One of my friends who is a professional videographer is thinking seriously of supplementing his Sony FS7 dedicated video camera with the new Panasonic GH5S. He's looked closely at the files and finds a lot to like about them. We were sitting around having coffee and he asked me for recommendations of lenses to use with the new camera. His requirements (or strong preferences) are to have lenses that have apertures of f1.8 and faster for each lens. He would also like to keep cost down; if possible.
My first suggestion was that he consider the three new f1.2 Pro lenses from Olympus. All three have been well reviewed and seem to have superior imaging characteristics as well as the ability to move into a manual focusing mode that has hard stops for minimum and maximum focusing distances. We both are on the fence about this family of lenses, we love the "idea" of them but also feel that there are more cost effective options in the overall m4:3 universe which might not be the highest performance where high resolution still photography files are wanted but which would definitely do justice to the 4K video files he (and I ) will likely shoot.
Now, this is a topic I like to sink my teeth into. He also stated that he was more interested in using lenses specifically designed for the format instead of trying to match lenses from other systems via various mechanical adapters.
I started making a list. The first lens on my notepad was the Panasonic 42.5mm f1.7 short telephoto. It fills an important slot as a perfect focal length for intimate video interviews. It's also fast enough that when used close in allows for dropping backgrounds out of focus in a very nice way. I bought my second copy several months back and, in the past, found this lens model to be a bit sharper, wide open, than the Olympus 45mm and it also features lens based image stabilization. It's a solid recommendation for a low cost video centric kit. We wish the focusing ring had hard stops in manual focus but you can't always get what you want at the price you're happy to pay. If you want good, sharp performance at a bargain price then this is the system lens I start with.
My next suggestion is a cheat because it violates his first preference of only considering lenses faster than f1.8. I'm suggesting that everyone who shoots longer focal lengths with the m4:3 cameras get their hands on the Sigma 60mm f2.8 DN Art lens. Of course I understand that it's a stop and a third slower than my friend's limit but it's so sharp and so inexpensive that you just can't go wrong. This is a lens that you can set at its widest aperture of f2.8 and never have a moment's hesitation about its optical performance. At an equivalent of a 120mm lens in the full frame world its a focal length that's almost perfect for classical, tight head shots. Sorry, no built in image stabilization so it's either no coffee or a tripod if you want those frames to be nice and sharp. I love the sleek and minimalist lens body design but it's not everyone's cup of tea. Especially those who shoot year round with soft wool gloves. Not enough grippiness to make those folks happy...
Next up on my list of really good and really well priced fast(er) primes is the universally well-reviewed Sigma 30mm f1.4 DC DN Contemporary lens. It's priced at $339 (or close by) and this will be the second time I've owned this product (albeit in a different mount: I had it for the Sony a6300). On the APS-C frame of the Sony it's the equivalent (FF) of a 45mm lens but on the m4:3 it's closer to 60mm and that's a focal length of happiness for me. I ordered the m4:3 model last week and it came this Tues. Today is the first time I've had enough free schedule to walk around and shoot with it but the first few hundred frames I shot today reminded me what I like about this lens: the center of the frame is nicely sharp and contrasty at f1.4. The lens is a bit bigger than other m4:3 lenses but it's not nearly as big or heavy as the Olympus Pro series primes. If you like slightly long normal lenses this might be a lens you put on the front of your camera and never take off. I recommend it whole-heartedly.
Heading down to the wider focal lengths puts me into territory that I only care about when clients request it. The shortest lens I would work with for my personal work would be the 25mm focal lengths for this format which, of course, yield an angle of view like a 50mm lens on full frame. My first choice here (at prices much lower than the Pro series) would be the Panasonic-Leica 25mm f1.4 which is getting long in the tooth but is also a very well made and good performing lens. It's a classic fast lens with the best performance at wider apertures being in the center 2/3rds of the frame. It's not a lens for flat field macro work but if you like shooting fast and you're working in the video world the performance will exceed the resolution the video files well past 4K. So, it's my first choice in this focal length range for the Panasonic cameras. Important to note that this lens does not offer image stabilization either so it's best used on the latest cameras (G9, GH5) for stills or on a tripod or gimbal if paired with the new GH5S.
If price is an object (and of course it is since we've rejected the budget busting territory of our first choice of the Pro series lenses) then there is one more normal lens that I can recommend with no trepidation or hesitation and that is the Panasonic 25mm f1.7. It's exactly what you might think of as the system version of the Canon or Nikon "nifty-fifty" lenses for full frame bodies. It's decent wide open and then sharpens up very nicely so that by f4.0 and above it's almost on par with the pricier options. This lens is priced at around $250+ but it goes on sale with clock-setting regularity for the blow-out price of $159 and I think it's well worth that price. You can use it wide open and get most of the frame into the very good to excellent category or you can stop it down to f4.5 and get sparkly sharpness throughout.
As we move down into wider lens territory I can only parrot what I hear from my experienced users and take my cues from them. If I were not content with my Olympus 12-100mm Pro lens and I wanted to stay away from zoom lenses with slower maximum apertures the one additional prime I am actively considering buying is the Panasonic-Leica 15mm f1.7 lens. It seems well made, gets high marks across the reviewing world and seems affordable for 28-30mm equivalent users at around $549.
I'd suggest lenses wider than 15mm if I knew of any that were really any better than the zooms that cover the wider ranges (Olympus Pro 7-14mm, Panasonic-Leica 8-18mm) but I think when you get into focal lengths under 15mm the inherent depth of field of any of the available primes is no smaller than that of slower zooms; in a practical sense. I can't think that an 8mm f1.8 would have that much less depth of field that the 8mm end of a zoom at f2.8. The zooms I mentioned both have high optical quality; especially near their wider ends so it's not really a question of the primes delivering better image quality. In the end, the flexibility and quality of the two wide zooms wins out in the actual world of making photographs or videos. An added note: I bought (and am happy with...) the Panasonic 8-18mm zoom specifically because it is capable of taking filters directly on the front of the lens. The Olympus Pro and the older Panasonic 7-14 both have bulbous front elements which make it impossible to use conventional, screw-in filters on them. This will be more important to people who want to make video outside and less important to those who dismiss video entirely.
My ideal kit for the m4:3 cameras would include the three fast Olympus Pro Primes, the Olympus 40-150mm f2.8 Pro and the (incredibly flexible) 12-100mm lens and all of these would be supplemented by wider zoom options (the Panasonic-Leica gets my cash because it has filter threads and I can use variable ND filters on it).
I haven't covered long, fast lenses because I just don't think you can do better than the 40-150mm f2.8. If you need longer or faster you'll probably head into adaptations. The 75mm Olympus f1.8 gets very high marks and I consider it somewhat of a speciality lens. One I'd like to own but one that I have to work hard to justify.
Everyone's choices will be different. I'd opt for different lenses if I were photographing solely for my own pleasure. I'd be happy with a 25 and a 45 and I'd be opting out of the buying cycle after locking down those two models. But here I am on the cusp of a week long shoot for a large medical practice that will call for very wide shots, very tight shots, large depth of field and shallow depth of field in a random pattern throughout each day of the assignment. It helps me to justify the choices I've made!
To my videographer friend: I hope this is helpful.
Have I left any good lenses out of the mix that I should know about or learn about? Let me know!