Found this on the web. It might be worth looking at.

I've been experiencing a clicking sound when the aperture of my lens changes during live view when using manual focus, I don't know if this is meant to be happening or not...

The clicking sound in live view is caused by the fact that the maximum aperture of your lens changes with focal length (i.e. it is something like 18-55/3.5-5.6).

The D7500 live view uses the actual selected aperture for the live view preview. When you zoom the lens and the maximum aperture changes, D7500 has to adjust the aperture blades to keep the actual aperture constant. That causes the clicking and is quite normal.

If you have a constant-aperture zoom like 17-50/2.8, there's no clicking sound as there's no need to adjust aperture when you zoom.

https://www.dpreview.com/forums/thread/4208035

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One of the main reasons to use BBF is to be able to set the autofocus and the exposure separately. So, lets say I am shooting a waterfall with dark mountains. I cannot focus accurately on moving water so I move my focus indicator just to the side of the running water, which will then be on the dark mountain, and I press my BBF to set focus. What I need to do now, however, is to set my exposure on the brightest part of the moving water in order to get a correct exposure for this shot. BBF sets and leaves the focus set unless I hit it again, which I do not do in this case. What I do is move my autofocus indicator button (in shutter mode this button connects auto focus and exposure), which is set separately from auto focus in BBF, to the brightest part of the moving water and the exposure will be automatically corrected. At this point I might take a test shot to see if the exposure works and perhaps take the exposure down a stop or two if it is too bright. So, you don't really need to have a separate exposure button with BBF, at least not in this type of situation.

An online friend has been impressed with some of the photography I’ve posted online, so he asked me for a recommendation for a sort of online tutor. He’s looking for someone to give him assignments and then critique his results.

He’s not a complete beginner. He’s been looking at YouTube videos, and is comfortable leaving the autoexposure feature behind and take control of ISO, aperture and shutter speed. He’s been using GIMP as an image editor.

I consider myself only an intermediate photographer, and unqualified to be the tutor he needs. In chatting with him, I think his biggest needs are learning more about composition and post-processing. He complained that his photographs didn’t reflect his experience level — he said he felt he had hit a wall in advancing his skills.

I know various pre-packaged training materials are available, but I think he’s looking for something a little more tailored for his needs and skill level. Perhaps a hybrid course is what he needs. Any recommendations I can give him?

The Touch Shutter: Touch controls can be used to focus and release the shutter. Touch the display to focus and lift your finger to release the shutter.

touch shutter

Tap the icon shown in the illustration to choose the operation performed by tapping the display in shooting mode. Choose from the following options:

Touch: Touch the display to position the focus point and focus (autofocus only; the touch shutter cannot be used to focus in manual focus mode). Focus locks while your finger remains on the display; lift your finger to release the shutter. Available only in photo mode.
Touch AF: As above, except that lifting your finger from the display does not release the shutter. If auto-area AF is selected for AF-area mode, the camera will track the selected subject as it moves through the frame; to switch to a different subject, tap it in the display.
Off: Touch shutter disabled.