the digital camera buying guide
National Photographer is a photography business and also offers photography training and advice, Often there are many people who are looking at buying a digital camera or upgrading and even photographers converting from Film cameras to digital for the first time.
This Buyers guide to Digital cameras will be a little technical for those who want to know the details to make a more informed choice when buying there digital camera and I will also address some of the myths.
Digital cameras an over view:
Digital cameras are electronic devices with a diode that captures light as a replacement to film cameras that used a chemical reaction to record the light, Early Digital cameras had around 3 MP and now you can buy a top of the line Digital Large format camera with in excess of 72 Mega pixels.
Much the same as 35mm film cameras the Digital camera is designed for easy use for all, the main call for digital cameras in the home was the simple and easy production of images with out a processing lab to develop the film, this was replaced by the more common uptake of computers in most homes and the ease of plug and play.
Digital cameras had always had an issue with the dynamic range in the production of images that were true to life. The Dynamic range was the sensors ability to capture the highlights and the low lights in a image. This therefore meant that you would lose detail in over 60% of your image in exchange for the ease of producing images in seconds rather than weeks where film cameras were concerned.
Compact cameras are usually designed to be easy to use, sacrificing advanced features and picture quality for compactness and simplicity. Compact cameras are designed to be small and portable and are particularly suitable for casual and “snapshot” use, thus are also called point-and-shoot camera as they have little input from the person taking the photo. – you will notice I do not say photographer as a photographers work is more than pushing a button.
Digital cameras can do things film cameras cannot which speeds things along, and digital cameras can display images on a screen immediately after they are recorded, storing thousands of images on a single small memory device, recording video with sound, and deleting images to free up storage space to take more pictures.
The concept of digitising images on scanners, and the concept of digitising video signals, predate the concept of making still pictures by digitising signals from an array of discrete sensor elements. At Philip’s Labs. in New York, USA Edward Stupp, Pieter Cath and Zsolt Szilagyi filed for a patent on “All Solid State Radiation Imagers” on Sept. 6, 1968 and constructed a flat screen target for receiving and storing an optical image on a matrix composed of an array of photo-diodes connected to a capacitor to form an array of two terminal devices connected in rows and columns, a US patent was granted on Nov. 10, 1970..
This is where the preview screen is shown on the backs of many digital cameras today, or is known as Live view for DSLR’s.
The first consumer camera with a liquid crystal display (LCD) on the back was the Casio QV-10 in 1995.
The first recorded attempt at building a digital camera was in 1975 by Steven Sasson, an engineer at Eastman Kodak. It used the then-new solid-state CCD image sensor chips developed by Fairchild Semiconductor in 1973. The camera weighed 8 pounds (3.6 kg), recorded black and white images to a cassette tape, had a resolution of 0.01 mega-pixels (10,000 pixels), and took 23 seconds to capture its first image in December 1975.
When digital cameras came to the consumer the main issue was the time the camera would take to power on and take the actual picture. Shutter lag was one of the main concerns in Digital cameras in the late 1990′s and through to the late 2000′s. In 1991, Kodak brought to market the Kodak DCS-100, the beginning of a long line of professional Kodak DCS SLR cameras that were based in part on film camera bodies, often Nikon’s. It used a 1.3 mega-pixel sensor and was priced at $13,000.
1999 saw the introduction of the Nikon D1, which had a 2.74 mega-pixel sensor that was the first Digital SLR developed entirely by a major manufacturer. The Nikon D1 cost just under $6,000 on its introduction and was affordable to professional photographers and high end consumers. This camera also used Nikon F-mount lenses, which meant film photographers could use many of the same lenses they already owned.
The Mega Pixel:
Often most digital cameras are purchased by their MP number and this is a myth to the quality of the camera, it was said that the cameras were marketed on the number of pixels and not on the image quality. This has somewhat been a sticking point for most consumer cameras and is reflected within the price of the camera regardless of features and quality of the images produced.
A friend of mine was proud to show off his new 12mp point and shoot camera, where I had a 6mp DSLR camera, Asking him to take a picture and then compare this to a photo I had taken on my DSLR as medium quality, it was clear that the SLR had a better reproduction and a more sharp image.
The resolution of a digital camera is often limited by the camera sensor (typically a CCD or CMOS sensor chip) that turns light into discrete signals, replacing the job of film in traditional photography.
The sensor is made up of millions of “buckets” that essentially count the number of photons that strike the sensor. This means that the brighter the image at a given point on the sensor, the larger the value that is ready for that pixel. Depending on the physical structure of the sensor, a colour filter array may be used which requires a demosaicing/interpolation algorithm.
