Tamron SP 90/2,8 vs Canon 100/2,8

[Tomasz Dziechciarz]

Hi,

Any ideas which is better any why?
I consider to buy one of these two lenses. Any experience?

[J Rabin]

I've used these lenses below. They are all brutally sharp. The new Sigma 150mm f/2.8 is very good, if it fits your needs. Here's the way to think about working distance when these lenses are focused at full 1:1 magnification:

60mm Canon = 10 cm working distance @ $450
100mm Canon = 15 cm working distance @ $480
150mm Sigma = 20 cm working distance @ $620
180mm Tamron = 26cm working distance @ $690
180mm Canon = 25 cm working distance @ $1,300

You only pay $30 to add 5 cm of working distance from Canon's 60 to 100mm macro lenses. Unless you need the 60mm for a specific use (I do at work), the 100mm Canon macro is a best all around value in working distance and flexible use for most people. Due to the floating internal elements, the Canon 100mm has a shorter internal focal length at 1:1, probably around 70-80mm, keeping the field of view nice while still getting the 14.9 cm distance.

To step up, you pay additional $140 for the 2nd 5cm distance gained from the Canon 100mm to the Sigma 150mm. This, and the fact the Sigma comes with a hood, tripod mount, HSM auto focus, with full-time manual over ride. (I shut off auto focus and manually focus much of the time with macro lenses) makes it an interesting middle contender.

The Tamron has the longest working distance, but I have not used it.

Step up on more time, and you pay an additional $700 for the next 5 cm working distance between the Sigma 150mm and the Canon 180mm. This is an amazing optic, almost no diffraction even when stopped down to f/22-32! Ultimate in working distance. It's big and long and prefers to be used tripod mounted, except when "butterfly hunting."

What is working distance? Working distance is the distance from the front of lens element to the subject when the lenses are focuused at their closest focus 1:1 magnification. The lenses all focus continuously to infinity also, but we are only calculating close focus distance above.

Calculate Working Distance to subject =
published close focus spec for lens - lens length - distance between rear element and sensor or film plane (which is 4.4 cm for Canon EOS cameras.

Working distance is a BIG limiting use factor (in addition to the full 2 f/stops of light loss @ 1:1 magnification), so get as much as you can afford.

If you're serious about macro, do not buy any macro lens where the barrel length changes during focus. For casual macro users, this is OK (like carrying the old Canon 50mm f/2.5 in a pocket out for a hike).

When we mean macro, we mean life size reproduction, (1:1) magnification or greater. There is loads of fun "close-up" photography at less than life size, say 0.25x to 0.70x (butterfly and dragonfly hunting range) that you can do with diopters, close focusing zooms, etc. A cheap Canon XXmm-300mm zoom with a Canon 500D ($140) +2 diopter makes a good butterfly hunter, providing about 0.4-0.7x depending on focal length.

Hope that helps. J

[Jon]

I'd question whether you should avoid "any macro lens where the barrel length changes during focus." The only ways for a lens to not change the barrel length during focus are if it changes the focal length instead or for it to have a barrel that's long enough to accomodate the full focussing range of the freely-moving elements inside. A barrel long enough to allow the second approach would cause severe vignetting at infinity (it would be effectively a 100 mm deep lens hood on a 100 mm lens), or would resemble a blunderbus.