Tag Archives: digital

The Digital Negative


The Digital Negative by Jeff Schewe, published by Peachpit Press, ISBN: 13 978-0-321-83957-2.

I have just read this book to try to get a better understanding of digital photography.  Schewe is a photographer who has also been working with the boffins at Adobe since the early 1990’s to help develop RAW, Photoshop and more recently Lightroom for photographers from a photographer’s point-of-view.  His books are therefore as close as you can get to finding a first class knowledgable author.  He has published two books ‘The Digital Negative’ and “The Digital Print’ the later I have just began to read.

The Digital Print briefly covers the basic background of how the digital image is made in the camera but drills in to the featured and functions in both RAW and Lightroom that you will use to process your RAW file in to a presentable photo.  This includes a recommended and sensible workflow, background information from the Adobe engineers explaining why certain features work the way they do.  Chapters 4 and 5 a dedicated to Photoshop for advanced editing beyond the capabilities of RAW and Lightroom for those images worth the extra effort.  Chapter 6 covers the recommended workflow from importing pictures from the camera, storing, backing-up, making copies, cataloguing on to developing.  This book does not however cover printing as this is a topic for his second publication.

This is a good book to read, I learned a few new features in Lightroom that I was unaware of and also instructed me in the use of RAW that I am unfamiliar with as I have only used Lightroom so far.  Lightroom was was developed with a lot of the features from RAW and both will talk to one another but changes made in one will alter the other’s parameters and this is a useful thing to be aware of if you use both RAW and Lightroom.  If you want a better understanding of Lightroom, RAW and Photoshop this ids the book to read.  This is not however a detailed book for Photoshop it covers the topics that most photographers need but doesn’t look at all the magic tricks possible in Photoshop.  This is a book intended to help the modern photographer become confident and proficient developing digital photographs to a point that they can print or advance to higher levels of editing using Photoshop and plug-ins.  Not too technically challenging and easy to read and fairly easy to understand without an engineering degree.

A very good book that I would recommend.

Exercise – Higher and lower sensitivity

In this exercise, I took my DSLR camera in to a local market on an overcast day and took a range of photographs adjusting the ISO from 800 to 100 in order to practice taking advantage of the adjustability to sensitivity to light that modern digital cameras have and see what trade offs were made for the greater sensitivity.

The following images were taken altering the ISO whilst keeping the internal reflective light meter centred for the cameras recommended exposure settings:

ISO 100, 1/60, f/19
ISO-100-a (1 of 1)
ISO 800, 1/350, f/22
ISO-800-a (1 of 1)

ISO 100, 1/60, f/11
ISO-100-b (1 of 1)
ISO 800, 1/180, f/22
ISO-800-b (1 of 1)

ISO 100, 1/90, f/9.5
ISO-100-c (1 of 1)
ISO 800, 1/500, f/16
ISO-800-c (1 of 1)

ISO 100, 1/125, f/5.6
ISO-100-g (1 of 1)
ISO 800, 1/60, f/22
ISO-800-g (1 of 1)

ISO 100, 1/60, f/11
ISO-100-h (1 of 1)
ISO 800, 1/90, f/22
ISO-800-h (1 of 1)

ISO 100, 1/30, f/16
ISO-100-i (1 of 1)
ISO 800, 1/125, f/22
ISO-800-i (1 of 1)

ISO 100, 1/20, f/8
ISO-100-k (1 of 1)
ISO 800, 1/500, f/4.8
ISO-800-k (1 of 1)
Note from the exposure information included with each image that when set to a higher ISO setting in most cases I obtained both a faster shutter speed and a higher aperture for a greater depth-of-field.

The digital revolution in photography now gives photographers the ability to adjust the sensitivity of light exposure without having to swap film to a faster or slower ASA speed.

The advantage of this new feature is that photographers can now quickly and easily adjust the sensitivity of their cameras to get that shot when in less light than was ever possible in the past.

However, just as in the days of film a price still has to be paid for this greater light sensitivity. In the past it was a graininess in the image when a photo taken using a fast film was enlarged and printed. This was produced by the tiny silver-oxide crystals in the light sensitive film emulsion which were much larger in the faster / more light sensitive films than they were in the slower / less sensitive films. Now we have a similar effect that we call noise, a grainy speckle of different coloured tiny dots that can appear in the darker parts of an image, produced by the light sensitive pixels from the electronic light sensor which again becomes more noticeable when the image is enlarged and printed.

Exercise – Colours into tones in black-and-white

In this exercise, I created a still life using sweets, modelling clay and drinking straws laid on my grey card that I use for manually setting the white balance. The object of this exercise is to use colour filters when converting a colour image to black and white to improve the tone and contrast of the black and white picture. This can be achieved with digital photography by using the colour filter options in Photoshop or Lightroom by adding or subtracting the colour values on the control sliders found in the greyscales functions, available to both of these programs. These features simulates in a more controllable way the adding of a coloured filter to the end of a lens on a camera when photographing with black and white film.

I began this exercise by using my grey card to set the white balance for my camera, I then I set up my still-life with the camera set on a tripod positioned over the subject. I used my 105mm lens, manually focused and set to aperture priority, ISO 100 and I used a cable remote to trip the camera.

First image remains as shot in colour.
Second altered in Photoshop with the greyscale function with no filter adjustments.
Third, fourth, fifth and sixth images all adjusted in Photoshop with one filter raised to simulate a coloured filter over the lens but with the other primary colour sliders lowered to adjust tone and contrast.

Apart from sharpening this image has been untouched and simply converted to JPEG.

Photoshop – Filters – Camera Raw filter – HSL/Greyscale – tick box “Convert to Greyscale”.
This image has been simply converted to the grey scale in Photoshop without any adjustments to the colour filter sliders which were set to the following default settings:
RED – +7, Orange – +2, Yellow – 0, Greens – -13, Aquas – -22 Blues – +5, Purples – +5,
Magentas – +7.

Red filter.
Filter sliders:
RED – +100, Orange – -27, Yellow – -36, Greens – -41, Aquas – -22 Blues – -69, Purples – +5,
Magentas – +7.

Yellow filter.
Adding_yellow _filter_and_reducing_green_blue_red-resized
Filter sliders:
RED – -42, Orange – -8, Yellow – +11, Greens – -19, Aquas – -22 Blues – -23, Purples – +5,
Magentas – +7.

Adding_green _filter_and_reducing_yellow_blue_red-resized
Filter sliders:
RED – -49, Orange – -21, Yellow – -33, Greens – +78, Aquas – -22 Blues – -13, Purples – +5,
Magentas – +7.

Adding_blue _filter_and_reducing_yellow_green_red-resized
Filter sliders:
RED – -12, Orange – -29, Yellow – -33, Greens – -77, Aquas – -22 Blues – +100, Purples – +5,
Magentas – +7.

By playing with these colour filters in the grey scale I have been able to alter the appearance of all the items on the grey background. However, the grey background itself, has remained constant in all the images.