Night Capable Camera

Photo 1: Jupiter and diffuse, but bright aurora on our first night. f/3.5, 5 sec, ISO 4000, 20mm

This is part 2 of a multi-part series on observing and photographing an Aurora. Please read Aurora: The Bewitching Glow for background information including information about what an aurora is, when, how and where it can be seen, and photographs from Aurorae we observed near Fairbanks, Alaska.

So I Have to Get Lucky?

Before we jump into the details and the 3 keys for getting a good aurora photo, I think it is wise to set expectations about how likely you are to see a truly astounding aurora. Photo 1, above is one of the first captures I got on the first night on site (December 14). It was unexpected because the weather had been completely overcast all day. On December 17, the display was ASTOUNDING. I asked staff at Borealis Basecamp – which caters to aurora goers – as well as locals in Fairbanks, and I poured over the data to determine just how lucky we were to see the jaw dropping display we observed. The short answer is… “luck comes over time”. We used the Book and Hope method described in the first article to observe the aurora, arriving on December 14, 2023 and departing on December 18th – that is 4 nights onsite. But because we didn’t use the Monitor and Go method what we couldn’t have foreknown is how much the sun would cooperate with our aurorae dreams.

Diagram 1: M and X class solar flares in December, 2023.

Take a glance at Diagram 1, above from the SpaceWeatherLive.com archive. Fortuitously the most energetic solar flare (category X) in the preceding SIX YEARS occurred on the first day we arrived (and on New Years eve). The solar wind travels at over a million miles an hour (1.6 million kilometers per hour). But the sun is 92 million miles (147 million kilometers) away, so the effect of the flare on aurora production may occur in as little as 36 hours or as many as 4 days later. Even during a solar maximum events of this magnitude only occur infrequently. December 2023 saw two X class flares in one month – there were zero X class flares in the prior 5 months at all! The Kp Index exceeded 5 a total of 16 times in the 4 month period which means an exceptional once a week event might be a reasonable expectation during this part of the solar cycle.

Eli Fox, the chief photographer at Borealis Basecamp and the man who runs much of the Borealis Basecamp social media [Instagram] [Facebook] told me that exceptional aurora events occur on average about once a month or less.

A solid plan and good luck go hand in hand. But do not let that dissuade you. The displays we saw on two other nights were very pleasing and still produced great pictures.

Can I Get a Good Photo with ANY Camera?

Photographing aurorae is not different from the night photography we cover extensively on this site. If your camera is able to take acceptable Milky Way photos, it’s a good candidate – the aurora is generally much brighter than the brightest portions of the Milky Way.

Photo 2: Looking up. Bright fast moving aurora. Notice The big dipper at the left.
f/2.8, 2 sec, ISO 6400, 18 mm

While these articles are now starting to show their age, the principles still apply:

  1. High performing cameras (or see Which Camera is Better for Night Photography?)
  2. What to Look For in a Night Photography Lens

Surprisingly, some cell phones can do a respectable job and we will cover using cellphones in the next article in the series.

For any night photography the following minimums are recommended:

It also helps to become very familiar with the settings and controls for your camera and tripod – familiar enough that you can operate them in the dark with little or no additional light. That level of familiarity comes with practice… so if you are out of the habit, we strongly suggest practicing in your back yard (or in a dark closet). Practice while wearing the gloves that you intend to use! I discovered that merino wool glove liners were sufficient to keep my dominant hand warm even when the temperature dipped to -20F – but there was no wind and I avoided allowing any snow to remain on my glove liner – preferring to use my gloved hand or jacket sleeve when brushing away snow. Snow on my glove liner would have melted due to my body heat and made me miserable. I carried a pair of outer gloves with me, in fact, I kept a glove on my non-dominant hand at all times while my dominant hand had only the glove liner. The other outer glove remained in my pocked with a chemical hand warmer activated should my hand get cold!

