Deanie1113

I have owned the Lumix GX8 (similar to the G9, but I think a little smaller). I used it with the Leica 100-400 for birding. It was a very lightweight system that I loved, HOWEVER, since it was a MFT, I had to bump up my ISO all the time and it was annoying -- it just didn't handle the low light like my little Nikon D5500 could. In addition to that, know that the 100-400, while it gives fantastic range, bringing those birds in close, it is super-delicate with a cheap plastic mount. The first time the camera was dropped (while in the bag) the lens busted to smithereens, scratching the oh-so-vulnerable sensor on the camera in the process. And for birding with a G9, you will want the 100-400, a great lens surely. But if you go that way, I would highly recommend getting insurance on both the camera and lens and treat it especially carefully. As of now, I have been without my Panny system for nearly two months as they take their sweet time repairing it -- a regular repair shop cannot repair this as they could a Nikon or Canon.

BJW

I own the D500 and have rented the G9 for indoor ice hockey. With the former I use a Tamron 70-200. The latter a 35-100 Lumix. The pros vs the cons of the respective sensor sizes, weight, etc.,are stated elsewhere by the others who have responded to the OP.
I wanted to replace my D500 with the G9 because of weight and size. But for now I am sticking with the D500 for one major reason: BUFFER SIZE especially when using high speed continuous shutter. The fps, I find, is not as important as buffer size. With the D500 you can shoot up to 200 frames without delay in between capture and writing to card-no missing a shot with the D500! With the G9 I found an annoying delay after shooting about 10 frames. In fast action sports that’s really frustrating. I presume with wildlife too especially BIF. The delay causes missed shots. The 4K burst mode on the G9 is not an adequate alternative for my use.
The AF on the D500 is more reliable than the G9. (Here, Steve Perry’s Nikon Auto Focus eBook is invaluable)
The viewfinder of the D500 is better and portrays color more accurately.
On balance, for the action sports that I do, I’m sticking with the D500 for now—but I do love the Lumix brand and especially the Leica glass that I have for my Lumix G85.
And, because I do suffer from GAS, I am going to check out the XT-3.

Rent and try out before you buy.

Happy shooting, either way!

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

A D850 with a 24-120mm F4 and a 500mm F5.6, or if you can justify the cost - the new 180-400 F4 with the dedicated 1.4X TC, will handle both admirably. Everything else is a compromise in one way or another. The G9 XT3 aand the D500 are all great cameras, but not in the same league as a D850. For excellent low light, high resolution (with good lenses), high dynamic range images, it's not easy to beat the D850.

Between the G9 and D500, I'd have to go with the D500, if landscape is important to you. M4/3 cameras are not noted for outstanding landscape, and for that matter neither are APS-C, but you can get away with one in a pinch. One important gotcha that no one likes to talk about in reference to M4/3 cameras is diffraction, which effectively limits the size of the smallest aperture you can use to maybe F8. Bigger sensors can handle F11 and some even F16 before diffraction begins to seriously impact sharpness.

RKL349 Loc: Connecticut

I will assume, maybe improperly, that you have handled both the G9 and D500, at least, in a retail store, in person. The next step would be to rent each for a week and do your own test to determine which you like better. Then make your choice. Many of those on this site will recommend their personal preferences, and you will be encouraged to look also beyond these two because that is what they like and own. Make your purchase decision based on your own hands-on experience. Good luck with your choice.

camerapapi Loc: Miami, Fl.

Nikon D500.

jerryc41 Loc: Catskill Mts of NY

Once again, my comparison sites -

Read comparisons and specs, and decide what features are important to you.
(Reviews) https://www.youtube.com/user/TheCameraStoreTV/videos
http://www.cameradecision.com/
http://cameras.reviewed.com/
http://camerasize.com/
http://www.imaging-resource.com/IMCOMP/COMPS01.HTM
http://snapsort.com/compare
http://www.dpreview.com/products/compare/cameras?utm_campaign=internal-link&utm_source=mainmenu&utm_medium=text&ref=mainmenu

mizzee Loc: Boston,Ma

How much weight and bulk are you willing to lug around? Both are excellent cameras. Do you have Nikon lenses? I reached a point after a long trip with all my Nikon gear that weight and bulk was too much. I switched to micro 4/3s, traded in my Nikon gear and am reinvigorated.

