Paul Diamond Loc: Atlanta, GA, USA

I have a Tamron 150-600 and saw the 'weather sealing' comment as questionable. I have to send my 150-600 back to Tamron for a repair quote. An unexpected rain destroyed my 150-600 while not hurting my D850 at all. So, I can't agree with a 'weather sealing' advantage to the Tamron over the Nikon 200-500. After the failure of the Tamron, I bought my 200-500 and find it sharper at 500 mm than the Tamron was as 400-500-600. And the Nikon will autofocus as close as 7 1/3 feet to give me the ability to enlarge a small part of the image for fantastic near-macro shots of birds, insects, etc. - Most people who shoot birds and nature subjects want/lust for a longer focal length lens IF they can afford it and can realistically carry something of that weight into the field to get the shots they want (600mm/800mm). My moon shots with the 200-500 are quite good at 500mm, even a few that are hand held. I'll post one here in the future.

47greyfox Loc: on the edge of the Colorado front range

And I thought it was just me.....🥺🥴😳

RichardSM Loc: Back in Texas

I agree. With SFT just consider the source.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

The D750 is a FF camera but has a feature that will allow you to crop to a cropped sensor camera. BUT, you also lose a lot of pixels doing this and many feel the sacrifice is not worth it.
Personally, I believe your better off using a cropped sensor camera that will put 24 megs into that same small area giving better results at distance using the same lens on FF and cropped sensor.
D500, D7000, D7100, D7200, and D7500 are the cropped sensor Nikon camera's I would recommend.

Architect1776 Loc: In my mind

Preference for me is zoom definitely.
Most good zooms are on par with most primes.
The huge difference is versatility and portability.
A zoom is easy to carry compared to a 200mm, 300mm, 400mm and 500mm. Plus you get all the focal lengths in between.
IQ difference is not observable with top zooms unless you magnify so there are 5 pixels showing on your monitor ( Pixel Peeping).
Do you want versatility or a fixed series of primes you have to carry and chang each time you need a different focal length?
You have to decide, we cannot do it for you.

Paul Diamond Loc: Atlanta, GA, USA

re: the TC-14E II teleconverter. Nikon does not recommend using a Nikon brand teleconverter with the 200-500 or any other zoom with high MP cameras. The D750 is 24 MP. You can test your TC-14E II with the 200-500, but will probably not be happy with the results. Will the 300mm PF lens + TC-14E II be good enough for you to want to continue to use it? Unless someone here has all of the exact same equipment, tell us what you think when you test and compare both.

Gjb1706 Loc: Central Florida

Nice, thank you.

amfoto1 Loc: San Jose, Calif. USA

I shoot Canon gear, so my choices are somewhat different, but I use both zooms and primes: 300mm f/4 (with & without 1.4X) and 100-400mm f/4.5-5.6 (with & without 1.4X).

I use the 100-400mm when light is good and I need the versatility of a zoom. It's fairly large and heavy, approx. 3.5 lb. (though that's not as large & heavy as the 5 lb. Nikkor 200-500mm). That gets tiring during long shooting sessions.

When light is a bit more challenging... or I want a smaller/lighter load... I'll switch to the 2.6 lb. 300mm f/4 prime instead. The extra stop of light helps.

I also have a 300mm f/2.8 that I'll use in really tough lighting conditions, but much larger and at around 6 lb. it usually requires a tripod with a gimbal head, which makes me much less mobile than the other two lenses. Still, the additional stop (compared to the f/4 lens) or two stops (compared to the zoom at f/5.6) can be a make or break factor in some situations.

I'm lucky that all three Canon lenses are quite sharp and good... and all three work very well with the Canon 1.4X I use. The 300mm f/4 is the oldest design of the bunch (dating from the last few years of the last century), with the least effective image stabilization (rated for 2 to 3 stops, versus 3 to 4 stops in the other lenses). It's also the only one of the three that doesn't have fluorite in its optical formula... but seems to get by well without it.

I'm mostly shooting sports... but sometimes wildlife, too.

I think you can make an argument for both lenses... If you hike a lot with your gear, mostly shoot large wildlife and often are working in marginal light, the 300mm f/4 is considerably smaller and about 1/3 the weight of the 200-500mm. I don't know how well they each work with Nikon's 1.4X (Canon's earlier DO lenses, which use design similar to Nikon's PF, did not work well with 1.4X... later DO lenses work a lot better with 1.4X). OTOH, zooms typically don't work as well with teleconverters as primes do (the Canon 100-400mm II that I use is an exception... works quite well with Canon's more recent 1.4X). One consideration... with the 1.4X that 200-500mm will "become" an effective 280-700mm f/8 lens. Can your camera focus f/8? Are you limited to a single point or fewer AF points, with an f/8 combo? Does AF slow down with an f/8 combo? With the 1.4X, the 300mm f/4 "becomes" a 420mm f/5.6... and that combo's AF performance might be better. I don't know one way or the other, how the D750 works in those situations... but it's something you should consider.

