Macro lenses

[zjs3]

If have a zoom lens all the way out to 250mm and am standing at the closest focusing point for the lens to my subject, say 1m then would the image on the sensor be any bigger then say a 50mm macro lens or 90mm macro lens at its closest point of say .4m? I'm not looking for an exact answer (as in the mathmatical computations). What I am getting at is, I understand that a macro lens contains an element that allows you to focus closer up to your subject but besides that whats the difference between that and zooming in really close with a zoom lens at the closest point? I have taken some decent shots of flowers etc with a zoom lens and achieved nice detail so whats the difference?

Thanks!!

[inkista]

Ok, let's put it this way.

If you're shooting with the Canon EF-S 55-250 IS lens then your maximum magnification (from the specs) is 0.31x, or ~1:3 magnification (actually a little less). Chances are good, btw, that that magnification isn't at the long end of the lens. Typically, the longer the focal length gets, the longer the minimum focus distance gets (e.g., my 400mm lens has a minimum focus distance of about 10 feet).

The EF-S 60mm f/2.8 USM Macro, however, has magnification of 1:1.

So, if you had an object that was the same size as the sensor (22.3mm x 14.9mm), you could fill the entire frame with that object with the macro lens. But you could only fill a third of the frame with that same object with the 55-250. You get any closer to the subject to try and fill the frame, and you won't be able to focus.