Tag 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.

UV Filter for Protection!?

I see the question asked a lot. Should I get a UV filter to prevent my (expensive) lens from being damaged should something bad happen? Or “the salesperson told me I’d get better photos if I used a UV filter.”

In a nutshell my answers are no and wrong.  The thinking that a $25, $50 or $150 piece of glass in front of a $1,000 lens is going to somehow protect the lens element from harm seems a bit absurd except in a very few scenarios which I’ll address in a moment.  Moreover, to assume that a thousand dollar lens’ image quality will be improved by a filter is unlikely.

Here are some of the arguments for NOT using a filter (clear, UV or any other for that matter).

  1. A filter creates another surface that may cause additional flare, glare or reflection.
  2. For all but the most perfectly polished and coated filters, optical degradation is certain with a filter.
  3. Filters can introduce color casts and vignetting.
  4. Putting a thinner shatterable piece of glass in front of a lens provides a source of sharp shards with which to to scratch the front lens element.
  5. Those who leave a filter on all the time often find their protection becomes unremovable preventing them from using a more useful filter like a polarizer or neutral density filter.

But… That Filter Might Save My Bacon!

Think about it. In what scenario will a filter protect the lens? A blow by a golf ball, baseball or softball? Nah, a direct blow will shatter the filter and drive shards of glass into the front element.  A drop onto the floor, lens first? Maybe. The filter holder may provide a little extra protection to the lens barrel, but again, when the glass filter shatters you’ve got shards of sharp up against your expensive glass.  What about a fall onto a rock?  Yep, a filter might help a little, but a lens hood would help a lot more – as would a lens cap.

Block UV rays

What about the argument that a UV filter will “block UV rays” and improve the contrast and exposure?  That is part true – if you’re shooting film. DSLRs are far less sensitive to UV light than film and that filter is more likely to become a source of glare, flare, internal reflection and vignetting.  That UV filter is also yet another expense and item to carry around.

When Does it Make Sense to use a UV/Clear Filter?

If you have burning metal or corrosive substances flying at your camera, I would certainly prefer that they strike a cheap(ish) piece of replaceable glass rather than my expensive lens. Also, some lenses are only well sealed against rain and dust if you put a filter on them. So an excessively wet, dusty or sandy environment might be a good candidate for filter use.

Under Fire [C_041883]

What Do I Do to Protect My Lens?

Aside from being careful, I would argue that using a lens hood is an almost ideal solution. A lens hood helps keep things away from the front element and it also serves the important additional photographically USEFUL function of keeping off-axis light out of your shot. Off-axis light can cause significant glare and flare and attendant loss of contrast.  Even the best filters are little or no help with off-axis light.

My personal policy is also to “cap the lens” whenever  I am not shooting and definitely before I move anywhere. The cap stays accessible in my back pocket and it goes on the camera before I move it. Much like my seatbelt is always fastened before I start the car.

The Elusive Milky Way – Capture an Image

I assume you already read part one of this article which describes a bit about what the Milky Way is and what times and seasons are best for photographing the cloud-like expanse of innumerable stars.  In this installment we describe the equipment and settings you will need.

Just Ahead: A Universe of Possibilities

f/2.8, ISO 3200, 30 seconds, post processed and combined with shots of the bridge that were lit with a spotlight.

Standard Capture

To get a passable or better image of the rather dim Milky Way you need:

  • A high performing low light camera (more on that in a moment)
  • A large aperture (f/2.8)
  • A wide angle lens. Ultra wide even.
  • A cool/cold night
  • As little city glow and moonlight* as possible – see below for an image taken in twilight
  • A solid tripod
  • Patience
  • To know where and when to look!

To get a recognizable Milky Way in a single frame, you’ll want to use somewhere between 2000 and 6400 ISO at f/2.8 or wider setting. That’s very high, and a wider aperture than many people have paid for.  You’ll also want to expose as long as you can before stars are streaking.  We recommend starting at 30 seconds, and reducing your exposure time if the streaking is objectionable. Below is an image taken when the rising moon was beginning to wash out the sky and this may be typical of attempting to capture the Milky Way in a less than ideally dark scenario.

Group Hug

Moonlight and Twilight begin to overwhelm the Milky Way in Alabama Hills, California; 30 seconds, ISO 3200, f/2.8, 17mm

Some image degradation is to expected. For example vignetting and coma are both more obvious at lower f/stops. Coma is a comma or “bird-wing” like appearance of stars near the corners of the image.  Both coma and vignetting can be overcome by stopping down the shot – but resist the temptation because stopping down means losing some or perhaps all of the wispy milky goodness that you are trying to capture. Exposing longer will only help if you have some special apparatus (see Tracked Capture below). Are you wondering why exposing longer does not solve the problem? We have tackled the issue in two different styles: a cheerful allegorical example, and a recent math savvy explication.

