I have both those lenses. Excellent. I have used my Sigma 1.4X TC, but as said you have to use manual focus. Better to get closer to birds one way or another. I would not sell my 70-200 Sigma! Too good. You might do better to buy a Tamron 500mm mirror lens or similar to get the 500mm fl. Russian 3M5A mirror lens is another cheaper but quality 500mm lens.Some very cheap manual lenses out there as well. eg 400mm f6.3 or f5.6. These give quite reasonable quality. cheers
bb2

I find it hard to take my Sigma 70-200 Hsm 2 macro off the K5!!!
From birds in flight to close ups to sports photos it's great.
bb2

I have the Helios 44M with M42 mount. It's probably my favourite lens for taking orchid photos.cheers
bb2
[IMG]http://i427.photobucket.com/albums/pp357/beachboy2_photos/Orchids/IMGK7147-Blue-China-Orchid-.jpg[/IMG]

Just picked up a copy of :
The Ultimate Asahi Pentax Screw Mount Guide by Gerjan van Oosten (ISBN 90-76537-02-X)from Amazon UK. Several copies still for sale.
bb2

I recently bought the Sigma 70-200 F2.8 Macro 2 HSM. It's brilliant. Price reduced here makes it very attractive option.
bb2

Just picked up a Refconverter A. Excellent for focussing and for not getting neck strain doing macros.
bb2

From adaptall-2.org:
Tamron SP 300mm F/5.6 Model 54B: A very good fixed focal length lens with excellent macro capabilities. Lens continuously focuses from infinity to 1:3.3 macro and features a built-in lens hood. Most importantly, this lens features a special "spherical aberration compensator group" (the light blue shaded elements in the above drawing) to remove the focus group's spherical aberration and field curvature when close focusing. A similar optical group is also found in several other SP telephoto lenses which Tamron produced during the 1980s. This lens is worth the price if you need a lens for macro work yet need considerable working distance from the subject for personal safety or other reasons. This lens should have sold better in its day, but few photographers understood or appreciated the benefit of the spherical aberration compensator group used within this lens for close focus work.

Lens Specifications:

Lens Model 54B
Focal Length 300mm
Aperture Range f/5.6 — 32, AE
Angle of View 8°
Optical Construction
(Groups / Elements) 5 / 6
Min. Focus from Film Plane 55.1" (1.4m)
Macro Mag. Ratio [w/2X Converter] 1:3.3 [1:1.6]
Filter Size 58mm
Diameter 2.5" (64.5mm)
Length at
[w/Nikon mount] 6.4" (163.5mm)
[6.6" (168mm)]
Weight 21.5 oz. (610g)
Lens Hood Built-in type, retractable.
Accessory Accepts SP 2X tele-converter #01F. Tripod mounting ring available as optional extra.

bb2

I bought a new one here in Perth Western Australia 2 weeks ago for equiv of 500GBP. Price must have come down somewhat!
bb2

I couldn't bear to part with mine, so I lend it to my (adult) kids and take it back when I go travelling (smaller and lighter).
bb2

I have the Komine and the Super Taks in 135mm. They are both excellent.
bb2