In another thread the question was more or less asked "What's a good setup for long distance bird
photography." https://www.democraticunderground.com/103662692
Everything that follows is assuming we all start from itch (one step before scratch) and aren't invested in a system.
The question pre-supposed a full frame DSLR. Sorry, but a FF DSLR is NOT a good choice for wildlife, street, candid or any other form of photography that requires movement and fast adjustment.
I speak with some assurance because when I graduated college with my MS in Photography my kit consisted of two 35mm bodies and lenses from 21 to 300mm, an RB67 with two lenses and a 4x5 Calumet with two lenses. To go with this there had to be a tripod for the RB and Calumet (one that I could literally sit on) and another for the 35s as well as a mono-pod for sports. It basically filled all the storage space in my '65 VW.
Cameras are tools. Tools do a job. The two should match.
A full frame DSLR with a pro standard lens is about the same weight as my old RB67. The image quality is commiserate with the size of the format (sensor). They are large, heavy and produce exceptional tonal range and quality. Not as good as my Calumet and Schneider but better than the OM 2. Try shooting a football scrimmage with a Calumet.
All that said, if you're a pro portrait or wedding photographer you need a FF for the set shots--bride & groom, parents etc and it will pass for candids. If the world you live in is studio then a Hasselblad or Mimiya with a digital back is called for unless you can afford an even larger format. For everything else there's crop frame APS sensors or (OMG) cell phones.
So lets look at crop sensors. There is basically Canon, Nikon and 4/3rds. Nikon has the largest, Canon next and 4/3 bringing up the rear. How much difference is there? Nikon has about 20% more square area than 4/3 and Canon about 13% more. If the 35mm aspect ratio is cropped to fit most standard formats (4x5, 5x7, 8x10, 11x14 or 16x20) there's only about 5% and 1% difference respectively. I will not argue that Full Frame and 4/3 are equivalent but an argument can be made that crop frame sensors from Nikon and Canon are not a measurable advantage. Technically speaking. Functionally speaking it's altogether different.
Both Nikon and Canon make full frame and crop frame sensors so their lenses are made to cover the full frame sensor. That makes them necessarily larger. 4/3 systems (basically Leica, Panasonic and Oly) only make 4/3 sensors so the lenses are proportionately smaller. Add in the crop factor (Nikon 1:5, Canon 1
and 4/3 1:2) and magnification factor for lenses is greater.
If I were doing Ansel Adams style photography (ala Demotex, whatta' guy!) a full frame camera is the tool to use. If you're doing pro work at a portrait studio or weddings a full frame camera is the tool--plus the size is impressive to a client, it looks big and complicated and PROFESSIONAL. If, on the other hand (there is always that other hand), your style is everyday street photography or extreme wildlife the the smaller 4/3 format is best suited. It's smaller and more portable, image quality is indistinguishable from other crop fame sensors and really good post processing can get close to that full frame dynamic range.
Cell phone cameras are absolutely phenomenal for what the can offer. Don't use the zoom feature and use the whole frame and 13x19 images are easy. That kinda' hurts to say as a man suffering from GAS (gear acquisition syndrome). I don't know what kind of digital magic the processor works but dynamic range and saturation is really good on wife's Samsung S7. No wonder the point & shoot market is dead!
If I were invested in a brand, I'd do my best to find a solution that didn't require $17,000 for a lens.
So, to answer the question in the source post, if I had $17,000 to spend I'd buy an OMD EM1 Mark II with a 300mm f4 (600mm equivalent) plus the matched 1.4 extender and the EE1 red dot finder. Total cost less than $7000, total weight about 4 pounds with image stabilization in body and lens. The OMD has an image capture feature that records one second of frames in buffer when the shutter button locks focus and then writes them to disk when the first exposure is made. It tracks focus even at 60 fps and has more razzel dazzel for wildlife than anything I know of (and I admit I don't know Canikon).
Next kit would be a Panasonic G8 and the Pana/Leica 100-400 zoom also with lens and in body stabilization with the EE1 finder.
Compared to the $17,000 800mm Nikkor I could buy, use and resell the above kits and still have a capture rate of of one in ten with a keep rate of 1 in 100. Not likely with the 20 pound full frame camera and massive lens.
A Calumet can be forced to make candid portraits, an RB67 can be forced to make wedding candids but neither can be forced to cover sports from the sidelines.
Pick the tool for the job.
Make pictures, save memories, enjoy life.