Lagoonguy Loc: New Smyrna Beach, FL

I only dabble with birds with a modest D7100 & a Tamron 100-400. I recently purchased a G9 for foreign travel to reduce weight and I can tell you I am amazed at the quality of it’s images including landscape & modest low light conditions (cathedral interiors) with a 2.8-4 lens. I used the G-9 along with a D750 and a Nikon 16-35 f/4 and found the G9 to be equal to the Nikon kit. I used a 1.4 prime with G9 for night cityscapes and they were excellent. I have considered a D500 for bird usage and may still bite but I probably will not buy a heavier lens because at 74 I just no longer want to fight heavy gear. I am leery of the Panasonic Leica 100-400 due to other Ugly members having significant dust & repair issues with this lens. Perhaps others here have had no issues with the lens. The 200mm 2.8 with a 1.4 might be great but it is not a zoom and nor is the excellent Olympus 300mm. I wanted you to know that I’m very happy with the G9 but that these other considerations have me pointed toward the D500 for wildlife.

gary8803

I have a G9 and it takes great pictures but for birds my old D3 with a 500mm prime lens does better. But the G9 is easier to hand hold plus pre shot burst makes for great shots. Birds in flight will be better on the Nikon just my opinion. I like the G9 because I can have fun with old glass.

burkphoto Loc: High Point, NC

These two cameras are top-of-class — in two very different classes. You would do well to read their in-depth reviews at http://www.dpreview.com and http://www.dxomark.com. Additionally, watch some of the reviews on YouTube. PLEASE, read this G9 review by one of our members, Daniel J. Cox. It links to a lot of other important reviews.

http://naturalexposures.com/panasonics-lumix-g9/

As you read and watch the reviews, note those things about each camera that are important TO YOU. EVERY camera is a collection of necessary compromises. You want to have an acceptable set of compromises for your needs!

For example: The Nikon D500 has a larger sensor. The Lumix G9 plus a kit of lenses with the same coverage and the same maximum apertures has MUCH less bulk and weight. One of these very different attributes is probably more important to you. If you make a list, you will probably see your eventual choice appear.

I will tell you that I'm a former Nikon and Canon user who now uses Lumix. In 50 years of serious photography, I've used a lot of different gear. The Lumix cameras are some of the most intelligently designed and well-made cameras ever conceived. But so are the top cameras from Nikon, Canon, Sony, Olympus, and Fujifilm. It's hard to say any of them is the absolute best without starting an argument. The proper question is, "Which is best for MY purposes, or on a certain list of particular attributes?" or, "Which camera checks the most boxes on MY list?"

RolandDieter

If weight and convenience are issues to you, go for the G9. I use them. Excellent stabilization and there are many fabulous light-weight m4/3 lenses. This is a much better combination than excellent stabilization but with heavy full-frame or almost as heavy APS-sized lenses. I also use a full frame (Sony a9), but for me it is a more rarely used, special purpose camera for which I do not even want many lenses at all. Many recommend Fuji, and if I were to go APS-C it would be my pick.

burkphoto Loc: High Point, NC

One more decent review link for the G9: www.helenhookerphotography.co.uk/inspiration-and-education/2018/2/20/panasonic-lumix-g9-review

tdekany Loc: Oregon

For landscape work, the 80mp hi res feature on the G9 is going to beat the D500. Easily.

But for the rest of your post, I agree.

Architect1776 Loc: In my mind

Lumix G9 obviously.
Why settle for less.

Bill Koepsel Loc: Oconomowoc, Wisconsin

Thanks all for very interesting ideas on this subject. I now have some direction.....