I spend a fair amount of time on this blog talking about delicious bokeh. And why not? One of the things that is difficult to do on these ever better phone cameras is a soft background with creamy bokeh. These phone manufacturers are moving towards software enhancements aka ‘portrait mode’ to emulate the classic portrait look. Honestly the latest generation is pretty good, but what they still haven’t done and likely will never do is the telephoto compression effect.
New Orleans, LA, 2016
Using a true optical telephoto does more than just bring the subject “closer”. It creates a ‘compression’ effect that is very difficult to emulate with software. The image of the French Quarter in New Orleans to the left was taken with a Canon EOS M3 with an 80-200 zoom set at 121mm (35mm equivalent 194mm). Even with this modest level of telephoto, the compression effect is evident. Look how the background high rises are stuffed up close to the mid ground and foreground.
Camera manufacturers used to have lens guides to help sell SLR users on the benefits of buying additional lenses. Odd that they don’t do that much anymore. These guides often had two charts showing a wide range of focal lengths. The first was an angle of view or magnification chart, the second a perspective chart.
The angle of view chart would take a camera placed in the exact same location pointed at a target in the distance. The first lens was typically the widest lens available maybe a 15mm fish-eye then subsequently longer lenses that effectively brought some distant subject, rendered nearly invisible with the fish-eye, shockingly close with the long telephoto of 800mm or 1200mm. Modern digital cameras with enough pixels can effectively achieve the optical telephoto “effect” with a digital zoom. For every 2x of magnification 4x fewer pixels are used. If a 12mp camera delivers a 4:3 ratio 4000 x 3000 pixel image a 2x digital crop becomes a 2000 x 1500 pixel image. Yes that 12mp camera at 2x digital zoom is now a 3mp camera. 4x digital zoom drops the resolution to 1000 x 750 pixels and that is a mere 0.75mp image. On a full frame camera this is the equivalent of going from a 50mm lens to a 200mm lens but you are cropping away 93.75% of your pixels. Although a photo with as few as 640 x 480 pixels can look fine on a Facebook post it cannot be blown up much or printed very well, nor can it be manipulated in Lightroom or Photoshop type software without major digital noise developing. Digital zoom simply sucks and honestly even a camera with a whopping 108mp, would still be limited to an effective digital zoom magnification ratio of 6x while still maintaining high quality editable images of about 3mp.
Of further note, the camera in phones often use tiny little sensors and focal lengths so short that depth of field is nearly infinite. This is why soft out of focus backgrounds have to be software created (aka “fake”) on phone cameras. The tiny sensors have itty-bitty little pixels that do not gather light well and that leads to more digital noise when shooting in low light or more importantly, when editing images in software programs on your pc.
Canon USA, 1977
Camera phones do perform exceptionally well outdoors and on close focus subjects like people. They are crisp and sharp. But how many people shoot a “selfie” and think, I don’t look right? Well the camera phone is using a fairly wide-angle lens, otherwise you could not hold the camera in you hand and get your whole face in the picture.
Shooting a head shot with a wide-angle lens is rarely flattering to the subject. The relative distance from the camera to various contours of the face are exaggerated with the wide-angle lens because you are so close to the subject. Look at it this way: If a tight head shot is taken with a 24mm lens on a FF DSLR, the camera will be about 12-15 inches from the subject. If it is 12 inches away focused on the eyes. the person’s nose would be 10.0 inches away and the eyes 12 inches and the ears 15 inches. This is how the exaggeration occurs, the relative difference is steep as the ears are 50% further away from the image plane as the tip of the nose. The same image made from further away with a 105mm lens would yield the same head shot but with a “flatter” look to the face. Why? Because now the camera is 5 times further away at 60 inches. The tip of the nose is 58 inches and the ears are 63 inches, which is the same 5 inches as before. The relative difference between the tip of the nose and the ears is now only 8% from the position of the camera.
This is where those old school lens brochure’s perspective charts were so revealing. These charts actually showed a fixed subject, say a person and then changed through a series of lenses in the example to the right, from 17mm to 200mm. They kept the subject roughly the same size in the picture. So now the camera had to be moved for each lens to keep the subject the same size. This showed us the perspective of using different lenses. The 17mm shot had the camera up uncomfortably close to the subject which created an illusion that the subject was very far away from the background and distorted the features of the subject. As the lens’ focal length increased the background became increasingly more compressed relative to the subject. A building fifty feet behind the subject now appears to be immediately behind her with a medium telephoto 200mm. Why? Because to keep the subject the same size, the 200mm lens required the camera to be 50 feet away from the subject and thus both the subject and the background were relatively far away. This flattening effect is flattering to the human face as it dis-enhances the natural contours of the face. On full frame cameras the 85mm-135mm range is ideal for portraits.
It is important to remember that depth of field is entirely a matter of focal length, aperture, and distance. In this modern digital world we make comparisons to the “standard” 35mm or ‘full frame’ when comparing lenses across sensor sizes. A 50mm lens on a Canon APS/c camera is “equivalent” to a 80mm lens on 35mm or FF. But it really isn’t. The angle of view is equivalent, but that’s it. The longer 80mm FF lens at the same f-stop will have a more shallow depth of field. The 50mm lens on the APS/c would remain at the same subject to camera distance because the shorter focal length is equally offset by the cropped sensor. All else equal the focal length is shorter and the depth of field is greater. Throwing the background out of focus will be harder on the APS/c than the full frame. So for portraits a 50mm on a Canon 7d is NOT the true equivalent of an 80mm on a 5d.
We are nowhere near the point where a cell phone camera or even a good compact camera can deliver the capability of a DSLR or Compact System Camera. I shoot a lot of photos on my phone because I always have it on me, but I shoot more photos on my ‘real’ cameras because they just do more and they do it better!
Canon USA, 1977
'Couv' Camera 