Which Digital SLR Camera?

There are a couple of new cameras in the Nikon line-up: The D90 is the replacement for the D80, but the D80 is still available and at a reduced price, it is still a great camera and better value than ever. The D700 has also been added between the D300 and the D3. I shall give a brief description each of these, but for many the mid-range D80 or D90 is the ideal choice. These are good either for the enthusiast or beginner.

I have been using Nikons for many years and the D80 or new D90 camera is quite light and compact compared to some earlier Nikon film cameras although not as small as the less expensive D40, D50 and D60 models. It fits nicely in the hand despite being small (I actually prefer cameras to be bigger than this, but I am probably quite old fashioned and in a minority) and all of the important functions are easily accessible even while looking through the view-finder. In fact the main functions are in exactly the same place they have always been on F series film cameras for the last few decades. The D80 is very well made when you consider the price and the lens-mount feels solid and robust when changing lenses. It also seems to be nicely sealed from the elements with rubber seals covering the important connectors etc.

My only complaint is that is doesn't allow me to use the aperture ring on my old lenses. It's not a big problem as the aperture is now set using a very useful finger-wheel which seems to have become the new standard for all SLRs. The old lenses work very well with the D80 body. I just need to remember to lock the aperture ring to minimum aperture setting. Also of course the sensor is smaller than a 35mm slide, so wide angle lenses are a bit less wide-angle than they would have been on a film camera and telephoto lenses a bit more telephoto, but that too appears to be the new standard except for very expensive professional cameras such as the Nikon D3 and now the new D700 "prosumer" model, which both have a full-frame sensor.

As for the photographic results, I certainly can't complain. The metering and focusing are excellent and colours appear very vibrant and images very sharp.

Overall this is a very good mid-priced DSLR sitting between the inexpensive new D60 and the more expensive "prosumer" D300, in terms of price, functionality and robustness. It is a widely available product and very popular. The built-in auto-focus motor allows it to be used with a very wide variety of lenses from Nikor/Nikon and several other manufacturers (The D40, D50 and D60 do not have an auto-focus motor and can only be used with the latest lenses with internal motors)

Difference between D90 and D80

The D90 has a new improved 12.5MP APS sized sensor, similar to the more expensive D300, giving slightly better resolution.

Summary: Good inexpensive alternative to the Nikon D300

What is an SLR?

An SLR is a "Single Lens Reflex" meaning that when composing the picture you are using the same lens to compose the photograph through an optical viewfinder as you will use to expose the photograph. In the past there were also twin-lens reflex cameras, which like many compacts use a different lens for the viewfinder although most digital compacts now use the main lens and photo-sensor, but the image is composed on the screen at the back of the camera. The complex shutter and mirror that allow the same lens to be used for both functions in the SLR make the camera bigger and heavier. For a detailed comparison between the Nikon D80 and a good Canon compact digital Please read this article

Why should you carry around a big digital SLR rather than a small compact camera?

I am not going to tell you that compact cameras are rubbish and you should always use an SLR, in fact many photographs are only captured because someone happened to have a compact in their pocket or handbag. In good lighting conditions the results from a compact can be extremely good, but an SLR gives far more creative control over the picture and in more difficult conditions will significantly outperform optically. I have written an article about how to choose a compact camera

If an SLR and a compact both have the same number of pixels they must both be the same quality?

The two main differences are that the controls are bigger on the SLR and usually much more accessible (i.e. not lots of fiddly menu functions, but discrete buttons and knobs and complete manual over-ride of the automatic functions) and the lenses and sensor are generally bigger in the SLR. You can also change lenses on the SLR rather than having just one general purpose lens. I have written more about different types of sensor below, but generally, the bigger the sensor the better. A small sensor with many pixels will be noisier than a larger sensor with the same number of pixels, which means dark areas in the photograph will be peppered with white dots or random electronic noise. Some compact cameras have tiny sensors, whereas most SLRs have an APS sized sensor (see below) which is a bit smaller than the old 35mm film size used in most film cameras although some expensive ones have the full-frame 35mm size. There are even some very expensive professional "medium format" cameras with enormous sensors.

All Nikon DSLR bodies are well made and robust, for the price, with excellent well thought out controls. There are a few extra features as you go up the range, and the cheaper ones have less buttons and simpler options. The image quality also increases as you more up the range, but even at the bottom end this is excellent. All modern lenses (i.e. less than a few decade old) will fit all of the bodies, although some autofocus lenses will only have manual focus on the cheaper models (see description below)

D40x, D50, D60 - good, small, inexpensive 10 MP DSLR cameras which are ideal for the beginner (there is also a 6MP D40) These do not have an internal motor and should be avoided if you have older autofocus Nikon lenses that you want to use (although they can still be used manually)

D5000 (new) - good, small, inexpensive 12 MP DSLR cameras which are ideal for the beginner. This, like the D60, does not have an internal motor and should be avoided if you have older autofocus Nikon lenses that you want to use (although they can still be used manually)

D80 - As reviewed above. An excellent mid-priced 10 MP, which will be replaced by the D90, but still offered great value for money.

