Overcoming Coma Aberration - Part 2

Stars and coma: Capturing stars as points of light is a challenge in optical design. Without the addition of special aspherical elements, stars and other points of light are often reproduced with great distortion, particularly near the edges of a photograph. This lens aberration is called coma. Stopping down the lens to a smaller aperture can overcome some of this distortion, but not all of it. Surprisingly, very few general photography lenses come with coma correction!

Canon 24mm f/1.4L II lens

A disappointing experience: Since the typical photographer rarely photographs subjects that require coma correction, most general photography lenses do not incorporate aspherical elements in their lens designs. For this reason, I was quite surprised when I spent $1,800 in 2011 for one of Canon's best 24mm lenses, only to be extremely disappointed with it's wide-open performance when photographing stars (the lens works great for everything else).

The Canon 24mm f/1.4L II lens seemed like the perfect answer for my star photography. All the reviews I read said that it performed well, even wide open, with only moderate vignetting (which is important when you want to stitch several images together into a panorama). By being able to shoot at f/1.4, I could lower my ISO and greatly reduce the noise I had been getting in my starry night skies.

None of the reviews mentioned the problem of coma. To my horror, I noticed stars in my photographs that were shaped more like white doves in flight! Returning to the Canon dealer in distress, I was told the only solution was to stop down my new 24mm lens. (Note: Not all aspherical lens designs are created equal. This expensive Canon lens has two high-precision aspherical elements, and 2-UD elements, but exhibits much more coma than another prime lens costing about one-third the price!)

Canon 24mm @ f/1.4: enlarged area near the edge shows stars with severe coma distortion (click image to enlarge).

My tests soon revealed that at f/2.8 most of the coma did indeed go away, but I was now back to using the same aperture as my other less expensive lenses! It seemed like there was no way to avoid coma without shooting at f/2.8 or using an even smaller aperture. This meant using longer exposures, but that produces star movement or trails. I could use higher ISO's to the prevent longer exposures, but that meant increased digital noise. (Click image below to enlarge.)

Aspherical elements in Samyang Optics 24mm f/1.4

Samyang Optics to the rescue: Canon and Nikon have chosen to make only a few prime lenses with aspherical elements that control coma. Over the past year I have discovered there is a manufacturer that does make fast prime lenses with aspherical elements, and at inexpensive prices: The South Korean optical company, Samyang Optics. Samyang produces three wide-aperture aspherical lenses under a variety of brand names (Rokinon, Bower, Samyang, and ProOptic). These lenses are often one-half to one-fourth the price of Canon and Nikon lenses with similar focal lengths and maximum apertures specifications. The Samyang / Rokinon / Bower lenses that I recommend for starscape photography are the 14mm Ultra Wide-Angle f/2.8 IF ED UMC, the 24mm f/1.4 ED AS UMC Wide-Angle, and the 35mm f/1.4 Wide-Angle US UM. All three have the largest apertures in their class, and all three have aspherical elements.

COMPARE the same stars near the edge of the photograph (shown at 100% enlargement) with the $600 Samyang/Rokinon lens vs. the $1,800+ Canon lens. Coma is almost completely controlled on the left image; however, light fall off or vignetting is more noticeable. Vignetting can be corrected with software. Coma cannot! [Click or touch image to enlarge] ~ © Royce Bair

The Samyang / Rokinon / Bower 24mm lens also includes ED elements that are usually reserved for more expensive lenses. (ED means extra-low dispersion, referring to a type of glass that disperses light less than ordinary glass. Dispersion is the breaking up light into its original colors. Because dispersion can cause chromatic aberration, ED glass elements help reduce purple fringing and other chromatic aberrations.)

Aspherical lenses by Samyang Opics: 14mm f/2.8 - 24mm f/1.4 - 35mm f/1.4

Manual everything reduces their cost: What makes the Samyang lenses so inexpensive is that they lack all of the automatic features we've come to rely on, i.e. auto focus and electronic coupling with our digital cameras. However, none of these features matter much to an astro-landscape photographer. Auto focus does not work on a night sky, so we must resort to manual focus, anyway. Lack of auto aperture (where the camera stops down the lens' aperture to the preset aperture value) is of little concern when you plan to use the lens wide open.