The number of resulting pixels in the image determines its “pixel count”. For example, a 640×480 image would have 307,200 pixels, or approximately 307 kilopixels; a 3872×2592 image would have 10,036,224 pixels, or approximately 10 mega-pixels.
The pixel count alone is commonly presumed to indicate the resolution of a camera, but this simple figure of merit is a misconception. Other factors impact a sensor’s resolution, including sensor size, lens quality, and the organisation of the pixels
Many digital compact cameras are criticised for having excessive pixels.
Sensors can be so small that their ‘buckets’ can easily overfill; again, resolution of a sensor can become greater than the camera lens could possibly deliver.
Professionals will look at the camera for its pixel density per square centimetre (cm2) and As seen on DPreview you can see that the prime information is based on the pixel and density as well as the lens, the two most important factors in purchasing a digital camera.
Taking two cameras – one Point and shoot (consumer cameras ) and a SLR (professional camera) at random you can see the difference in the pixels; the Finepix J120 is a 10 Mega pixel camera with a density of 35MP Cm2 where as the Finepix S5 Pro has 6mp (12) and has a density of 1.7 MP Cm2.
The difference between the sensors starts at the physical size of the cameras sensor.
The Picture above shows the small sensor of the point and shoot camera. The problem begins with the size of the sensor being the same for many of the cameras, this means that there are more pixels crammed into the same space.
Digital SLR cameras have a much larger sensor but this can not be really seen in these two images so to give you a size measurement of the sensors can show you the actual size of a PAS and DSLR.
PAS = (6.16 x 4.62 mm, 0.28 cm²)
DSLR = 23 x 15.5 mm (3.56 cm²)
Pixels can offer more detail or more noise, typically smaller sensors with more pixels means worse images where the EM (electro magnetic)Field effects the diode next to it as it operates. the less dense the less noise will be in the image especially at a higher ISO setting, which is in actual fact the gain on each of the sensors pixels.
The lenses:
All cameras are as good as their lenses will allow, it is the sole most important factor in the quality of the image over MP.
Buying lenses is important and cost more or as much as the camera itself but is limited within the PAS cameras.
F *.* you will see these numbers on all lenses and it is important to know that the Lower the number such as F1.2 is a faster lens than the more common F4.5, this will effect the cameras performance dramatically.
Taking a photo indoors in poor light (say a 40watt house light) will make a big difference, and to give you some idea as to the difference in the performance of the lenses here are the settings that would change for the camera based on the two lenses.
F1.2 ISO 200, Shutter 125.
F4.5 ISO 800 Shutter 65
In layman’s terms this means that a shot can be light and sharp or blurred and dull, it can also effect the AF and the image quality having to use a higher ISO. Lenses tend to show two F numbers (apertures) if they are a zoom lens which refers to the Wide and telefocal lengths.
To check out your cameras lens you can set the camera in to manual (if available) and take one photo fully zoomed and one at wide and you can see the difference. For those of you with a Point and shoot camera, simply look at the details of the photo to see the setting differences (exif information)
The modern Point and shoot camera:
Todays Digital cameras are much better than they were 4 or so years ago, the shutter lag is mostly gone as processors have been developed inside of the cameras, and technology has caught up.
Metering is much better as are the sensors meaning that the cameras will do most of the work for you , giving you better photo’s.
Digital cameras today are more complex with tools like:
Smile detection; the ability to stop taking a photo until a person smiles and it is detected by the camera allowing the shutter to work or a warning is displayed on the screen after the picture is taken.
Blink detection; Digital cameras have a focal and face detection system, it simply looks for the key parts of a persons face and looks for the two white eyes and detects this in much the same way as the smile detection.
Focal points; All digital cameras has an array of modes or setting to suit a range of usage, landscape mode will adjust the greens, and contrast in a picture as well as change the focal area to infinity or closest subject. For portraits the camera will look for eyes and boost the skin tones. for group photos the camera will detect the heads and make a focal calculation based on this. Different cameras will have different numbers of heads it will detected based on its sensor and processor to make the camera able to think.
In general the PAS have evolved to use many of the technologies of the top of the range digital cameras of yester year, meaning that there are some cuts but over all great advances as well. In simple terms most of todays (and from 2009) have taken the thought out of the persons hands holding the camera and put them into the chips and processors inside the camera.
With that said there is more to photography that cameras still cant help you with.
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