Wednesday 5 March 2014

How do Camera Sensor Sizes Affect Lens Choices?

How do Camera Sensor Sizes Affect Lens Choices?

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How do Camera Sensor Sizes Affect Lens Choices?

Posted: 05 Mar 2014 01:23 AM PST

So you’ve purchased a DSLR and now you’re considering the acquisition of more lenses to expand your creative capabilities. It may be as simple as getting another lens from the same manufacturer, designed for your camera. But is it?

camera lens

“Life through the lens…” captured by Michelle Hobson (Click image to see more from Hobson.)

For the purposes of this article, I am going to refer only to (arguably) the two biggest camera manufacturers to keep things simple: Canon and Nikon. Each of these manufacturers offers two types of DSLR; consumer level with an APS-C sensor, and pro level with a full frame (FF) sensor.

Sensor Sizes

Canon’s APS-C sensor is approximately 22 x 15mm while Nikon’s is approximately 24 x 16mm. No significant difference there, but compare those with a FF sensor (common to both brands) which measures 36 x 24mm. Does that size sound familiar? If it does, you probably shot on 35mm film at one point in your life, because that’s the size of a negative or slide in that film format.

Why the concern over sensor sizes, and what’s that got to do with lenses? If you consider that a lens projects a circular image onto the back of the camera and where the sensor is mounted, the diameter of that ‘image circle’ will determine whether or not it will completely cover the sensor. A lens designed for a full frame camera will certainly do that for both APS-C and FF sensors, but one designed for APS-C cameras will only have an image circle large enough to cover the APS-C sensor.

full-frame photography

“Yossarian the (Full Frame!) Cat” captured by Tom Bricker using a Nikon D700 camera with full-frame sensor.

Canon distinguishes between the two designs by marking its APS-C-only lenses (sometimes called digital-only) with EF-S while full frame lenses are designated EF. Similarly, Nikon designates theirs as DX and FX for APS-C and full frame, respectively. If you try to attach an EF-S lens to a full frame Canon DSLR, for example, it won’t go. One of the reasons that the manufacturer intentionally makes the mounts incompatible is that the image circle of the EF-S lens will not completely cover the sensor. They are knowingly preventing you from taking ‘vignetted’ shots with dark corners. Conversely, however, you can certainly attach an EF lens to either an APS-C or a pro level Canon DSLR.

Crop Factor

Having made that last statement, some further qualification is required. Imagine that full frame lens projecting an image whose circle more than adequately covers the FF sensor from corner to corner. If you were to project that same image circle onto the much smaller APS-C sensor, the sensor is now only intercepting a fraction of the image circle that the FF sensor intercepted. As a result, the APS-C sensor only ‘sees’ a fraction of the image ‘seen’ by the FF sensor. This is equivalent to zooming in on the full frame image, and is called crop factor. It is typically about 1.6 times between the two formats.

full frame vs. cropped frame camera sensors

“Full Frame Sensor vs 1.6 Crop” captured by Steve Koukoulas

Note that crop factor refers to the sensor size ratio and is not affected by the lens, as long as the focal length of the lens is constant in both cases. So, if we attached a 50mm lens to an APS-C camera and an 80mm lens to a full frame camera, they would capture images that were approximately the same. This is because the 50mm lens on the APS-C camera apparently magnifies the focal length to 50mm x 1.6 = 80mm.

So how does this affect your lens purchases today? Let’s say you’re currently using an APS-C camera, but you want to advance to a FF camera in the future. After all, these large sensor camera bodies are becoming more and more attractively priced, and offer generally better noise performance at higher ISO settings. If you buy all your lenses now in EF-S or DX format, you will have to sell the lot when you buy the pro level body, and will have to buy a complete suite of EF or FX lenses instead. If, however, you buy full frame lenses now, you will not only be able to use them on your current camera but on your future one as well.

Yes, you will pay more for pro level lenses, but chances are you are getting better glass and probably more solid construction. And remember–you don’t have to buy the camera manufacturer’s brands. Third-party lens manufacturers offer lenses in various mounts. Just be sure that you’re buying the full frame version if you decide to go that route.

 About the Author:
Gordon Wood (www.filmscapes.ca) is an engineer, technical writer, photographer and photography instructor.


