Wow! Thank you for your insight post. Huge help. I use my prime 35mm lens 99% of the time. My other lens is huge lol. I even have a mid end manfrotto Tripod which rarely use that is only collecting dust. I have no idea what a flashgun is but I will look into it. I have one of those huge diffuser attachments for the flash as well but not taking advantage of it. Thanks again.
You'd be amazed at what you can do with a tripod... especially playing around with long exposures. You can also see a difference in many detailed shots like landscapes when you use a tripod. It also helps when you wan to blend exposures, experiment with focus stacking, use a neutral density filter, get a shot perfectly leveled and lined up, etc. Modern cameras with better high ISO and handheld stabilization technology have made the tripod less necessary than it used to be for some photos, but a tripod can still help you get the best out of your gear. I probably only use mind for about 10 to 20 % of my shots, but those often end up being some of my best photos. I like working with a tripod because it makes me slow down and really fine-tune the composition and exposure.
A flashgun is just an external flash that you either attach to the top of the camera or use wirelessly while it is off camera. They can range in price from well under $100 to many hundreds of dollars. You don't need to spend a lot to get a good flashgun, but you might have to spend more (or buy used) to get one that will work wirelessly with your Nikon. The primary advantage when using it on the camera is that it gets the flash higher from the camera, and it allows you to angle the flash so it bounces off walls and ceilings. A diffuser placed around the built-in flash certainly helps soften the light, but it's still a direct flash source. Bouncing the flash makes the light even more evenly distributed, but results depend on what you have to bounce off of. High ceilings and dark walls aren't good reflectors.
It sounds like you already have a very capable kit. The 35mm prime is my favorite focal length for general photography on cameras like your D7000. Many famous photographers throughout history shot everything (or almost everything) with a single focal length. You could use their example to justify either a D7000 with a 35mm prime or a smartphone with only one or two focal lengths. Personally I would rather shoot with a D7000 because of the viewfinder, manual controls, comfortable ergonomics, and overall superior image quality. I'd rather carry an iPhone X.
And for some photos that iPhone X will help me capture exactly what I want with excellent results. For other photos the D7000 will produce better results. When it comes to video, I'd probably go with the 4K capability of the iPhone X.
I wouldn't think of the iPhone X as a DSLR replacement, but simply as another piece of camera kit that can compliment your DSLR. Whether or not you need the DSLR in addition to your iPhone really comes down to your needs and preferences as a photographer. I've seen iPhone photos printed large in galleries that looked great from an artistic perspective. These were taken on older iPhones (or perhaps Android phones) so the technical quality wasn't up there with the prints out of better cameras (or modern smartphones), but technical quality isn't everything. A great photo can transcend technical flaws. That said I think your D7000 will give you more to play with if you want to learn and develop as a photographer. On the other hand if you're an amateur like me it should be a fun process, so ultimately you should use what you like.
Sean
