I am looking for a 200/4 equivalent macro lenses. Definitely I will not go for an used Minolta, because of the skyhigh prices on 2nd hand market.
Other options are Sigma 150 and Tamron 180.
I have a few questions for the Sigma
1. Is there an optical quality difference between older non OS version and the newer OS version?
2. Is the OS in lens stability usable in all Minolta/Sony bodies?
3. Will it better than the Tamron one?

I am interested in the Sigma 150 too.

Generally speaking, the longer the better. There was a Sigma 180 years back but Sigma 150 has become the new popular macro in local nature photography field.

However, local price increase comparing to old one is significant, approximately 130% increase comparing to the old version. I am looking for reason to justify this difference.

Isn't the newest version of the Sigma 150 (Sigma 150mm F2.8 EX DG OS Macro HSM, to be precise) a splash-proof design, too?

Yes, I did a little bit home work and found it to be weather sealed, OS capable, heavier, with a larger lens hood.

One more thing is that there is no lenses for alpha mount yet.

At Sigma Benelux there is a APO MACRO 150mm F2.8 EX DG OS HSM listed for A-mount.

EDIT: oh wait, it is not: This lens is available from April 2011 for Canon, Nikon and Sigma mount. The availability for Sony and Pentax mounts follow once they are known. The retail price is € 1.225, -

Hum ... two years ago I have done all the research and review on the internet to find the best alternative to the great 100mm 2.8 where sometime I needed more reach on the Full frame body. The result was that the Sigma was not that good really on Full Frame ... (it depend on your taste ...).

On FF 100mm 2.8 is difficult for stressed insects . But, one thing become mandatory with longer Macro lens like the 200mm 4.0 is the tripod ... or a really steady position. The 1/200-250 limitation of the shutter with the Twin Macro Flash of Minolta/Sony (I have both) become limit to get sharp picture.

I have also tried to put some extension tube on the 200mm 2.8 , and also the 300mm 2.8 ... but always the image was not that sharp has the sur-real 200mm 4.0 Macro. Even with a 1.4x on the A900, you cannot see a lost in detail with the lens almost wide open. But yes, it is &*%^# expensive ...

I recently start to explain to my friend the strange law of macro lens and price on used market, where the price is Square 2 each time you double the focal lenght starting from 50mm. the 50mm 2.8 is half the price of the 100mm 2.8. The 200mm 4.0 is 4 time the ~ price of the 100mm 2.8.

Regards,

Frank

Frank...I have borrowed a Canon extension tube but I have never used it.... I wonder if I can use my old Minolta 100 2.8 macro with A77 for better reach. Again my a850 is a better candidate because of the creamy image quality as compared to A77

Can I change my 135/1.8 to a macro lens with an extension tube.

Construction of macro lenses somehow differ from other lenses. Using an extension tube allows to use any lens as a "macro" but the result might/will differ from a true macro with an extension tube.

Extension tubes are really good value if you are interested in macro photography, you can still use them with a macro lens when you get one. They don’t convert a standard lens into a macro lens but the thing you will notice though besides getting you closer with more magnification is the much shallower DOF, requiring you to stop down more, f11 at least but most likely f14, f16 even f22 and that’s where you might notice that the standard type lens is not quite as good as a macro lens, with increased diffraction.
Another thing I can think of is be careful not to get el-cheapo tubes that don’t have contacts, as f-stops are set on and controlled by the camera now and not by the f-stop ring on the lens, without contacts there is no way to regulate the f-stop/exposure with modern camera systems.
With a standard lens and tubes you could still do stacking if you had some way of racking the camera back or forth smoothly (used mainly in very high magnification work but can be used more generally as well), changing the focus instead to do a stack most likely will also change the magnification between shots, and that could make it difficult for the stacking software.
Greg

spoke to Sigma rep @ a trade show today & he kindly phoned Sigma UK's office to check for me - as far as they know there are currently no plans to produce Alpha mount versions of the 150 OS Macro HSM, 120-300/2.8 OS HSM or 12-24 HSM II (the 3 lenses that I was possibly interested in)...

I revisited Photozone and found to my surprise the Sigma 150 actually accepts teleconverter. In anytime it becomes a 225/4 macro lens.

Sigma UK (management) have me down on the list to test the 12-24mm MkII as soon as it's available in Sony mount - and they did not say anything about it not being made in Alpha fit.

David