Additional Photo Gear for Dealing with Excessive Cold

I brought quite a lot of gear to prepare for the affects of extreme cold on my person and my camera equipment. The camera equipment I brought included:

1. Five power banks – these were used to power “dew heaters” (aka lens warmers), as well as heated clothing.
2. Four of the powerbanks also were hand-warmers, most have built in lights.
3. Pouches in which I could keep the powerbanks, chemical handwarmers, as well as cables.
4. A large sealable plastic bag that can hold the entire camera and lens.
5. Carabiners to hold the pouches to my tripod.
6. And my standard practice of affixing velcro to key places near the top of my tripod with the mating velcro on the back of my intervalometer(s). This keeps the intervalometer in a usable place and prevents it from falling or catching the wind.

The pouches had operational electric hand warmers or chemical hand warmers to keep the power bank in them warm. I thought about, but did not use external batteries for my camera. Conceptually using external batteries permits using a larger battery (or using plug-in power) as well as keeping the camera batteries warm without warming the camera. The extreme cold is GOOD for your images. Deep sky astrophotographers typically use super-cooled sensors for their work, and your camera benefits from the cold, too, in the form of less noise.

If you use chemical hand warmers (charcoal, salt and iron filings), they need some airflow to keep generating heat – so don’t put them in a bag with no airflow. Indeed, if you want to reuse them, you can put them in as small a possible plastic bag to extend their life.

However I did keep spare batteries in my interior pockets where my body heat would keep them warm should I need to swap batteries. With the power banks, I also brought extra cables, an extension cord, and a 7 station USB charger. Of course all the regular stuff is needed, too… battery chargers for your camera batteries, cables, lens cloths and more. Another item I strongly recommend is gaffers tape which you can use to seal viewfinders, and lock down focus settings. And a large Ziplock bag. I also like to use a lens band (basically a large rubber band) to prevent focus or zoom settings from changing unexpectedly.

What Can Go Wrong?

Several aurora photographers wondered why I brought dew-heaters (lens warmers). These devices wrap around the end of the lens and via a power bank keep the lens warmer than the surrounding air to prevent dew (condensation) or frost from forming on the lens. Those with more experience than me typically did not use such devices because in the extreme cold dew is not typically a problem. BUT I did have complications I didn’t anticipate. In warmer, more humid climates, dew heaters can be the difference between getting a shot of “lens fog” and getting a great night shot.
The lens warmer is attached by cable to a power bank. More than once the pouch containing the power bank got bumped off my tripod yanking down on the lens ring which, unfortunately, altered either the zoom or the focus of the lens. In part for that reason I stopped using the lens warmer. But I did notice that more than once my breath crystalized on the outer lens surface. The take away here: in the extreme cold, keep your breath away from the camera as much as possible! And if you do use a lens warmer, find a secure way to attach it to your tripod so it can not yank on your lens.

From time to time I would use the viewfinder to frame my shot. But on my Sony Alpha 7R III camera, the frost from my breath condensed on the viewfinder resulting in two problems. The moist air from my breath froze on and made the viewfinder cloudy and I couldn’t see through it, and the sensor that turns off the back LCD when your eye is at the sensor got confused and refused to turn the LCD on. Effectively I was unable to use the LCD or the viewfinder to make adjustments. Fortunately this happened as the aurora was quiescing so I put my camera in a SEALABLE plastic bag, and brought it indoors.

Bag Your Camera! And Other Tips…

Why bag your camera? If you take your very cold camera indoors it will almost immediately form frost and condensation in the warmer more humid air – much like your iced drink glass forms condensation. Unfortunately condensation can occur INSIDE the lens and INSIDE the camera (e.g. on the sensor). Whenever I move the camera from a cold environment to a warmer one I bag and seal it and keep it in the bag until it has warmed to room temperature (about 1 to 3 hours). I can take it back out to a cold environment immediately if I wish. Keeping desiccant in the bag is not a bad idea, either! Oh, and you may find it advisable to remove your memory card and battery from the camera before bagging it so that you can examine the contents of the card or charge the battery while you have the bagged camera in a warmer environment.

Another unanticipated problem was that the extreme cold made the intervalometer cord quite stiff. It behaved more like a coat hanger than a wire. I strongly recommend using either a corded, or cordless intervalometer – you need it as a shutter release. The reason for the shutter release is to keep from adding any shake or wobble to the process of taking a photo – which occurs just by pressing the shutter button. A shutter release locked in “on mode” also allows you to take endless shots unattended which if you wish, you can assemble into a star trail like the photo below.

