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Originally Posted by Boobster Yandros, Looked at that thread whilst searching and it's pretty confusing. I'm too much of a novice to understand the terminology for lenses just yet. Thanks for your suggestions though. Much appreciated.  |
Im only just starting out but hopefully this will be some help (apologies if Im teaching granny to suck eggs).
The measurements that you see (e.g. 18-55mm) is the focal length, basically the distance from the lens to the sensor (canon call it the focal plane). The higher the number the "closer" you will get to the subject. Lets say you want to do landscape work you need a wide angle lens (low numbers). On the other hand if you wanted to catch wildlife you probably wont be able to get so close, so a zoom lens is needed (e.g. 70-300). This is exactly the same as film cameras, except that to compare them you need to multiply the digital lens by the focal length multipler (sometimes called the crop factor). For the canon it is 1.6, the Nikon 1.5.. so for example a Nikon 18-55 lens is the 35mm film equivelent of 27-82mm. This link explains it better
Focal Length Multiplier: Optical: Glossary: Learn: Digital Photography Review This was very handy when speaking to a couple of film SLR guys about lenses so we could talk on equal terms!
The lenses that only have one length advertised (someone mentioned a 30mm f1.4) are called prime lenses, as you might of guessed there is no zoom - you want more or less in the picture ? you have to move nearer or further away. The advantage is that generally the lenses are much sharper and will give a better image than a zoom.
The aperture advertised for a lens is the widest it will do - what does it matter ? well lets say we have an f2.8 lens and an f4 lens, in theory using the f2.8 lens means we can use a faster shutter speed, because more light can get through the lens/body to the sensor. Why does it matter? imagine taking shots of sports, kids running about or a bird flying.. a longer shutter time means the camera will "see" movement, which will show in your picture as a blur, so having a faster shutter time means the camera wont "see" the movement, resulting in no blur.
Cheaper lenses are advertised as say 18-55mm, f3.5-5.6. This means at 18mm the lowest aperture the lens will do is f3.5, at 55 the lowest it will do is f5.6. Some lenses are advertised as (say) 24-105mm f4, this lens will do f4 no matter what focal length.
The biggest thing about lenses is distortion, you will see this mentioned in reviews. It also seems common for lenses to go "soft" (i.e. not very sharp) at full zoom, some are better than others.
From what I read lens selection is very subjective, I've read poor reviews on lenses to go and read forums where someone has posted saying they love the lens and posted sample images far better than the ones in the reviews - what gives ? I have also seen people buy a lens, not be happy, obtain a replacement and been far happier - the inference being that the first lens, whilst not faulty was of a lower accuracy/standard. I don't doubt that some of this could be placebo effect, but there must be some truth in it somewhere.
The bit that really gets me is the image stablisation, each manufacturer calls it something different (Nikon is VR, Canon is IS, Sigma is OS, Tamron is VC (just looked them up

). No doubt Sony/Pentax call it something else too.
Any corrections to the above welcome, probably not the best description but gives you an idea
Got my 450D on Sunday, just with the kit lens. Had a few of hours with it and so far Im pretty happy, I've got to grips with the basic controls, going to start playing more with it now