I used to frequent this forum but haven't in the past couple of years. However, two days ago I returned from a 3 week photo safari in Kenya/Tanzania using OMs and I thought I'd post my choices/conclusions. To start with, at the time of safari planning last year, I owned a Nikon D5100 with a zoom that covered from 18-200 mm (or 27-300 mm in 35mm equivalent which I'll refer to as "35E") and an OMD EM5 with a 12 (24 in 35E), a 45 (90 in 35E) and a 14-150 (28-300 in 35E). The Nikon lens was neither wide enough or long enough to be a "taker" and neither was the Oly zoom. There was no doubt in my mind that the D5100 would be a superior weapon when simply looking at the camera capability. But, of course, there is much more to it than that in the real world.... I thought about taking the M5 with the 12mm and buying a long zoom for the Nikon but first, of course was the size/weight/cost involved. Plus, I wanted zooms for both the low and high end for added flexibility. Here's a critical point: IMO, you MUST have two cameras, one with a short lens and one with a long. This ain't landscape or architectural photography and sometimes things move...FAST. One body with a couple of lenses that you intend to change is really a non-starter for this job for two big reasons. You will miss a LOT of pictures fooling around with changing lenses and it is VERY dusty. I'm talking CLOUDS of dust on many occasions, caused by the vehicles. The dust will end up in the camera. One body/changing lenses is just not practical. So that means two cameras. And two OMDs/lenses are much smaller/lighter and less expensive than buying a 600mm (35E) nikon lens. OK, to be honest, the weight while actually out taking pics is not really a big deal because you will be doing virtually all shooting from a vehicle. No company is going to allow you to get out of the vehicle/wander around taking photos in the bush; to lions/leopards,etc, "dumb tourist" and "meal" are interchangeable words. You need something at least as wide as 24mm (35E) and as long as 600mm (35E). And really, 600mm (35E) was often a bit short! So...I decided to buy an OMD M1, a Oly 12-40 2.8 Pro lens (24-80 in 35E) and an Oly 75-300 (150-600 in 35E. I put the long lens on the M1 and the short one on the M5 and fooled around with them for several months. Then, about a month ago, we departed San Antonio for 7 flights to our first destination. The flight legs were: San Antonio - Dallas, Dallas-London, London-Nairobi, Nairobi-Kilimanjaro, Kilimanjaro-Arusha, Arusha -Lake Manyara, Lake M to a bush dirt strip, followed by a 40 minute jeep ride to the first camp. What follows in the next paragraph are my thoughts re the cameras/lenses but I must say that there were folks in all the camps/lodges (5) where we stayed that did all the photos with an iPhone so what you "NEED" for a photo safari is really based on your own preference for picture quality/the use you will put the pics to. If you are just going to send some pics/videos via text messaging/emails, obviously the requirements/expectations are much different. Re that...many places will not have internet available and you may not be able to send anything anywhere until you get to a different camp/lodge. We mostly did NOT have internet available during the 3 week trip; it was very "occasional," with some places that were supposed to have wifi...not actually having it. Cell phone service is so expensive in Tanzania even where it IS available that tourists are advised to just turn off the phone while you are there. The 12-40 2.8 was an absolute joy to use, extremely quick to focus and it took tack sharp pics. It worked fine on the M5 with the camera mostly set to P mode/center-weighted metering. It's a great lens, and I don't need to say any more about it. The 75-300 did a nice job as well but there are some things to be aware of. It's aperture is rather slow so shutter speeds in daylight in shaded areas frequently dropped to around 1/640 at 300mm/ISO200, which is pretty much a minimum shutter speed for that focal length. But coupled with the excellent M1 image stabilization, it wasn't an issue for stationary subjects and I got some keeper shots as the sun was going down with shutter speeds dropping as low a 1/80! However, since stabilization doesn't "stop" action, motion blur can be a problem with moving objects at speeds below the "thousands" at the long end if you are not somewhat adept at panning with the subject. But generally, it wasn't an issue and in open country the shutter speed was well into the 1/1250 or higher range during the day. I set the camera to Aperture mode to use the widest lens opening at all