bath/cam_chart.html at main · gr5/bath · GitHub

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<!DOCTYPE html>
<head>
<title>camera chart</title>
</head>

<h2>Encircled region shows what mirror types can be tested with that camera</h2>

<body>
<div id='aaa' style='width:1100px;height:550px;'></div>

<input type='button' value='zoom out (default)' id='idBtnZoomout'>&nbsp;&nbsp;&nbsp;&nbsp;
<input type='button' value='zoom out more' id='idBtnZoomoutMore'>
<p>
<h3><font color='blue'>click and drag mouse over graph to zoom in</font></h3>
<p>
<input type="checkbox" id="c1" value="c1"     onclick="radioChange()" checked ><label for="c1">Nikon D3100 w/50mm f/1.8</label><br>
<input type="checkbox" id="c2" value="c2"     onclick="radioChange()"         ><label for="c2">Nikon D3200 w/50mm f/1.8</label><br>
<input type="checkbox" id="c3" value="c3"     onclick="radioChange()"         ><label for="c3">Nikon D3200 w/85mm f/1.8</label><br>
<input type="checkbox" id="c4" value="c4"     onclick="radioChange()"         ><label for="c4">Nikon D3200 w/35mm f/1.8</label><br>
<input type="checkbox" id="c5" value="c5"     onclick="radioChange()"         ><label for="c5">Nikon Z7 full frame w/85mm f/1.8</label><br>
<input type="checkbox" id="c5b" value="c5b"     onclick="radioChange()"         ><label for="c5b">Rasp Pi HQ cam w/16mm F/1.4</label><br>

<input type="checkbox" id="c6" value="c6"     onclick="radioChange()"         ><label for="c6">Custom</label>
sensor size vertical(mm): <input type='text' id='idCamVert' size=2 value=24>
sensor pixels vertical: <input type='text' id='idCamPix' size=3 value=4000>
lens FL (mm) <input type='text' id='idCamLens' size=2 value=50>
Lens minimum focus distance (meters): <input type='text' id='idCamMinFocus' size=2 value=.45>
<input type='button' value='Calculate' onclick='makeCustomPoints()'> This doesn't take into account stop cropping (virtual pin hole). Many lenses have stop cropping issues.

<br>
<p>
<input type="checkbox" id="chkInch" value="chkInch"     onclick="unitsChange()"         ><label for="chkInch">change units to cm</label><br>
Add your own mirror - diameter:
<input type='text' id='idDiam' size=3 value='8'> &nbsp;&nbsp;&nbsp; f/#: <input type='text' id='idFnum' size=2 value='5'>
<input type='button' onclick='addCustomMirror()' value='Set'>
<p>
How to use this chart.  If your mirrors to be tested on a Bath Interferometer are within the encircled blue region then a used Nikon D3100 with a 50mm f/1.8 lens will work for you ($200 for used body, $50 for used lens on ebay).  If one of your mirrors is outside this region, try some of the other options here (these are not the only options).  If your mirror is right on the edge, try this utility for more info:
<a href="cam.html">camera chooser</a>
<p>
The top of the region is set by camera resolution and the size of the igram on the camera sensor.  I chose a minimum of 600 pixels across the diameter of the igram.  This is a bit arbitrary and you would be fine to test with just 200 pixels across the mirror.
<p>The left side of the region is set by the minimum focal distance of the lens being used.  The mirror to be tested will be at RoC (double the focal length) from the Bath and camera. It's unlikely you have a mirror so small it hits this limit.  I included 1 inch for the distance from the camera lens to the Coc.
<p>The bottom of the graph is set based on the size of the igram in the field of view - any lower f/# mirror and the igram will be cropped at the top and bottom of the field of
view. I included a very small margin (about 10% arbitrarily) as if you are right on the edge then it's a royal pain to position the camera such that it isn't cropping at the top or bottom of the igram.  There is another type of cropping, "crop stopping" or "virtual pinhole cropping". I own the 3 lenses above and they don't have stop cropping issues - the worst is the 35mm F/1.8 which needs to be almost touching the Bath splitter cube or it will crop the field of view. The other 2 lenses can be quite far behind the splitter cube.
<p>The right edge of the region is a curve set by how tiny the fringes are and the pixel resolution of these fringes on the camera.  Cameras with more megapixels will move this curve to the right.  I picked 6 pixels per fringe in the best case igram to set the position of this line but in reality you can go down to 4 pixels (just barely) if the fringes are vertical or horizontal (worst case - can go even lower if none of the fringes are vertical or horizontal).


