This is a time-lapse video of a quick study of a tomato. I used two pencils (a 2H and a B) and a kneaded eraser.
This is a time laps video of my process for drawing a study of an apple. I start with a soft pencil establishing the proportions of the big shapes. Then I switch to a harder pencil to refine the contours. After lightly erasing the initial marks made with the softer pencil, I begin to indicate the light on form with the same harder pencil. Notice I start with a mid tone applied everywhere except in the area of the high light. I continue to develop the light on form switching to softer pencils as needed to establish the darker tones.
This is the contour drawing done with a #B pencil
Using the same #B, I rendered the light side in one continuous tone being sure to save the high light a little bigger than I saw it. Then I used #2B to indicate the shadow side in one continuous tone, several steps darker than the light side.
This is the finished drawing. Notice that I did not lighten the shadow side to indicate the reflected light, rather I only darkened the core shadow which makes the reflected light appear lighter than originally done.
This is what the camera saw.
This is a photo of the subject for my drawing with the terms used to indicate the tonal steps (modeling factors) labeled.
To start, I do a careful contour drawing plus indicating the location of the high lights, terminator, and cast shadow.
Next, to save the high lights I make everything else several shades darker. For this light halftone I use a #H pencil.
Now I have made a darker mid tone to seperate the light side from the shadow side using a #HB pencil. Still only two values plus the white of the paper.
Finally, I add the darker values indicating the pattern on the light side with a #H or HB, being careful to keep them no darker than the light tones of the shadow side. Then likewise I add the darker values, using a #HB and 2B pencil, indicating the pattern on the shadow side along with the core, occlusion, and cast shadow.