In most camera phones, there isn’t any variable aperture or mechanical shutter. The so called shutter speed is basically the image processor switching on the sensor for a fixed time, then turning it off. It’s completely electronics. This reduces costs & sensor complexity but comes at the price of not being able to use the Xenon Flash.
The reason is most smartphone sensors are Interline Transfer type meaning after the sensor is on, the voltage levels are “read” line by line. For still subject, this is no issue. However, when the camera is moved from side to side or the subject moves very fast across the screen, the pictures gets distorted. You can test your own camera phone by taking video & panning the phone quickly. If you start to see blocks of the picture getting distorted like blobs of jelly, your sensor is of the Interline Transfer type. The Lumia 920 is definitely of this type although it reads its lines much faster than other smartphones.
This brings me to the Xenon Flash. Unlike the LED light, Xenon Flash has a much higher intensity & much shorter duration, probably around 1/100s for the Lumia 1020. In that time, the image processor would only have enough time to read a portion of the lines in the entire frame. So the picture will have bright band with high dynamic range sandwiched between dark bands with very little details. I know this because someone fired a flash while I was taking a picture on my Lumia 920 at the same time and my picture had this strange effect where the bottom half was brighter than the top half. Took me a while to realize what happened that day.
I know that the sensor on the Lumia 1020 is an Interline Transfer type because when taking video and panning, the picture will wobble. Nokia did this to reduce the overall costs of the Lumia 1020 but still gave it the imaging capability of prosumer digitals & with the huge sensor, the sensitivity & quality that surpass even Prosumer digitals like the Canon G16. This is due to the Pureview oversampling technology as mentioned before.
Having said that, anyone trying to convince you that the Lumia 1020 can take on a DSLR imaging capability is just sprouting nonsense.
Its image quality might be pretty close to an entry-level 4/3 system but once those cameras change to better lens, they’ll leave the Lumia 1020 in the dust, not to mention they can take pictures at >4fps while the Lumia 1020 has to wait 3s to take the next shot.
That said, for its size & weight and the fact that it’s always in your pocket, this kind of quality & value is unbeatable! You don’t need to carry a Point-&-Shoot or even a Prosumer ever again!
In the Lumia 1020, the mechanical shutter is needed to prevent the type of distortion shown above. After the flash is fired, the shutter is closed to prevent additional light from changing the sensor voltage while the image processor reads the sensor line-by-line.
So how does the shutter speed affect photography on the Lumia 1020? Since it doesn’t have a variable aperture to control the amount of light hitting the sensor, the shutter on the Lumia most likely uses both mechanical & electronics technique. The mechanical shutter opens to let in a certain amount of light to simulate an aperture while the CMOS sensor switches on for light metering & off to capture the image. The shutter speed setting in Nokia Camera refers to the electronics shutter.
What shutter speed to use depends on the shooting situation. When you’re shooting a fast moving object, you need a fast shutter speed so that the subject light doesn’t smeared across the sensor creating motion blur. This is especially important when shooting a fast object outside the range of your flash. Remember that the faster your shutter speed, the less light enters the sensor? Without additional light from your flash, the only way to capture more light is to increase the ISO to amplify the signal. That’s why it’s not unusual to see more noise in “sports” photography. Setting shutter speed to 1/200s should do it or you can use the Sports mode.
When shooting a night portrait, you’d need to reduce the shutter speed to allow more light in. This comes at the danger of your subject or your camera phone moving & ruining the shot. On the Lumia 1020, the solution is the Xenon Flash to freeze the subject by allowing a faster shutter speed & OIS to reduce sensor movement, all the while keeping ISO low for lower noise & higher image quality. For this, the Full Auto mode is ok or if you want lower noise, fix the ISO at 200 with Flash ON. Nokia Camera will pick the appropriate shutter speed.
But what if you are taking a skyline at night or you want to take a night portrait in front of a nice background? The only way on the Lumia 1020 is to go Full Manual.
With tripod, set ISO to 200, Flash to ON, shutter speed to 1s. Ask your subject nicely to stay very still.
Without tripod or shooting restless subject, set ISO to 400, Flash to ON, shutter speed 0.5s.
If you’re just taking night scenery, remember to OFF the Flash.
* As a side note, it seems like we cannot set the shutter speed faster than a certain value when using Flash. I’m not sure why but my guess is, Nokia hasn’t fully worked out how powerful the Flash is and how much Luminance it’ll provide. If you set the shutter speed to super-slow, the Flash will actually fire twice!
The most challenging shooting scenarios are taking photos in museum or zoos that doesn’t allow Flash. For this, you can either carry a tripod/monopod around (& remember to bring your Lumia 1020 camera grip), or you can test yourself how stable you can hold your Lumia 1020.