Why not the Canon 50/2.5 macro or 100/2.8 macro?

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I have the Canon EF-S 60mm F/2.8 USM and it is a very nice lens.  The front
element neither rotates nor extends during focussing either and the focus
ring doesn't turn during focusing either so there are no visible moving
parts to scare away your subjects.  This is a nice feature.  The lens is
also quite light (335g) and small and can be stopped down to F/32.  As usual
Canon does not supply the hood and it is a pricey extra although it is a
good one.  The focusing is a bit slow which is needed for macro distances,
but there is not a switch for focus limiting although it can be switched to
manual with focus confirmation.  There is also full time manual focus in
auto mode.  It has a metal lens mount and seems to be fairly well built and
it takes inexpensive 52mm filters.

If you are considering the Sigma 70mm, then why not the Sigma 50 macro or
the 105 macro?  Both of those are less expensive than the 70 and they both
reach 1:1 and both stop down 2 stops further (F/45) than the 70 (F/22) for
more depth of field when that is more important than absolute sharpness.
The 50 and 105 do extend during focusing although they don't rotate.  I do
not know about the 70mm and Sigma doesn't say on their website.  Sigma also
makes a 150 and 180 macro but these are much more expensive.  Sigma does
include a threaded hood and has a focus limiter.  The 70mm is also 525 grams
and is not a full frame image like the Sigma 50 and 105.  The 70 also takes
larger and more expensive 62mm filters than the 50 and 105 which take 55 and
58mm filters respectively.

Both the Sigma 50 and 105mm macro lenses are lighter, smaller, cheaper,
cheaper for filters, produce a full size image circle, stop down further and
are fairly well regarded.  What is the possible draw to the 70mm lens over
the previous offerings unless you really need that particular viewing angle?

Personally, I would watch for a good deal somewhere or even used on a Canon
100mm macro although I am very pleased with the 60mm and do not plan on
replacing it.

I have the Canon EF-S 60mm F/2.8 USM and it is a very nice lens.  The front
element neither rotates nor extends during focusing either and the focus
ring doesn't turn during focusing either so there are no visible moving
parts to scare away your subjects.  This is a nice feature.  The lens is
also quite light (335g) and small and can be stopped down to F/32.  As usual
Canon does not supply the hood and it is a pricey extra although it is a
good one.  The focusing is a bit slow which is needed for macro distances,
but there is not a switch for focus limiting although it can be switched to
manual with focus confirmation.  There is also full time manual focus in
auto mode.  It has a metal lens mount and seems to be fairly well built and
it takes inexpensive 52mm filters.

If you are considering the Sigma 70mm, then why not the Sigma 50 macro or
the 105 macro?  Both of those are less expensive than the 70 and they both
reach 1:1 and both stop down 2 stops further (F/45) than the 70 (F/22) for
more depth of field when that is more important than absolute sharpness.
The 50 and 105 do extend during focusing although they don't rotate.  I do
not know about the 70mm and Sigma doesn't say on their website.  Sigma also
makes a 150 and 180 macro but these are much more expensive.  Sigma does
include a threaded hood and has a focus limiter.  The 70mm is also 525 grams
which is quite a bit for a small lens.  The 70mm lens also takes larger and
more expensive 62mm filters than the 50 and 105 which take 55 and 58mm
filters respectively.

Both the Sigma 50 and 105mm macro lenses are lighter, smaller, cheaper,
cheaper for filters, stop down further and are fairly well regarded.  What
is the possible draw to the 70mm lens over the previous offerings unless you
really need that particular viewing angle?

I had said in a previous post that the 70mm lens is not full frame, this is
wrong, the 70 is full frame, but I am do not know what makes it better than
the 50 or 105 to justify being more expensive than either of them.

Personally, I would watch for a good deal somewhere or even used on a Canon
100mm macro although I am very pleased with the 60mm and do not plan on
replacing it.