<script type="text/javascript" src="prototype.js"></script>
<script type="text/javascript" src="flotr-0.2.0-alpha.js"></script>
<script>

function getRadio(n)
{
  return document.getElementById('c'+n).checked;
}
function radioChange()
{
  load_up_data();
  makeCustomPoints();
}
var customDiam=0;
var customFnum=0;
function addCustomMirror()
{
  bCM = document.getElementById('chkInch').checked;
  customDiam = parseFloat(document.getElementById('idDiam').value);
  customFnum = parseFloat(document.getElementById('idFnum').value);
  if (bCM) customDiam/=2.54;
  load_up_data();
  makeCustomPoints();
}

function unitsChange()
{
  bCM = document.getElementById('chkInch').checked;
  var multiplier = bCM ? 2.54 : 1/2.54;
  load_up_data();
  if (lastArea != null && lastArea != "out")
  {
    lastArea.x1 *= multiplier;
    lastArea.x2 *= multiplier;
  }
  makeCustomPoints();
}
/*
    tilt=-z8*7+4;
    defocus=-z8*1.2+.3;
    astig=0;
*/


function fill_left(data, min_focus) // min_focus in inches
{
  var minf = data[0][1];
  var maxf = data[data.length-1][1];
  var mirror_diam;
  for (f=maxf; f> minf; f-=0.3)
  {
    mirror_diam = (min_focus-1)/f/2;
    data.push([mirror_diam, f]);
  }
  mirror_diam = (min_focus-1)/minf/2;
  data.push([mirror_diam, minf]);

  data.push([data[0][0], minf]);

}
var customSeries=[];
var series;
function load_up_data()
{
  series=[];
  if (getRadio(1))
    series.push({label:'D3100 w/50mm', color:"#00A8F0",data:makePoints(15.4,3072,50,0.45)});
  if (getRadio(2))
    series.push({label:'D3200 w/50mm', color:"#CB4B4B",data:[[9.6,1.8],[18.6,2.5],[26.7,3],[36.3,3.5],[47.3,4],[105,6],[185,8],[332,10.8]]}); // 600 pixels f13.0
  if (getRadio(3))
    series.push({label:'D3200 w/85mm', color:"#4DA74D",data:[[45.5,3],[81,4],[179,6],[498,10],[1630,18.4]]});//600
  if (getRadio(4))
    series.push({label:'D3200 w/35mm', color:"#9440ED",data:[[4,1.4],[8.2,2],[18.3,3],[32.3,4],[72,6],[113,7.57]]});
  if (getRadio(5))
    series.push({label:'Z7 w/85mm', color:"#000000",data:[[18,2],[28,2.5],[40,3],[55,3.5], [75,4.1], [125,5.3], [179,6.35], [500,10.7], [1140,16.3]]});
  if (getRadio('5b'))
  {
    series.push({label:'HQ cam w/16mm', color:"#d0d000",data:[]});
    series[series.length-1].data=makePoints(4.712, 3040, 16, 0.275);
  }


  if (getRadio(6))
  {
    series.push({label:'custom', color:"#ff8000",data:[]});
    series[series.length-1].data = customSeries.slice(); // makes fresh copy
  }
  series.push({label:'typical amateur mirrors', color:"#808080",data:[[4,10],[6,5],[6,8],[6,10],[8,6],[12,6],[12,5],[12,4],[18,4],[18,3.6],[29,3.3],[32,3]],points:{show:true}});


  if (customDiam !=0)
  {
    series.push({label:'your mirror', color:'#00c000',data:[],points:{show:true}});
    series[series.length-1].data.push([customDiam, customFnum]);
  }