Recommendations and Reviews: Several of my night photography friends have purchased these lenses and recommend them. For example, Masahiro Miyasaka (Astrononomy Photographer of the Year 2012) uses the 14mm; Mike Berenson uses the 24mm; and David Kingham uses the 35mm for awesome panoramas. I have the 24mm and the 14mm.

Grand Canyon with the Milky Way - taken with Rokinon 14mm f/2.8 ~ © Royce Bair (click to enlarge)

The Samyang / Rokinon 14mm has a 114º angle of coverage, and produces awesome vistas of the Milky Way. It has so much depth of field, even at f/2.8, that some have difficulty focusing it, but its worth the extra effort! It has a little more barrel distortion than than the $1700 Nikon 14mm f/2.8D ED, and more barrel distortion than the $2400 Canon EF 14mm f/2.8 L II USM. Both the Canon and the Nikon are excellent choices for architectural photography, where it is important to maintain straight lines, but you're probably not going to notice this too much on landscapes and starscapes. Here is a Digital-Picture review on the Samyang 14mm.

Grand Canyon - Nankoweep area - taken with Rokinon 24mm f/1.4 ~ © Royce Bair (click to enlarge)

The Samyang / Rokinon 24mm is a favorite lens because of its 84º angle of view, its fast, f/1.4 aperture, and its excellent correction for coma and fringe color. For starscapes, I would actually prefer the wider coverage of the 14mm, but its slower f/2.8 aperture gives overall preference to the 24mm. A Flickr contact of mine, Rick Whitacre, did this coma comparison between the Canon 24mm f/1.4 and the Rokinon 24mm f/1.4 (here's a 260% larger view). Rick did other tests on sharpness, brightness, and vignetting starting here (click image to view all sizes). Nikon users will want to see this LensTip coma comparison between the Nikon Nikkor AF-S 24 mm f/1.4G ED and the Samyang 24mm. Here's a Digital-Picture review on the Samyang 24mm.

The Samyang / Rokinon 35mm is probably the least purchased starscape lens because of its narrower 63º angle of view. However, because it has a less distorted view (closer to that of a normal lens) than most wider angle lenses, it is preferred by many photographers for panoramas, where several vertical images are stitched together (like this one by David Kingham). Here's a Digital-Picture review on the Samyang 35mm.

NOTE: All of these lenses are designed for full-frame camera sensors (i.e. a Nikon FX). They can be used on a Nikon DX camera or a Canon camera with an APS-C size sensor, but the angles of view are less. The angle of view with the 14mm becomes 94º using the Nikon APS-C sensor, and 90º using the Canon APS-C sensor. The angle of view with the 24mm becomes 62º using the Nikon APS-C sensor, and 58º using the Canon APS-C sensor. The angle of view with the 35mm becomes 43º using the Nikon APS-C sensor, and 41º using the Canon APS-C sensor.

Pricing and ordering: (the links are to B&H, which often has lower than list pricing)
Rokinon 14mm f/2.8 Nikon mount - Canon mount - Sony mount ~ List: $399.00
Rokinon 24mm f/1.4 Nikon mount - Canon mount - Sony mount ~ List: $599.00
Rokinon 35mm f/1.4 Nikon mount - Canon mount - Sony mount ~ List: $499.00
(Disclosure: using these links give me a 2% referral commission, but add nothing to your cost. Thanks for your support!)

More Low Coma Lens Recommendation

Here is my first article on Overcoming Coma.

More Low Coma Lenses for NightScape Photography

Comparing for coma aberration —the same stars in the night sky (image edge enlarged to 100%). Most general photography camera lenses do NOT reproduce stars as "points" of light. They suffer from coma aberration. Coma is most apparent near the edges of the image, especially when a lens is used at its maximum or widest aperture. The expensive ($1,800) Canon lens on the right is bested by a $600 Rokinon lens on the left, which is specially designed to reduce coma. ~ © Royce Bair

At only $299 (some camera mounts are higher), the Rokinon 14mm f/2.8 lens is one of the most popular low coma ultra wides on the market (shown mounted to the Sony A7r II via a $99 Fotodiox EF-Sny(E) Fusion Smart AF Lens Mount Adapter —enabling me to use my older Rokinon lens with a Canon mount) ~ © Royce Bair

This is my second list of low coma lenses that I recommend for starry night photography. To receive my recommendation, the lens must be able to reproduce stars near the edges of the image with very little coma aberration, even when the lens is used at its maximum aperture, which should be f/2.8 or wider. One can get by with an f/3.5 or f/4.0 lens, if it has low coma, but these lenses lack the versatility a faster lens offers.

