EXERCISE: Your tolerance for noise

Find a picture situation that fulfils the following criteria:-

Daylight indoors (for the amount of light – outdoor sunlight would be too bright and to allow high ISO settings, while much darker would involve long time exposure)

A combination of sharp detail and textureless areas (such as a white wall), with some of the textureless area in shadow

Set the camera on a tripod.  Start by taking a series of identical photographs, changing the ISO setting from one to the next.

Use the aperture-priority setting so that there will be no differences in depth of field (you may need to experiment with the aperture to avoid any exposures more than about 1/2 second – which could introduce another kind of noise).

Cover the whole range of ISO settings available on your camera.  Not the results in your learning log.

Firstly, the required scene for this exercise was difficult to find as the sun barley reaches my apartment at this time of the year, unless you count when it is setting, so to find daylight, indoors with lots of shadows was a challenge.  Secondly, I do not have any plain white (or light) walls or wallpaper that does not contain pattern, so I have had to compromise and use a bed sheet, draped over a bookcase.  For this shoot I have used a wooden easel as my model, as it has some very rich colours and the shape casts interesting shadows, which would assist in achieving the results of the exercise.

As suggested by the coursework, I set my camera on my tripod and set my exposure to aperture priority.  To achieve the slowest recommended shutter speed of 1/2, I selected my widest aperture for the conditions, which read F5.6, and I was not sure of the rooms colour temperature, I set my white balance to auto.

My camera has a range of twenty-five ISO settings, ranging from the lowest setting of L1.0, which equates too ISO 64, through to the highest setting of H2.0, which equates too ISO 25,600 which is a mind blowing number and possibly a setting I will never use – but then again, never say never…  I have had a couple of instances recently where I have used higher ISO settings, during my nephews christening and during the night photography I conducted in Singapore, both of which were successful and confirmed to me that my camera could manage well in low light situations.

First I produced a contact sheet of the original 25 images.

Contact Sheet of Noise Images Taken

Contact Sheet of Noise Images Taken

As my camera has so many ISO settings, for comparison in this exercise I have chosen to display five in total ranging from the lowest setting of ISO 64 to the highest at ISO 25,600.

Whilst processing these images – and it should be noted that although I have used the RAW files as my template to produce JPEG files, I have made no post-processing alterations to the images at all, apart from the crop, to show the noise detail in each example.

ISO 64

ISO 64

ISO 64 Cropped

ISO 64 Cropped

As expected, at the lowest ISO setting, there is little noise present in the photo and I think that the mottling effect that can be seen is down to the pattern (and creases) in the cotton fabric.

ISO 200

ISO 200

ISO 200 Cropped

ISO 200 Cropped

There really is little change in this photo, apart from the fact that it seems a little brighter than the previous shot.  The top left-hand corner of the frame is a little rougher in appearance, but again I think that is down to the way the light is hitting the fabric over the graininess found in image noise.

ISO 1000

ISO 1000

ISO 1000 Cropped

ISO 1000 Cropped

Again, the change between this image and the previous one (ISO 200) is negligible, although the creases in this image are beginning to show a roughness to their folds.  When I used this ISO setting for my night photography, shown as an example in the previous post, noise was not really an issue as the photo had an earthy feel to it anyway, but here we would be pushing the limits a little if we decided to enlarge this photo for printing, as the white is beginning to loose its crispness and colour.

ISO 2500

ISO 2500

ISO 2500 Cropped

ISO 2500 Cropped

Ramping up the ISO in this image has produced a big change in not only the shadows, but in the cloth itself, as the noise is easier to see now and even the lighter areas are beginning to show signs of the roughness of noise.  Looking closely at the wood, you can also see that noise is beginning to effect its appearance making it looked blurred and slightly out of focus.

ISO 25600

ISO 25600

ISO 25600 Cropped

ISO 25600 Cropped

As expected by increasing the ISO to its highest setting, the noise is very evident in this shot. The cloth is now taking on a mixture of different colours and the wood, not only looks very blurred but also dull in comparison to the previous images.  This confirms to me that a photo containing this much noise is not something I would like to hang on my wall.

We conducted noise exercises during TAOP, and back then it was something I had never really come across, as I had never changed my ISO setting before embarking on this course.  As we learn, and play with our camera settings more, and push ourselves further within our photography, our tolerance to noise needs to be taken into consideration, as there will be times when noise is okay, and we may even want to add a little to get certain effects.  For example, the noise present in my photos from Singapore is fine as the scene managed the increase well, but during my photo-shoot at the christening, I had to be very aware of my noise levels, as there is nothing worse than not being able to print off photos due to them being grainy and dull, especially when they shouldn’t be.

As I had read during my research that some modern camera’s have additional noise reducing features built-in to their systems, out of curiosity I looked to see if my camera had any of these features.  I was not really surprised to find that there were two settings that could be altered to help counterbalance noise, the first being Long Exposure NR (NR being Noise Reduction) and the second, High ISO NR.  Surrounding High ISO NR, the Nikon manual states:

Option

Description

High Reduce noise (randomly-spaced bright pixels, lines, or fog), particularly in photographs taken at high ISO sensitivities.  Choose the amount of noise reduction performed from High, Normal, and Low.
Normal
Low
Off Noise reduction is performed only at sensitivities of 1600 and higher.  The amount of noise reduction is less than the amount performed when Low is selected for High ISO NR

(Nikon 2011)

Now I was curious to see that if turning the High ISO NR off, I currently had it set to high, whether there would be much, or in fact any different to my photographs, especially as it states that at sensitivities of 1600 and higher there is still noise reduction assistance, but it should be much less than I had experienced in the previous shots.  Therefore, I set about taking a range of photos from ISO 1000 through to ISO 25600 and will show three of the cropped images below.

ISO 1000 Cropped

ISO 1000 Cropped

ISO 1000 Cropped with High ISO NR off

ISO 1000 Cropped with High ISO NR off

Right from the off we can see that the first image, which has the High ISO NR assistance enabled is clearer than the second image, which has no High ISO NR.  The obvious areas (shadows and creases) are showing increased signs of roughness, but so is the wood, which was not affected previously until much higher ISO settings were used.

ISO 2500 Cropped

ISO 2500 Cropped

ISO 2500 Cropped with High ISO NR off

ISO 2500 Cropped with High ISO NR off

Again, as with the previous set of images, the noise is much more prominent in the image that has no High ISO NR assistance and although this is the same pattern of events as we saw in the exercise photographs, the onset of noise is much faster now and far more server.

ISO 25600 Cropped

ISO 25600 Cropped

ISO 25600 Cropped with High ISO NR off

ISO 25600 Cropped with High ISO NR off

In this last set of images, we can really see how much the High ISO NR assistance has assisted with reducing noise.  The original photo is not that pretty, but putting it alongside the image that has the High ISO NR turned off, you can see that this setting on the camera really does its job, as the noise in the second photo is quiet bad.

When I took this second batch of photos I was quiet dubious and keen to see whether this in-camera setting was going to make any difference or not.  I was pleasantly surprised to see that there is quiet a substantial difference in the photos taken firstly, with the High ISO NR turned on, and secondly with it turned off.  It will be interesting to see if the same results are true of the Long Exposure NR, but I am silently confident that they will be.

Source:

Reference:

Nikon Corporation.  (2011) Nikon Digital Camera D800, D800E User Manual.  Europe.

Advertisements
This entry was posted in Digital Image Qualities ~ Exercises and tagged , . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s