Photo 6: Applying Comet style star trails (with a satellite) (97) 6-second exposures. (each f/3.5, ISO 4000, 19mm) Total 9 min 42 secs.

Finally, I had difficulty adjusting the settings using the top dial on my camera – I believe also due to frost from my breath. I say “I believe” because it occurs to me that with my lightly gloved hand I may have been trying to rotate the function knob instead of the upper adjustment wheel. REMINDER: Get familiar with your camera before you get into the exciting environment where you may easily forget a step or two while gawking at the sky.

The Three Most Important Aurora Tips

Once you have all your gear, have a solid tripod (which you set up properly and securely) and are ready to begin photographing the amazing aurora… there are three very important things to NOT skimp on doing and double checking.

  1. Confirm (check) focus frequently especially after any bumps or changes in zoom.
  2. Do NOT judge the quality of the exposure by the display on the LCD. The only way to insure a good exposure is to look at the histogram (separate RGB channels is best).
  3. Adjust your exposure as needed to meet the circumstance. Aurora can go from dim to very bright and very bright to dim. They can move hardly at all, and they can dance about in the sky at a dizzying pace. So this means not only should you pay attention to those exposures, but you might want to avoid fixating on one area of the sky.

Tip 1: Checking and Setting Focus

The best way to check focus is to shoot an image and zoom in and check for the sharpness of any stars on the LCD. The best way to get focus right is to pre-focus at infinity when there is sufficient light (e.g. using a streetlight, the moon or a very bright star). While cameras can SOMETIMES successfully self focus most of the time they cannot without bright, motionless light in the distance. One way to get a good focus is to use live view, zoom in and hand adjust focus until a star is as compact as possible. But do not stop there… TURN OFF auto focus! You can set some lenses to “MF” or “Manual Focus”, but another strategy – perhaps easier – is to set your camera to do focus only when you press a separate focus button. Typically a camera is set to focus as you press the shutter – and that’s definitely NOT what you want.
If you’re not sure where to focus, we recommend either focusing on stars or if that seems difficult, you can focus on anything that is more than 50 feet away from you and that will be sufficient for wide-angle lenses.

Then take an exposure and confirm the focus is spot on. I took a whole sequence of exposures with lovely snow flocked trees in the foreground, but I made the mistake of not confirming my focus was spot on! It is also worth noting that the aurora may be diffuse and therefore not have a clear focus point… so don’t judge by the aurora! By the way, we also strongly recommend that you set a fixed White Balance (e.g. cloudy or daylight), disable long exposure noise reduction, and turn on high ISO noise reduction.

Some cameras have a “focus peaking” setting that you can enable. Focus peaking colors those areas of the image that are in focus (red is easier to distinguish in a night shot). This tip comes from Eli Fox, and is something I did not know is present on my Sony!

One last tip, focus MAY change as the lens gets colder or warmer – so do check periodically.

Tip 2: Verify Proper Exposure using the Histogram Feature

Diagram 2: An aurora photo with over exposed elements (see red pointers). The histogram (top right) shows a spike at the right – brightest end – of the range.

My modus operandi when shooting is to hand shoot a few images doing the focus check AND a histogram check before I set the camera up to take continuous exposures. I then periodically stop the exposures to double check the histogram. One additional help here is to turn on over exposure highlighting if your camera supplies it. With that feature on, over exposed areas will generally blink where there are overexposed pixels to let you know what areas are over. Overexposure is very difficult to recover from. The goal is to minimize the overexposures but get the images as “bright” as possible to capture the most information. I then usually shoot a shot with the lens cap on (or my hand covering the lens) so I can tell that I’ve changed settings or adjusted the field of view. Elements at the “bright” end of the spectrum by themselves don’t mean there are over exposures. By the way this is also why we strongly recommend you shoot your photos in RAW – or like we do RAW plus the smallest JPEGs.