Low Coma Zoom Lenses

Nikon AF-S NIKKOR 14-24mm f/2.8G ED - $1,899.95 MSRP • Nikon mount

A classic. Highly recommended for Nikon full frame (FX) camera users who can afford this great lens. I used the economical Rokinon 14mm f/2.8 for two years with good results, until I closely compare the images from my workshop students who were using the Nikon 14-24mm. The Nikon lens was better built (allowing for heavy professional use), and its images were a little sharper, had better image contrast, had much less vignetting (light fall off near the edges), was easier to manual focus, and of course had auto focus as well as auto diaphragm control for daytime use. Some of my Canon colleagues were even buying the Nikon and adapting it to their Canon cameras, even though they lost electronic coupling and all the automatic controls.  Keep in mind that the large front element on this ultra wide lens (as well as the Tamron 15-30mm and Rokinon 14mm) make attaching filters difficult (there are no threads), if not almost impossible.

Canon EF 16-35mm f/2.8L II USM - $1,499.00 MSRP • Canon mount

Highly recommended for Canon full frame camera users. This lens is a great all-around performer, albeit my tests have shown it to be just a wee bit softer wide open (f/2.8), near the edges, than the Nikon or Tamron 15-30mm, but still sharper than the Rokinon 14mm f/2.8. I also found its coma (near the edges, when shooting at f/2.8) to be just a little more objectionable than the other three lens. Although the Canon EF 16‑35mm f/4L IS USM has Image Stabilization and is $500 cheaper, this is still the better lens for night and general photography, if you can afford it. It’s 108º angle of view is 2 degrees narrower than the Tamron 15-30mm and 6 degrees narrower than the Nikon 14-24mm or Rokinon 14mm. Unlike the Nikon 14-24mm and the Tamron 15-30mm, this ultra wide angle lens does accept front screw on filters (82mm), which is a big plus for many photographers. I recommend the continuous use of a clear filter for this lens as the weather seal works best when a filter is in place, due to the lens’ focus design. A normal thickness UV filter causes some vignetting at 16mm, so I’d recommend a thinner filter, like the B+W 82mm XS-Pro UV.

Tamron SP 15-30mm f/2.8 Di VC USD - $1,199.00 MSRP
• Nikon mount • Canon mount
Highly recommended for both Canon and Nikon full frame cameras. It can also be used on Sony mirrorless E-Mount cameras like the a7s II and the a7r II, by purchasing the Canon mount and using a Metabones adapter. This ultra wide angle zoom lens has become my personal favorite for both starry night and general photography. The construction on this lens is very solid, maybe a little too good (it weighs 100g more than the Nikon 14-24mm and about 460g more than the Canon 16-35mm). Coma is very low, as is almost every other lens aberration. Sharpness and contrast are superb. Many, who have compared this lens with the venerable Nikon 14-24mm, give a slight edge to the Tamron in almost every category (here’s an example). The Tamron is about $700 less than the Nikon 14-24mm and about $300 less than the Canon 16-35mm f/2.8L II. The Tamron also has image stabilization (branded as “VC” or Vibration Compensation), a feature both Nikon and Canon lack. My own tests with this lens showed that the VC feature usually allows me to handhold this lens at least two and even three shutter speeds slower than without VC. On the minus side, the 15mm angle of view was 110.5 degrees compared to 114 degrees for 14mm, and that 3.5 degree coverage difference is occasionally missed when I’m in a tight situation. However, I’ve also appreciated the extra 6 millimeters of closeness I get on the other end of the zoom range (30mm vs. 24mm).

Tokina AT-X 116 PRO DX-II 11-16mm f/2.8 - $489.00 MSRP
• Nikon mount • Canon mount • Sony Alpha mount
Highly recommended for Canon, Nikon and Sony users with cropped, APS-C size sensors. This lens is an incredible value. As far as I know, the Tokina 11-16mm is the world's fastest ultra wide lens for the small or cropped format cameras. It's also well made, very sharp and performs better than Canon’s 10-22mm f/3.5-4.5 (about $650), Nikon’s 12-24mm f/4 (almost $1,000), and far better than the Sony 11-18mm f/4.5-5.6 DT (about $800) — and with lower coma than any of these three lenses. Light falloff or corner vignetting is also quite low.

