Category Archives: Lens

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.


Hunting Comets and other faint objects in not-dark skies

AirGlow Comet [5_070386]

It turns out the much hyped PanSTARRS C/2011L4 Comet is not living up to the hype. Unfortunately failure to meet the over exhuberant expectations  is common since predicting brightness and visibility of an object like a comet is a difficult science. In fact, it’s part science, part black art and part good guessing – mostly the latter.

The photo above was taken on March 12 when the moon and PanSTARRS nestled closely together. The close quarters made finding the comet much easier despite the bands of clouds passing by.  The strategy for finding the comet in that case was simple: use a telephoto lens, put the moon at the right edge of the photo and take different exposures periodically and at different settings (e.g. +2, 0, and -2 stops). Then hunt for smudges.

The IDEAL telephoto lens would be one that was a few angular degrees wider than the difference between the moon’s position and the comet’s position. How to determine the position of each is discussed in the last section below. Figuring out the angular view of your lens is easy using online tools like this one from Tawbaware, makers of Image Stacker (like that program!). If you know the field of view at your minimum and maximum zoom, you can use that information to your advantage.

Finding the Comet with a Nearby Moon

The point at the moon strategy made finding the comet easy because:

  1. There is no way you’d be able to see the comet if you were not able to find the much brighter moon nearby.
  2. On that one night, the comet and the moon were within 4 degrees of one another.  That’s quite close.

I know some people tried to find the comet using wide angle lenses. That strategy might work, but the comet is such a tiny thing and it’s visibility is so tenuous based on the atmosphere, light pollution, and sky brightness that you may only realize – as many did – that you captured the comet after carefully inspecting your photos at home.

Contrails and Comet Tails [B_050938]

The truth is you are unlikely to see PanSTARRS by eye or in your camera’s view finder unless your conditions are nearly ideal.  Hopefully ISON which is coming in December will be brighter and better.

Finding the Comet when the Moon is Farther Away

The following night, both the comet and the moon had moved relative to the sky. On March 13, the moon was 12.5 degrees above the comet and about 4 degrees farther west (again, how I knew this is coming in just a minute).  So one simple strategy for finding the comet would be to zoom your telephoto lens so that it has a field of view of about 14 to 15 degrees in the long direction which for me, is 80 millimeters focal length on a 1.6 crop factor camera.

On a tripod with the camera in portrait orientation adjust the view so that the the moon is in the upper left of the frame. Shoot bracketed shots. Check the lower right corner of each one for the tell-tale comet smudge.  Keep readjusting the view so the moon remains in the upper left for each shot. Zoom out a little bit too, in case your geometry is a little off. Eventually as it gets dark enough or the sky clear enough you should find it.

In fact the way I found the comet last night without using my camera but by using my telescope. The program Clinometer (on my iPhone) measures angles. I sighted the moon with my 8″ Dobsonian telescope and measured the angle along the telescope barrel using the inclinometer program. I then lowered the altitude (elevation angle) of the telescope by 12 degrees to match the altitude of the comet. Then I slowly rotated the telescope northward until I found the comet.  It wasn’t easy from my urban location, but it wasn’t impossible either.  By the time I was able to find the comet it was only about 6 degrees high in the sky – that’s way too low if you have trees, hills, and houses nearby to deal with.  In theory, this strategy would work with a telephoto lens or with binoculars, however, binoculars need to be steady and where I spied from last night had streetlights in the distance and the flare and glare from those streetlights made finding the faint comet nigh impossible.

What if there is no Moon to Find the Comet With?

Unfortunately starting on March 14th, the moon will be quite far from the comet, so the opposite strategy is required:  Use a landmark in a known direction as the starting point and look “upward” from the horizon.  In other words, zoom your telephoto lens so that the field of view covers the angle from the horizon to the comets altitude (angle) above the horizon.  Don’t forget that as the earth spins this angle changes every minute! Orient you camera in landscape mode and point it as close as you can to the correct direction (azimuth). Look along the top of the frame to see if you’ve captured the comet.


SpyGlass’s view shows the direction the camera is facing (Azimuth) and the elevation angle (Altitude)

But what direction should you point your lens or telescope? Use a compass application or actual compass. BEWARE however as the compass applications have lots of gotchas and are only accurate to about 5-10 degrees.  And if you aren’t sure how to use a real compass your local magnetic declination might bite you. Better would be a GPS with a built-in calibrate-able compass.  And perhaps even better still would be to use an application like TPE (which I discuss in my Catching the Moon Webinars) to calculate the correct azimuth from the location you plan to stand.  An application that might help a lot is “SpyGlass
however don’t forget that I found the directional accuracy of my iPhone and iPad to be pretty poor.  Being off by 5 degrees may mean looking in the wrong place.

How Do I Know the Altitude and Azimuth for the Comet?


Unfortunately, that’s a tough one.  I use the free program Stellarium. I then added the comet to the “Solar System Data Base” (search around on the web and you’ll find instructions). I selected my viewing location, dialed in the time, did a search for good ‘ol C/2011 L4 and let it tell me the azimuth and altitude.


Above I’ve dialed up the time and clicked the moon. The highlighted line shows me the azimuth (direction) and altitude (angle above the horizon) for the moon which at that time are 264 degrees or just a little south of west, and 30.5 degrees high.  Clicking on the comet shows 272 degrees – a tiny bit north of west and 9.5 degrees.  So now we know that the comet will be 8 degrees north and 21 degrees south of the moon – and that won’t change significantly for the rest of the night.

Since we also know the direction for the comet is about due west at this time, we can apply the telephoto-lens horizon trick I described earlier.

Another way you can find the azimuth and altitude is by checking my animation HERE – note that the animation is correct for San Francisco  (and most places nearby).  There is also a table of the azimuth and elevation in the text of the Flickr post.


By the way, one way to find the right spot on the horizon is to use the sunset location as a guide.