I've been watching this thread with interest as I'm looking for a longer range lens for my EM1.2. I'm renting both the Pana 100-300 II and Pan-Leica 100-400 to do some side by side comparisons, including comparing it to the Oly 40-150 + TC which I already have. The 40-150mm is great, but like others have mentioned I was disappointed when using it with the TC (thus, I never use the TC anymore). Much of what I shoot is at significant distance (multiple kilometers) and atmospheric effects are usually the limiter in IQ.
I shot with both the Pan 100-300 II and the Pan-Leica 100-400 for a few days and did some comparisons. I also did a few comparisons with my Oly 40-150 Pro f2.8. While I wouldn't consider it formal lens testing (I didn't use a resolution chart nor did I have an optical bench for precise alignment), I did shoot hundreds of shots with each lens and got a good sense of the differences, at least for my purposes. All shots were done on a Oly EM1.2. These are the only non-Oly m4/3 lenses I have used.
First, the obvious for those that have already handled these lenses. The P-L 100-400 is a big, heavy, solidly built metal lens. It's very similar in size/weight/build to the Oly 40-150 Pro. The Pan 100-300 II is significantly smaller, lighter, and molded plastic housing. The Pan 100-300 II is also weather resistant as I believe the P-L 100-400 is although I didn't see that in the specs. The Pan 100-300 II is much less expensive than the Pan-Leica 100-400.
Bottom line is that I found both lenses impressive. I'm going to list a number of observations from my testing.
- Neither lens had quite the IQ of the Oly 40-150 Pro at 100mm or 150mm.
- The Pan-Leica had better IQ/sharpness in the corners compared to the 100-300.
- The 100-300 may have been ever so slightly sharper in the center wide open only.
- I thought the Pan-Leica performed well at 400mm although I've seen forum posts of people commenting about image degradation on the long end (similar comments seen for the Pan 100-300 at the long end, but it did well too in the center but not so much in the corners). We already had a discussion how some of these observations might be related to atmospheric influence at distance. I was able to use the 100-400 @ 400mm to identify a house at a distance of 15km.
- The OIS image stabilization on the Pan-Leica was amazing and noticeably better than the Pan 100-300. Now you have to take into account I was using this on the OMD1.2 which I don't think will do Sync IS with non-Oly lenses (I did have the just released V1.2 fw on the Pan-Leica though). I'm also wondering if the increased weight of the Pan-Leica made it easier to hand hold steady. I found that I got a bit better results with the OIS of the Pan 100-300 turned off and only using the IBIS on the Oly OMD1.2. On the Pan-Leica 100-400 I got some sharp images @ 400mm at 1/20th second hand held. At 1/30th or so, I consistently got sharp images at the long end of the Pan-Leica. BTW, the best I was able to get was a couple of sharp images @ 400mm @ 1/8th hand held (sitting down braced), but these were outliers.
- In one series of tests, I had some issues getting tack sharp images at 400mm on the P-L mounted on the tripod at slow shutter speeds (between 1/4th-1/20th sec). In retrospect (and after repeating the test), I think I must have had some vibration in the mounting system because I could get tack sharp images in a similar setup hand-held at faster shutter speeds. On the tripod, I had no such issues with the Pan 100-300 II.
- The Pan-Leica didn't seem to perfectly autofocus at 100mm with some closer range shots. I got better results manually focusing in this scenario.
Other observations/comments:
- Olympus Pro Capture mode doesn't work on either of the lenses (the option is greyed out)
- I've seen people complain about the very stiff zoom on the Pan-Leica 100-400. The lens has a "zoom lock" feature and you have to make sure it is completely unlocked, otherwise it's very hard to zoom. Placing the lock ring in the completely unlocked position was not obvious on initial use.
- I do not believe (from reading other posts) either of these lenses will work in Sync IS mode on an Oly body. I would hope the two companies would work together to make that happen in a future fw update. I have to imagine Dual IS with Panasonic bodies would be amazing, but I don't have a Panasonic body to try that.
- In one shoulder bag, I can have a travel kit with three lenses that cover the continuous FF equivalent of 14mm all the way to 600mm or 800mm. That wouldn't be close to possible with my FF setup.
- For my purposes, I ended up ordering the Pan-Leica 100-400mm. The deciding factor was the extra range, better IS performance on the OMD1.2, and corner sharpness. However, I think both lenses are great options.