Low Coma Prime Lenses

NOTE: Many of my prime lens recommendations are for the Rokinon brand (also branded as "Samyang", as both are made by Samyang Optics in South Korea). These lenses have low coma and high optical performance for their price; however, they do not have auto focus, auto diaphragm or electronic coupling (so there is no EXIF info transferred to the camera). Since NightScape photography requires manual focus and using your camera's manual shooting mode, this is usually not a problem, albeit you'll have to write down the f/stop you were using, if this information is important to you ;-)

Rokinon 7.5mm f/3.5 Ultra Wide-Angle Fisheye for Micro 4/3 - $349.00 MSRP
• Micro Four Thirds mount ~ priced at $249.
This fisheye lens gives you a 180° view with dramatic, exaggerated perspective when used with a Micro 4/3 camera. With hybrid aspherical lenses, multi-layer coating and a built-in petal lens hood, you'll be able to produce sharply defined images with a minimum of flare and ghosting.

Rokinon 8mm f/2.8 UMC Fisheye II  - $399.00 MRSP
• Canon EF-M mount • Sony E mount • Sony E mount (silver) • Fujifilm X mount • Fujifilm X mount (silver) • Samsung NX mount • Samsung NX mount (silver) ~ all lenses priced under $300.
This fisheye lens is specifically designed for APS-C sized image sensors. It provide a 35mm-equivalent focal length of 12mm and a full 180° angle of view. Its fast f/2.8 maximum aperture is beneficial for working in low-light conditions. The lens' design features a built-in lens hood and a UMC coating has been applied to the lens elements to reduce surface reflections and prevent lens flare and ghosting for improved light transmission and more contrast-rich imagery.

Rokinon 8mm f/3.5 HD Fisheye with Removable Hood - $399.00 MRSP
• Nikon mount • Canon mount • Sony Alpha mount • Pentax K mount ~ all lenses priced under $280.
This fisheye lens gives you a 167º view with dramatic, exaggerated perspective when used with an APS-C camera, or a powerful circular image floating in the frame when used with a full frame camera. Hybrid aspherical elements and multi-layer coating produce sharply defined images with a minimum of flare and ghosting. The 8mm lens focuses as close as 12" (30.48 cm) from the lens. This version of the 8mm f/3.8 Fisheye lens comes with a removable lens hood that will offer glare reduction and lens protection, but can be removed to offer an increased and unobstructed angle of view when shooting with full frame digital cameras.

Rokinon 10mm f/2.8 ED AS NCS CS - $599.00 MSRP
• Nikon mount • Canon EF mount • Canon EF-M mount • Sony E mount • Micro Four Thirds mount • Fujifilm X mount • Pentax K mount • Samsung NX mount ~ all lenses priced under $420.
This wide-angle lens designed specifically for use with APS-C sized image sensors. It has a 35mm-equivalent focal length of 16mm and a broad 105.9° angle of view. One extra-low dispersion element and two aspherical elements have been incorporated into the optical design to minimize chromatic aberrations and distortion in order to produce sharper images. A Nano Coating System (NCS) has been applied to the lens elements in order to reduce surface reflections and prevent lens flare and ghosting for improved light transmission and more contrast-rich imagery.

Rokinon 12mm f/2.0 NCS CS - $499.00 MSRP
• Canon EF-M mount • Sony E mount • Sony E mount (silver) • Micro Four Thirds mount • Micro Four Thirds mount (silver) • Fujifilm X mount • Fujifilm X mount (silver) • Samsung NX mount • Samsung NX mount (silver) ~ all lenses priced under $400.
This high speed wide-angle lens is designed specifically for use with APS-C sized image sensors. It has a 35mm-equivalent focal length of 18mm and a broad 98.9° angle of view. It’s fast f/2.0 maximum aperture is beneficial for working in low-light conditions. Three extra-low dispersion elements and two aspherical elements have been incorporated into the optical design to minimize chromatic aberrations and distortion in order to produce sharper images. Additionally, a Nano Coating System (NCS) has been applied to the lens elements in order to reduce surface reflections and prevent lens flare and ghosting for improved light transmission and more contrast-rich imagery.

