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07-14-2010, 03:25 AM   #1
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Old sigma 70-200 vs New hsm 70-200

I am trying to understand why Sigma when doing an "advancement/upgrade" such as going to the HSM; messes with the optical formula and would make a lens that is not the same or better image quality? Is that, in fact, what sigma did in this particular situation? What's the deal?

07-14-2010, 04:54 AM   #2
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QuoteOriginally posted by 41ants Quote
I am trying to understand why Sigma when doing an "advancement/upgrade" such as going to the HSM; messes with the optical formula and would make a lens that is not the same or better image quality? Is that, in fact, what sigma did in this particular situation? What's the deal?
Essentially I think what Sigma did was reduce the minimum focus distance by, I believe, adding a floating element to the optical design. This enables roughly 1:3 macro performance but has degraded image quality a little, especially at 200mm.

Why they did this I don't know but I suspect it's because they wanted to aim the new lens at a more consumer orientated market to increase it's desirability and potential sales. They also may have wished to try to differentiate the lens from Canon, Nikon etc.

I think their new 70-200 OS adds weight to this general belief because this lens has a traditional 1.4m mimimum focus distance and is clearly being sold as an image quality orientated product. If Sigma had planned to do this all along it might explain why they didn't mind the image quality being negatively affected by the shortening of the minimum focus distance in the 'Macro' upgrade of the original lens.

In essence the replacement for the original 70-200 is in fact the new 70-200 OS not the 70-200 Macro

This is just what I think might be the case.
07-14-2010, 05:16 AM   #3
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All lens design is a balancing act of compromises.

I have the origonal SIGMA APO 70-200F2.8 and am very pleased with the lens and its sharpness at all focal lengths wide open.

But, I think as lens designs progress and newer materials make potential significant cost reductions or improvements in performance at one point at the expense of another.

There may also be issues relating to the incorporation of SDM technology and OS technology that require changing the focusing element location or in the case of OS the group locations that force optical formula design changes.

For me, I am happy with what I have, but note that my lens sold for $1200 2003 dollars, not the 899 the lens sells for today.
07-14-2010, 06:38 AM   #4
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Thanks for the clarification. I was thinking the macro version was the replacement. I didn't even know about the 70-200OS.

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