Uses of different focal lengths and lenses.
Lens flare is light that got lost inside your lens. Ghosting vs veiling glare, what coatings do, the price of a cheap filter, and the limit of a hood.
Which f-stop is your lens sharpest at? Why the sweet spot sits 2-3 stops down, how diffraction softens f/16, and when peak sharpness is the wrong choice.
What bokeh is and how it differs from depth of field: what shapes bokeh balls, why some blur looks creamy and some looks nervous, and how to get better bokeh.
What depth of field is and what stays sharp: how aperture, distance, focal length and sensor size set the zone of focus, explained for beginners.
The full-stop ladder, third stops, what f/3.5-5.6 on your kit lens means, and T-stops: decoding the language of aperture numbers.
A guide arguing the real decision in portrait lenses is perspective and shooting distance: how focal lengths shape the face, aperture choice and budget picks.
The differences between 50mm and 35mm, the crop factor, and which suits which shooting style when picking your first prime lens.
Which focal length — 24, 35, 50, 85 and 100mm+ — suits which type of shooting, plus choosing between prime and zoom lenses.
What do f/1.8 and f/16 actually do? See how aperture and f-stops control light, background blur (bokeh) and depth of field, with clear examples.