Tip 3: Do Not Fixate

This tip has two parts. Do not forget to recheck at LEAST your exposure histograms periodically, and do not fail to look around in the sky. While you might have the perfect foreground, the aurora behind you or above you may be the most spectacular thing you will ever see. If you do not get a photo, it may as well have never happened! And while we are on this subject, do you notice how GREEN the snow appears in the right side of the photo below (as well as earlier photos)? They are reflecting the predominate color (557.7 nano meters wavelength) coming from the aurora. This is one of the possible problems with obtaining natural looking aurora photos.

Photo 5: The recorded color (right) gives an eerie green, but the left is hand desaturated in post processing.

As noted in Aurora: The Bewitching Glow (part one of this series), there are other colors as well. This can have the affect of making the landscape look “eerie”. Eerie landscapse can be combatted in two ways. One way is to be thankful for and take advantage of light pollution (or some moonlight), and the other is to post process the photo to desaturate the areas that look unnatural e.g. as is done above in photo 5. All the other rules of good photo composition apply as well. If the photo would look pleasing without an aurora, then it will be even better if there is an aurora. But if the scene is chaotic or not well framed, it will take an incredibly amazing aurora to save it. I think the main take away here is: experiment with different compositions, directions and settings.

One last point. The aurora can move very slowly or surprisingly rapidly. If you take a long exposure for a fast moving aurora it will “smear”. But a dim, slow moving aurora may require a longer exposure or a higher ISO or both. Consider the examples below. At the left is an approximation of one ten second, ISO-6400 exposure (f/2.8, 18 mm) created by combining 5 2-second exposures and the second is a single 2 second exposure. The “eye” of the aurora is overexposed and much of the swirly detail is lost. However even if the ISO had been dialed down or the aperture stopped down to prevent overexposure, the capture over the longer time interval would lose some of the fine detail – in much the way that a moving flashlight or a moving camera would create a smear. But do notice that more stars are visible in the longer exposure because 10 seconds is sufficiently short for an 18mm shot that the stars themselves are not smeared (much). To understand this a bit better, the best resource we know of is
described in our article: 600 Rule?

In fact, if you’d like to get an idea how fast an aurora CAN move in real time, here is a video sequence – not a timelapse – from Eli Fox

VIDEO: Real Time aurora used by permission from Eli Fox.

Well, that’s it for how to use a “night capable camera” to take aurora photos. But stay tuned, we have at least two more articles on the subject coming soon including:

How to Take Aurora Photos with a Cell Phone

All about Borealis Basecamp

As always, feel free to ask questions using the comments below. Thanks for the gift of your time reading this… and if you’ve found value in it, please do share the link with those you know who would appreciate it.

What to Look For in a Night Photography Lens

Last Updated: December 1, 2017
Original Publication: Oct 20, 2013

As Numerous at the Grains of Sand

Taken with a 15mm f/2.8 Canon Fish-eye Lens – partially “defished” using Adobe Camera Raw

Obviously here at StarCircleAcademy we love our night shooting. And because many of you love it as well, we get asked a lot of questions about gear: which lens, which camera body, which tripod. To be frank we try not to answer questions about specific gear because there are many tradeoffs that you must consider when choosing. Those tradeoffs revolve around your budget, desire, goals, current equipment, and the mix of photography that you do.

If you’ve already invested $4,000 in Nikon, it really doesn’t make sense for us to recommend a Canon-only lens… and vice versa.  If you do a lot of wildlife photography and only occasionally dabble in night photography an ultrawide fish-eye lens may not make sense in your camera bag.  However, there are some important considerations for night photography that may not be obvious so in this article we are going to tell you what the most important characteristics of a Night Photography oriented lens are… things you may not have considered when choosing a lens for other purposes.

Things that Do NOT Matter

Let’s first set aside a few myths and talk about lens features that get hotly discussed in flame wars on photography boards.  Those include things like:

  • Prime vs Zoom
  • Wide Angle vs Super Wide Angle
  • Rectilinear vs Fish Eye

A lens for night photography can be any and all of the above. Ultimately the question is how good is the lens? Whether it’s a prime, zoom, macro, or not is irrelevant. No lens should be disqualified because it’s a zoom or a fish-eye.  There are theoretical reasons why a well made prime lens will outperform a well made zoom lens… but that doesn’t mean that any given prime will out (or under) perform any other lens. There are dozens of compromises to be made for any lens and some compromises severely hamper the usefulness of a lens at night.

