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

You are not alone in your internal debate, many photographers face exactly that conundrum.
There is however, an easy fix. I currently use the D500 and D850 and use them both for what they excel at. Both will give me excellent and sharp 30X40 prints.
I use the D500 for wildlife photography with my 200-500 5.6 and 500 5.6 PF lenses. I use my D850 for landscapes using primarily the Nikon 16-35 f4 and the 24-120 f4, both lenses take the same filter size so it saves me time when I am in the field.
I use FX lenses on both camera's so I have no cross over problems. I do use the D850 with the 200-500 and 500 PF on occasion.
Good luck and keep on shooting until the end.

mg1962

All of the "new" photographers here would not understand. After using film cameras for years, the photographer "knew" what the field of view was. Along comes digital with its smaller than film sensor, now the photographer has to learn all the camera/lens all over again due to the "crop factor". Once the photographer was able to use a full frame sensor, field of view was back to "as remembered". Both formats have their specialties. I use my D850 with my primes for landscapes, and my D7200 with my 200-500mm for BIF.

camerapapi Loc: Miami, Fl.

Yes, we have seen this type of debate before. As has been stated, it could be very difficult to point a finger to an image made with a FX camera when compared to an image of a DX camera IF the same lens and identical lighting conditions were used. Both will be great images.
If your D7100 is not doing the job you are expecting from it that is a different story. It is a different story also IF you want to buy a FX body. There is a difference between I need and I want.

CHG_CANON Loc: the Windy City

Creativity takes the courage to buy a better camera.

burkphoto Loc: High Point, NC

Rolling on the floor laughing!...

Keep taking the pot shots, Paul.

burkphoto Loc: High Point, NC

Watch this Zach Arias video: https://youtu.be/PHYidejT3KY

He aptly skewers the whole debate.

Sometimes it's important. Sometimes it's irrelevant. Let the circumstances — your real needs and budget — decide.

brontodon

>> do I upgrade to a D750 or not? <<

What are you doing with your images? If you're viewing them on a phone or computer, or posting them to Facebook, I don't think there's any real reason to go to FX. If you're printing them fairly large and want the highest image quality, then an FX sensor should give you better results than a DX.

The Capt.

I upgraded from a D3300 (24MP) to the D850 and now the D3300 sits in the backpack and never gets used. If for any reason I want to shoot with a DX sensor the D850's DX sensor has better than 25MP.

Drbobcameraguy Loc: Eaton Ohio

Lol I second the motion. Roflmao.

ronpier Loc: Poland Ohio

I shoot with three Nikon DX cameras and am perfectly satisfied. 6mp, 12mp and 24mp. Each camera has its own use based on low light, sunlight, etc. and each produces its own unique IQ. Most of my lenses both DX and FX work on all three cameras. I have never shot full frame but crop sensors seem to work for me.

jlrivera Loc: Round Lake, Illinois

The bigger the negative the better.

Paul Diamond Loc: Atlanta, GA, USA

I had high expectations when I upgraded from dx to the D800e. The high MP images are far superior in detail, tonal range, etc. for a 'pixel peeper'. But the high MP D800-D850 demand more of the photographer - if you want to achieve what the camera is capable of producing.

I've seen Ansel Adams' photos on display many times - physical prints from large format negatives, perfectly printed. And I've seen here on UHH images from much earlier (Yosemite) on 8"x10" negatives with lenses that were not nearly as good as Ansel's. If Ansel were still alive and working, he would prefer the high MP camera with high resolution lenses plus meticulous attention to detail in using them for the final output.

When I bought my D850, I told myself that I was getting a camera capable of taking "epic photos" - higher detail, higher tonal range, higher resolution that deserved the best from the lenses put on it and the best from me. I got the top lenses and then began working on improving me, my technique and my compensation for no longer being in my 20's or 30's. Still working on it. But, I am getting results worthy of the financial investment and the personal investment. I've had to learn and re-learn some of the basics as required by the quality of the hardware I am happily using.

baron_silverton Loc: Los Angeles, CA

There is a difference with respect to noise. All other things being equal (i.e. sensors from the same era/generation, same image processor in the camera), a larger sensor has less noise at the same ISO. The math works out to something like multiplying your ISO by 2.25 to determine the equivalent ISO for the crop sensor from a noise standpont. So a shot at 100 ISO on your DX camera will display the roughly the same noise at a shot at 225 ISO on a full frame camera (call it 250 for practical purposes). Not such a big deal at low ISO but this stacks up quickly at higher ISO's (e.g. a shot at ISO 3200 on your DX camera is roughly equivalent in displayed noise to a shot at ISO 7200 - much noisier.

As such, if you normally shoot with plenty of light then it is probably not necessary to go full frame. For Landscape you will be using f/11 or f/16 which means that the shallower DOF of full frame (at equal aperture and distance to the subject) is irrelevant to you - this matters more if you are a portrait photographer.

That said, you did mention night photography. If you are doing this often, then the full frame will yield better results as the noise at higher ISO is better on full frame.

The D750 is a workhorse of a camera. That said, it is utilizing the Expeed 4 processor while the newer D780 is utilizing the much newer (2 generations newer) Expeed 6 processor. This means that the noise should be even better controlled on the D780, but I have not tested this myself. Either way, the D750 should control noise better than your D7200, so if this issue is a deal point for you get the full frame (D750 or D780 if you can afford it). If you are not interested in noise because you mainly shoot with lots of light during the day, then you can stick with your D7200.

Hope this helps :)
-B

amfoto1 Loc: San Jose, Calif. USA

It depends upon what you shoot and what you do with your images.

With recent DX cameras, if you don't make fairly large prints... larger than about 13x19"... you will see little to no difference. Especially compared to an FX camera that only has 24MP.

If you shoot wildlife or sports, the DX camera gives you more "reach" with the same lens. Or, another way of looking at it, allows you to use smaller, lighter, less expensive telephotos.

If you shoot portraits with a large aperture or low light at higher ISOs a lot, an FX camera might be preferable.

If you shoot landscapes or architecture frequently, with small apertures and often with wide angle lenses, the FX camera may be the better choice. Although I'd probably look for a camera with more than the D750's 24MP.

I'm referring to the optimal camera for each purpose. Of course, you can do all these things with the opposite type of camera... there's nothing to stop you using a DX for portraits, landscapes or architecture. Your lens selection might be different... such as a 50mm instead of an 85mm.... or a 10mm instead of a 16mm. Conversely it's only the size of your wallet and willingness to lug around big heavy lenses that might limit you from using FX for sports or wildlife.

But... regardless... if all you ever do is share your images online at Internet sizes and resolutions, you almost certainly don't need an FX camera. The end use of your images plays a major role in camera selection, too.