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The FA 100mm 3.5 Macro?

Started Oct 13, 2004 | Discussions thread
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Re: The FA 100mm 3.5 Macro?
In reply to erwinv, Oct 14, 2004

erwinv wrote:

I have the FA 100 f3.5, and wouldn't exchange it for anything
(except perhaps an A 100 f4.0). Not that I wouldn't want a "better"
macro lens in addition, but not instead of, because this lens has
several advantages over "better" lenses.
a) it's very light and relativily compact, so easy to take along

The Pentax 50mm f/2.8 A lens is even more compact and light weight, but it is better built. The chief complaint about the FA 100 f/3.5 and its Vivitar equivalent is the build quality.

b) it has great bokeh, not all IF macro's have that
c) being not IF, it has the longest possible working distance for a
100 macro, important for butterflies and dragonflies. I believe it
comes to 1:1 (with tubes) at a longer working distance than the
Sigma 180mm macro.

The Pentax 100mm f/2.8 is not internal focusing either.

d) it has a small extending front tube, (with a, for me,
interesting 49mm filter size) which means you can do pretty close
macro with the camera's pop up flash, so no need to take an
external flash along for the occasional macro shot.

At 1/2 magnification, the barrel of many macro lenses are not long enough to block the flash. This is especially true of IF lenses. The Pentax 50mm f/2.8 manual focus also does not block the pop up flash even at 1:2 magnification.

Sharpness is very good stopped down (macro is usually stopped down
because of DOF), but less so wide open (a bit better in macro range
then at infinity). I also had a some disappointng wide open shot's
because of poor contrast/flare problems.
Further disadvantages are build quality, and the very long
focussing throw, being non IF. If this lens starts hunting, you are
in serious trouble.

This lens does offer surprisingly good image quality for its price but distortion is higher than the more expensive macro lenses. You don't get something for nothing.

I would not advise it as a "super sharp" portrait lens, because of
hunting and wide open performance, although the bokeh is very
nice. At f8.0 it's quite nice though for (outdoors) portraits with
a distant background.

If you had the time, you could wait for how the new D-FA 100 macro
performs, because it seems closer to the FA 3.5 in size and weight
then to the old FA 2.8. But you don't have time to wait for that
one, so the FA100 f3.5 might work for you, untill the 77limited

If you don't already own tubes, I would also seriously consider the
"original" Vivtar/Cosina version, because that one comes with a 1:1


For some reason, the Vivitar/Cosina version of this lens scores much lower in photodo.com test than the Pentax FA. Perhaps it is due to sample to sample variation. Even if that is true, it does not inspire confidence. You may get a bad sample if you are unlucky. Since sharpness is the holy grail in macro photography, I would suggest getting the sharpest lens available if you can afford it. A used F version of the 100mm f/2.8 is the sharpest available for the Pentax mount and it is also reasonably priced since it is used.

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