Firstly understand Field of View Cropping. FOVC
On most digital SLR’s the capture device is smaller in size than a 35 mm negative and the field of view provided by a lens is effectively cropped (in the case of the Nikon D70 the crop factor is 1.5x). This used to be referred to as 'focal length multiplier' although this term is actually inaccurate as it is not a multiplication but a crop, we prefer to refer to it as Field Of View crop (FOV crop). Thus the 18 - 70 mm lens provides a field of view approximately equivalent to a 27 - 105 mm lens on a 35 mm film camera. This of course helps out those who have long zooms by making them longer but causes problems for those with wide angle lenses by decreasing their effectiveness by changing most of them to standard lenses.
It should not to be too difficult to choose a digital SLR as the immediate factor is if you already own any SLR auto focus lenses they may work with an existing Digital SLR bodies currently available. For example you have a Canon Auto Focus lens from the last 20 years it may well work. Its worth checking with us or Canon, also check if you have any other SLR equipment such as flash guns or extension tubes if these are compatible. There are also a lot of other lenses out there too by Tamron or Sigma for example that you may have, its worth checking via the manufacturers website to see if the lenses will work.
If you don’t own a lens or related equipment then you can choose from a increasing range of Digital SLR’s.
Consider your needs.
Its best to figure out what you need your new SLR to do. If its your first venture into photography then the lighter models that come with lenses or the entry level digital SLR’s will suit your needs. Buying with a “kit” lens is the most cost effective way to get both the camera and body. They often come with a useful lens for everyday use and cover a good working range of focal lengths. With everyday photography in mind, holidays, portraits landscapes etc, not anything too specialist.
If its is for sports or newspaper work then you probably know what you need already but these cameras may not be the highest of resolutions but will be very fast and a have a high frame rate of around 8 frame per second and have a high price tag too. Great for rapid shooting of fast –high paced actions sports.
For the serious professional for very large prints there is the full frame SLR’s where the capture device is the same size as a normal 35mm film frame which means there is no “field of view crop” and a 18mm lens is an 18mm and not in the case of the main stream digital SLR’s where their capture devices are smaller.
Lens options
Lenses vary greatly in price with different qualities of glass and focal lengths and speed. A lens with the best glass and a fixed aperture could cost five times as much as one with cheaper glass and a variable f-stop. Its quite important to know what you want and buy what’s right.
Normal fixed or Zoom
The focal length of this camera lens is measured in millimeters and determines the lens's viewing angle. Camera lenses with a 35mm - 105mm viewing angle are called normal lenses. These camera lenses have a wide range of use and are very popular.
Wide Angle
Wide-angle camera lenses are excellent for capturing large scenes or big groups of people. They are not as good for close-up portraiture, as they tend to distort the subject. Tilting a wide-angle up or down creates converging or diverging lines out of lines that are parallel. Also, people's heads at the edge of a wide-angle frame can be very distorted. Wide-angles are great for shooting architectural interiors (watching out for those converging/diverging lines) as they give a wonderful sense of space. Please note as don’t forget to allow for FOVC
Telephoto
Telephoto lenses bring your subject closer to you. Because they also magnify camera shake they can be a problem, producing blurred pictures, therefore a tripod is recommended. Although they are usually heavy and bulky some have integrated optical stabilization combating some of the shake, telephoto lenses are ideal for use in many situations. Telephotos not only get you close to faraway subjects, they also compress foreground and background and have an inherently shallow depth of field. Moderate (85 to 200mm) lenses are great for portraiture. Such lenses flatter most peoples' faces and blur backgrounds, thus helping to focus on the subject. Large (300mm and up) telephoto lenses are a must for sports and wildlife photography.
Extenders
By adding an extender lens, (optical extenders are best) to your existing camera lens you can bring your subject closer by 2 times magnification.
Memory choice
Digital SLR’s take a variety of memory and its best to buy the best you can afford. Often there are faster cards available that help your camera read and write the images as fast as it is capable of. Unfortunately is not always easiest to tell how fast this is going to be but one man dedicated to the task of finding out is Rob Galbraith at www.robgalbraith.com and he has Compact Flash card database which helps. Most but not all SLR’s use CF but this can used as a guide for other models.
Power
For extra power to your camera there may be a battery grip available, these grips normally accept two of your camera batteries or a number of AA’s. They often give your camera and extra fire button or an addition mode dial to access some camera functions. You can double you power this way for long uninterrupted shooting.
Tripods
As a rule choose something sturdy and solid that will stand a few knocks and bumps, but at the same time not be too heavy. A good tripod will be headless and you have the freedom to choose the head you require. There are some good tripods with heads attached already but look for something that can handle the combined weight of your camera plus your heaviest lens. For the those that don’t have heads, look for kick legs or legs that can be set to 90 degrees to the column for various bracing options when in awkward places. Also a column that can be reversed for low lever shooting or even one that can be inserted into shoulders of the tripod parallel to the ground for copy work.
If your tripod is sturdy and its extremely windy or you are worried it may topple over due to the angle then it will handle the weight of hanging your kit bag over or under it steady it from vibration and lower its center of gravity to prevent it toppling.
Manfrotto show us how to use a tripod with some good basic tips.