What DOES Matter

Because there is so little light to focus, an autofocus lens is not particularly helpful. In fact some standard lenses that are designed to autofocus are notoriously difficult to get focused at night. Here are the considerations we believe are most important, roughly in priority order:

  1. Usable Aperture
  2. Manual Focus & Maximum Sharpness
  3. Accurate Lens Markings
  4. Minimum Distortion and Coma
  5. Limited Vignetting
  6. Build Quality (Mechanical reliability and sturdiness)
  7. Weather Sealing
  8. Dew Shield/Lens Hood
  9. Cost

Usable Aperture

A lens that tempts you with an incredibly fast aperture of f/1.2 is all but useless if you have to stop it down to f/7 to make it acceptably sharp. Usable Aperture refers to the maximum aperture at which you can make exposures that you would be proud to hang as poster sized prints on your wall, and yes, that is very subjective. In night photography, as in astronomy, aperture wins.  The more light a lens can drink in, the more stars and dim details the lens can capture.  The f/ number is a ratio of the size of the front glass to the focal length of the lens. That means that the larger the front element, the more light it can drink – all other things being equal.  There is no substitute for “fast”.  Another advantage to a fast lens is that you’ll get more detail in your viewfinder.  You may be able to make out foreground objects in an f/1.4 lens that will be entirely inscrutable at f/4.

A zoom lens may have a variable f-stop ratio. This may be a detriment. If the ratio changes, e.g. from 2.8 to 4.5 then you’ll lose quite a lot of light when you use the zoom.

Manual Focus & Maximum Sharpness

Sadly, lenses designed to autofocus quickly are often the worst choices for night photography. Take the Canon 50mm f/1.4 lens, for example. The amount of play in the focus ring is miniscule so manually adjusting focus for a night shot is a lot like trying to peel a grape while wearing mittens. A tiny 1/128th of a turn takes the shot from out of focus in one direction to out-of-focus in the other.  The lens, therefore, is only usable if there is enough light to get it to autofocus before taking the shot.  By contrast nearly all manual focus lenses are designed to allow plenty of room for focusing. A Rokinon 24mm f/1.4 allows me to turn the focus ring almost 360 degrees to adjust the focus.  That is a big plus when you want to get focus just right – it also means that slight errors in focus are less drastic. Avoid a lens that does not have a manual focus ring. Unfortunately more and more of the kit lenses are dropping the manual focus ring and lens markings.

Accurate Markings

A lens with nicely tunable manual focus is not so nice to use if you can’t start close to the correct focus location.  Many really cheap lenses have done away with the lens markings all together. We recommend you avoid those lenses.  An accurate marking may allow you to dial and shoot without having to check and recheck focus. That can be a time and patience saver.

Minimal Distortion / Chromatic Aberration

No lens is perfect. If you found a perfect lens, you will have paid an enormous price for it. Every lens must make trade-offs. Some of the less desirable trade-offs for night photography include coma – bird wing or “comma-like” stars most notable in the corners of the frame and at wide open apertures. My expensive Canon 16-35mm f/2.8 L II lens has pretty awful coma in the corners.  That doesn’t mean I don’t use the lens, it means when I want the whole field of view I need to either stop down to reduce the coma, zoom in, or plan to crop:  all compromises that are unpleasant – but – my work with the 16-35mm lens sells just as well as with other lenses and it is a sturdy, well made lens.

Chromatic aberration – color fringing – is also a common distortion problem. Sometimes night shots reveal chromatic aberration more significantly than any other shots because of the sharp differences between say a bright moon and a dark sky.

Ghosting and flare are two other villains that produce strange artifacts on your shots.

Finally there is distortion due to the lens geometry. For example, fish-eye lenses render elements at the edges of the frame with odd curvature. Sometimes this is a really pleasing thing, sometimes not.  Fish-eye lenses also often suffer from “Mustache” distortion which causes a strange bowing of the bottom middle of the frame. Other standard distortions include pincushion and barrel distortion where the center of the image appears to be shrunken or enlarged. Many of these distortions can be corrected in post processing – but that doesn’t mean the image is going to be perfect.