Rokinon 12mm f/2.8 ED AS IF NCS UMC Fisheye - $599 MRSP
• Nikon mount • Canon mount • Sony Alpha mount • Sony E mount ~ all lenses priced under $440.
This lens provides a 180º diagonal angle of view on full-frame cameras for an ultra-wide angle, distorted perspective. The f/2.8 maximum aperture is effective in low light situations. The lens' sophisticated optical design consists of 12 lens elements arranged in 8 groups including three elements made of low dispersion ED glass and two aspherical lens elements to minimize coma and chromatic aberrations. Highly effective nanocrystal anti-reflection (NCS) coating applied together with UMC coatings improve light transmission and reduce ghosting. Its internal focus system keeps the front element from extending during focus.

Rokinon 16mm f/2.0 ED AS UMC CS - $499 MSRP
• Nikon mount • Canon mount • Canon EF-M mount • Sony Alpha mount • Sony E mount • Micro Four Thirds mount • Fujifilm X mount • Pentax K mount • Samsung NX mount ~ all lenses priced under $380.
This high speed wide-angle lens is designed for use with APS-C sized image sensors. It has a 35mm-equivalent focal length of 25.6mm and a 79.5° angle of view. A fast maximum aperture of f/2.0 is effective in low light shooting and provides shallow depth of field. With two aspherical lens elements and one extra-low dispersion element, chromatic aberrations are minimized and sharp, color-accurate images are the result. UMC lens coating facilitates even light transmission and reduces ghosting and flare.

- - -

This page is under continuous update. Please return for recommendations and reviews on the follow lenses:

Rokinon 14mm Ultra Wide-Angle f/2.8 IF ED UMC
Zeiss Batis 18mm f/2.8
Sigma 20mm F1.4 DG HSM | Art
Nikon 20mm f/1.8G
Rokinon 24mm f/1.4 ED AS UMC
Sigma 24mm F1.4 DG HSM | Art
Rokinon 35mm f/1.4 AS UMC
Sigma 35mm F1.4 DG HSM | Art
Rokinon 50mm f/1.4 AS IF UMC
Sigma 50mm F1.4 DG HSM | Art
Rokinon 85mm f/1.4 UMC

 

Rokinon 24mm f/1.4 Review

The Rokinon 24mm f/1.4 compared to the Canon EF24mm f/1.4 on the right ($550 vs. $1750)

The Rokinon 24mm f/1.4 ED AS UMC Wide-Angle Lens is hybrid aspherical that is particularly suitable for astro-landscape photography because of its excellent correction for coma aberration, even when used wide open.

Although I have long recommended this and two other lenses made by the Samyang Optics, I have recently received several email messages from prospective buyers, worried about negative reviews they have seen about this lens. This lens is not for general use. It is a totally manual lens —no electronic linkage to the camera, whatsoever. Despite this, it is well suited for astro photography.

Advantages of a f/1.4 Aperture: I have several lenses that I use for astro-landscapes. All but the Rokinon 24mm lens have f/2.8 as their widest aperture. The Rokinon 24mm's f/1.4 provides several nice options.

• Using f/1.4 allows you to lower your ISO, or...
• Shorten your exposure time (to reduce star trailing), or...
• Do both: reduce ISO and shorten your exposure time, or you can...
• Stop down to f/2.0 to increase sharpness and reduce lens vignetting

A typical exposure with the an ultra wide angle lens is f/2.8 for 25 to 30 seconds @ ISO 6400. With the 24mm f/1.4 you could go f/1.4 @ for 25 to 30 seconds @ ISO 1600. However, because of it's longer focal length, you'll get less star movement by going 13 to 15 seconds @ ISO 3200. And if you've got a good low-noise camera sensor, you won't mind going to ISO 6400 and closing down to f/2.0 for the increase in depth of field (for close foreground objects) and significantly reducing the lens' vignetting (see "My Personal Preferences", below).

Comparison: Let me share a comparison I did with my $1,750 Canon EF24mm f/1.4L II USM and the $550 Rokinon 24mm f/1.4. (The Rokinon is also branded as a Samyang or Bower. They are all the same lens, made by Samyang Optics.) The following test photos were taken about 15 miles away from Salt Lake City, at the Brighton Ski Resort. Being this close to SLC, the skies are still polluted with light from the valley below, but for a 30-minute drive, it still allows one to record the medium to bright stars.

