Oh, Those Stars at Night

Milky Way Galaxy as Seen From Chambers Lake in Northern Colorado

I’ve always had a fascination with night photography.

Most of the photographs I’ve taken of the night skies over the years have been fairly simple. A wide angle, fast aperture lens mounted to a camera, supported by a sturdy tripod. Great for landscape photos, star trails, Milky Way galaxy. But this is a fairly limiting approach.

I broke out my telescopes this winter and was looking at ways to mount a DSLR to them. I quickly discovered that the optical quality and construction of my telescopes, while quite suitable for viewing, did not really equate to high quality photographs.

The basic formula for photographing celestial objects is called the rule of 500, sometimes referred to as the rule of 600.  The rule is a mathematics rule that tells you what the maximum exposure time one can use to photograph stars or the moon or other fixed night sky subjects without a visual blur to the stars due to the earth’s rotation. I’ve found the rule of 600 works fairly good with wide angle lenses, and when using a super-telephoto lens I revert to the rule of 500. Simply stated, divide 600 or 500 by the focal length of the lens, and you get the maximum exposure time you should use to prevent the blur.  This simple rule works fairly well on a full frame sensor and crop sensor. With the crop sensor camera, you must calculate the effective focal length of the lens by multiplying the crop sensor crop factor by the focal length.

For example. If you wish to photograph the moon with a 500mm lens on a full frame sensor I would use the rule of 500. 500/500 = 1 second exposure time max.  The same photograph taken at a 250 mm focal length on a full frame sensor would be 500/250 = 2 second exposure time max.

For a crop sensor camera, lets say a Nikon D7200 (it’s what I have), you multiply the focal length of the lens by the crop factor. In my case with the D7200, the math is 500mm x 1.5 (crop factor), so the effective focal length is now 750 mm, Using the rule of 500, you divide 500/750 = .66 seconds maximum exposure time. The crop factor increases the effective focal length of the lens and consequently reduces the amount of time you can expose without apparent movement of the night sky objects. Simple stuff.

For wide angle photography, one gets a little more exposure time by virtue of the wider focal angle. For example, if I wish to use a 20 mm prime lens on my D7200, I multiply 20 x 1.5 and get an effective focal length of 30mm. Using the rule of 600 (my wide angle rule) I calculate the maximum exposure as 600/30 = 20 seconds. The wider focal angle reduces the relative movement of the stars over time, so you can expose for a longer period of time and/or reduce the ISO, thus making for less noise in the image. There are trade-offs and tricks you lean once you understand the basics of night photography but these are the foundations we start with.

The moon is a sunlit object, so a 1 or 2 second exposure time is more than adequate to get a good exposure at just about any ISO setting.  For stars, there is less light so longer exposure times are preferred to capturing more light at the sensor and getting more stars in the photo. This is all beginners stuff and something easily learned.

Milky Way photos are fairly easy if you are in a dark sky area but again, you’re stuck with the calculated time limits if you want sharp images.

But, stars and the moon aren’t the only objects out there in space. There are galaxies, nebula, and other things. Most of which can’t be seen with the naked eye, so a telescope is really required to view them.

The very best telescopes have what are called equatorial drives attached to them. The equatorial drive is essentially a motor driven device that will move the telescope in synchronization with the objects rotating around the earth.  If you want to photograph something like the Orion Nebula, or a distant galaxy, which are very dim objects, one must find a way to increase the exposure times on photographs. The equatorial drive provides a stationary view of a moving object, thus the exposure times can be increased dramatically.  Light is additive, so longer exposure times means more light gathered and better noise free photographs.  Using special software these longer exposure images can be filtered and stacked together using computer software to get really nice results. So I’ve heard.

I’ve never attempted this before, but I do have a few friends who have thrown their efforts at this and I’m convinced that I too can do it if I have the proper equipment.

I’ve heard tales of photographers dropping tens of thousands of dollars into astro-photography equipment. A good quality telescope with equatorial drive can run several thousand dollars all by itself. Start throwing in the different gizmos and doodads and like any expensive hobby, it can become a money pit.

My telescopes don’t have equatorial drives and their optics aren’t very good for quality so what to do?

Well, I have high quality optics in my camera lenses and the best approach for me at the moment would be to take advantage of the gear I do have.  I can cover any focal length between 20mm and 750mm, so all I really need is an equatorial drive to wade into the money pit.

