Before launching into this article I’d like to thank one of our readers, Srikanth, for his recent comment on my The Power of Simplicity article which served as the spark for this posting. This article discusses some simple landscape photography considerations that you can keep in mind which may help you create better quality images. This posting also raises some other things to consider when shooting landscape images with cameras of different sensor sizes.
NOTE: click on images to enlarge.
Srikanth’s question centred around how to achieve ‘focus’ with images similar to the one above. By ‘focus’ I interpreted that the question was about the amount of depth-of-field in a landscape image, i.e. how much of the image was in focus from foreground to background.
This article will attempt to address Srikanth’s question, and also outline some related issues to consider when creating landscape images, regardless of the camera gear you are using.
ISO impact on dynamic range and colour depth
Since landscape images often have a wide range of colours and contrast (i.e. highlights through to shadows) in them, photographers will choose to shoot at the lowest ISO setting possible. All digital cameras will have the best colour depth (i.e. range of colours) and dynamic range (i.e. highlight to shadow detail) performance when used at their lowest ISO setting. As soon as ISO is increased sensor performance on both of these dimensions begins to drop.
Sensor size can impact dynamic range and colour depth performance. For example, my Nikon 1 J5’s small 1″ CX sensor is rated by DxO at 22.1 bits of colour depth and 12 EVs of dynamic range. Both of these scores are considered to be ‘excellent’ by DxO.
However, by comparison the full frame sensor in the Nikon D610 has 25.1-bits of colour depth and 14.36 EV’s of dynamic range. A difference of 1-bit of colour depth and 0.5 EV of dynamic range will be noticeable for most people. At base ISO (i.e. the lowest standard ISO setting on a camera) there is no question that the Nikon 610 would significantly outperform the Nikon 1 J5 on these two important sensor performance measures.
Why sensor performance is important from a practical sense is there will be a lot more highlight and shadow details, as well as colour range and colour differentiation, with the D610 RAW files compared to the Nikon 1 J5 when both are shot at base ISO. This gives a photographer a lot more adjustment latitude when doing post processing of RAW images, and it can have a big impact on how a final image looks.
Shutter speed and subject movement
While many landscape images are captured during very calm conditions, other photographs like the two contained in this article involve some subject movement either due to moving elements in the photograph itself such as the waterfall below or the waves in the beach scene, or caused by wind. How a photographer wants to deal with movement in a landscape image is a creative choice.
At times a slow shutter speed is chosen to create a smoothing effect as in the waterfall image above. In the case of our subject beach image, a somewhat faster shutter speed was used to ‘freeze’ the motion of the waves lapping up on shore, thus achieving a sharper overall look and helping the foreground look ‘in focus’. On a breezy day using a faster shutter speed is important if one wants to avoid blurry looking leaves, grass and flowers.
Depth-of-field and focal length
When creating landscape images most photographers want as much depth-of-field as possible in their photographs. Depth-of-field is the amount of the image from foreground through to background that appears to be in sharp focus. A key point here is that lenses of different focal lengths provide very different amounts of depth-of-field when shot at exactly the same aperture. The wider the angle of the lens the more depth-of-field it will have at any given aperture.
Equivalent field-of-view (efov)
The sensor size in your camera doesn’t impact depth-of-field, but it does impact field-of-view. This is the amount of a scene that the combination of your camera and lens allows you to see.
For illustrative purposes let’s imagine that I was side-by side with another photographer. We both were crouching down capturing the identical beach image featured in this article, but we were using very different gear to do so. In my case let’s say (for comparative purposes) I was using a Nikon 1 J5 with a 1 Nikon 10 mm f/2.8 prime (the image in this article was actually shot with a 10-100 mm non-PD @ 10 mm) . This set up would provide an equivalent field-of-view of 27 mm compared to a full frame body since the J5 uses a small, CX sensor with a 2.7X crop factor.
Now let’s imagine that the other photographer was shooting with a Nikon D610 full frame camera with a Nikkor 28 mm f/1.8 prime lens. Without question the full frame sensor in the other photographer’s D610 would blow my Nikon 1 J5 out of the water in terms of its performance at identical ISO settings. From an equivalent- field-of-view perspective there would be almost no difference at all in what out mutual camera/lens combinations allowed us to see in the frame i.e. 27 mm efov vs 28 mm. The native sizes of our image files would be reasonably close as well (J5 = 5584 x 3724 pixels, D610 = 6080 x 4028 pixels).
