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BIRDER'S JOURNAL
March 15, 2016

SUBJECT: Sony A6300 Resolution Comparison

PLEASE NOTE: This is really geeky. Read at your own risk...

The tests conducted in this review are designed specifically to reproduce results that a wildlife or bird photographer might encounter while photographing their subjects from a fixed distance. In most cases, we do not enjoy the luxury of being able to move closer to our subjects. Because of this scenario, results can be quite different compared to the many resolution/noise tests found on the Internet.

For example, comparison shots found on DPreview and Imaging Resource are great for portrait/wedding photographers who can move closer or further away to fill the frame of an image. The test results found on their websites are a fair comparison for those types of photographers.

In the world of a bird photographer however, we shoot from where we stand and then crop in post-production. This levels the playing field a bit. Full-frame sensors need to be cropped heavier while cropped sensors cameras require less cropping in post-production.

Below are two images taken from a fixed-distance. The one on the left was taken with the Sony A7RII which is a full-frame sensor camera. The one on the right was taken with the A6300 which is a APC sensor camera. The Sony a6300's sensor is about 35 percent smaller than a full-frame sensor and "pre-crops" the image before you even take the shot:

A7RII, 600mm @ ~25' A6300, 600mm @ ~25'

At first glance, you may say that the A6300 image on the right gives you much better "reach" or magnification. Although it appears that way, the image is simply pre-cropped compared to a standard 35mm image. This supposed extra reach capability has become so rampant on the Internet that even camera manufacturer's are now touting their cameras as having "extra reach" capability.

It's just as if the image was already cropped. Whenever an image is cropped, the subject matter in the image fills the frame more fully. Great! But there is a price. The noise level becomes magnified along with the image. Quite typically a photographer will then crop the images in post-production. The end result is an image that is cropped twice: once by the camera and once by the photographer.

One final note on cropped vs full-frame sensors. My preference is for a full-frame sensor camera as long as it can meeting other criteria listed below. Why? If I have a bald eagle or a heron or other bird flying in close range to me, I'd much rather have a wider field-of-view so that I don't accidently clip a wing out of frame. I can always crop accordingly in post-processing.

The bottom line is there's other criteria more important to what makes an excellent camera for bird photography:

  • Autofocus - It has to be responsive and accurate.

  • FPS - Frames-Per-Second. At a bare minimum 5fps is required. Best is 8-10 fps and beyond depending upon what kind of bird is being photographed. (The smaller the bird, the faster the wingbeat. Ducks for example are best photographed at above 10 fps to get the perfect bird-in-flight wing position whereas a lumbering pelican can be photographed at 5 fps.)

  • Image Quality. Image quality is typically determined by three factors: Dynamic range, noise and resolution.
    • Dynamic range refers to the levels of light a camera sees. The greater the range, the better it can reproduce what the human eye can see. Without going into too much detail here, the greater the dynamic range the more you can manipulate exposure in an image to bring out shadows or reduce highlights without degrading an image.

    • Noise degrades the image. The more of it there is, the more distracting it becomes to both images and video. Whenever an image is cropped, the noise becomes more apparent.

    • Resolution. Resolution is typically determined by the density of the sensor's pixels. The smaller the pixels, the greater the resolution. As a sensor's resolution increases so does the noise levels, producing grainier images.

Let's expand on resolution a bit, because that's really what this post is all about -- testing the resolution of the new A6300 and how it compares (along with noise) with other cameras for bird photography.

Resolution has to do with the density of the sensor's pixels not the crop factor (physical dimensions) of the sensor. This is the one of the factors that determine resolution. The other has to do with how strong of a filter is used over the sensor to prevent unnatural artifacts. That's a subject for another day.

Going back to the subject of resolution and crop factors, just be aware that cropped sensors may not necessarily give you better resolution than a full size sensor. Sometimes they are almost the same.

For example, the Canon 7D Mark II camera is a 20.2MP, 1.6x cropped sensor camera. If it were made into a full frame sensor, the number of megapixels would be close to a 52MP sensor. Canon also makes a high-resolution, full-frame sensor camera called the 5DS. It has a 50.6MP sensor.

One is a cropped-sensor camera (7D Mark II) and the other is a full-frame sensor camera (5DS) and they both produce about the same resolution and about the same amount of noise. There is no extra "reach" with the 7D Mark II compared to the 5DS. The only difference is that the 7D Mark II does not have a full-frame sensor and produces "pre-cropped" images sort-of-speak. (Similar to the above images.)

Looking through the 7D's viewfinder, everything will appear closer, but when photographing from a fixed distance, both cameras produce similar quality images.

Onwards to the comparison...
Please be aware this test was conducted with three cameras from a fixed distance using the Canon 600mm f/4 II lens. This is similar to what one may find in the field -- unable to move closer to the subject. The three cameras tested in this scenario are: Canon 7D Mark II, Sony A7RII and the new Sony A6300.

Tests were conducted at various ISO's with similar results. Shown below are samples taken at ISO's 800 and 1,600. Each image was cropped in post-production to frame the subject (fake owl) identically at 400 ppi. The A7RII required heavier cropping due to it's full-frame sensor while the Canon 7D Mark II required the least amount of cropping due to its 1.6x cropped sensor.

ISO 800, Resolution, 100% pixel level (Click on image for larger view)

 

ISO 800, Noise, 100% pixel level (Click on image for larger view)

 

ISO 1600, Resolution, 100% pixel level (Click on image for larger view)

 

ISO 1600, Noise, 100% pixel level (Click on image for larger view)

Reviewing these samples, the A6300 has a slightly higher resolution compared to the other three cameras. It is minuscule however and not worth writing home about. With the 7D Mark II, I expected slightly better resolution than the A7RII, but probably due to a slightly stronger anti-aliasing filter it's resolution is slightly lower than the other two cameras. That stated, the differences are minuscule and all three produce exceptional resolution.

From a noise level standpoint, the A7RII did the best, followed by the 7D Mark II and finally the A6300. This is what I expected. The smaller the pixel size, the higher the noise. There's no such thing as a free lunch. The higher the resolution, the higher the noise. The lower the resolution, the lower the noise.

Conclusion
All three of these cameras produce excellent results. The bottom line is the A6300 produces slightly higher-resolution images at slightly higher noise levels. After post-processing all three of these camera's images, you'd be hard pressed to tell them apart. Heck, even before post-processing, they look almost identical!

I would look at other criteria to determine if the A6300 is suitable for your needs.

In my opinion, the 7D Mark II would still get my vote as the best all-around birding camera due to it's better autofocus system. Both cameras offer roughly the same fps, but Canon's autofocusing system is more reliable for birds-in-flight and faster focus hunt times. If however you also are in need of a camera with 4k video capabilities, the A6300 has it while the Canon 7D Mark II does not.

I am looking forward to trying the new Sigma MC-11 adapter with the Sigma 150-600mm lens on the A6300. This may improve the autofocus capability of the A6300 but only using Sigma lenses. Canon lenses will not work with the Sigma MC-11 from what I have learned.

Above: Feather detail of a Blue Jay taken with the Sony A6300 at ISO 1600. This image is untouched. It was converted from a raw file using Sony's Image Data Converter - Click on the above image to see pixel-level detail.

—Alan Stankevitz

 

 
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