Night Ski above Brighton Ski Resort ~ Taken with the Canon EF24mm f/1.4 @ f/2.8
(This lens must be stopped down to at least f/2.8 in order to correct its coma aberration.)
At f/2.8, the Canon performed slightly better than the Rokinon, but at f/1.4 and f/2.0,
the Rokinon out-performed the Canon in sharpness and coma correction.

The following images are directly from the camera JPEGs with no post-processing correction for white balance, noise, or lens vignetting:

Full-Frame comparisons: The color rendition of the Rokinon is slightly different from the Canon,
but the most significant difference is lens vignetting. For the extra $1,200 you pay for the
Canon lens, you get about one-stop less lens vignetting in the corners. However, this
can easily be corrected in the Adobe Raw Converter software. (Click to enlarge)

Center enlargements @ 100%: Neither lens exhibits coma in the center, but the Canon is slightly
less sharp and has a touch more color fringing (click to enlarge).

Edge enlargements @ 100%: The Rokinon exhibits about 1/2-stop fall-off on the edges, and about
1-stop fall-off in the corners compared to the Canon. Sharpness is about the same.  However,
the big difference is coma. Canon's coma in the edges and corners is so bad, it's off the chart;
whereas the Rokinon exhibits only minor coma aberration, albeit some color fringing.
(Click to enlarge. Note: the "stick" in the sky is a snow marker for snow plows.)

Manual Focus: the Rokinon is manual everything, including focus —which is not a problem, since auto
focus doesn't work in the dark, anyway! As with any lens used for starry night photography, I find it
a good idea to focus on an "infinity" object (i.e. a tree on the horizon, about 200+ feet away) during
the daytime. I use the camera's "live view" function and magnify my image 10X on the LCD
screen. I've marked that position with a green dot on the lens focusing ring (green turns
black under red headlamp light). The red dot is this lens' 50 feet mark.

Angle of view: About half of my NightScapes are taken with a 14mm (114º angle of view), and the other
half with the 24mm's 84º angle of view. You can capture more of the sky with the 14mm, but when
I want to emphasis the beauty and drama of the Milky Way's Central Bulge, the 24mm is a
perfect fit!  ~ Alabama Hills with the 24mm Rokinon, @ f/2.0, 13", ISO 6400.

My personal Preferences: About 80% of my Rokinon 24mm shooting is done at f/2.0. I prefer to stop down for a little extra sharpness, better depth of field for foreground objects, and a significant reduction in lens vignetting (even though this can be corrected in software, you do run the risk of color cross-overs in your corners, which can also be corrected, but it is an extra post-processing hassle that I'll discuss in another blog post, someday). My typical exposure with my Canon 5D Mark III is f2.0, for 13 seconds @ ISO 6400. This short exposure produces extremely sharp and almost perfectly round stars. Even a two second increase to 15 seconds can sometime produce elliptical-shaped stars, and a 20-seconds exposure is almost sure to have some significant star movement. Mind you, this movement is only noticeable in large prints of 20x30 inches or larger —but that's the kind of quality I'm shooting for.

Conclusion: I find the Rokinon 24mm f/1.4 lens offers great performance, especially when one considers the price. The advantage of having an f/1.4 aperture in your arsenal of lenses provides many options that other lenses don't offer.

Pro: Low price. Good sharpness. Excellent coma corrections. Fast, f/1.4 aperture. Good construction. Cons: Significant lens vignetting, but this can be mostly corrected with software. Many non-critical (low-tolerance) components are made of plastic to reduce cost. This does not affect performance, but can affect long-term durability in rough environments and handling. Manual everything: Manual focus, manual aperture, and no electronic coupling to your camera body (no EXIF info can be transmitted to the image file).

The Rokinon 24mm is available through B&H in the Canon mount, Nikon mount, and Sony mount. Note: The Nikon mount includes an electronic focus confirmation and auto aperture chip that adds about $50 to the price.

Night Focusing the Rokinon 14mm Lens

MilkyWay over String Lake, taken with the Rokinon 14mm lens ~ © Royce Bair

Many have purchased the Rokinon 14mm f/2.8 lens for starry night photography, at my recommendation, and then have written to me about their difficultly in focusing this lens for night photography.

Focus Frustrations and Fix: I must admit, that the first time I tried to focus this manual lens I was a bit bewildered. It seemed to stay in focus no matter what I did! This is due to the incredible depth of field of this 114º angle lens, even wide open. After considerable tests in the daylight and field testing at night, I can make the following recommendations: Don't focus on the infinity mark (some are even confused as to what position the infinity mark is located on the lens barrel).

