Photography

I do think that this looks better than last time, especially the backdrop. Also, it's clear that you cleaned up the dust/fuzz a bit to make the instruments pop a bit more.

If you want to go for a darker black background, you are going to have to either get comfortable with post-processing your raws or shooting with manual settings (probably some combination of both). You have the advantage while shooting still-life that your subject is not moving and you can take as many shots as you want to really dial in settings.

The reason that your black sheet ended up looking gray is that the auto setting is usually trying to normalize the average brightness to somewhere in the middle of the sensor's range. This works in reverse too. If you had a bright white background, the auto settings would adjust to make that end up looking duller and grayer. If you are serious about getting black backgrounds still, then your best bet would be a sweep made of matte black paper. When I want to have a very white background, this kind of paper is the best there is.

Moving away from auto settings means that you are going to be playing with three settings for the most part (sometimes referred to as the "exposure triangle"). It's really not that scary, and all the settings are basically different ways to control how much light you have in the image. I have written super basic summaries below, but I recommend finding some other reading or videos where they can show images/examples of how these things influence your photographs.

Shutter speed/exposure - the amount of time that the sensor is exposed, usually expressed in some fraction of a second. For example, a shutter speed of 1/100 means that the sensor is only collecting light for 1/100th of a second. Some important shutter speeds to know are that 1/100 is about as long an exposure as I can set and get reliable shots without stabilizing my camera in some way (tripod or similar). Also, 1/200 is the fastest shutter speed you can set and still get reliable results while using a flash. Otherwise only part of the picture will see the subject illuminated (unless you have HSS which kinda sucks but is a whole can of worms). In summary, a longer exposure/slower shutter speed means a brighter image because you are collecting light for a longer period of time.

Aperture/f-stop - this is telling you how wide open the aperture is to let more or less light through the lens and onto the sensor. This number is confusing for a while until you get used to it in that it is expressed as a fraction like f/2.8 or f/4. The larger the denominator, the less light that you let in. So, f/1.4 lets in more light than f/4. This lets you influence how much light you collect independently of the shutter speed. So, if you are shooting something like a sports game with quick moving subjects, you might want a fast shutter speed, but to collect enough light for a good image, you can open your aperture way up.

Aperture also controls one other important part of your image, the depth of field. The more open your aperture is (smaller the f-stop number), the narrower your depth of field becomes. So, lots of photographers that do things like portraits like to shoot with lenses that can have very wide apertures. This makes the subject (person) be in focus while the background melts away as a big blurry blob of bokeh. It helps separate the subject of the photo from potentially distracting things in the background. Alternatively, shooting something like a landscape often means that you want both the bushes near you and the mountains in the distance to be in focus at the same time. So, that means you need to shoot with a stopped down aperture. For the product photography that I do, I tend to shoot with a very narrow aperture so that the foreground and background parts of the product are in focus.

ISO - This is basically telling the camera how much to amplify the light that hits the sensor. So, turning up the ISO means that you don't need to collect as much light since your camera amplifies the light that does hit the sensor, but it also means that you see much more noise in your image due to this. Cranking up the ISO is pretty common when shooting subjects at night or in dark settings (concerts, etc.). It is also another dial you can control to adjust the amount of light you need to collect to get a good image. So, if your aperture is all the way open and you can't increase the exposure any more without a tripod, but it is still too dark? Then you turn up the ISO. This is usually the last thing I turn to when I need more light in my image as I really don't like digital noise in my images. I try to keep my ISO <800, but this can vary a lot depending on the camera/sensor.