Currently, I use a Pana 45-200 for bird and wildlife photography. Last week, on a excursion, I found that I desired a little more reach than 200mm.

I'm looking at both the Pana 100-300 and the Oly 70-300. I currently have the Pana 20mm, Oly 14-42mm, the Pana 45-200, and an adapted Canon 50mm FD, all on an EPL-1 body.

Any thoughts, specifically on the 100-300 vs. the 70-300 as it pertains to build quality, optical quality, and real-world usage?

Thanks!

if you are using a panny body, go with the panny lens, the ois is useful. The long end of it is a tad soft. And on a pen body, it really throws out the balance of the smaller body.

There still is not allot of info the 75-300. But it is much lighter and balance better on the pens. It seems to AF faster then the 100-300 when I played around with both in the shop.

I believe the oly 70-300 is 4/3 ...why wouldn't you look at the m4/3 75-300 oly?

The Panasonic 100-300 IMHO is just too big & heavy. I might as well use my DSLR & 70-300....

The Olympus 75-300 is my preference....

Sorry, I meant the 75-300mm.

Don't apologize, I have been told the 70-300 is a great lense, but it would be even more of a brick than the 100-300. I have the 45-200 as well, and take into account that the 100-300 will be larger and heavier, I believe. The oly 75-300 should be smaller or the same size as 45-200. If you have an oly body, I'd think the oly should be a strong contender. I can't say which stands out in regards to IQ... Panny lenses always seem to be held in high regard, and I have no complaints with the two that I have. I am debating the same situation as yourself, but have put it on the back burner for now as I have an OM 75-150 awaiting an adapter.

the 70-300 is not that much larger then the 100-300 actually. they are about the same size, just add the length of the mm2 adapter. And it is allot sharper then the 100-300 at 300mm. It is a very good 4/3 lens.

Not to diminish the 70-300 from Oly, but I'm really looking for a comparison of the 75-300 and the 100-300. I'm leaning towards the Pana, simply because of price, even though I'd like the extra 25mm I'd get on the wide end of the Oly.

The Internet doesn't seem to have many comparisons available. What did you end up doing?

I think I'm going to go with the Pana 100-300mm because of price. However, not the question is whether to buy it or the Oly 9-18mm first. I have another thread going on that quandary!