How to put light reflections on a camera lens drawing (Tikz)?

Question

I have to do a schematic featuring a camera lens so I tried my best to make the drawing look like an actual lens. I've been told several times that it looks a lot more like a speaker than a camera lens.

In order to improve this drawing I thought that a good starting point would be to put some reflections on what is supposed to be the lens glass. But I have no idea how to proceed in Tikz. Most transparency and shade effects that I tried make it look even worse...

Here is a MWE of what I tried

\documentclass[tikz]{standalone}
\usetikzlibrary{calc}
\usetikzlibrary{fadings}
\usetikzlibrary{decorations.text}
\tikzfading[name=fade inside, inner color=transparent!90, outer color=transparent!40]

\begin{document}
    \begin{tikzpicture} 
        \coordinate (baseSupportLunette) at (0,-4);
        \coordinate (coinSupportCameras) at  -- ($(baseSupportLunette)+(-3,1.75)$);
        \coordinate (moteurTilt) at (-1.75,0);

        \draw[very thick,gray,dashed] (baseSupportLunette) -- (0,3);

        % lens 
        \filldraw[black!85] (0,0) circle (1.75cm);
        \draw[darkgray] (0,0) circle (0.2);
        \shade [ball color=white,path fading=fade inside] (0,0) circle (0.195);
        \draw[gray] (0,0) circle (0.5);
        \draw[] (0,0) circle (0.6);
        \draw[darkgray] (0,0) circle (0.75);
        \shade [ball color=white,path fading=fade inside] (0,0) circle (1.245);
        \draw[darkgray,thick] (0,0) circle (1.25);
        \draw[thick] (0,0) circle (1.35);       

        % lens support
        \draw[line width=1mm,darkgray] (0,-2.25) -- (baseSupportLunette); 

        % structure
        \draw[darkgray,line width=1mm,rounded corners] (1.75,0)%
        -- (2.3,0)%
        -- (2.3,-2.25)%
        -- (coinSupportCameras)%
        -- (-3,0) -- (moteurTilt); 

        % lens border
        \draw[very thick] (0,0) circle (1.75); 

        % top rotation arrow
        \draw[very thick,stealth-stealth] (-0.125,2.625) arc [start angle=100, end angle=440,x radius=0.75cm, y radius=0.125cm];   

        % side rotation arrow
        \draw[very thick,stealth-stealth] (-2.25,0.125) arc [start angle=10, end angle=350,x radius=0.125cm, y radius=0.75cm];

        % lens label
        \path [postaction={decorate,decoration%
        ={raise=0pt,text along path, reverse path=true,%
        text align/align=center,%
        text align/left indent={4.5553093477052cm},%
        text color=lightgray,%
        text=|\sffamily\scriptsize|CAMERA LENS}}]%
         (0,0) circle (1.45cm);         
    \end{tikzpicture}
\end{document}

Answer 1

TikZ is not the tool for lighting effects. Not unless you wish to draw them pixel by pixel, which is always an option if you don't need something scalable, I suppose. The package just isn't designed for it.

Mark Wibrow will come up with something which reflects prismatic light in real time, thus proving me conclusively wrong. But TikZ still isn't a good choice for this, since other tools ... well, there are tools which have actually heard about light ....

Caveat emptor ...

\documentclass[border=10pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{calc,fadings,decorations.text}
\tikzfading[name=fade inside, inner color=transparent!90, outer color=transparent!40]

\begin{document}
\begin{tikzpicture}
  \coordinate (baseSupportLunette) at (0,-4);
  \coordinate (coinSupportCameras) at  -- ($(baseSupportLunette)+(-3,1.75)$);
  \coordinate (moteurTilt) at (-1.75,0);

  \draw[very thick,gray,dashed] (baseSupportLunette) -- (0,3);