Test shots done with the Nikkor 300mm PF vs the Nikkor 200-500mm @ 300mm focal length and both wide open.... The center of the image area looks very similar. The prime lens is clearly sharper than the zoom in the mid-frame and toward the edges....

https://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=1040&Camera=614&FLI=0&API=0&LensComp=1035&Sample=0&CameraComp=614&FLIComp=0&APIComp=0

It's harder to compare how the two lenses perform with 1.4X added, because the zoom is set to it's 500mm focal length for the tests... So we end up comparing 420mm f/5.6 against 700mm f/8. In this case, there's not a lot of difference, but the zoom + 1.4X appears to have somewhat more chromatic aberration, especially toward the edges.

https://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=1040&Camera=614&Sample=0&FLI=1&API=1&LensComp=1035&CameraComp=614&SampleComp=0&FLIComp=4&APIComp=0

Maybe you can find some more head-to-head comparisons of these lenses, out there on the Internet.

You also might want to compare Tamron and Sigma 100-400mm zooms (the Tamron has advantage of being able to optionally add a tripod mounting ring... but the IQ of the Sigma appears slightly sharper and it's smaller, but there's no way to add a tripod ring). Also, if their greater size and weight isn't a concern, the Tamron 150-600mm "G2" and the Sigma 160-500mm "C" or larger/heavier/more expensive "Sport" all might be worth a look. These are probably all less usable with a 1.4X... though I can't say from personal experience.

Another thing you really might want to consider.... pick up a nice, used D7200 if you can find one at a good price. With any telephoto lens the APS-C/.DX camera will give you the effect of a "free" 1.5X teleconverter.... more reach than the telephoto on a full frame camera, without the light loss that occurs with an actual teleconverter. An APS-C camera neatly "leverages" telephoto lenses. OTOH, the D750 is more ideal for wide angle lens work and usable at about one stop higher ISO, making it a bit better for low light conditions. So hang onto your FX D750 too. The two cameras can complement each other nicely: Both 24MP with design, layout, controls and functions similar enough that switching back and forth between them would be relatively easy.

EDIT: I just checked the Nikon web site and see that while the D750 and D7200 have very similar 51-point AF systems... both usable to as low as -3EV, both with 15 cross type AF sensors.... the D750 is "f/8 capable" at eleven AF points while the D7200 only at one (the center AF point). Of course, f/8 capability becomes a concern when you add a teleconverter to an f/5.6 lens... and since the D7200 has effectively a "built in" 1.5X thanks to its APS-C crop sensor, it's less likely to need a 1.4X TC too (but can still work with one).

Finally, D7500 is another APS-C option.... But doesn't have quite as wide dynamic range or bit depth and is a little lower resolution than the D7200. D7500 has faster frame rate than either D7200 or D7200, as well as a slightly more advanced AF system. But it also lacks dual memory card slots found on D7200 and D750. Either DX camera... D7500 or D7200... would give you one stop faster top shutter speed than your D750 (1/8000 vs 1/4000)... Faster flash sync too (1/250 vs 1/200). Those might come in handy occasionally.

You also mention moon photography... for that, you may want to rent a longer lens! Below is a composite image I did some time ago... I photographed the moon with 500mm lens with 2X on a Canon APS-C camera. So, that was equivalent to 1600mm focal length on your D750. Even with an image stabilized lens, it took a very sturdy tripod to shoot. It was done some years ago using a 6MP camera and the moon image was slightly cropped... I still ended up softening the detail in the moon a bit for this composite that was printed 11x14". (The wolf was photographed with a 28-135mm lens on a film camera, with fill flash. That shot was digitized with a Nikon 4000ED film scanner.)

rkaminer Loc: New York, NY

The f stop of the 200-500 lens will be a problem with the 1.4x teleconverter. You will lose 1.4x the lowest f stop which could make the autofocus erratic. therefore the teleconverter is not recommended with a f5.6 lens.

FTn

Not true according to Nikon USA. The Nikon TC-1.4 III is recommended on the 200-500mm provided that the camera body can autofocus with a f8 lens. The problem that you run into is that your auto focus points are decreased to only 15 on a D850. I don't know how many autofocus points the D750 has with an f8 lens.

- FTn

DaveyDitzer Loc: Western PA

I had the 300 and now have the 200-500 and prefer the latter

Beachhawk

You won't go wrong with either lens, but for wildlife I would want as much reach as I can afford. I just bought the Nikon 200-500 and a TC-17E III for my D850 and D810.

Paul Diamond Loc: Atlanta, GA, USA

I carry my Nikon camera and Nikon 200-500 via the tripod 'foot' for short or long walks - 3 miles is a typical minimum distance. I'm OK with carrying it and, if necessary, an attached medium weight monopod.

Gjb1706 Loc: Central Florida

Thank you all for your responses. It gives me a lot of information to digest.

joer Loc: Colorado/Illinois

I owned the 200-500 5.6 and 1.4X II, used the 300 f4E for a short period when shooting Nikon. If I made the choice today it would be the 300mm. Image quality, focusing speed, size and weight are more important to me than a slight loss of zoom range.

The 200-500 is a good lens for the price, but it's not great.