6 --> High ISO NR) set to NORMAL, and yes, these are .jpgs out of the camera. You can read more about how I get low-noise images taken at high ISO in Section 15.8.But first, let’s see just how noise increases with ISO values. You can see the tradeoffs in the .jpg examples in Figure 6-27. It is important to note that high ISO noise affects the shadows more than lighter areas, which is why a darker area is being used for comparison purposes – that is where the noise will be most noticeable. These images were taken with the in-camera noise reduction feature (MENU --> 6 --> High ISO NR) set to NORMAL, and yes, these are .jpgs out of the camera. You can read more about how I get low-noise images taken at high ISO in Section 15.8.
Another thing worth noticing is that the black areas get blacker as the ISO gets higher. This is a result of the sensor's dynamic range getting a little narrower as the ISO increases.
Figure 6-27: ISO and Noise. These are .jpgs straight from the camera with High ISO Noise Reduction set to Normal. |
So let’s look at the ISO menu choices, starting from the top:
The Multi-Frame Noise Reduction (MFNR) feature was designed to combat this truth: Long exposures with digital cameras produce more noise. One great technique for minimizing that noise is to take multiple shots and merge the shots together, averaging away the random noise that can occur in each image.
When the ISO is set to “MFNR”, the camera will take four or 12 sequential pictures at the user-specified ISO, align them, and then merge them, averaging away the noise in the process. A good example of this feature appears in Figure 6-28. Now you have half a chance of taking a sellable shot even if you forgot your tripod!
Figure 6-28: A very low light shot, ISO 400 with MFNR. Much lower noise than if any other method had been used. |
To invoke the MFNR setting: go to MENU --> 
4 --> ISO (or, if you’re like me, you’ll just call it up in the Fn menu) and then scroll all the way up. The setting above AUTO is MFNR, and it looks like Figure 6-29. Move to the right, and use the UP and DOWN cursor keys to choose an ISO. Then move to the right once more and choose the number of pictures to take – “Standard” will merge 4 shots; “High” will merge 12. (May as well go for 12.) Then hit the center button to select. That’s it! The ISO you choose should be no different than the speed you would choose normally for the ambient light that you have – for example, choosing ISO 100 (the lowest
Figure 6-29: Multi-Frame Noise Reduction has a new feature – on the right you can select “Standard” (which merges 4 frames) or “High” (which merges 12 frames). 12 frames will average away the most amount of noise. |
number it will allow) would indeed yield the lowest noise, but if the light is too low for you to handhold your shot, the camera will be trying to merge four blurry, long-exposure images. You should expect that MFNR will reduce the amount of visible noise by between two and three stops – that is, MFNR at ISO 800 will produce noise that is visibly similar to a single shot taken at between ISO 160 and 200. Also, unlike earlier implementations, MFNR AUTO will honor your Auto ISO values you have set (next section).
TIP 1: Handheld Twilight, Anti-Motion Blur, and MFNR modes only work in JPG mode. If you’re shooting in RAW or RAW + JPG, the camera will yell at you if you try to set MFNR. You must physically change out of RAW or RAW+JPG first. On the other hand, if you’re in RAW or RAW + JPG and you choose Handheld Twilight, the camera will just change the image quality to “Fine” without telling you. And then change it back when you leave HHT mode. It would have been nice if the camera had behaved consistently when trying to invoke non-RAW compatible features. TIP 2: Enabling MFNR mode will disable any form of continuous shooting mode. TIP 3: Unlike previous cameras, you can now use the self-timer function in MFNR mode. Hooray! TIP 4: MFNR is also incompatible with any flash mode, so whatever flash mode you have set will be disabled. |
Auto ISO doesn’t do what you think it does out of the box. (Come to think of it, you don’t want it to do what you think it does!) Just as you give the camera free range to pick a shutter speed and f/stop when you’re in Program mode, it sure would be nice for the camera to pick an ISO for you too, leaving you mentally unencumbered to concentrate on your subject and composition (and, hopefully, your light).
Left to its own devices, the camera might routinely choose very high ISO values like 51,200 under common indoor shooting situations. That just leads to noisy pictures and unhappy beginners (who will then spread their ire all over the internet). Which is why Auto ISO has a top default limit of 3200 – if you want it to be higher, you have to set it that way yourself. (Class-action lawsuit avoided.)
TIP: The A6300 offers an Auto ISO in Manual Exposure mode. Normally that is seen as incompatible, since (for example) if you wanted to underexpose by 1 stop, the AUTO ISO might kick in and raise the ISO sensitivity to guarantee an average exposure – defeating your artistic vision! But Nikon owners have been screaming for this feature for years. So if you set your camera to Manual Exposure and discover that the image is not getting brighter or darker when you adjust the controls, this is why. Just remember to set it to a fixed ISO when in Manual. |