D90 - 12 MP APS sized sensor

D200 - 10 MP APS sized sensor. Now replaced by the D300

D300 - 12 MP APS sized sensor. Excellent Prosumer camera, but not as good as the new more expensive D700

D700 - A cut-down version of the D3, with a fantastic, extremely sensitive full-frame 12 MP sensor. I want this one, but it is expensive.

D3 - Huge, expensive professional machine. Very fast. Excellent, but with many features only needed by the professional sports photographer, but only 12 MP (unlike the equivalent Canon that has 24MP)

D3x - Updated D3 Now with 24MP The best DSLR in the world at the moment?

This is my old Nikon F4

Not Impressed...

There has been a long debate about which is better film or digital. This debate is getting more and more one-sided as the progress of digital cameras continues. The ultimate resolution may still be from slide-film, although some digital cameras now have more than 20 MP and even that claim looks difficult to justify. I still have several film cameras and of course a huge archive of film and slides going back decades. I think I may finally retire the old camera, but I shall continue scanning my old slides and negatives until I have them all in digital form.

I have written a separate article about classic film cameras, here

A typical scanned slide on a 4000 dpi scanner is 140 MB or 70 MP, arguably a higher resolution than any full-frame digital SLR, but there is also grain on the film, which gives an effective resolution equivalent to rather less than 70MP, depending on the film used. Film can be scanned at higher resolution than 4000dpi, but with diminishing improvement in quality. Scanned film also has the disadvantage that there is an extra stage, during which imperfections may be introduced, between taking the photo and getting the digital image.

I have written a separate article about scanners, here

Whether scanning negatives and/or slides, or using a digital SLR or compact camera you need photo-editing software to improve the results: crop them to get better composition, adjust colours and brightness or just to remove read-eye. There are many great software programs, such as Adobe Photoshop, but you can also download a good free tool called GIMP (This is more complicated, so I have written a separate article about that - see below)

Free Photo-Editing Software (GIMP)

Compacts

Compacts have various sizes of sensor and when choosing it is worth checking the specification, but most importantly read reviews of the camera because the quality will vary a lot for small cameras. The size is just one thing to consider.

To confuse things further, compact camera sensor sizes are often measured differently to DSLRs. Some sensors are wide-screen and some have an aspect ratio of 4:3. The size is often denoted as a fraction of an inch e.g. 1/3" but may even appear as something like 1/3.6" or 1/1.8" (the crop factor is the relative size compared to 35mm film i.e. a sensor with a crop factor of 2.0 is half the linear size or a quarter of the area)

1/3.6" = 4.0 x 3.0mm = area 12.0mm2 (crop factor 8.7)
1/2.5" = 5.8 x 4.3mm = area 24.7mm2 (crop factor 6.0)
4/3" = 17.3 x 13.0mm = area 225mm2 (crop factor 2.0)

As I said before always read a review of the performance in addition to the size specification.

DSLRs

SLRs have a few different sensor sizes, including Full-frame, APS and Four-Thirds, most are APS, but even these come with variations:

APS-C:

Nikon "DX" format have a crop factor of 1.5
(Nikon, Pentax, Konica, Minolta, Sony and Fuji DSLRs)

Canon entry level cameras have a crop factor of 1.6
Sigma have a crop factor of 1.7

APS-H:

Canon professional DSLRs. These are virtually full-frame and have a crop factor of 1.3

Four Thirds

e.g. Olympus have a crop factor of 2.0

Full Frame
24mm x 36mm i.e. crop factor 1.0

Nikon D3 and D700

The bigger the sensor the easier it is to get low noise and high sensitivity, but the cost and size of the camera will also increase. There are a new range of smaller, lighter, much cheaper lenses from various manufacturers that will only work well with APS and smaller sensors. Always check reviews and don't just go for the biggest sensor.

Which is better CMOS or CCD? First of all, what is the difference and what does it mean?

As I said before always check the reviews before buying, because to say one is better than another is a huge generalisation.

I am a silicon chip design consultant, so I have designed chips similar to these.

CCD

A CCD is a charge-coupled device. Photons (i.e. light "particles") fall onto a matrix of light-sensitive material on the surface of the sensor after being focused by the camera lens and a charge builds up, according to the number of photons hitting each pixel (there are coloured filters to differentiate between red, green and blue light frequencies) When the picture has been taken, the charge from each pixel is then swept off to some computer circuitry where its magnitude is measured, converted to a number and it is processed and stored in the camera memory.

CMOS

CMOS is Complimentary Metal Oxide Semiconductor (or Silicon) i.e. it is a standard silicon chip. There are two main types of silicon chip: CMOS which is small and low-powered and Bipolar which expensive, fast, much larger and uses lots of power and is used for very high-end digital and analogue circuits (my speciality). CMOS is what powers your computer CPU, memory, CD player etc. It has the unfortunate feature of being light sensitive, which is why chips are usually sealed in small black plastic cases, but it also means we can make cheap sensors on a normal chip production line with all of the computer circuitry built into the same chip. The matrix of pixels is similar to the CCD, except there is electronic circuitry between the pixels in the matrix, causing some additional electronic noise. The production is cheaper, so money can be spent elsewhere.

So which is better? That really depends on the individual camera. Always read reviews, but most SLRs, whether CMOS or CCD will have very good, low-noise sensors and generally the bigger the better.