What will an image look like captured with 3200 ISO? It may look like the image on the left below which is “straight out of the camera” – but perhaps not for you as this image was taken in a VERY dark sky area in Nevada.  On the right is the same Milky Way with some simple processing we will describe in the next installment.

SOOTC (and not SOOTC) [C_039467]

What is a “High Performing” Camera?

I qualified my statement earlier by indicating a “high performing” camera is needed for a standard capture like those I’ve shown above.  Since it would be impossible to keep an up-to-date list of the current “high performing cameras,” let me instead point out a few characteristics common to all high performers:

  1. Recent generation (2 or 3 years since introduction) is preferable because technology has steadily improved.
  2. Large pixels (to collect more light).  A common measure of the pixel size is in microns. Generally this puts full frame cameras ahead of cropped cameras.
  3. High “ISO at Unity Gain” – this is a measurement of the efficiency of the sensor. There are two good sources for this information: the DxO Sensor Scores and ClarkVision’s (older) tables.
Don’t be fooled by the “highest ISO” setting advertised. That number is completely meaningless.
As of April 14, 2014, the highest performers are listed by manufacturer and in order of performance. E.g. the Nikon D3s is better than the D800 – though the difference is small. Indeed, the D800 excels in some categories over the D3s. Cropped cameras are shown in italics – note that there fewer of them and none of the crop cameras exceed their full frame siblings. The underlined Nikon cameras are literally the topmost performers over all cameras.

Nikon: Df, D3s, D4s, D600, D800E, D4, D610, D800, D700, D3, D3X, D3300, D5200, D7100, D5100, D7000, CoolPix A, D3200
Canon: 1Dx, 6D, 5D Mark III, 5D II, 1DS III, 1DS II, 5D, 1D III, 1D VI, 1D III, 1 D II
Sony: A7R, DSC-RX1R, RX1, A7, Alpha 99, Alpha 900, Alpha 850, A6000, Alpha 580, NEX-F3, NEX-C3, NEX-5N, NEX-3N, NEX-6, NEX-7
Leica: M Typ 240, X Vario
Phase One: P40 Plus, P65 Plus
Pentax: 645D, K-5 II, K-5 IIS, K5, K-50, K-01, K-30
FujiFilm: FinePix X100
Not in contention: any cameras by: Casio, Hasselblad, Konica Minolta, Mamiya, Nokia, Olympus, Panasonic, Ricoh, Samsung or Sigma.

The list above shows all cameras having a DxO Sports (low light) score of 1000 or higher.

Cameras like the Nikon D90, Canon 1D II N, Phase One IQ 180, Canon 1Ds, Nikon D3100 and Leica M9 fall just below this threshold and may also be suitable.  The first eight Nikon models outperform the Canon 1Dx, and after the 1DX is the Sony A7R. The Fujifilm just barely cracks the list in 43rd and last place.

If you want the camera to cost less than $2,000 USD your current top choices are: Nikon D610, Canon 6D, Sony A7, Sony Alpha 850 or the Nikon D3300.  If we were to make a recommendation, we’d recommend any of the full frame choices over the smaller sensor cameras.  Note that prices vary dramatically, and you may find used higher performing cameras for less than $2000.

Stacked Capture

A “stacked” capture is what you may need to resort to if your camera performance is not so spiffy.  The approach applies astrophotography techniques to create a lower-noise version of an image.  The technique requires MANY shots of the same view. However using this approach you will want to avoid having anything but sky in your photo. Terrestrial elements will make stacking the image tricky.

Urban Milky Way [C_036919-23PSavg]The image at the left is a stacked capture to illustrate the point, however it was done with a high performing camera and only 5 images.  A lower performing camera will require as many as 20 or so captures to combat the noise. The method is described in my a “Astrophotography 101” Webinar and details are walked through in Astrophotography 301.  On the other hand, this image was captured in a location where the Milky Way was quite faint – alongside 7 million people in the San Francisco Bay Area so there is hope even where the Milky Way can only faintly be seen.

Details about the stacking method appeared in an earlier column as well as in an an earlier webinar.

Tracked Capture

The last way to get a great shot of the Milky Way is to track the sky with an apparatus called an Equatorial Mount.  By tracking the sky at the rate of the earth’s rotation you can lengthen a 20 second capture to perhaps a 60 second one. You can also use several such captures to create a stunning “Stacked Capture”. Again, however, shots which include the land are a bit harder to pull off unless you resort to layering. What do you need to do a tracked capture? We cover that in detail in the Astrophotography 101 Webinar, but in short, you’ll want an Equatorial Mount of some sort – not an Altitude-Azimuth (aka Alt-Az) mount! A device that looks intriguing and not terribly expensive is the Polarie.

Once you get that image (or those images), you will no doubt want to tease the most pleasing photo you can out of your data. That is a topic we’ll cover in the next installment: Processing your Milky Way images.