How the beach scene image was shot
This photograph was captured hand-held with a Nikon 1 J5 using a 10mm focal length, at an aperture of f/5.6 with a shutter speed of 1/640, at ISO-160 (the lowest ISO setting available on my Nikon 1 J5). I captured the image using a single auto-focus point.
In an earlier article, The Importance of Knowing Your Gear, I mentioned the importance of understanding the depth-of-field characteristics of the lenses we own. From experience I knew that shooting at a 10mm focal length at f/5.6 would create sufficient depth-of-field for the beach image as long as I chose an appropriate focusing point distance. In this case I focused 1.7 metres (5.5 feet) away from where I was crouching. This created depth-of-field from about 0.8 metres (2.6 feet) away from me all the way out to infinity. This depth-of-field range covered the foreground adequately in the photograph. There are Smartphone apps and websites that provide ‘depth-of-field calculators’ for folks that are interested.
Another key point with the beach scene was there was a sufficient amount of light to give me a shutter speed of 1/640. I knew this would be fast enough to ‘freeze’ the wave motion in the photograph and negate the need to shoot at a higher ISO.
Let’s cycle back to that imaginary photographer standing next to me on the beach with their Nikon D610 and Nikkor 28 mm f/2.8, and photographing the exact same scene, using the exact same focusing point.
Specific image creation dynamics can level out sensor size performance differences
As mentioned earlier, all things being equal the sensor in a larger format camera like a D610 will significantly outperform those in smaller format cameras like the Nikon 1 J5. But, all things are not always equal in terms of the settings needed to capture a specific image, and most importantly achieve the desired amount of depth-of-field in a landscape image.
Shooting with a D610 using a Nikkor 28 mm lens set at f/5.6 with a focusing point 1.7 metres away creates a total depth-of-field of roughly 1.3 metres. To achieve the same depth-of-field from 0.8 metres to infinity using the exact same focusing point as I did with a 10 mm focal length, would require an aperture setting of f/16 on the 28 mm lens.
By pushing the focusing point out by about 0.5 metres and sacrificing a bit of depth-of-field in the foreground our imaginary photographer could have shot with their D610 with an aperture of f/11. They would have probably framed the image a bit differently though to allow for the slight difference in depth-of-field at f/11 compared to f/16 and the focusing point being about 0.5 metres further away.
But, let’s compare apples to apples and assume that the imaginary photographer did set their lens at f/16, and used the exact same focus point 1.7 metres away that I did to get the exact same desired depth-of-field. They would now face an issue with either their ISO setting or shutter speed as the image would now be significantly underexposed.
Using the same shutter speed of 1/640 at ISO-100 the image would be underexposed by about 3 stops. With the aperture locked in at f/16 to get the desired depth-of-field and the shutter locked in at 1/640 to ‘freeze’ the wave motion, the only other option left would be to change the ISO setting up 3 stops from ISO-100 to ISO-800 to get a proper exposure. And this ISO change impacts sensor performance.
Nikon 1 J5 at ISO-160 vs. D610 at ISO-800
Let’s have a look at how the far superior full frame sensor in the D610 performs when ISO is adjusted by 3 stops from ISO-100 up to ISO-800 compared to the Nikon 1 J5 at base ISO-160. You can see in the data below that increasing ISO by 3 stops levels out sensor performance with the J5.
Colour depth: J5 = 22.1 bits, D610 = 22-bits
Dynamic range: J5 = 12EV, D610 = 12.2EV
Tonal range: J5 = 8.2-bits, D610 = 8.3-bits
Signal to Noise Ratio: J5 = 36.7 db, D610 = 37db
Obviously I’m not stating that a small sensor camera like the Nikon 1 J5 can compete head-to-head with a full frame D610 in terms of image quality. This simply isn’t true. What I am pointing out is that smaller sensor cameras do allow for the use of wider angles lenses to achieve equivalent fields-of-view. And, since wider angle lenses deliver more depth-of-field at a specific aperture setting, smaller sensor cameras that use M4/3 and CX-sized sensors can be excellent tools to use for landscape photography, especially when shot at f/4 to f/5.6 using wide angle focal lengths.
In situations where a photographer is shooting from a tripod, is able to use their camera’s base ISO, and where using a slower shutter speed is not an issue so lenses can be stopped down to achieve desired depth-of-field, a larger sensor camera will produce better quality landscape images than those with smaller sensor cameras.
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