Some years ago I had an Olympus OM system worth, in 1989 about £14,000. Olympus kept saying they would bring out digital cameras that would take my lenses etc, etc. In the end, about 2003 I gave up, sold my kit on eBay for about £2,000 and bought a Nikon D100 and 3 lenses. I chose Nikon for the simple reason that they had maintained mount backward compatibility for 40+ years.

I gave up what I consider to be the best camera ever designed, the OM4-Ti, 7 fast primes, flash equipment and macro gear for a very limited set up and a large financial loss. Do I regret it? No, but, I will never willingly buy or recommend that anyone else buy Olympus equipment, they just don’t care about their customers.

Incidentally, I kept my OM1 and 35mm f/2 and since then I have been given an OM4, OM2, 135mm f/3.5, vivitar macro 2x converter, T32, vivitar 28mm and several 50mm lenses.

Danny

I have the G2, I replaced my Nikkor 80-400mm with it. Excellent lens and you can get it for about $1000 second hand. It is worth getting the G2.

Danny

We used to ask prospective students for 50 images but the lecturers rebelled as that was far too many. Go for 6-12 really good images. Get prints as they have more impact than an iPad screen.

I have the Kenko 1.4x and 2x that I use on my Nikon gear I also have Nikkor versions. The Nikkor ones are very specific to particular lenses, the Kenko are not. Adding any extra glass, especially cheap, badly designed/made glass in the light path will degrade the image. However, when you need them they are invaluable and I have never really regretted using the Kenko ones. I would start with the 1.4x Kenko ans see if you like them. However, resist the temptation to be this silly https://m.youtube.com/watch?v=GbPhKfbQqUE

I don’t see why the camera matters. You get great pics from an old Leica, great, well done. I use all sorts of cameras and get what I think are great pics too. I don’t use Leica they are just too expensive and the latest ones are likely to need a new sensor in 10 years so they aren’t such great value for money anymore.
I do wonder what you are missing though, you say you like macro, do you stack images with film? Keep insects captive until you can check that you got the shot? Experiment with really high magnification using microscope lenses adapted to your camera? Leica are great, we have all been told that, but there are things that they just cant do, I guess you are happy with that limit.

Don’t forget that you need a higher shutter speed with the d810 try shooting at 1/(2 x focal length) minimum and see what happens, also try to keep with a 3:1 or better zoom ratio, the higher the ratio the more compromise is made in the design.

If you need the d810 you need decent glass wit no more than a 3:1 zoom ratio preferably 2:1 and primes for the occasion when you really need the sharpness. Be aware also that you need faster shutter speeds than you are used to, I like to be better that 1/200th with a 100mm lens. I use the 24-85mm f/2.8-4 as a walk about lens and I am very happy with it.a lot less weight than the f/2.8 “pro” glass.

When I lost my Pentax and Minolta gear I went to Olympus OM. These days I would probably go Nikon F3, Df and D850 with a range of lenses. Assuming I got reasonable value I would also go Fuji MF and a couple of lenses.
Danny

Have a look at the lenses from Laowa, https://www.venuslens.net they are amazingly low distortion, I have the 15mm f/4. In your situation I would want a full frame camera, the 15mm Laowa, a good tripod, a panoramic head or at least a bode plate and L-bracket and a surveyors measuring tape.
In order to photograph a long object close up place the camera in portrait orientation unless landscape gives you the height you need, point it at one end of the object, at right angles to it make sure it covers one end, make sure the camera is level not pointing up. Take picture, remember what was 1/3 of the way into the frame, move until that is at the other third, take picture. Repeat until you reach the far end, join in photoshop or similar.
What I am saying is that you don’t have to take a panorama from one place. The tape is because, once you have worked out how far to move with the first shot measuring the same distance is quicker.
Watch out that you allow for superstructure when deciding on portrait/landscape orientation.
Danny

A few years ago I was short of cash and my pc died. I found a last years model in the January sales, Toshiba, i5, 8gb ram 1Tb hard disk for about £300. It wasn’t ideal, especially after I got a d810, but it worked. I suggest you do something like that.

If you want to do macro with Nikon and flash have a look at the Nikon R1C1 macro flash set up. I have used both ring flashes and other lighting for macro and the R1C1 is by far the best set I have ever used.

Danny

It will do either there is an option for it.

Ok start with the 50, put it on, don’t take any other lenses and go take pics. Remember what Cartier-Bresson said, the best Zoom is your feet. Take 50 pics at least and look at them, think about what you wanted to show. Post a few and listen to the criticism. When you start running into things you can’t get with the 50 then you can think about the other lenses.

By the way, they actually make 2 setups, R1 which has no SU-800 and R1C1 which does. Sounds like you got an R1 so if it was advertised as an R1C1 you should complain.

I must admit that, even though the D810 can trigger the SB200s, I would not give up the SU-800.
They can be triggered by any of the speedlights that are in the CL group but the extra flash can make life difficult. There is a third party copy of the SU-800 but I don't know if it is any good.
https://www.ebay.co.uk/itm/1X-Debao-SU-800-SU800-Wireless-Speedlite-Transmitter-Commander-for-Nikon-UPOO/153114588409?hash=item23a65734f9:g:v2MAAOSwDthZn-aJ
and it is possible to find the SU-800 for less than £200 https://www.ebay.co.uk/itm/Nikon-SU-800-Wireless-Speedlight-Commander-Funkadapter-Blitzgerat-Fernsteuerung/132817837100?epid=1104653523&hash=item1eec8f5c2c:g:ZPAAAOSwcWJbwP1v