Lens

A Hidden Gem - For Night Sky Photography

I bet you never heard of Rokinon before, but the Rokinon name is a well known gem among night scape photographers everywhere.  Want stunning night-scapes? Fast-glass is the key factor to create stunning night-time images.

Image By David Kingham

Image By David Kingham

The most important factor is how much light a lens will let in so we can shoot at lower ISO's. This means we'll need a lens with apertures of 2.8 or greater. But most consumer zoom lenses don't go to 2.8, while this is perfectly okay for daytime photography, it's not ideal for nightscapes. 

Here's where prime lens come in. A prime lens is a fixed focal length that is designed to have much larger apertures. If you have every looked into the major manufacturer's primes (such as Nikon, Canon, or Sony) you may be thinking I'm crazy because they are expensive! Anywhere from $1000-$2500 dollars.

Image by Joe Parks

Image by Joe Parks

Relax, here is where Rokinon lens come to the rescue. A 14mm Rokinon f/2.8 lens is only around $360 dollars US. How can that be, you say?. Rokinon lens are totally manual, and have no autofocus. 

Now before you go screaming into the night yelling MANUAL!! , NO AUTOFOCUS!!.. Think about it for a second.. If your shooting the night sky, autofocus is useless anyway. You must manually focus night sky shots for the best results. Is this starting to make sense? All you should care about is image quality.. how sharp are the optics, that's whats important.

Why spend $2000 dollars just to get autofocus?

The Rokinon 14mm f/2.8 is remarkably sharp and free of coma at f/2.8. Solid construction, very precise focus ring. It's one of my favorite lenses and insanely affordable. This is a great lens to get your feet wet in night photography.

Do you know your Lens Sweet Spot

Ever wondered why your cameras sharpness seems to vary from shot to shot.  One shot would be tack sharp, another shot just didn't have the same sharpness and would be a little murky . While there are many factors that affect an image sharpness, you can increase your chances of a tack sharp shot by knowing your lens' sweet spot.

That's right, every lens has a sweet spot.  The sweet spot refers to the aperture setting of a given lens that yields the best overall sharpness. The fact is, that lenses are not uniformly sharp at every aperture, nor at every focusing distance.

So how does one go about identifying a lens' sweet spot?

Here's what you'll need:

  1. DSLR Camera w/ a self timer

  2. A Tripod

  3. Newspaper or sheet of paper with printed text on it.

Now, tape the newspaper to a wall making sure that it's as flat to the wall as possible. If the light is required then set it up and shine it on the newspaper. Next, set up your tripod with the camera on it at a distance that will allow you to fill the frame with the newspaper. Set your camera on aperture priority mode. Set your aperture to the maximum that the lens will allow. Depending on the lens that you are working with, the minimum and maximum aperture values will be different.

For the purpose of this article I will be using the Canon EF 50mm f1.8 II.The maximum aperture of this lens is f1.8 and the minimum aperture is f22. Next, focus the lens on the newspaper.  For each shot we will us the cameras built-in 2 second self timer function to prevent any vibration caused from pressing the shutter . Next we want to take a series of images carefully adjusting the aperture down by one stop at a time (example – f1.8, f2.8, f4.0, f5.6, f8.0, f11, f16, f22). Once we have completed each of the exposures it’s time to download the images to our computer and have a look!

The above image shows 100% crop examples taken from the top left corner of each of the images.

  • F1.8 is downright fussy & soft.

  • F2.8 is better, but still soft.

  • F4.0 is much better.

  • F5.6 better still!

  • F8.0 Now that's sharp as a tack.

  • F11 softening a bit.

  • F16 still softer.

  • F22 softer still.

Well based on results from the above examples, this particular lens offers the best overall sharpness at F8.0.

For my Canon 50mm f1.8 - The SWEET SPOT is F8!

Now go ahead and test all of your lenses, and identify the "sweet spot", the results may surprise you!

 

Do you wear protection? Expensive Lesson, Easily Prevented

Image By: Axel Drainville http://www.flickr.com/photos/axelrd/

Image By: Axel Drainville http://www.flickr.com/photos/axelrd/

Back in the days of shooting film, color was physically split into red, blue and green layers. Oddly enough, the blue layer was found to be particularly sensitive  to ultraviolet rays. In certain situations where there was excessive UV light — for example, a bright sunny day on the beach,  cameras would produce pictures with a blue-tinted haze and greatly reduced constrast. Thus the the invention of the UV filter. UV filters are specifically designed to absorb ultraviolet rays, thus eliminating the undesirable blue haze from our pictures.
Todays digital cameras have coatings and filters built-in to stop everything from Infrared to UV light from interfering with your pictures. With todays cameras not really needing that protection, a UV filter doesn't make a whole lot of sense — at least, not for the purpose it was originally conceived.

So why use UV filters? In one word, PROTECTION.

Let’s face it, lenses are expensive. UV Filter protect the front lens element against scratches, dust, flying sand, sea water spray and the like, plus it can be kept on the lens at all times. Many photographers use UV filters as a added layer of protection for their lenses' glass and special lens coatings.  Remember, it’s much cheaper to replace a scratched or broken filter than replace a $1000 lens. 

A few words on choosing a UV filter: This is not the time to cheap-out. Always go for the high-end glass filters! It makes no sense to spend tens of thousands of dollars on cameras and lenses, only to save a few bucks by buying sub-par plastic filters. The filter is the first piece of glass through which light passes, and its quality must match that of your camera and lens. Cheap filters will introduce lens flare and have an negative impact on contrast and sharpness.

Here are the main points to look out for when choosing a quality UV filter.

Ensure that it’s crafted from high quality, optical glass. Also ensure that the filter is multi-coated for reducing flare, ghosting, and reflections on the filter surface. 

I highly recommend B+W filters, these are considered to one of the finest glass filters on the market today. I use B+W on all my lens.

Don't own one of these? You should!

The world famous 50mm Prime Lens, better known as the infamous “Nifty Fifty”. Dollar for dollar, you would be hard pressed to beat it. A prime 50mm will outshine any kit lens and even outshines most  zooms too.

50mm lenses mimic the field of vision of the human eye and therefore this translates into a accurate scene for your photos. This is partially why sometimes 50mm lens are called, “normal lenses.” or “standard”, when combined with good photographic technique, a 50mm can make people feel more as if they are actually in the moment you are capturing.

The most exciting aspect of a 50mm lens is it’s wide aperture.. It's fast glass! Generally, most 50mm lens have a aperture of f1.8 or wider. That’s a lot of light gathering! It makes all the difference in the world shooting in low light.

Now for the best part.. KILLER BOKEH… Bokeh is the Japanese word for a aesthetic quality of blur. Bokeh occurs for parts of the scene that lie outside the depth of field. Photographers sometimes deliberately use a shallow focus technique to create images with prominent out-of-focus regions.

ladybokeh.jpg

We’ve all seen the photos of a beautiful woman in perfect focus while the background is a creamy out of focus blur. That’s BOKEH! A 50mm is worth the investment just for the bokeh alone! Every photographer should own one. If you're still shooting with the standard kit lens that came with your camera, do yourself a favor and take the plunge. You won't regret it!

Now get out and shoot!