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I'll probably swap for an FX because the DX results seem to be no better than my compact Vivitar.

The sensor size (the area) of the DX is about 10 times bigger than that of your Vivitar, and you don't see any significant difference in image quality.

Now you are going to get an FX sensor that has only about twice the area of the DX and you are expecting to see a difference?

Interesting question. I think an individual pixel cannot be "in focus" or "out of focus". It only registers the intensity of light (R, G, or .

So "being in focus" is a collective property of several neighbouring pixels and Nikon D850 is already showing this information in live view. It is called "focus peaking".

Tests for D7100 rather D7000 but Sandisk Extreme Pro 95 MB/s would still be my choice:

http://www.cameramem...-sd-card-tests/

It is more satisfying to use primes, especially fast primes. When you have time to compose your image, adjust depth of field - prime is the king. You cannot beat a fast prime lens for low light photography.

Chasing kids with a prime might be a bit frustrating though... For family photos I would personally stick with a kit lens and don't bother.

For landscapes either AF-P DX NIKKOR 10-20mm f/4.5-5.6G VR or Sigma 10-20mm f/3.5 EX DC HSM zooms are worth a look. Sigma is a bit better built and faster but has no VR and is a bit bigger.

The 16-80 or 16-85 are both much bigger and more expensive than the kit lens. They are good though and very versatile.

However, when I step down the aperture, there is increasingly longer shutter lag and very blurry pics, starting at around f/7.1.  At f/16, the shutter lag and blurriness are ridiculous.

Hi. It sounds like you are shooting handheld and confusing shutter lag (how responsive the camera is to pressing the shutter release) with shutter speed (how long the sensor is exposed to light).

If you are shooting f/16 indoors, the shutter speed can easily be a few seconds. Hence the blurry photos due to the camera shake. Have you tried doing the same using a tripod?

I have two samples attached.  Both taken in autofocus and basically the same composition.

They do not have the same composition. They are two completely different images.

The bottom part of each image seems to be in sharp focus. I don't think there is any camera shake in either case.

What you see is a shallow depth of field typical for close up images. The tighter the framing, the more blur you get around the areas of sharp focus. F/10 or even F/22 can often be not enough to render the whole image sharp. That's why people use focus stacking when photographing flowers, mushrooms and such. 

If you scroll down to the bottom of the page

http://snapsort.com/...kon_D3000/specs

you will see that low light ISO performance is about 2.5 times better on the D5500. If you are happy with your prints from the D3000 at ISO1600, you can shoot D5500 at ISO4000 and get about the same noise levels.

Have you considered a used 7100/7200?

While you are waiting you might be missing some photo opportunities and are not getting used to your equipment.

Any DSLR made in last 10 years is probably going to offer you more than you need to be honest. Practice is much more important.

Camera on the tripod, manual exposure mode, manual focus, fixed ISO. Change shutter speed to produce images with different exposure.

Then combine the images on the computer.

Need to dial exposure back a little to avoid blowing the red channel.

Putting some diffuser on the flash will also help reducing hot spots and softening the shadows.

Each lens has a minimum focus distance (MFD), and in case of zoom lenses, the MFD increases with focal length and can be anywhere between say a foot and 8 feet for a telephoto lens. The lens cannot physically be focused on anything that is closer than the MFD.

It certainly looks like you could have used flash, which means the sun must have been behind you. Try shooting subjects at an angle to the light direction (as opposed to being parallel to it).

There was no sun. There are no shadows and the exposure parameters are about 5 stops below the sunny 16 rule.

Tony, as others said an off camera flash would have given you (1) more light, (2) better subject-background separation (3) some shadows for a 3D effect.

What is a typical shutter speed? If you are shooting handheld, there might be some camera shake. 

Not familiar with D3400 but most likely that the Auto mode is not only adjusting exposure parameters but is also changing JPEG rendering settings depending on the "Scene mode" it automatically selects, e.g. "Portrait", "Beach", "Landscape", "Snow" etc...