Left: This is NOT the infinity position. Right: This is the infinity position.
HOWEVER, I recommend the following focus position below:

This is the focus position I recommend when shooting 'NightScapes':
Shoot at f/2.8, and set your focus halfway between the 10-feet mark and the infinity mark.

Hyperfocal Distance correction: Some hyperfocal charts will recommend focusing on 7-feet (actually, 7.62 feet—saying that everything from 3.81 feet to infinity will now be in focus). I find that I get better infinity sharpness at my focus position, and I still get good depth of field in to about 10 feet. I think this is because most hyperfocal DOF charts are based on the sharpness quality of an 8x10 inch print, whereas I want 16x20 and even 30x40 quality. (Quoting the Cambridge in Colour website about hyperfocal distances: "... it's often helpful to use a more rigorous requirement for 'acceptably sharp,' or to focus slightly further and improve background sharpness.")

Best Ultra-Wide Lenses for Starry Night Photography: The Rokinon 14mm f/2.8 lens has incredible coma correction and quality for a lens of it's price (about $350). It surpasses the coma aberration correction (even wide open) of most lenses in its ultra wide-angle category. I find it has about 1.5 stops of light fall-off in the corners (vignetting), which is easily corrected in the Adobe Raw Converter (via Photoshop or Lightroom). It is also a little soft in the edges, unless you stop down to about f5.6 or smaller; however, I don't recommend doing that if you're using the lens for high-ISO night photography—just keep this lens wide open, and place important areas away from the edges or corners of your composition. When doing daylight landscape photography, I found this lens performed optimally at f/11, with the focus set at 7-feet (f/16 was also very good, but at f/22, I began to notice a little bit of diffraction).  If you're a Nikon user (and can afford to shell out about $2,000), the only other lens I'd recommend in this category is the Nikkor 14-24mm f/2.8 lens. This lens is well-corrected in every area, and is sharper than most prime lenses. It is a little sharper than the Rokinon, especially in the corners. Some Canon users like it so much, they even have the Nikon mount adapted to fit their EOS bodies!

Full-resolution crop of the top photo. Enlarge or download this image to see for yourself the quality of the
Rokinon 14mm when used wide open at f/2.8—just keep in mind that you're also seeing the coarseness of an
ISO 6400 image that has had some noise reduction in the ARC software (which tends to soften shadow detail).

Sale Alert! Bower 14mm f/2.8 Lens for $329

One of my favorite lenses for starry night landscape photography is on sale at B&H (ending Tuesday, April 30, 2013)! This lens typically lists for $349 to $399, and is on sale for $329. This article that I wrote a couple of months ago will explain why I recommend this and two other lenses manufactured by Samyang Optics.

Bower 14mm f/2.8 Ultra Wide Angle Lens

(a.k.a. Samyang, Rokinon)

$329 thru April 30, 2013 @ B&H Photo Video

Bower 14mm f/2.8 Ultra Wide Angle Manual Focus Lens

The Bower lens is a branding of the Samyang (a.k.a "Rokinon") 14mm f/2.8 lens. All three lenses are made by Samyang and have the same specifications.

Concerns about optical quality: On the the B&H site, you'll read this information:

This bright lens provides an ultra wide 89° angle view in digital SLR cameras with APS-C size sensors and a 114° angle of view when used with full frame DSLRs* so you can capture sweeping vistas, dramatic architectural compositions and panoramas. Additionally, its minimum focusing distance of only 11" (0.28 m) will allow you to move in close on your subjects to achieve amazing perspectives. With a fast f/2.8 aperture photographers can create dynamic photographs that take full advantage of the characteristics of the lens.

* Note: Though this lens will cover the imaging sensor of a full-frame DSLR, it is better optimized for use with DSLRs containing smaller APS-C format sensors. As such you might notice softer focus and some light fall-off towards the edges of the frame when using a full-frame DSLR. If you do plan on using this lens with a full-frame DSLR we recommend you set the lens no wider (faster) than f/8 for optimum image quality.