times. One thing to be aware of is that for some reason, the 75-300 - at least the one I had - was occasionally inconsistent in sharpness. Sometimes, with two identical shots, one immediately after the other, one shot would be sharp and the other slightly soft. This happened even though lighting and all settings were unchanged on an unmoving subject. Admittedly for the most part the difference was not noticeable at the original picture size, becoming visible when zoomed in in post processing. I don't know why this occurred. But overall I was quite happy with the lens and its results ON THE M1. No, the lens won't match a Nikon DSLR with a 600mm F4 for this application but the Oly lens doesn't cost 9000+USD and weigh 11 pounds! As far as the cameras and the shooting environment, the M5 would have been unsuitable IMO with the long lens. Its image stabilization is not as effective as the M1 and it's high ISO is also a bit under the capability of the M1. I set the max ISO to 1600 for the M5 and 3200 for the M1. Also, the M1 is much easier to use as far as quick setting changes. I frequently went from center weighted to spot metering and from Single Frame AF to manual focus and back, which the M1 button placement makes easier, at least to me. Also, a CRITICAL item IMO is that the M1 has the ability to switch the camera so that it never goes to sleep. If the M5 can do that, I couldn't find it (don't get me started on Oly's menu system!) This overcomes one of the big limitations that I found with the M5 in the 4 years I have owned it - missing shots while awaiting wake-up. I promise you that a leopard can be gone out of the tree and into the bushes while the camera is waking up. No need to ask me how I know that! Of course, the disadvantage of leaving the camera "on" is increased battery drain. But I had 6 batts with me and two chargers and power was available at all camps, as well as in all the safari vehicles so that wasn't really an issue. The way I used the cameras, the M5 used up one battery in a day while the M1 usually used 2 and was into it's 3rd each day. But, having learned the "don't let it sleep" lesson, I got a neat leopard shot some days later with the M1/300mm as she bolted from a tree. We saw the leopard and as she moved I literally just lifted the camera up and shot by reaction. There was no "aiming" at all, just pure luck that I whipped the camera around with no aiming at all, pressing the shutter by reflex as it pointed in the general direction. If the camera had been in sleep mode it would have just been a shot of "where a leopard had been." Re battery life, I have always felt that OMD battery life was abysmal compared to an SLR but that's just a fact of having the EVF, I guess. But the main reason that the M1 went through a lot more batteries than the m5 wasn't just because of the always-on mode. The reality is that 80+% of all the pics over the three weeks were taken with the M1/long lens. IOW, if I was FORCED to go to Africa with only one camera/lens, it would be the M1/75-300. If forced, I could get by with an iPhone for the close stuff! I also did some video with the M1 which also uses a lot more power. I didn't use the rear display at all for picture/video taking on either camera. I only occasionally glanced at some pics on the display as we were heading back to camp so the display saw very little use. I used Sanden 64GB cards in both cameras and downloaded the pics daily onto a 13" macbook Air. I did not remove the pics from the cards and, after 3 weeks, still had room for nearly 500 pics on the M1's card and nearly 3000 on the M5's. I shot only in raw. The ONE place I found that the M1 suffered a bit compared to using an SLR was in focusing/tracking fast-moving birds. Although I have a few decent pics of such subjects, basically it just didn't work very well for me, especially with the long lens at 300mm. It would often focus/then drop the subject/totally blur as it tried to re-focus. It didn't matter which focus mode it was in; I tried them all. An optical viewfinder/SLR focus tracking is much superior. But since flying birds wasn't a priority for me, it wasn't a big issue. And maybe if I practiced doing it a lot, I might find that it works OK but it's not as easy as it is with an SLR. So, given that flying birds isn't high on my list, If I was to go back to Africa, I'd take the same equipment, set up exactly the same way. In the next few days I'll try to post some pics/videos on google that folks can access. I'll try to find a couple that, when enlarged, show the slightly soft/sharp difference between two essentially identical shots taken with the 75-300.