Well without comparing the two that looks fantastic but since you're drawing Lennon based on that picture what I can point out are the tones on his face are a little darker on yours and the proportions and placement of the features are a little bit off.

Hi David, Apologies if I repeat anything previously said. Not trying to beat a dead horse, I just try not to read other criticism so it won't influence what I'm about to say. As far as the actual construction of the drawing, I took the reference photo and overlaid it on top of your charcoal. The results are included in the first picture. Typically, if I do a photo study, I will do the sketch, do a trace of the photo, overlay it on top of the drawing and see what I did, then I will redraw the sketch with the notes I have in mind. One of the things this does is lets you know errors you consistently make; for example, I also draw noses too long and eyes too big very often, so it's something I know to keep in mind when I do my next study. This may be helpful for you. Next, I moved the facial features around in accordance where they are on the overlay, and proceeded to do a paint-over to correct some values. I think when you were in the process of making your piece, you really wanted to display the forms on the face. Which is great, and you did a great job of that! Unfortunately, this picture is really washed out on one side, so the effort to show the forms compromised the values in the reference photo. There's not really anything wrong with that, but if you want it to look exactly like the photo, the values do need to be lighter on the right side of the face. Overall I think you did a good job. Keep up the good work!

Regarding likeness, pay attention to the light area of his face (right side). Trace that shape over the photo and compare it with yours.

I think you made the shadow side to dark. Compare to yours and the pic the shadow side has some more lighter tons on the eye then the one you put.

I believe, like some others have said, that the face is a bit too wide. In the original, his face is much more elongated and the features are a bit more spaced out from each other, the eyes are smaller and the chin a bit longer. Also, your drawing has a bit of a sad look to it. I think it might be the angle of the eyes near the end, especially with the thick shading of the upper lid near the end of the eye. Instead of it looking like eyelashes or something similar, it almost seems like the lid intrudes, almost drooping on the eye instead of being smooth and light like in the picture. Otherwise, this is an impressive study!

Depending on how quick you’re working (I personally find) there will be things that aren’t so important for you in the study to obtain. I guess what’s important to ask is what you are trying to achieve most with the quick study? Is it proportions? Sense of light? Form? For example, with a 20 minute pose I can try to achieve a few things like proportions and sense of form, but I will for sure sacrifice things like details or shading since doing all that at once in such a short time might be to much to focus on. What I decide to achieve with that 20 minutes would be much different than what I decide to achieve with a full 2 week pose with 24+ hours worked on. Based on the reference what sticks out to me most is the angles of the eyebrows, eyes, nose, and mouth don’t quite match that of the reference. It looks like in the reference his head is just slightly angled up with a small turn and with a tilt and in your drawing it’s looking more straight on. However, if I just look at your drawing you did really well lining up those points to one another. Also the proportions are a bit off if you’re trying to replicate the reference. He has a rather long and thin looking face, I think the jaw line can be pushed down a bit to give more space there. That aside I think your drawing is really solid for a quick study. The values are easily distinguishable, the darks are pushed well in contrast to the lightest lights and there is a good sense of form.

Nice work, David. For one thing I think you are trying to make everything too vertical. The original all has a slight angle to it that I don't think you really have. I also think you have the face too short or the eyes too big... hard to tell. I like your style though!

The left side of his face is too wide? It’s way better than I can do either way. Keep going