Originally posted by rasith I'm also finding it hard understanding zoom lenses. I know that 50 - 200m would mean a 4x zoom lens in compact camera terms. I understand in telescopes a smaller eyepiece give you better magnification. Is it the same with lens? Would a 18 - 200mm give you more zoom than a 75 - 200mm or would they both be the same when zoomed to 200mm?
All lenses that can do 200mm, when zoomed to 200mm will give the same result.
A prime 200mm a xx-200mm or a say 150-400mm. All the same at 200mm.
The only thing that changes is the image quality (IQ), that depends on the build of the lens.
Here you can learn a bit about focal length :
Wiki: Focal Length
And also, don't mess up digital zoom and optical zoom which can both exist on a compact camera.
On a DSLR, you only have optical zoom. But I don't know anyone who refers to a 50-200mm as a 4x zoom lens.
Since a 100-400mm would also be a 4x zoom lens, but they have nothing to do with eachother.
We always use the focal length (range, if there is one -> no range in a prime lens since it has a fixed focal length).
Originally posted by rasith Final question! Can you recommend a macro lens for a beginner. It will be for flowers/insects?
Thanks for your help.
for flowers, a 35mm, 50mm, 60mm or 70mm will do.
For insects, you need a bit more distance, otherwise, they'll flee (if they can
).
So maybe look for a not too heavy one if you have shake-problems.
Like those ones:
Tamron 90mm
Pentax 100mm
Sigma 105mm
About SR (or OS as Sigma says), I don't know if it is a good thing to use
both body SR and lens SR.. maybe someone else could answer this?