The one distortion I despise the most is coma. Second most: chromatic aberration.

Minimal Vignetting

If you want to use the whole field of view, it’s not helpful if the corners are two or three stops darker than the center of the frame.  While the correct term for this phenomenon is light fall off, most people know it as vignetting. Picking on the Canon 16-35mm f/2.8 L II, it vignettes heavily at 16mm.  I find I have to zoom to 17 or 18 mm to reduce that effect. As with other distortions noted earlier, some post processing can remediate, but not eliminate the vignetting.

Other Obvious Tangibles Common to All Lenses

  • Build Quality
  • Weather sealing
  • Dew and/or Lens Hood
  • Cost

A well designed lens hood is very useful for keeping off-axis light out of your shot and protecting the front element from damage and dew. A lens hood is more important in night photography than in daylight!

Keep in mind that lenses generally hold their value very well. A lens you pay $1000 for today will probably be worth that much or nearly as much (or even more!) in 3 or 4 years. By contrast, your camera body will probably be worth less than half of what you paid for it because a newer, more featured, more powerful body will have replaced it. In the old days you could get better pictures by taking your good camera and putting better film in it. In the digital world the better film comes at the cost of a new camera.

The Top 5 Night Photo Mistakes

Bixby Panorama

Intern: I would like to follow in your footsteps to become an executive like you. What is the most important thing I need to learn?
Executive: That’s easy, do not make mistakes!
Intern: But how do I learn not to make mistakes??
Executive: You learn best how to NOT make mistakes by learning from the mistakes you do make. Also pay attention to the mistakes others make. You won’t have enough time to make all those mistakes yourself!

So what are the most common foibles that you hopefully won’t have to make yourself when shooting at night?

  1. Failing to turn off AutoFocus. Unfortunately at night autofocus is usually not a help as many cameras will seek focus and not finding it, refuse to take a photo. Or just as bad, will hunt for focus, and settle on something that is way out of focus for each shot. In the same league: forgetting to check focus!
  2. Forgetting to format the Memory Card. You’ve got autofocus off, and you’re really excited about that timelapse or star trail so you get your intervalometer all set and start. Whoops. That card is nearly full so instead of hours of great stuff you’ll get minutes and a full card.  It is best to format the card in camera to avoid possible problems if the card was formatted on a computer or in a different camera.
  3. Omitting a check for tripod stability. Uh oh. If you blow this one, it might mean your camera falls over and smashes against the rocks. We’ve been horrified to witness such a spectacle on more than one occasion.  Or about as bad: your camera waves in the breeze and gives continuously fuzzy results.  Step away from that tripod and look from different angles. Is the center column vertical?  If you push in different directions does the tripod move? Did you forget to fully tighten the leg locks? Center column lock? Head? Check again, just in case!  Steven snapped a lens in half because his leg lock wasn’t snug and the camera simply collapsed in the direction of the unlocked leg.
  4. Neglecting to start the intervalometer.  If you’re using an intervalometer it’s not difficult to press the start button and walk away only to discover you really didn’t press the start button OR the intervalometer was locked in OFF mode so just completely ignored what you wanted to do.
  5. Wrong settings. It’s easy to do, you spent the afternoon getting perfectly framed milky-smooth waterfalls.  Now it’s night time and you set your exposure to 30 seconds, but you left your aperture at f/16 and your ISO at 50!  Ooops. Or you just took that super high ISO test shot … and in your eagerness to catch some meteors you leave the ISO in the stratosphere.

You’ll notice we didn’t mention:

  • Failing to take the lens cap off.
  • Forgetting to charge the battery.
  • Failing to bring memory cards with you.
  • Leaving the quick release plate at home.
  • Toting your camera bag up a mountain while your camera remains in your car.
  • Leaving the polarizer on…

We’ve done all of the above. You might find our “Stackers Checklist” helpful to avoid these pitfalls and many more. Many of our students carry laminated copies with them.

What was your most embarrassing or frustrating camera faux pas?

