Long Exposure Photography Fun with Oneplus One Camera

One of the stand-out built in default camera app of the Oneplus One (by Cynogenmod) is the ability to do slow shutter speed, up to 8 seconds long. I have explored the capabilities of the Oneplus One camera and found that it performs admirably well in general shooting conditions (please read here if you have not). In this blog entry, I shall explore the camera further by doing long exposure shooting. The choice of camera app this time was the default camera app, instead of Camera FV-5, because the slow shutter speed in the default app can capture full size 13MP images (while the Camera FV-5 is limited to 2MP, which is actually the direct live view feed from the LCD screen). 

I am going to be honest and start off by saying, in order to do long exposure photography you do need to have some fundamental understanding of photography basics. You need to know how to control shutter speed, aperture and ISO, and you need to know about metering and general available light circumstances. I can share all the settings and steps I took to produce the images shown here but they will not be much of a help if you cannot understand why and how I applied them. Please do read up on photography basics if you intend to pursue any kind of photography further, even if it is just mobile phone photography. 

And yes, I do intend to share my techniques and setup. 

Oneplus One in action, image taken by Olympus PEN E-PL5

Kuala Lumpur City Skyline

4sec, ISO79, F2

Just a brief introduction of long exposure photography before we move on further. Long exposure is a technique in photography used to capture slow shutter speed images (typically half a second shutter speed, or longer). There are many reasons why slow shutter speed is needed and employed, first and foremost, to drag the shutter open for a longer period of time, allowing more light to come into the image sensor, which may be necessary in low light conditions so that sufficient light is gathered to accomplish a well-balanced lit image. The long exposure technique may also allow lower ISO setting to be used, lowering the high ISO noise level. On the other hand, slow shutter speed has been used to add creative spin in photography, capturing motion as well as expressing movement which is intended to be shown. Slowing down the shutter speed allows light trails and motion blur to be captured, as shown in many images here in this blog. A simple example would be moving water: a fast shutter speed freezes the water, while slow shutter speed smoothens the water (if it was very slow, the water becomes all silk and "misty"). 

1) USE TRIPOD

For any kind of slow shutter photography, a use of tripod is a must. Do not even try to attempt shooting long exposure hand-held. Anything with slow shutter speed, you will need a tripod to steady your camera/phone hence no blur due to shake will happen. I bought an RM12 Clip with tripod mount, and attached that to a cheapo RM15 tripod (since the Oneplus One was so small and light in comparison to a real camera I can do away with smaller and lighter tripod). The total cost was RM27 (about USD8) but these tools allow me to do slow shutter speed shots. 

2) USE SELF TIMER

Even by lightly tapping on the LCD screen of the phone, it was enough shake to destabilize the image, causing blur, which will be noticeable in the final image. In order to prevent this, I enabled the 2 seconds timer. 

3) FIXED APERTURE AND AUTO ISO

I actually did not know until I got this phone that the aperture on most mobile phones (not sure if it is ALL) is fixed at a certain value. For the case of Oneplus One, the aperture is constant F2, with no option to stop down like a normal camera. This poses a huge problem, because in situations when you need longer shutter speed to capture motion effects (light trails, for example). sometimes F2 is too wide and may cause overexposure. Therefore, it is necessary to enable the Auto ISO. The lowest ISO setting allowed by the camera to be set manually was ISO100, but at Auto ISO, the camera metering will detect when lower ISO values are needed, and compensated accordingly, down to ISO20 as observed from this session. I left the ISO to Auto but I do inspect the EXIF data after the images were taken to ensure that the ISO value is as low as possible. 

4) SHUTTER SPEED

From the default Cynogenmod Camera App, select "Slow Shutter", and do all the above steps. How long the shutter speed you will need, depends on the particular scene that you shoot. I personally needed to experiment and do some trial and error before deciding the best shutter speed. I have used 1/2 second fastest to 4 seconds slowest. I would have used 8 seconds if the aperture value could be stopped down. 

Train Tunnel

4sec, ISO100, F2

4sec, ISO100, F2

4sec, ISO68, F2

4sec, ISO58, F2

1/2sec, ISO73, F2

2sec, ISO50, F2

2sec, ISO93, F2

How did the Oneplus One camera do with slow shutter speed?

The camera worked well, captured the image efficiently with no hiccup. It was easy to use and setup. As I have mentioned before, you do need some photography basics to know what you are doing and get what you want. 

I wish I can say the same thing about the final image output. I should not be having high expectations, but I do have to be honest with my observations. Usually, long exposure photography, even in a compact camera which I have bought in 2004, uses "Dark Frame Subtraction" technique to combat hot pixels due to the image sensor being exposed for a long period of time, resulting in a lot of "color pixels" similar to ugly color noise. I was surprised to find out that the Oneplus One did not use Dark Frame Subtraction method (if it does, the time to capture an image is doubled, read more here). Consequently the only possible way to get rid of the hot pixels was via software processing, which may have undesirable effects in image output. 

As suspected, scutimizing at the images even at very low ISO settings, they appear smudged and smeared, with almost no traces of fine details, and the edges appear sharp due to artifical sharpening (that also introduced ugly JPEG compression artifacts). The long exposure images do not look pretty at all. I am not sure what the reason was for not including the Dark Frame Subtraction method, which could obviously produce images with much higher fine detail intact and solve the hot pixel noise problem. 

Nevertheless, if you do not intend to use the images for anything serious (you do not want to print them large) and just view the images on social media (Facebook, Instagram, website) with reduced resolution display, such as what you are seeing here in this blog entry, then it should not be an issue. 

The up-side, you still get true slow shutter speed shooting, with total control of the shutter speed from 1/2 second, 1 second, 2 seconds, 4 seconds and 8 seconds, allowing creative options if needed. 

I also must note that the purple fringing can be quite obvious in high contrast areas, and the images has high tendency of highlight clipping, both expected as common issues in all cameras (especially mobile phone cameras). 

ADDITIONAL NOTE:

I am not sure if the Oneplus One (or any other smartphone cameras) uses Electronic Shutter or Mechanical Shutter. If the Oneplus One uses Mechanical Shutter then there is no excuse why Dark Frame Subtraction method should be used. I have a feeling that the shutter is electronic, thus posing some practical issues (in order for Dark Subtraction Method to work, the sensor needs to be exposed while the shutter is fully closed). 

2sec, ISO48, F2

I admit, the Oneplus One is quite a joy to use. If you are not expecting anything serious in the image ouput, and just use the images for online viewing, I am sure the Oneplus One camera's slow shutter speed images are great.