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Rescued Pelican Taught How to Fly and Documented on Camera (Video)

Posted: 04 Mar 2014 03:33 PM PST

What happens when you find a young pelican, all alone, washed up on a beach after a storm? You teach him to fly and put a small camera on his beak, of course:

This Great White Pelican, or “Big Bird” as the staff at Greystoke Mahale Park affectionately named him, was only about three months old when he paddled ashore from Lake Tanganyika following a large storm.  Initially, the staff and guests on the beach were very puzzled by Big Bird’s sudden appearance, because the nearest known flock of  Great White Pelicans is about 150 kilometers away in Katavi National Park.  According to the Greystoke Mahale’s blog, it is believed that Big Bird may have been sucked up into a cumulonimbus storm cell which relocated him on the lake.

animal action photo

Look closely and you can see the GoPro camera attached to Big Bird’s beak.

The staff at the park said they asked for permission from the park authority, Tanapa, to feed Big Bird fish since he was unable to fish by himself. The Great White Pelican, unlike the Brown Pelican, do not dive for fish individually. Instead, they work together to corral the fish into a single area, then scoop them up into the large, stretchy pouches below their bills.

beach

Not only could Big Bird not fish for himself, but the Greystone Mahale staff found he couldn’t fly, either.

“We aren’t sure how much how much flying he may have already done before arriving here, but he was pretty shaky in his next attempts on the beach.”

The staff taught Big Bird how to fly by running up and down the beach and flapping their arms to simulate flying. He curiously watched them before giving it a try for himself.

animal photography

While the GoPro video of Big Bird shows him gliding smoothly through the air, one staff member says his first flight attempts were a bit rocky.

“[His first flight] was short and uncontrolled and we would look away when he was landing, as he seemed to not distinguish between ground and air speed–coming in way too fast and endangering our beach furniture.”

Judging by Big Bird’s footage, as well as one Striated Caracara’s documentation, it turns out that birds are natural videographers.


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Interesting Photo of the Day: Volcanic Lightning in Iceland

Posted: 04 Mar 2014 02:08 PM PST

Does the photograph below show the wrath of a Nordic god or a natural phenomenon? Maybe both. From the files of weird, wild, and magnificent Iceland comes this photograph by Skarphedinn Thrainsson:

volcanic lightning

The lightning inside this volcanic ash cloud is terrifying, yet beautiful. (Via Imgur.)

The image was taken in April 2010, during the most recent eruption of Eyjafjallajokull, an Icelandic volcano covered by an ice cap. Volcanic lightning–also known as a “dirty thunderstorm”–occurs when static charges are produced by rock fragments and ice particles colliding with the ash in a volcanic cloud.


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Tips and Tricks for Tilt-Shift Timelapse Videos

Posted: 04 Mar 2014 01:40 PM PST

If you’ve ever wanted to make your subjects look small–like, miniature-toy small–you may have investigated buying a tilt-shift lens for more than $2,500. But there are cheaper options. This video gives a host of helpful tips for achieving an awesome tilt-shift style using a normal DSLR lens:

California-based timelapse photographer Ryan Killackey gives the following tips:

  • Shoot downward from a high angle.
  • Don’t include at anything that couldn’t be replicated as a toy, e.g. the sun. Focus on cars, people, and trains.
  • Switch your lens to manual focus and flip off the image stabilization.
  • Instead of relying on an intervalometer, manually press the shutter release on your remote shutter cable and try to create a rhythm yourself.

“Toys move sporadically and with jitter, and we need to mimic that in our time-lapse. So that’s where an incredibly inaccurate remote shutter-release comes in.”

ryan-killackey-photo

Nix the auto setting and release your shutter manually for a more realistic time-lapse.

tilt-shift-video

Omit anything from the frame that could not be replicated in miniature.

Killackey’s video is remarkable to watch; you’d swear he was shooting model trains roll by. The ultimate effect is an inexpensive and very cool video technique that still feels fresh.


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Are Selfies Really So Bad? (Video)

Posted: 04 Mar 2014 12:09 PM PST

Let’s face it, there are a lot of bad selfies–a word which was named the word of year in 2013–floating around on the Internet. A lot. If you’re sick of seeing duck faces popping up all over your social media feeds, you’re not alone. But, according to the video below, we might be giving them a bad rap. Listen to one man’s argument about why we shouldn’t let a few bad photos bring down an entire genre of photography:

“Status updates, not just the text, but the whole set of actions and context comprising them are more like speech acts than they are like writing. In the same way, Instagram and more meaningfully the selfie, not just the photo, but the whole kit and photo caboodle is more like a speech act than like photography. A selfie isn’t exactly a photo, and maybe that’s why so many people hate them.”

selfie_defense_1

It’s an interesting concept. Do we perceive the selfies that flood Instagram and other social networks more like status updates than photography?


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