Many night photographers have use this lens extensively on full-frame cameras. It is true that this lens suffers from some vignetting until stopped down to about f/5.6 or f/8, but this problem can easily be overcome with software in post production (my more expensive Canon lenses suffer similar vignetting problems). You can also overcome the slight softness on foreground landscape objects by shooting at smaller apertures and then stacking or layering those areas in post with your wide-open aperture exposure of the starry night sky. What you cannot do in post is fix the coma aberration problems that other, more expensive lenses exhibit. This lens has excellent correction for coma, even wide open at the f/2.8 aperture! My $800 Canon EF 15mm f/2.8 Fisheye lens is a little sharper wide open than the Bower/Samyang/Rokinon 14mm lens, and it has a little less vignetting in the corners; however; this 14mm produces much sharper stars (points of light), especially in the corners than does my Canon 15mm. Overall, for "starry night landscape photography" this lens is best in its class, and I highly recommend it.

Yes, you can use it on cameras with smaller APS-C format sensors, and this will automatically eliminate most of the vignetting, but you'll also only get 89 degrees of view coverage vs. the 114 degrees of view coverage you'd get on a camera with a full-frame sensor.

< < This campfire photo (with moonglow and starry sky) was taken just last week with the Bower/Samyang/Rokinon 14mm lens (on a Canon 5D Mark III • f/2.8 • 8 seconds • ISO 3200). The people in the foreground are soft because they were moving during the 8-seconds exposure; however, the skyline and the stars are very sharp (click on image to enlarge).



Comparing Angle of View: Here's a quick comparison of the angle of view produced by the 24mm Bower/Samyang/Rokinon lens (84º), the Bower/Samyang/Rokinon 14mm lens (114º), and the Canon EF 15mm Fisheye lens (180º) — all on a full-frame sensor camera:

24mm, 14mm, and 15mm fisheye lens views (click to enlarge)

These were shot in my kitchen (my wife is upset that I didn't clean off the counters, first). All lenses views were aligned with the cupboard doors on the right side. You'll notice that the 14mm has considerable more coverage that the 24mm (30º more). Although the 15mm fisheye has more coverage, you get considerable barrel (curve) distortion as you get closer to the edges.

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Overcoming Coma in Starry Night Photography

A night photographer must learn how to control lens aberrations, like coma, in order to produce great photos of a star-filled sky that includes landscape features. (Click on above image for more information and a larger view.)

Those who are familiar with my recent style of NightScape work know that I'm photographing the stars as points of light, rather than as star trials. To do this, I must keep my exposures under 30 seconds, and often as short as eight seconds, depending on the focal length of the lens. In order to get the proper sky exposure, I must use high ISO's (typically above 6400), and large lens apertures, such as f/2.8 or wider.

The problem with shooting a lens wide open is that stars can really show off the faults or aberrations of a lens, especially coma. Comatic aberration causes point sources, such as stars, to appear distorted --appearing to have a tail (coma) like a comet. These coma "tails" are most apparent near the edges of a photo. The good news is that 50% of the distortion goes away when a well-designed lens is stopped down by one stop, and about 80% goes away by two stops. Unfortunately, with my night photography, I can't afford the light loss that comes with stopping down from f/2.8 to f/4.0 or f/5.6!

This is the reason I purchased the Canon EF 24mm f/1.4 L USM II Wide Angle Lens. This lens was used to photographed the above photo of the Milky Way over the Watchman, in Zion National Park. As you can (below) from my own tests on point sources of light, this lens is fairly well-corrected by f/2.8 (click on the image for a larger view):

You'll notice that by closing down two more stops, to f/5.6, does not produce as significant of an improvement! If I get in a pinch, and need more light, I can get acceptable results at f/2.0. But the real beauty of this lens is the bright image it gives you in the viewfinder. You can imagine that composing in near pitch black is made so much easier with this brilliant, f/1.4 lens!

I get similar results with my Canon EF 50mm f/1.4 USM Standard Lens. By stopping down to f/2.8, I've been able to make print enlargements up to 24x36 inches (and 30x40) with very pleasing results. Stopping down to f/2.0 reduces my print quality to about 18x24 inches (or 16x20). Shooting wide open (f/1.4) means I cannot enlarge my prints much beyond 8x10 or 11x14 inches (unless I don't want my name associated with them)!

Royce Bair is the editor of this blog and the photographer of the above images. Here is my gallery of NightScape images. My schedule of workshops, tutorials, and other events is available here. 

UPDATE - Inexpensive prime lenses with almost NO coma: Check out part II about the Samyang / Rokinon lenses. These lenses can be used wide open (at f/1.4), and have very little coma!