  % lens
  \filldraw[black!85] (0,0) circle (1.75cm);
  \draw [darkgray] (0,0) circle (0.2);
  \shade [ball color=white,path fading=fade inside] (0,0) circle (0.195);
  \draw [gray] (0,0) circle (0.5);
  \draw[] (0,0) circle (0.6);
  \draw [darkgray] (0,0) circle (0.75);
  \shade [ball color=white,path fading=fade inside] (0,0) circle (1.245);
  \draw [darkgray,thick] (0,0) circle (1.25);
  \draw [thick] (0,0) circle (1.35);
  \begin{scope}
    \clip (0,0) circle (1.75);
    \foreach \i in {8,...,10,11} \shade [ball color=white!85!blue, blend mode=hard light, opacity=1] (135:{1.3*(10-\i}) circle ({0.13*\i});
    \shade [ball color=white!85!blue, shading angle=0, blend mode=hard light, opacity=1] (0,0) circle (1.3);
  \end{scope}
  % lens support
  \draw[line width=1mm,darkgray] (0,-2.25) -- (baseSupportLunette);

  % structure
  \draw[darkgray,line width=1mm,rounded corners] (1.75,0)%
  -- (2.3,0)%
  -- (2.3,-2.25)%
  -- (coinSupportCameras)%
  -- (-3,0) -- (moteurTilt);

  % lens border
  \draw[very thick] (0,0) circle (1.75);

  % top rotation arrow
  \draw[very thick,stealth-stealth] (-0.125,2.625) arc [start angle=100, end angle=440,x radius=0.75cm, y radius=0.125cm];

  % side rotation arrow
  \draw[very thick,stealth-stealth] (-2.25,0.125) arc [start angle=10, end angle=350,x radius=0.125cm, y radius=0.75cm];

  % lens label
  \path [postaction={decorate,decoration%
    ={raise=0pt,text along path, reverse path=true,%
      text align/align=center,%
      text align/left indent={4.5553093477052cm},%
      text color=lightgray,%
      text=|\sffamily\scriptsize|CAMERA LENS}}]%
  (0,0) circle (1.45cm);
\end{tikzpicture}
\end{document}

EDIT

Here's the effect of adding the shadings library and

% Mark Wibrow's suggestion
    \shade [shading=color wheel, path fading=fade inside] circle (1.3);

as Mark Wibrow suggested.

Or, using

    \shade [shading=color wheel black center, path fading=fade inside] circle (1.3);

With a radius of only 1, as suggested, it looks strange to me.

But perhaps I'm just mistaken.

EDIT EDIT

Complete code for coloured versions:

% ateb: https://tex.stackexchange.com/a/375369/ addaswyd o gwestiwn jrojasqu: https://tex.stackexchange.com/q/375362/
\documentclass[border=10pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{fadings,decorations.text,shadings}
\tikzfading[name=fade inside, inner color=transparent!90, outer color=transparent!40]

\begin{document}
\begin{tikzpicture}
  \coordinate (baseSupportLunette) at (0,-4);
  \coordinate (moteurTilt) at (-1.75,0);

  % lens
  \filldraw[black!85] (0,0) circle (1.75cm);
  \draw [darkgray] (0,0) circle (0.2);
  \shade [ball color=white,path fading=fade inside] (0,0) circle (0.195);
  \draw [gray] (0,0) circle (0.5);
  \draw[] (0,0) circle (0.6);
  \draw [darkgray] (0,0) circle (0.75);
  \shade [ball color=white,path fading=fade inside] (0,0) circle (1.245);
  \draw [darkgray,thick] (0,0) circle (1.25);
  \draw [thick] (0,0) circle (1.35);
  \begin{scope}
    \clip (0,0) circle (1.75);
    % Mark Wibrow's suggestion
    \shade [shading=color wheel, path fading=fade inside] circle (1);
    \foreach \i in {8,...,10,11} \shade [ball color=white!85!blue, blend mode=hard light, opacity=1] (135:{1.3*(10-\i}) circle ({0.13*\i});
    \shade [ball color=white!85!blue, shading angle=0, blend mode=hard light, opacity=1] (0,0) circle (1.3);
  \end{scope}

