When I first started I measured the height wrong, so the bowl is the wrong shape. It’s so important to do the first measurements accurately.
I took a few specular hightlights to be white, and set the tones on the basis of this. This was a mistake. You need to ignore the small areas and set the tone for the larger areas.
The lighter areas are HB but you can’t see that at all in the scan, so perhaps I should stop using HB. Perhaps I’ll use white, 2B and 6B. But I don’t think this will be enough to make the object real. The above drawing looks like it is three tones (beacuse you can’t see the difference between HB and white), and it looks flat. Three tones don’t allow scope for detail. The trouble with the above was that the background was black, so I couldn’t use 6B on the bowl, just the background. You need to factor in the tone value of the background when planning the drawing. In this situation perhaps I could have used 6B on the bowl, even though there is nowhere on the bowl as dark as the background. Aonther option is to use 2B, 4B and 6B and white. I’ll try that.
So 6B, 2B and HB seem to have the best separation. Unfortunately HB doesn’t show up very well in scans. Adding this third tone to the pear:
I guessed the tones because the pear was not in front of me, which of course is bad. Apart from that, there are a few issues:
Even three tones look clumsy and need soft edges.
It’s hard to tell where the mid-tone begins and ends. The other two are simpler.
It’s easy to skew the tonal scale. If you press to hard on the mid-tone them the dark doesn’t look so dark any more, and the picture starts to look flat. And what if you can’t make the dark darker? Also, the light tone can take up too much of the white area, which can make you creep the mid-tone into the light area, then the dark into the mid-tone area, and the whole drawing looks to dark and flat.
So you need to be very clear on the three values, and start with them evn if you will add more, which you will need to to make the drawing more realistic. So the next step is to practice with just these three tones plus white, then add a couple other tones, so we have three mid-tones.