My wife was kind enough to give me an equatorial drive as a Christmas gift this year. A gizmo made by a company called iOptron. The gizmo is called the SkyGuide Pro camera mount. Essentially, it’s a single axis equatorial drive that attaches to my photography tripod and camera and once properly aligned to my photographic latitude and true north will provide me with a way to actually track and photograph a space object that moves with the earth’s rotation.

iOptron SkyGuide Pro With Nikon D7200 & 70-200mm f/4 Lens

The idea is that it will allow me to increase exposure times and that gives me more light to see things with the camera for longer periods of time.

Couple the equatorial drive with a good selection of high quality lenses on a high quality camera, the sky is the limit so to speak. No, it’s not the Hubble Telescope, but from the images I’ve seen on the internet using the SkyGuide Pro and similar camera equipment to mine, I should be able to get something nice out of it.

Night sky photography is tough in cities and areas with high light pollution.  Those city lights and smog and other things in the atmosphere degrade the visibility from the suburbs. Lucky me though, I have a cabin in the mountains of Northern Colorado and the night sky at my cabin is DARK. A perfect place to see stars and such and a perfect excuse for me to spend more time at my cabin.

This coming year is the year I learn astro-photography. Stay tuned in, I’ll report back with my results and experiences as I improve my knowledge and skills.

I suppose this is what old photographers do when they get bored.



The Eyes Have It

Talk to any experienced portrait photographer and they’ll explain the importance of the eyes in any close-up photograph. The best portraits display the subjects eyes clearly and distinctly. It is the eyes that attract the viewers gaze. An important aspect of those captivating eyes is the use of “catch light.”

Catch light is a specular highlight in the subjects eye(s) caused by a reflection of a bright light source.

Unlike a portrait studio where a light and reflectors can be positioned to enhance a human subject, photographic conditions for wildlife can be a bit more difficult to control. Absent the ability to control the light, one must consciously be aware of the possibility that natural light will produce a good result.

The most common technique I use is to position myself with the sun or bright sky to my 4 O’clock or 8 O’clock behind me.  By insuring I have a bright source of light at a suitable angle behind me, all I have to do is watch the animal’s movement and look for that reflection to appear in the eyes of the critter. Once the animal’s eyes are lit, I start firing shots. Once the animal moves and the specular highlight is no longer appearing, I stop shooting until I can see the animal’s eyes again. It’s an observational and reactionary technique called capturing the decisive moment.

For sunlight reflection, I’ve normally found the best conditions to be at sunrise and early morning after sunrise, or late afternoon, as the sun is low in the sky and beaming directly into the eyes of the animal. I try to position myself to get the sun at my 4 or 8 o’clock. Animals don’t normally like to look into the sun so they’ll often times reposition their head to minimize the glare and that can give you a nice angular field of view to their head, thus reducing the likelihood that the animal will be staring directly at the camera.

Bright blue sky can produce a very appealing catch light in the eyes as well. It will normally manifest itself as a half or partial reflection in the upper portion of the critter’s eyes. Again, one looks for the decisive moment. Simply ripping off shots may result in a frame or two with catch light, but waiting for it to happen and capturing it when it does is the secret here.

I’ve noticed a great reluctance on the part of wildlife photographers to use a flash when photographing animals. I’ve heard many reasons for not making use of a flash; I don’t have one, I’m afraid it will startle the animal and it will attack me, I don’t know how to use a flash, etc…

In my experience, firing a flash at an animal produces no response. I’ve never seen an animal react to a flash going off. They don’t know what it is and animals are more likely to react to something they identify as a potential threat. I believe that flash is just another bright light to critters and they are programed to deal with it the same as any other light they see. They react more to the sound of your camera shutter, and the beauty of a flash is that you aren’t likely to rip out a stream of shots, which can startle them. A rapid mechanical sound of a burst from your camera’s shutter is what they’ll react to. With the flash, you may get two or three frames off but that flash is going to have to recharge and this keeps the bursting down to a minimum while the camera waits for the flash to return to use.

Flash is particularly good with lighting the eyes of birds. The reflective properties of bird eyes are different from mammals and that flash can actually light up the eyes of the feathered creatures quite evenly and distinctly. I’ve never seen a bird react to a flash either.

Don’t be afraid to use your flash.

There are situations where you aren’t likely to get a good catch light and you’ll have no choice but to accept the light as it is. Backlit shots are what come to mind as being the mostly likely scenario. If there is no direct light to bounce of the animal’s eyes, you’ll get those deep shadows and you’ll have to rely on other composition techniques to make the photo stand out. Rim light, silhouettes, etc…

I continue to practice what I preach. and practice is where you’ll find the techniques and results that make compelling animal portraits. When you venture out into nature, take the time to concentrate on perfecting the techniques that work. The trick to getting good animal portraits is to be close to the animal and get those eyes lit up. Every animal has a different personality and it’s the portrait that gives us a look into the soul of the creature. It’s the catch light that draws the viewers eye into the photo and directly into the individual personality of the subject.

