Why do you need a macro?

[Photolistic]

I am not understanding the difference between a 100mm macro and a 100mm prime lens. Is it not the same thing?

[braduardo]

The 100mm Macro has a signifigantly shorter minimum focusing distance, which allows you to get so close to your subject that the recorded size on your sensor is the actual size the subject is in real life. For example, you could make a dime fill the frame. With a normal 100mm lens, the dime would only fill a small portion of the frame.

I don't have any handy examples, but I'm sure someone will post some up... Otherwise I will track some down for you.

[Photolistic]

ok tat makes complete sense!! Thanks

[Choderboy]

Gives you something else to look for when evaluating a lens: Maximum Magnification

Canon 100mm F2 is 0.14x magnification (very low) as it's closest focusing distance is 0.9m/3ft.
400L 5.6 is 0.12x, lower still.
Lowest is 1200L 5.6 at 0.09x.
90mm TS-E is 0.29X - high magnification (same as 24-70 2.8)
Highest non macro Canon lens is 0.3x ( 4 lenses)
Normal macro have 1x (life size) a 10mm long bug will be 10mm long on sensor. (at closest focusing distance )
MP-E65 has a 1 - 5 x range.

[zacwolf]

can someone explain why i was once told macro lenses are great for portraits?

[sirsloop]

they can still focus on things farter away than the minimum focus distance, so you could use a 60mm macro lens as a 60mm lens.

[braduardo]

can someone explain why i was once told macro lenses are great for portraits?

Also, because they are EXTREMELY sharp lenses.

[bolantej]

can someone explain why i was once told macro lenses are great for portraits?

maybe because they have a larger max aperture, offering more control over DOF? Just a guess. A lot of the macro lenses out there are very very sharp, too. that could also be a reason.

[braduardo]

Ok... Here we go...

The first one is taken at about 180mm with a normal lens, at the closest focus point.
http://img155.imageshack.us/img155/8480/nonmacromediumus3.jpg

And one with a 180mm Macro lens. *Note, I think I had a set or two of extension tubes on*
http://img155.imageshack.us/img155/3808/macromediumez9.jpg

[braduardo]

maybe because they have a larger max aperture, offering more control over DOF? Just a guess. A lot of the macro lenses out there are very very sharp, too. that could also be a reason.

Hey Jason! I'm still LOVING the 70-200...

[PetKal]

The 100 f/2.8 macro is also excellent for shots like these.

[Mollym/CA]

Wow. You must have a fast hand and eye. Is that the whole frame or a crop?

Pretty good demonstration of how fast the MkII is-- how many shots did you burn to get this one? Were you using the single-shot setting?

[PetKal]

Wow. You must have a fast hand and eye. Is that the whole frame or a crop?

Pretty good demonstration of how fast the MkII is-- how many shots did you burn to get this one? Were you using the single-shot setting?

Thankyou, that's an unprocessed JPG original.....if I was cropping it, the bird would not be flying out of the frame. With this lens I normally get a decent keeper ratio. But have not tried to shoot often anything smaller or faster than seagulls. Yes, I think single shot was used because they were not flying fast/erratic.
I have also found one Least Tern shot(JPG original).....however, the 100 f/2.8 AF would start to feel a bit slow for those fast birds, I suppose.

Again, the lens is capable of a very fine IQ, and the AF is fast enough for most applications.

[rdenney]

In addition to being able to magnify things to life size, macro lenses are also corrected for even performance into the corners, a completely flat focus plane, and zero distortion for copy work. I use my 50mm/2.5 macro as a copy lens, and it's sharp enough so that I can get results nearly as good as scanning on a flatbed scanner, and with much better color.

The 50mm macro has 9 elements, compared to the 5-7 elements in most 50mm lenses. The extra glass is there to provide a finer level of correction and flatness of field.

Rick "who needs a flat field and no distortion much more than 1:1" Denney

[PetKal]

In addition to being able to magnify things to life size, macro lenses are also corrected for even performance into the corners, a completely flat focus plane, and zero distortion for copy work. I use my 50mm/2.5 macro as a copy lens, and it's sharp enough so that I can get results nearly as good as scanning on a flatbed scanner, and with much better color.

The 50mm macro has 9 elements, compared to the 5-7 elements in most 50mm lenses. The extra glass is there to provide a finer level of correction and flatness of field.

Rick "who needs a flat field and no distortion much more than 1:1" Denney

An important feature indeed.
Petkal "who thinks Denney makes a startling but very pertinent discovery here and there".;) :D