I also have a couple of primes but purchased the 12-100 for when I travel outside the country and when I hike. Had the 12-40/2.8 zoom which I sold and this replaces it. It is incredibly sharp and has a nice range. Be advised it is quite a bit heaver then the 12-40 but to me the trade off is worth it. Also you get 6.5 stops of IBIS since the 12-100 has image stabilization in the lens. Go to lenstips and cha-cha the review of the lens. Very sharp throughout the whole range. It also focuses extremely fast. I use it on an EM-1 II and don't have a battery grip but I have no problem with the balance. I do have a RRS L brace on the camera however.
Highly recommended.
Jim
I had it and was impressed with the image quality. But I thought it was large for a carry-around lens for MFT and of course with f/4, you're limited in low light unless your subject is stationary. I ended up selling it with all my other 'large' MFT lenses when I bought into Canon mirrorless. Still, if you're looking for a do-it-all lens in MFT and you already have the f/1.2 lenses for low light, it's a great allrounder.
I think this is the perfect lens to accompany 1.2 pro's. Many people are concerned with F4 but you can't beat the range! I always shoot primes anyway when the light is poor. Are the Pro's that much better than my 1.8's however? I'd like to know.
I've had it since it came out and often use it in my 'small' travel outfit: 12-100, Laowa 7.5/2 and Oly 17/1.8. It may not be that small a lens, but it's on the camera 80-90% of the time, and the other two lenses are very small, so the whole thing isn't that big. And, it's such a good lens and so versatile with a fantastic stabilization system on Olympus cameras that it always delivers. I have a lot of other m43 lenses, but this one isn't leaving.
I've had two copies. Both have been razor sharp throughout the focal length. In my opinion, it's sets the standard of what a modern day zoom CAN be. I love my Sony 24-105, but at 85mm it's rubbish, even at F9. Not the case with the 12-100. It's worth every penny and the extra heft, IMO.
vrkala wrote:
I have the 1.2 trio primes. I am wondering if this is right time to add 12-100mm lens.
I bought the 12-100 last week and I used it for some Christmas mini session. I have to admit I am really shocked: it is so sharp that sometimes I have the impression I am using a prime lens yes, the 25/45 f/1.2 are a bit better, but just really a bit.
You won’t be disappointed!
Got to say the Oly zooms 12-100, 12-40 f2.8 are really good as are the primes. It is not an easy task to tell any of them apart by their images at comparable apertures.
PhotonBeam wrote:
I have been tempted to trade in my 12-40 pro for the 12-100 pro. However, I am not sure if I would miss f2.8.
I guess it depends on what you shoot and why you'd need that aperture.
When I got my 12-100 I figured I'd hang on to the 12-40 due to its speed. I haven't used the 12-40 once. Meanwhile the prices of used 12-40s keep dropping.
Honestly, I'd probably feel guilty selling the 12-40 knowing someone is spending money that could be better spent (on the 12-100).
PhotonBeam wrote:
I have been tempted to trade in my 12-40 pro for the 12-100 pro. However, I am not sure if I would miss f2.8.
I use to think that and honestly I don't anymore - but I can also say the 12-40 has it place and you might want to have both. I took this shot a couple of days ago which has been cropped and enlarged by 200%. The image is a little soft, especially after the upload, but I found the 12-100 offers me a lot more then the 12-40.
It is a marvelous lens. I don't think you'll beat it as a compliment to the 1.2 primes. IQ is as good as the primes at many FL's in my opinion and I've tested them (can send you the test shots if you want). You also have the stabilization which is nice to make up for the aperture if you have static subjects. F4 isn't awesome, but in decent lighting you will not beat this lens. I used to travel with it on the camera and the 17mm 1.8 in my pocket when I was traveling light.
I've switched to FF for the kind of things I used this lens for so I may let mine go soon--keep an eye on the buy/sell forum.
I have both. I bought the 12-40/2.8 soon after getting my EM1ii. Great lens for walk-around, travel, even indoor low light. I picked up a 'like-new' used 12-100/f4 a few months ago, also a great lens for travel. More versatile than the 12-40, obviously. I thought about selling the 12-40 but there are times when it works better. For low light shooting with either lens, it depends on what you're shooting. The 5-axis sync on the 12-100 will get you a sharp exposure of a still object by giving you a couple seconds shutter speed, which is very cool and can be handy. But if the subject is moving, like a kid moving around, the brighter aperture of the 12-40/ f2.8 will be what you want.
Years ago I was using a Canon 7D with a 70-200/f4 IS. I loved that combo for when my kid was playing sports, etc. But when he started playing HS varsity football and the games were at night instead of daytime and our home football field had crappy lights, I had to find a 70-200/f2.8 to get faster shutter speed to stop motion blur. Same when comparing the 12-40/f2.8 and the 12-100/f4 here, it seems to me.
yes, the 25/45 f/1.2 are a bit better, but just really a bit. 
