Macro ability of telephoto vs. 'true' macro

[jacknimble]

So I actually already bought my 100mm 2.8 lens, not knowing what the difference is between this and the macro ability of, say, my 70-200mm L lens is but trusting that it exists, and now i'm curious to hear it spelled out. The follow up to this question is that i'm realizing I need extension tubes to get the shots of dewdrops and other very tiny things and I just don't understand how you get those shots of flies and things with a 100mm and extenders and such, do you literally just pick a leaf and hold it there really close and hope a fly lands in that spot? It's boggling my mind how patient you must have to be for this and i'm wondering why I wouldn't want to use a longer lens to make that aspect a little easier. Sorry for the milti-tiered question:o

[krb]

The true value of a "real" macro lens is that they are pretty much all -incredibly- sharp and they will have very, very little distortion.

When shooting insects many people do in fact use longer telephoto lenses with extension tubes. I love my 100-400 with extension tubes as a butterfly lens.

There is some technique to shooting insects. Many of them will "make the rounds" of an area so if you see an insect in a spot it will fly away when you get close but if you sit still the insect often return.

[John_B]

jacknimble,
Well first your 70-200mm doesn't do true macro. True macro is when the subject shows as life size (1:1) on the sensor ex. a 15mm subject shows up as 15mm on the sensor. So your 100mm will make your subject larger on the sensor then your 70-200 will (more magnification). You have both lenses so try this: set your zoom to 100mm and to its closest focus point and take a photo of a still subject. Then take your 100mm f/2.8 and set it to its closest focus point and take a photo of the same subject. You should see a bit more then double the magnification with your 100mm f/2.8 ;)

Shooting live insects can be difficult but not impossible. A slow approach is usually needed and there maybe many times where the subject took off before you got it in focus. But when you get it right its that much more worth it. But holding the leaf isn't how I would do it, as I probably couldn't hold the leaf steady enough for it to be sharp macro photo :lol:

A longer lens adds more problems to macro subjects but also some positives. They are heavier and can be harder to hold steady enough but yet will give more room between the subject and lens. Most longer lenses (telephotos) aren't true macro lenses and wont have the small subject be large enough on the sensor.