I get it. Professional, constant-aperture telephoto zooms are always going to be big. I also get that this lens is in its own way unique, offering a constant f/2.8 100-400mm equivalent zoom range. But why is it bigger and heavier (and more expensive) than, let’s say, the Sony FE 70-200mm f/2.8 GM OSS II, a FULL FRAME LENS?
Let’s forget about equivalent focal lengths for a moment. Let’s do a straight comparison. If you could somehow fit an OM System mount on to the back of the Sony lens, you would still get an effective 140-400mm constant f/2.8 lens that was smaller and lighter than the new OM System 50-200mm f/2.8 IS PRO (oh, and cheaper, too).
Yes, the OM System lens is slightly wider at the short end of the zoom range than the Sony lens – 50mm vs 70mm, but it only has to cover an image circle one-quarter the size!
Of course OM System will have all sorts of technical reasons for making this lens the size (and price) it is. For all I know, it’s had to use much more expensive optical formulations and materials to accommodate the smaller MFT sensor format. Maybe the OM stabilization and AF is more sophisticated (unlikely, given that the Sony 70-200mm is a G Master lens). There are lots of maybes here.
But while I’m sure the OM System 50-200mm f/2.8 IS PRO has all the performance needed to justify its size and its price, I still cannot understand why a lens that only has to cover the MFT sensor area should end up near enough the same size as a full frame lens of similar focal range.
You could almost imagine OM System is porting over full frame lens designs to the MFT format and then boasting about their effective focal range. That would never happen, right?
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