Theory vs Reality in Photography

Several topics in this BLOG have provoked impassioned debate. We really appreciate that. Steven is a Software Engineer by training. Eric is a Molecular Biologist, and Harold is a jack of all trades. In addition to being an author and professional photographer, Harold’s background includes being an Attorney at Law and a Software Engineer. We do “geek” like nobody’s business!

I, Steven am raising the geek card just to let you know that we do care about precision – but we care MORE about great photography and applying real-world principles to real-world problems.

Streaking Or Not?

The biggest debate has been about what factors lead to streaking (trailing) in Night Photography shots of the stars. Shots of the night sky may produce noticeable streaks if the exposure length exceeds certain bounds with specific camera factors (focal length, sensor size and sensor geometry). But there are a huge set of assumptions behind the visibility of those streaks that are often overlooked. One assumption is that the finished image sizes are proportional to the size of the sensor used to create them – when does that happen in real life? Another assumption is that the viewing distance is proportionally related to the finished image size. These sound like they are reasonable, but in the real world, a print from a crop camera and a full-frame camera are extremely likely to  be made in the same finished sized and viewed from whatever distance the viewer chooses!

In the desire to get the math exactly right, many people trip over one or more of those assumptions. Our article about why the 600 Rule is a misguided way to determine the proper exposure length has had many proponents and opponents espousing the “inerrancy of the mathematics” and all the missing factors we may not have included. I love math, but: my assertion is that Reality beats theory when producing an image.  And that’s why the conclusion of the article is that the proper exposure length is an aesthetic decision more than a mathematical one.  The mathematics guide, but do not govern what the best choice(s) may be.

All Photography Involves Tradeoffs

I really enjoyed my Physics classes, especially mechanics. But I also remember all those exercises that included clauses like “neglecting friction”… In the real world friction with the the air and from tire contact on the ground is why a car on a flat road comes to a stop even though no brakes are applied.  Air friction (drag) is why it takes eight times as much power for a plane to fly twice as fast.

The reality of physic is why a lens, or sensor is always a tradeoff of something for something else. Perfect optics or a perfect sensor behavior is not possible at any cost. In the same way, a photographic exposure is always a tradeoff of one thing for another. If you need a faster exposure with a given amount of light you can: increase the exposure time, increase the sensitivity, or admit more light by opening the aperture. Of course you can also change more than one thing at a time. Indeed you MUST change more than one thing. Any change to one of the three factors requires a corresponding change to one or more of the other factors.

What Exposure Settings Should I Use?

If you ask me this question, I apologize in advance for rolling my eyes (it has been known to happen). I can give you a STARTING point, but remember that a starting point involves tradeoffs and conditions that can not be entirely foreseen. How warm is it? How much moisture, dust or particulates are in the air? How much turbulence in the atmosphere? How much artificial (or natural light)? What are the predominate colors of the light (white balance)? How efficient is your sensor? How sharp are your optics? How far away is your foreground from your background? What is that largest aperture available? How sharp is your lens at that aperture and at that zoom? What is important to you in the scene you’re trying to capture? And what are you trying to accomplish?

My best advice: try an exposure and see what you get. When all there was was film, precision was a lot more important than it is now in the digital world where you can immediately see the result with a histogram and a myriad of other data to help you decide what to try next.

In fact, here is your assignment.  Go out when it is dark and shoot a photo of the moon.  How dark is entirely up to you. Your photo MUST show the same kind of detail that you can see with your eye – the craters and the gradations from light to dark areas.  Use a telephoto lens – notice I am not telling you how telephoto, that’s also your choice. If the moon is “blown out” – and it probably will be, decrease the exposure. Keep taking photos until you get as much detail as you can.  You will almost certainly need to use manual mode to set your exposures.

What settings did you come up with?  In our “Catching the Moon” webinars we provide starting settings and also advice about how those settings may need to be changed.

For an extra challenge… see if you can get the moon AND stars in the same shot. What settings did that require?**

4 Moons 4 U [B_049969] Composite

**In retrospect, it was evil of me to suggest this. In only the most extraordinary circumstances is it possible with current technology to get a featured moon AND stars.  The example above required 3 separate exposures.