  % lens border
  \draw[very thick] (0,0) circle (1.75);

  % lens label
  \path [postaction={decorate,decoration%
    ={raise=0pt,text along path, reverse path=true,%
      text align/align=center,%
      text align/left indent={4.5553093477052cm},%
      text color=lightgray,%
      text=|\sffamily\scriptsize|CAMERA LENS}}]%
  (0,0) circle (1.45cm);
\end{tikzpicture}
\begin{tikzpicture}
  \coordinate (baseSupportLunette) at (0,-4);
  \coordinate (moteurTilt) at (-1.75,0);

  % lens
  \filldraw[black!85] (0,0) circle (1.75cm);
  \draw [darkgray] (0,0) circle (0.2);
  \shade [ball color=white,path fading=fade inside] (0,0) circle (0.195);
  \draw [gray] (0,0) circle (0.5);
  \draw[] (0,0) circle (0.6);
  \draw [darkgray] (0,0) circle (0.75);
  \shade [ball color=white,path fading=fade inside] (0,0) circle (1.245);
  \draw [darkgray,thick] (0,0) circle (1.25);
  \draw [thick] (0,0) circle (1.35);
  \begin{scope}
    \clip (0,0) circle (1.75);
    % Mark Wibrow's suggestion
    \shade [shading=color wheel, path fading=fade inside] circle (1.3);
    \foreach \i in {8,...,10,11} \shade [ball color=white!85!blue, blend mode=hard light, opacity=1] (135:{1.3*(10-\i}) circle ({0.13*\i});
    \shade [ball color=white!85!blue, shading angle=0, blend mode=hard light, opacity=1] (0,0) circle (1.3);
  \end{scope}

  % lens border
  \draw[very thick] (0,0) circle (1.75);

  % lens label
  \path [postaction={decorate,decoration%
    ={raise=0pt,text along path, reverse path=true,%
      text align/align=center,%
      text align/left indent={4.5553093477052cm},%
      text color=lightgray,%
      text=|\sffamily\scriptsize|CAMERA LENS}}]%
  (0,0) circle (1.45cm);
\end{tikzpicture}
\begin{tikzpicture}
  \coordinate (baseSupportLunette) at (0,-4);
  \coordinate (moteurTilt) at (-1.75,0);

  % lens
  \filldraw[black!85] (0,0) circle (1.75cm);
  \draw [darkgray] (0,0) circle (0.2);
  \shade [ball color=white,path fading=fade inside] (0,0) circle (0.195);
  \draw [gray] (0,0) circle (0.5);
  \draw[] (0,0) circle (0.6);
  \draw [darkgray] (0,0) circle (0.75);
  \shade [ball color=white,path fading=fade inside] (0,0) circle (1.245);
  \draw [darkgray,thick] (0,0) circle (1.25);
  \draw [thick] (0,0) circle (1.35);
  \begin{scope}
    \clip (0,0) circle (1.75);
    % Mark Wibrow's suggestion
    \shade [shading=color wheel black center, path fading=fade inside] circle (1.3);
    \foreach \i in {8,...,10,11} \shade [ball color=white!85!blue, blend mode=hard light, opacity=1] (135:{1.3*(10-\i}) circle ({0.13*\i});
    \shade [ball color=white!85!blue, shading angle=0, blend mode=hard light, opacity=1] (0,0) circle (1.3);
  \end{scope}

  % lens border
  \draw[very thick] (0,0) circle (1.75);

  % lens label
  \path [postaction={decorate,decoration%
    ={raise=0pt,text along path, reverse path=true,%
      text align/align=center,%
      text align/left indent={4.5553093477052cm},%
      text color=lightgray,%
      text=|\sffamily\scriptsize|CAMERA LENS}}]%
  (0,0) circle (1.45cm);
\end{tikzpicture}
\end{document}