Your tolerance for noise

The idea of this exercise is to check out the range of iso on my camera and also to look at the amount of noise and how it affects a photograph as the iso gets higher.

I use a nikon D300s and the range of iso on that camera is between 200 and 3200 but with the option to go three 1/3 ev stops either way in special conditions.  I decided to include these as well in the exercise and picked an aperture of F5.6 and began taking the photographs, as this exercise needed to be indoors and I had no white walls I finally settled on using my backdrop with a small red chair and teddy bear on it. This way I had some sharpness in the form of the chair to look at plus the white backdrop and also I thought it might be interesting to see how the 'fur' of the teddy bear reacted to the higher iso.

Above is the range of my camera, the one photograph came out very dark the only thing I can think of is that the sky clouded over slightly more for a second.
Having looked closer at the photographs I could see that there was no noise until the iso got to about 800 from there it started to get progressively worse, and by the time it reached the highest iso on my camera the effect was so bad it would render the photograph useless, not only could you see the deterioration in the white background but also in the chair and  it was very evident   in the fur of the teddy bear where there was some much noise the detail was lost.

these two photographs show there is no noise present in the lowest iso which is probably about iso 75 at a guess.

the three photographs above are the highest iso in my camera's range, I have included the photograph of the bear as I think the noise is clearer in this photograph than the one above.

ISO is also the third way of adjusting the amount of light that is let in, after the aperture and shutter speed, sometimes using a high iso and getting noise can add to the image, for example a band photograph might like the slightly 'gritty appearance'.

Interestingly I brought the April edition of Practical Photography and in it was an article on iso and grain they also had three photographs of coloured pencils at various iso settings which gave me another example to look at, they also go onto say that sometimes noise can be used as an effect for example on some black and white work.

So what have I learned from the exercise? I have learnt that you can adjust the iso and it can be a useful tool to use, sometimes to a great effect but I have also learnt that there is very often a trade off when using a very high iso, I think the motto is don't be afraid to alter the iso when the need is there but use it wisely.

Highlight clipping.

Highlight clipping is where an area of the photograph is in danger of having no detail retained in it, snow would be a good example of where highlight clipping could occur and also a bright day with detail lost in the sky., you can check for highlight clipping on the back of most camera and it normally shows up by flashing, by checking on this when you take the photographs it gives you the opportunity to alter your exposure if needed.

For this exercise I need to take a total of five photographs one where the highlight clipping just appears, then the next one one f stop lighter then the next three decreasing the exposure by one f stop at a time, the first challenge at the moment will be to find somewhere where I can produce a contrasty image with the weather as it is at the moment this may well have to be indoors possibly a still life but lit so I can 'control' the exposure and therefore the highlight clipping.

Well I have taken the photographs I went for something simple in fact it was the light coming through a tiny window in my house.


This was the metered shot but as you can see there is only a very small amount of highlight clipping to the photograph, burning out areas and showing no detail to the light areas at all.

the second one was taken at one f stop lighter this time the is a much larger area of highlight clipping and a much larger burnt out area with no detail, there is a slight colour cast and less definition to the flowers

the third shot is taken at one f stop darker than the original this time there are no clipped highlights and no areas that have lost detail around the flowers.

The fourth shot was taken at two stops darker than the original  the photograph is really getting dark now but detail is visible in the window that is missing in the first couple of photographs.

the fifth shot was taken at three stops darker than the original far More detail is visible in the window area, but the colour saturation is wrong on the  rest of the photograph.

It is difficult to talk about loss of saturation as the window is clear or frosted rather than a light colour I would like to re do this exercise with my black and white cat as I feel that it will be easier to examine the effects of highlight clipping in the mean time I will process the raw files of the other photographs and see what happens to them.

Below is the photograph with the recovery tool used however I don't think the effect can be seen too clearly on this photograph so #I have also taken the photograph taken a t one f stop lighter and used the recovery tool on this to a better effect.

i have taken the recovery slider about two thirds of the way along the scale and it is possible to see that some of the detail in the glass is now visible for example there is a leaf pattern in the glass which can now be seen.

Sensor Linear Capture

 For this exercise we need to take any JPEG or TIFF photograph open it in photoshop elements convert it to 16bit and then make a curve, this is a bit of a problem for me I have photoshop elements 11 but I can neither open the photograph in 16 bit ( although I am wondering if it is already showing in that) or find the curves control, I was under the impression that this was still missing from elements, so the only thing i can really do with this exercise at the moment is read through everything and try to make sense of it that way, I do confess I would much rather work it out step by step but I am unable to do this at the present time.

I always shoot in raw and jpeg and now have always know that raw files need to be 'processed' what I didn't realise was the work that happens 'behind the scenes in the camera' to help capture the detail that will be needed later,
I have since found out that I can do this exercise the notes are slightly round in the folder and I can't convert to 16 bit, but I do have a kind of curves and having located this I set to work with the image of a boat taken back in the summer.

The first one is the original JPEG and the second one has been darkend then lighten again to try to recreate the original picture, I found this interesting but quite challenging to do it may be because I don't have the proper curves facility or it maybe because I haven't had a lot of practice with it, you can see the noise in the darker shadow area of the boat, but  there is not too much on this image.