Macro lens and focal lengths (maybe a silly question).

[compleks]

This is probably a silly question, but I'm trying to learn a bit more about macro photography.

I was browsing eBay today and noticed the different focal lengths on some macro lenses. I was just wondering if the macro focal lengths are essentially the same as the focal lengths on your standard telephoto lenses?
I saw some lengths up to 150mm on a macro lens and was wondering if the higher values basically allow you to take good macro photographs without having to get as close to your subject?

Cheers.

[AgBeard]

Originally Posted by compleks

I saw some lengths up to 150mm on a macro lens and was wondering if the higher values basically allow you to take good macro photographs without having to get as close to your subject?

Cheers.

You've got it in one the longer the focal length the further away from the object - the easier to light & you don't spook the wildlife. The stat that you need to consider with a macro lens is the magnification factor i.e. what is the size of the object on the sensor, is it one to one.

[compleks]

Ah, thanks for the response.

I've heard the 1:1 ratio mentioned alot. Will a true Macro lens always achieve a 1:1 ratio?

[mschwarz]

And how important is a 1:1 ratio, as compared to a 1:3 ratio (as an example)? I'm investigating macro lenses myself, but not sure what to make of a lens that isn't 1:1.

Is it that important for standard size prints?

[daft_biker]

Originally Posted by mschwarz

And how important is a 1:1 ratio, as compared to a 1:3 ratio (as an example)? I'm investigating macro lenses myself, but not sure what to make of a lens that isn't 1:1.

Is it that important for standard size prints?

The magnificaion ratio, such as 1:1, along with information about the size of the sensor tells you how big a subject is. It also tells you how small a subject you can fill the frame with.

1:1 means 1mm of the subject is recorded on 1mm of the sensor - lifesize. eg on my 40D 1:1 would be for photographing an area 22mm x 15mm.

1:3 means 3mm of the subject is recorded on 1mm of the sensor - 1/3rd lifesize. eg on my 40D 1:3 would be for photographing an area 66mm x 45mm.

You can photograph something 3x bigger at 1:3 than you can at 1:1 so which better suits your needs depends on the size of the subjects you want to photograph. 1:1 lets you get closer than 1:3.

I'd want the dedicated macro lens that does 1:1 rather than a general purpose zoom that can only go down to 1:3 personally - you can get much closer and get much higher quality results out a "proper" macro lens compared to a budget zoom lens.