There’s more to getting an appealing catch light though. Post processing is always an option for enhancing the catch light.

For me, I never create an artificial catch light in Photoshop. A discerning viewer can tell when something is natural and creating a fake light in the eye, to me, is obvious and more often than not unnatural in appearance. I’m not suggesting you not try it or use it, but for me, I avoid faking something in post processing.

But, as with human portraits, you can and should enhance those eyes if it can be done with good effect. I have no qualms about zooming in on the eyes when editing and giving that specular highlight a little bump of brightness and contrast. I’ll sometimes do a little dodging and burning around the eyes to enhance the natural lines and details that grab the viewers attention. Sharpening the area around the eye ever so slightly improves the detail of the hairs, eyebrows and eyelids. Making those specular reflections just a touch brighter is quite effective too. I look at it as applying makeup to the subject, after the fact.

For me, the eyes have it.


This marmot head-shot was taken on top of Mt. Evans, Colorado. The critter was sitting on a rock and I had a bright, clear blue sky behind me.  The curious animal moved his head to an angle while I was framing him in the viewfinder. Once the catch light appeared, I ripped off a burst of shots.
Here’s an example of a moose with catch light. On this particular occasion, it was cloudy and the light was quite flat.  I was fairly close to this moose so I used an external flash to fill the face of the animal and the reflection of the flash gave me the catch light I wanted. The moose didn’t flinch.
Bison in Colorado
This bison photo was taken as a snow storm was clearing. The sky in the direction I pointed the camera was nearly totally white along with the snowy environment the bison was in. The clearing bright blue sky was directly behind me, so I had a nice flat light situation with a very bright blue sky to reflect in the eyes of the buffalo. I spot metered on the forehead of the bison to get the snow to saturate the exposure and give detail to the head of the animal. I let the sky do the rest of the talking. End result, a nice, high-key image with great catch light. Interestingly, this bison had blue eyes (yes, it happens in nature), so it gave me a nice positive reflective property that created an other-worldly appearance of this bison’s face.
Portrait of a mule deer doe with catch light and a neutral background.

The Photographic Cycles of Life in Colorado

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American Bison at the Rocky Mountain Arsenal National Wildlife Refuge

By mid-October, Winter weather begins its grip on Colorado. As a matter of fact, it’s snowing as I type this. Our first noticeable snow storm of the season here in Denver.

The warm season doesn’t last long here at high altitude. Mountain folk think of Denver and the Front Range dwellers as “flat-landers” to a certain degree.

Being a flat-lander doesn’t dial us suburban folks out of the mountains though. And it certainly doesn’t prevent us from experiencing and photographing wildlife. My primary residence is in the foothills on the South West side of the Denver metropolitan area and for me to get into the mountains is not much trouble. Living in the Denver area provides us locals with plenty of wildlife to photograph.

A popular location is the Rocky Mountain Arsenal National Wildlife Refuge, about 20 miles north-east of downtown Denver, near Denver International Airport.

My next photographic cycle of the season will involve returning the Arsenal for photographs of deer, eagles, hawks, coyote and bison. All of these subjects are worthy of the effort, as I sell quite a few stock photos of these critters. Most popular among them are the bison.

One of the “holy-grail” photos I’ll be after will be the snow covered buffalo. I have a few, some better than others, but there’s always a better shot to get and I will put forth the effort to find that new and better snowy buffalo.

I still call them buffalo too. Techincally speaking buffalo aren’t really buffalo. As every pedantic wildlife enthusiast in the area knows, they are American Bison, but who cares. Nobody ever heard of Bison Bill. He was called Buffalo Bill and he’s buried on top of Lookout Mountain near my house.

I read somewhere that there are over 500,000 buffalo in the United States, the majority of which are actually domestic livestock that are genetically a mix of regular cattle and buffalo. Buffalo meat is tasty and ranchers breed the buffalo with cattle to make the animal more docile and easy to manage in large numbers, though you’d be hard pressed to look at one and know if it’s a Beefalo or a Buffalo.

We have a number of genetically pure buffalo in the state though. The Arsenal herd is a genetically pure herd, so I try to keep it as authentic as possible and go for the pure species specimens.

So with all those happy thoughts evoked, my next goal is the Buffalo.