Before starting, let me clarify a few things
1. I have never tried shooting with a Nokia 1020
2. This is not a comparison between Nokia 1020 and any other phone.
3. This is not a critical review of Nokia Lumia 1020. I am mentioning it in this post, since it is considered as the benchmark for picture resolution.
4. It is just a rough guide for finding an ideal camera phone
Mobile phones have rapidly become the preferred photographic devices in the past 2-3 years. The trend is rooting itself firmly in place and the social media is full of pictures shot with mobile phones. The biggest surprise comes from Flickr, a platform in which amateur and professional photographers share pictures. iPhones top the list of the most popular cameras in the site.
Recently, I watched the Nokia Lumia 1020 ad campaign. In one of those ads, people fight to capture images of an event from the front row, while a couple sit in the last row to capture it with the phone’s 41 megapixel camera and crop it up close. Does it mean it is the best mobile phone camera ever made? The one with the most megapixels? Certainly not! MORE MEGAPIXELS DO NOT NECESSARILY MEAN BETTER IMAGE QUALITY!
If megapixels mean everything, professional photographers would ditch their Hasselblads and Mamiyas and get Nokia Lumia 1020 for professional photography. Even the venerable full frame Nikon D800 has a mere 36 MP sensor! If megapixels don’t mean anything, what matters the most in photography?
1. Sensor size: Pixel Density
Imagine a crate filled edge to edge with 12 round vessels. Your responsibility is to capture in those vessels as much water from a hose pipe as possible. 12 wide vessels capture certain amount of water in a given time. Replace the 12 vessels with 24 round vessels half their size. They would have collected less amount of water within that span, since more metal surfaces occupy more space and leave more gaps in between.
It is the same with an imaging sensor. In a full frame imaging sensor, 12 MP captures more light than a 24 MP sensor. Now, imagine shrinking the crate and vessels 8.5 times the original size. That is how a mobile phone sensor is designed. So, 12 Megapixels in a mobile phone sensor is not the same as it is in a DSLR sensor. With image processing getting better every year, it’s possible to have an acceptable 10 MP mobile camera. 41 is insane and it is just a marketing gimmick.
Besides, most of us do photography to fill facebook albums. Facebook does not store images in the same resolution as we upload. It downsizes and compresses the images to a lower quality (even with the high definition checked) that a 2MP image is ok for Facebook. A 4MP image has enough pixels to fill up a retina display with the highest resolution. An 8MP file can be printed on a A3 poster without perceivable loss in quality. 41 MP image is, in most situations, overkill or even worthless without downsizing! In a mobile phone, ideally, the sensor should be as big as possible and the megapixels should be kept within the sane best - 5 to 8 would be perfect, to achieve a good image quality.
2. Lens configuration:
In layman’s language, a camera’s lens captures image and shrinks it to fit in a sensor, where it would be converted into a digital image. It’s easy to describe like that; but lens is a very complex hardware; it’s not the same as the one used in a magnifying glass.
Light has three primary colours - Red, Blue and Green. Light bends, when it enters the lens. When it does, all the three colours do not bend at the same speed. So, more and more lens elements are added to realign them. If the colours are not realigned, chromatic aberration occurs. And a lens should not have reflections within; otherwise, the images are plagued by ghosting. So, special anti-reflection coatings are applied on lens elements, while manufacturing. There are a lot more issues, such as distortions, light fall-off, etc. Lens design has to keep those issues within acceptable limits.
With bigger lens barrels, SLRs have the luxury of having many lens elements to achieve the ideal quality of image captured on the sensor. Compact cameras have lesser space, as the lens barrel has to be retracted inside the camera body when switched off. Mobile phones are the least flexible in terms of lens design as they are tiny and fixed. Miniaturising an SLR lens setup to that extent is impossible. So, a mobile phone manufacturer’s ultimate goal is to use the limited space well to achieve the best image quality possible at a fixed wide angle without compromises.
Even in the case of Nikon’s D800 DSLR, the 36 MP sensor is highly demanding and many lenses do not meet the resolution of the sensor. Only the top grade lenses that cost a fortune can be used with a D800 to extract the quality out of it. It is nearly impossible to have a great lens for 41 MP mobile phone camera.
3. Low light performance
The ISO equivalent values of a sensor determine how a camera shoots in low light. The sensitivity of the sensor to light increases with the ISO value. When the sensor is more sensitive, the exposure time (shutter speed) can be very low despite poor lighting conditions, making it possible to capture a useful image at low light. If it takes more time to expose, the pictures will be shaky.
But not every camera captures useful images in low light, as boosting ISO values is tricky. When ISO increase boosts the sensitivity of the sensor, it does not just stop with amplifying the light signals/ pixels, it also amplifies the visible noise also. As a result, artefacts show up and there would be a loss of detail. It requires cutting edge firmware and software to keep the noise at bay and mitigate the details. The processing power of a camera is dedicated for that purpose.
But a mobile phone’s processing power is shared for many other purposes; infact, processing images is not its main purpose. Hence, no matter what, it is better not to force the phone to process too much of data (like giving a 41 megapixel file at high ISO to clean, remove noise and compress into a jpeg file). Otherwise, it would be stuck in terrible lag, lower battery life, etc.
4. Response
A camera should always be ready to take a photo when you wish to. Time taken to open the camera interface, focusing speed and shutter lag are some of the most vital things for a camera, because, these issues can ruin an opportunity to shoot a photo. A moment once missed may not show up again forever. While a 41MP mobile phone camera need not have any of those issues, it certainly will take more time to process the image and compress it into a jpeg file; meanwhile, you would have to wait until it allows you to shoot again.
If a mobile phone camera has a good sensor, lens, response times and low light performance, you can buy it without any doubts. But it would be vital to consider the following points before using a phone as your primary camera.
1. Shooting images with a smartphone for a long time may significantly reduce its battery life. Remember, you need battery life for more important purposes.
2. If you are serious about photography, buy a camera with manual controls. Smartphones don’t let you override their auto settings.
3. Smartphones don’t let you control the Depth Of the Field much. If you want to have a better control over aperture values, go and get a camera with manual controls; preferably an SLR.
4. If you want to set up creative lighting with speedlights/ studio setup, forget your mobile phone camera.
5. A mobile phone camera is not a professional tool. Yes, pictures shot with mobile phone cameras are being published these days. But those phones are not legitimate replacements for a dedicated camera. If you love photography and want to experiment, get a camera instead of a smartphone.