Is there anything I cannot do without a PRO lens on a (for instance) E-M1 Mark III? Apart from a further theoretical 0.5EV stop in IS, and a much better IQ?
Specifically, I'm interested in 12-100 PRO vs. either 12-200 or 14-150.
First and foremost, what are you expectations in terms of needed reach for your hikes? Will 100mm (200mm 35equivalent) be enough of a reach for you, or will 140-150mm be enough or else 200mm be enough?
100mm is considered just fine for sports, but too short for any wildlife shots or distance shots. 140-150mm is more ideal for larger wildlife shots and distance shots and 200mm is more ideal for medium wildlife shots and 400mm is more ideal for smaller wildlife shots.
Too often, people go for the shorter focal length, because they think a PRO lens will do everything. Well, a PRO lens can be sharper and faster than a consumer lens, but a shorter reach means you need to crop the image. Cropping the image will in the end rob you the detail and clarity, because you need to resize it back to native size. So that’s why we have PRO zooms such as the 40-150 f/2.8 if you need the 150mm reach or the 150-450 Pro lens if you need longer than 100mm reach. Both of them provide native reach and high resolution without needing to crop your shots.
So what are your expectations that you plan to shoot on your hikes? You didn’t provide those information to us, so it is very difficult to tell you which lens suits you.
For example, I shoot landscape and some large body wildlife such as a bear, with an emphasis of ultra wide and I carry the 7-14 f/2.8 Pro lens simply because, it’s sharp and fast, but it is known to be a heavy BRICK. I carry it, because it gives me that quality I need in my landscape shots that the 9-18 consumers lens could not give me and nor my 7.5mm fisheye I have and the weight of a brick is simply a consequence of needing that quality. And you will quickly notice it after a long 2 to 4 hr hike ascend up a hill! I started with a 7.5mm and upgraded to the 7-14mm PRO. As a short of compromise, I carried the 25mm Prime and the 35-100mm f/2.8. But I’m 50mm short from my 35-100mm f/2.8 and so, to mitigate that, I started carrying my Panasonic ZS-100 which gives me a max zoom of 250mm, which is perfect for that long landscape shots and the quality from my 1” sensor camera is more or less similar that what I get from my E-M5 Mark II anyhow. Even with 250mm, I still find it a bit short and the lens quality off the 1” camera isn’t great for larger prints. So now I’m mulling over either a 100-400 Oly or Pana Leica. As you can see from my progression to longer and better lenses; it’s coming from shooting experience and a valid need for a particular PRO lens and reach after using a consumer grade lens.
My combined combo camera and lens setup will deliver me a minimum of 16x20 prints and 20x30 prints would not be a problem as well. So I go with the PRO lens, because I may need to print BIG. But if your needs is simply to share your photos on social media and you don’t pixel peep like 400% to look for sharpness, then why would you need a PRO lens when a consumer lens with a longer reach such as the 14-150 or the 12-200 will fine for you for smaller prints or showing on a phone screen?
It’s all about what is your expectations. Price is simply to address those expectations, which is why I myself don’t talk about price. If I need equipment to produce large prints, then I have to pay MORE to get that equipment to do its job. Why buy more when you can get by with less.
What lens combination will get you out MORE to shoot? That’s important. Price and weight are inconsequential, because there is no point in getting a superior PRO lens when it ends up sitting on the shelf or in your bag most of the time, because it doesn’t fulfill your needs more so than a longer reach consumer lens with less than superior optical quality to a PRO lens.
If you look at my lens collection, I have a decent collection of PRO and consumer lenses, but I use them all most of the time. They never sit in the bag. They get used. If you have lenses that mostly sit in the bag or in the shelf, what good is it if it’s a PRO lens with superior lens qualities, but sits mostly unused?
This is my 2 cents..