Lens quality

Professional versus Consumer Lenses

No matter which camera system you own, you will find that there is a large, often bewildering large, selection of lenses available. These lenses come with a variety of cryptic and ill-documented codes. Prices vary enormously: for my Canon EOS camera I can buy new Canon lenses from £90 (EF 50mm f1.8 II) to £60,000 (no kidding! EF 1200mm f5.6L USM). Add to this the selection of lenses from independent makers and you can easily feel lost.

The purpose of this little guide is not to steer you through this maze of choices: that would be a much, much bigger document. Rather it is to try and provide an answer to the question “What do I get for all that money?”. What is the difference between and £100 and a £1,000 lens and will it matter to me?

This is not a comprehensive guide, but it should give you some idea of the benefits of expensive lenses. If it helps you to decide for yourself if they are really worth it for your pictures then I will be very happy. It is important not to listen to the hype: some people talk about “consumer lenses” with disdain in their voices, implying that you can not take any decent pictures with them but must pay ten times the price for a “professional lens”.

While there is no doubt that the professional lenses are better in many respects than their consumer relatives, it really all depends on what you want to use the pictures for. If you intend to make 30"×40" enlargements for commercial use from your 35mm negative then you will need the professional lens (you should really switch to a larger format but that's another story). However, if your aim is 6"×4" pictures for your granny then you probably don't. Read on, and see the difference for yourself.

The examples in this document are from my 35mm Canon EOS system. The Canon brand professional lenses are known as 'L' series lenses. You will recognise them by the capital L after the maximum aperture. So the EF 24-85mm f3.5-4.5 USM is a cheap-ish (£300) consumer zoom lens while the EF 28-70mm f2.8L USM is an expensive (£1,200) professional zoom lens. The pictures in these examples are from Photo CD scans by Kodak with the enlargements taken from the 3,072×2,048 scan.

A separate section discusses the quality of normal lenses (i.e. 50 mm lenses).

Sharpness

One of the first things you will hear people talk about when they talk about the expensive lenses is sharpness. The pictures from a professional lens are normally much sharper than a consumer lens.

This is not always a good thing! Portraits, for example, are not at their most flattering when they are very sharp and you can clearly see every blemish and imperfection in the skin. This is why you can buy special soft-focus lenses (e.g. the EF 135mm f2.8 SF).

But in general, if you want to make any sizable enlargement from the very small (24×36 mm) negative then the image has better be sharp. Sharpness is, in almost all cases, a Good Thing™.

The examples below show a view of St Albans Abbey Church through the EF 22-55mm f4-5.6 USM consumer lens and the specialist TS-E 24mm f3.5L professional tilt and shift lens (unshifted). Apart from the slightly wider coverage of the zoom lens (which was used at its widest 22mm setting) it is hard to tell the pictures apart.

Original 135 format images of St Albans Church

Canon EF 22-55 f4-5.6USM 1/400 f5.0	Canon TS-E 24mm f3.5L 1/44 f5.0

Canon EF 22-55mm f4-5.6USM 1/100 f11	Canon TS-E 24mm f3.5L 1/80 f11

You may notice a slight vignetting in the images from the 22-55mm lens. Other cheap lenses may or may not exhibit the same problem.

However, there is another difference which you will see with all cheap lenses and which accounts for much of the price difference. If we zoom in on the trees at the right of the image, you can see it clearly:

Effect of lens quality

Canon EF 22-55 f4-5.6USM 1/400 f5.0	Canon TS-E 24mm f3.5L 1/400 f5.0

Canon EF 22-55 f4-5.6USM 1/100 f11	Canon TS-E 24mm f3.5L 1/80 f11

No doubt about it: the image from the cheaper lens is "fuzzy" while the professional lens is sharp and shows the highlights in the trees even at this magnification. The enlargement is from approximately 3.8×4.4 mm on the original negative.

There is a difference in sharpness between the two lenses and you can see it with an 8× loupe on the light board or when you magnify the image. The question you have to answer is if this improvement is worth £1,000 to you.

Colours

The professional lenses often shows colours better but I'm struggling to show that on the web with it's limited image support and uncalibrated monitors. I hope to complete this section later. Meanwhile, suggestions for how to show this are welcome.

Choice

Specialist lenses are often only available in professional editions. The standard example is long zooms: all Canon fixed focal length lenses from 200 mm are 'L' series professional. Another example is the tilt and shift lens we have seen earlier. This lens is used to control depth of field (tilt) and converging verticals (shift). An example of the latter is shown below.

St Albans Abbey Church: with and without verticals corrected.
Unshifted	Lens shifted +10mm

A shift lens will never replace large format cameras for serious professional architecture photography, but it is a god-send when you want to capture a building on a trip where you use 35mm for everything. I wouldn't travel with a large camera, but I do travel with the Canon SLR.

Other Considerations

The professional lenses are normally built to a higher standard than the consumer versions. This is good, essential even, if you use and abuse your lenses a lot, as a professional who takes pictures every day is likely to do.

The down-side of the extra quality and faster lens is that the professional lenses are heavy. Often very heavy. This should be a serious consideration if you intend to travel with a selection of lenses: the pro versions can literally be a pain in the back and you may find that you can not carry your expensive glass on to the plan, but have to check them in the hold. For example, the EF 55-200mm f4.5-5.6 USM weighs 310g while the EF 70-200mm f2.8L USM is exactly one kilogram heavier at 1,310g. It you have to wear it around your neck all day it makes a difference. Remember that it is better to get a picture on a cheap lens than not get the picture at all because you got tired of carrying a heavy camera bag.