I posted a similar thread over on DPReview, but figured some better discussion might happen over here
I put together a short list (which you can feel free to add to!) of Prime Macro lenses in the 70 (was 90 - tkx Leo) to 105mm range, and their specs. Surprisingly to me, the Pentax lens seems to be the least expensive of the bunch! ($80cad less than the Sigma 100mm, which is $20 less than the Tamron 90mm)
Since the focal length of these is so close, as are the min focus distance specs AND the max aperture, I'm wondering aloud what would make me choose one of these over the others?? Obviously some will have better image quality of others, but these all seem to have higher quality optical elements.
So... Thoughts and opinions??
SIGMA 70MM F2.8 EX DG MACRO PENTAX ($699.99 @ Henry's)
# Focal Length: 70mm
# Minimum Aperture: F22
# Lens Construction: 10 Elements in 9 Groups
# Number of Diaphragm Blades: 9
# Minimum Focusing Distance: 25.7cm/10.1 in.
# Maximum Magnification 1:1
# Filter Size (diameter): 62mm
# Diameter: 3in (76mm)
# Length: 3.76in (95mm)
# Weight 525g (18.5 oz)
TAMRON 90MM F2.8 DI PENTAX MACRO ($649.99 @ Henry's)
# Focal Length: 90mm
# Minimum Aperture: F32
# Lens Construction: 10 Elements in 9 Groups
# Number of Diaphragm Blades: 9
# Minimum Focusing Distance: 11.4in (29.0cm)
# Maximum Magnification: 1:1
# Filter Size (diameter): 55mm
# Diameter: 2.8in
# Length: 3.8in
# Weight: 405g
# Accessory: Lens hood, Case
PENTAX D FA 100MM F2.8 MACRO W/CS ($549.99 @ Henry's)
# Focal Length: 100mm
# Minimum Aperture: F32
# Lens Construction: 9 Elements in 8 Groups
# Number of Diaphragm Blades: 8
# Minimum Focusing Distance: 11.93in (30.3cm)
# Working Distance - 5.12in (0.130m)
# Maximum Magnification: 1:1
# Filter Size (diameter): 49mm
# Maximum Diameter: 2.7in (67.5mm)
# Maximum Length: 3.2in (80.5mm)
# Weight (w/o Hood): 12.2 oz. (345g)
# Accessory: Hood - PH-RBC 49mm (included)
SIGMA 105MM F2.8 EX DG PENTAX MACRO 58MM ($629.99 @ Henry's)
# Focal Length: 105mm
# Minimum Aperture: F32
# Lens Construction: 11 Elements in 10 Groups
# Number of Diaphragm Blades: 8
# Minimum Focusing Distance: 12.2in (31.2cm)
# Maximum Magnification: 1:1
# Filter Size (diameter): 58mm
# Diameter: 2.9in (74mm)
# Length: 3.7in (95mm)
# Weight: 450g (15.8 oz.)
# Focusing System: Floating Internal Focusing