ISO Test for Sony A6300

This is a study undertaken to assess the options for shooting in low-light conditions, for example a low-light church setting. This is commonplace during a wedding, where photographers cannot use flash and must use silent shooting mode. Post-production in lightroom will be needed to mitigate noise, but this study aims to demonstrate how far one can push the ISO before photo quality is permanently compromised.

Equipment

Sony A6300 Mirrorless with 16-50mm lens.

Conditions

Low-light in my kitchen at approximately 9pm on 5th November 2019. No additional light, one room light lit. Here is a shot demonstrating the light as captured by the camera at the following low-light settings.

Click the image to enlarge it. All images processed for web in Irfanview to 1000 x 667 and displayed here as a thumbnail. 

ISO 400 – F4.5 – 1/60th

As you can see this is very dark and the low ISO renders the image virtually completely dark. We have a number of options to improve the photo quality. Obviously all of these options can be done in tandem.

1. Decrease the F-Stop 

On the 16-50mm lens, which is often purchased as a wide-angle starter lens with the A6300 base, the F-Stop can be decreased to 3.5. If a 50mm 1.8 lens was used, this would lighten the image if the F-Stop was reduced to 1.8, however, the compromise and challenge would be that if the bride and groom were not standing directly in line and the photographer did not capture the perfect point for focus purposes, one or both people could be out of focus, thus ruining the image. Therefore, we should have a focal stop of 5.0 or above to give us that security of focus.

2. Decrease shutter speed

Decreasing the shutter speed will improve the light, unfortunately at a certain point for you, the photographer, camera shake, person movement or both will be introduced. We want as sharp an image as possible, so having a higher shutter speed and finding a balance that gives us light images that need as little post-production editing as possible is required. I find that 1/60th works for me. If you are prone to shaking 1/80th or 1/100th should be fine. However, this means a higher ISO, as we will now discuss.

3. Increase the ISO

Without using external flash for assistance, which is simply not an option during the service, the only option is to increase the ISO. Yes, you will need to post-produce and use techniques to reduce noise, that is a given. But unless you want dark images this is the only way. The better camera you have the better you can copy with ISO increases and if you own a base unit above the cost of £1,600 you are probably getting close to professional equipment that performs really well.

Let’s look at some examples of how the A6300 performs at higher ISO, before we look at edited versions of the same image.

ISO 3200 – F4.5 – 1/60th

With the ISO increased to a level of 3200, the image is beginning to lighten. I’ve left the F-Stop at 4.5 because in a wedding I would want to ensure bride and groom and probably the vicar or priest were in focus. As discussed the 1/60th shutter speed gives me some shake margin for error. It’s getting there, but it’s not enough. But compare it to the shot above and it’s night and day. I will increase the ISO and try again, let’s double it to:

ISO 6400 – F4.5 – 1/60th 

Better again. Click on the image and you will see that there is some noise though, which isn’t ideal. I will need to post-produce this. It is still not light enough for me, so boldly going where some photographers do not wish to go I take advantage of test conditions and whack up the ISO to 20000 and try again. I also lowered the shutter to 1/80th as I would prefer that extra chance not to get any shake or unwanted subject movement.

ISO 20000 – F4.5 – 1/80th 

Without a doubt the brightness is good, but if you click the image you will notice there is a lot of noise. Even the bravest photographer wouldn’t want this level of noise, but if you have a high-performing low-light beast of a camera (I’ve read that Sony A7iii is very good but I’ve never tried it) then it might look better. If I’m honest, 20000 is higher than I’d dare go, but look where we started from.

Post Production

In a cold sweat we move to post production to see if we can make these images even better. We have a great tool at our disposal, once we have tweaked the exposure. In Lightroom, go to DETAIL then where it says LUMINANCE, move the cursor to the right until the noise in the viewfinder has diminished. Go no further than you need to avoid image damage.

In each image I am ONLY altering the exposure, highlights, shadows and treating the noise, adjusting the detail too. Obviously there is a ton of other things you can do, like levelling for example, but let’s focus on the issues we need which is brightness in low-light and getting rid of as much noise as we can.

Image 1 – ISO 400 – F4.5 – 1/60th

The edits made to this starting image were as follows: the edited image is below;

  • Exposure +4.17
  • Highlights +24
  • Shadows +57
  • Luminance +92

Analysis

The edits in Lightroom have saved this image from a very dark and worrying start. This should reassure you that most images are savable in post-production. Unfortunately the image was so dark that when the significant edits were added detail was lost. The bottle clock near the bottle picture is blurred for instance.

Image 2 – ISO 3200 – F4.5 – 1/60th

The edits made to this starting image were as follows: the edited image is below;

    • Exposure +2.02
    • Highlights +17
    • Shadows +7
    • Luminance +94

Analysis

The edits in Lightroom have improved the brightness of the image and increased the detail of the noise reduction I can almost make out the time on the clock, which we simply couldn’t in Image 1, despite saving it. We have a nice image with reduced noise, although it is still visible. With additional clarity, whites, blacks adjustments this image could be improved even further. If there was a person in the photo, skin softening, iris enhance and teeth whitening would help improve this type of image.

Image 3 – ISO 6400 – F4.5 – 1/60th

The edits made to this starting image were as follows: the edited image is below;

    • Exposure +0.95
    • Highlights +17
    • Shadows -5
    • Luminance +99

Analysis

The image does not require much additional exposure. Most of the work goes into the noise reduction and level of detail, including colour adjustment which gives good control over how these treatments affect the image. Much of the detail is retained, even at 6400, which is reassuring.

Image 4 – ISO 20000 – F4.5 – 1/80th 

The edits made to this starting image were as follows: the edited image is below;

    • Exposure -0.48
    • Highlights -12
    • Shadows -7
    • Luminance +100

Analysis

The image was a little too bright. The correct ISO would have been 12800. The good news is that I was able to use the luminance tool to dramatically improve the level of detail I could retain. At 20000 ISO, following post-production with no brightness required (look again at unedited Image 1), this is encouraging.

Conclusion 

At each editing, from the low ISO of 400 to the ISO 20000 image, I was required to treat the images with almost the same level of luminance adjustment to mitigate noise. This suggests that even if you take a shot at lower ISO than is required, all is not lost. I have learned to focus on what I can control. Get the shutter speed right and focus distance to give myself margin for error. Imperfections are guaranteed without the use of external flash, however, high ISO does not mean grainy photos. With faces, more testing will be required as to how far I can go with ISO and noise mitigation.

However, it is worth remembering that the only shots you almost always will need to do without flash are inside the wedding. The rest of the posed shots can and should be captured with external flash, external lighting, reflectors if necessary with a lighting assistant if possible. In the ceremony, it is about subtlety and capturing a moment.

What encourages me greatly is that the lighting in my kitchen this evening was darker than any church would ever be and I managed to capture decent shots in dark conditions. Courage and trust in post-production options will ensure good photographs. But if you can get hold of the best low-light performing cameras that’s even better and that is certainly my medium-term aim.

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