iPhone 5S Low-light / High ISO Performance Test

December 22, 2013

iPhone 5S low light performance test

In the second part of our iPhone 5S camera review I will talk about the iPhone 5S high ISO performance.  The high ISO performance test was made to give you a good understanding of the sensor and image processor capabilities.  The iPhone 5S features a 1/3″ sensor and 8MP megapixel resolution. Although the sensor is a bit larger than the iPhone 5S and 5C, it’s still a very small sensor.  So how good is the iPhone 5S low-light performance? — Let’s find out.

Let’s admit it, nobody likes image noise. Image noise is destructive to the photo because it reduces the amount of details in the image and produces artifacts that are very hard to impossible to remove in noise reduction software. Most photographers prefer shooting with the lowest ISO possible, as it gives the cleanest results. In general, the larger the pixel size the better the high ISO performance, but there are other factors like sensor technology and image processing that counts to.

When I got my hands on the Apple iPhone 5S phone, one of the first things I wanted to do is to check how good its high ISO performance is, and what is the maximum usable ISO – the one that you can manage to get small prints from.

I did my test in a my room, nothing too fancy. One issue that I had is that the iPhone 5S doesn’t give you manual control over the ISO sensitivity or aperture. Therefore I played with the ambient light in order to get the various ISO sensitivity settings. The test was made up to ISO 1600, because from that point on I didn’t have the right equipment to produce a higher ISO. I could have done it with putting off the lights almost completely, but then I would get a very dark image and that’s doesn’t help with analyzing the images.

The iPhone 5S rear-facing camera has a f/2.2 maximum aperture lens. This is a very fast lens that should help the iPhone 5S camera to perform better in low-light (compare to a slower lens, one with higher f-number and considering the same sensor).

So without further ado, let’s take a look at the sample images and then I will share some more important information with you.

Some products on a wooden table, iPhone 5S high ISO test

Testing the iPhone 5S high ISO performance / low-light performance (click to view on Flickr)

Click the above images to view all the full resolution photos on Flickr.

Not let’s take a look at some full size crops and inspect the image quality in various high ISO settings.

iPhone 5S high ISO noise test

iPhone 5S high ISO noise test - high resolution / 100% scale crops

In the above image you can see some crops taken from the 100% enlarged original image.  The photos were taken handheld and therefore the focus is on the noise levels, rather than sharpness and fine details.

The iPhone 5S ISO range starts from ISO32 up to ISO3200. It’s always better to shoot at the lowest ISO possible because you get less noise, more detailed image and the highest dynamic range.

Up to around ISO 320 you can see that the image is relatively very clean with little amount of image noise.  If you are want the optimal image quality, you should shoot your photos below ISO 320.  Because you don’t have a way to control the ISO sensitivity, you should prefer shooting in good lighting conditions. If you are shooting indoors or in low light, you should prefer shooting with the built-in LED flash or use an external light source to lit of your subject. More light will force the camera to shoot at lower ISO. For example, I was shooting a subject in my room. Without a flash the camera has chosen ISO 320, but with a flash it took the shot at ISO 32, which is the minimum ISO available.

Here are some reduce-size sample images taken with the Apple iPhone 5S rear-facing camera. The first one was taken in different lighting conditions, with and without a flash. You can see that the built-in dual LED flash really helps to lit up the subject and its surrounding. Without a flash you would get an almost dark image with lots of image noise (probably ISO 3200).

iPhone 5S with and without flash

iPhone 5S with and without flash - scene comparison

I usually prefer to shoot without a flash and prefer the camera to pick the ambient light for more natural capture. However, there are times that even the f/2.2 fast aperture just don’t let enough light for an optimal exposure.  If you shoot without a flash, the camera has no other option but to push the ISO upwards and the result is an increase of image noise.

Many people love editing their photos on their phone and apply different filters and effects. I think that it’s better to use the built-in flash and apply a filter that will make the image appear less artificial. A positive thing that I have to say about the iPhone 5S flash is that it produces really natural results and natural skin tones. My Panasonic point-and-shoot digital camera also produces quite similar result, but the iPhone 5S does this using dual LED flash (each one with a different color tone), rather than all via software image processing.

If you don’t need make large prints and you mostly capture images for online sharing with friends and family, you might be able to get very usable results up to ISO 1600, and even using ISO 3200 after applying some noise reduction. You can check out the iPhone 5S ISO 1600 image and reduce it’s size. You can see that the noise is much less prominent compared to out it looks when viewing it in full size.

I’ve seen many sample images from conventional digital cameras with 1/3.2″ sensors, and I must say that the iPhone 5S yield pretty impressive results.

All in all, I am very impressed with the iPhone 5S high ISO performance. The iPhone 5S main camera main strength is at low ISO, but you should be afraid shooting at up to ~ISO320 without risking too much.  This means that you can trust the iPhone 5S to deliver very good results when shooting indoors, where is a medium amount of ambient light. For low-light situations, I prefer taking advantage of the built-in flash. You can even shoot with the built-in flash even when there is enough light as a fill flash, and to make sure that the camera uses the lowest possible ISO.

View part 1 of our review, iPhone 5S image quality.

View original sizes photos on Flickr.

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