  var i=0;
  if (getRadio(1))
    i++;
  if (getRadio(2))
    fill_left(series[i++].data, 17.76);
  if (getRadio(3))
    fill_left(series[i++].data, 31.44);
  if (getRadio(4))
    fill_left(series[i++].data, 11.8);
  if (getRadio(5))
    fill_left(series[i++].data, 31.44);

  if (document.getElementById('chkInch').checked)
  {
    // convert all values from inches to cm
    var i,j,data;
    for (i=0;i<series.length;i++)
    {
      data=series[i].data;
      for (j=0;j<data.length;j++)
      {
        data[j][0] *= 2.54;
      }
    }
  }
}


function calc_ppf(z8, tilt, defocus, astig, pixels)
{
    // now find highest slope - look only along the X axis and only check X slope
    let maxSlope=0;
    let maxSlopeX=0;
    let slope=0;
    for (x=-1; x<=1; x+=.01) // check 200 positions
    {
        let x3 = x*x*x;

        slope = z8*6*(4*x3-2*x) + tilt + defocus*4*x + astig*2*x;

        if (Math.abs(slope) > Math.abs(maxSlope))
        {
            maxSlope = slope;
            maxSlopeX=x;
        }
    }

    // maxSlope is now in waves per unit circle radius
    maxSlope = maxSlope/(pixels/2);  // now in waves per pixel

    return Math.abs(1/maxSlope);
}

function inch_fnum_to_ppf(inch, fnum, pixels)
{
	const wl=650;
	let mirror_diam = inch*25.4;
	const cc= -1;
	let z8 = cc*(mirror_diam/(wl/1000000))/(3072 * fnum * fnum * fnum);
	let tilt=-z8*7+4;
	let defocus=-z8*1.2+.3;
	const astig=0;

	return calc_ppf(z8, tilt, defocus, astig, pixels);

}

function right_edge_fnum_to_inch(fnum, minpixels, camSizeLens, camSizeMM, camSizePix)
{


  camFOV = camSizeLens/camSizeMM;
  mirrorFOV = fnum*2;

  inch_low=0.01;
  inch_high=10000;

  igramPixels = camSizePix * camFOV/mirrorFOV;

  for(i=1; i<20; i++)
  {
    inch = (inch_low+inch_high)/2;
	if (inch_fnum_to_ppf(inch, fnum, igramPixels)>minpixels)
	{
	  // we can go more inches
	  inch_low = inch;
	}
	else
	{
	  inch_high = inch;
	}
  }
  inch = (inch_low+inch_high)/2;
  return inch;
}

function makePoints(camSizeMM, camSizePix, camSizeLens, camFocus)
{
  // last parameter, camFocus is in meters but I convert to inches

  camFocus *=1000; // convert meters to mm
  camFocus /=25.4; // convert mm to inches


  camFOV = camSizeLens/camSizeMM;

  //mirrorFOV = mirrorFNum*2;
  //igramPixels = sensorPixels * camFOV/mirrorFOV;

  // calculate topfnum
  var mirrorFOV = camSizePix * camFOV / 600;
  var topfnum = mirrorFOV / 2;

  // calculate botfnum where mirrorFOV=CAMfov*85%

  var mirrorFOV = camFOV/.9;
  var botfnum = mirrorFOV / 2;
  let inch = right_edge_fnum_to_inch(botfnum, 6, camSizeLens, camSizeMM, camSizePix)
  let mirror_diam = (camFocus-1)/botfnum/2;
  if (inch < mirror_diam)
  {
    // need to find intersection of two curves
	let f_min = botfnum;
	let f_max = topfnum;
	for (let i=0; i<10; i++)
	{
	  f = (f_min+f_max)/2;
	  inch = right_edge_fnum_to_inch(f, 6, camSizeLens, camSizeMM, camSizePix)
	  mirror_diam = (camFocus-1)/f/2;
	  if (inch < mirror_diam)
	    f_min = f; // increase f
	  else
	    f_max = f;
	}
	botfnum = (f_min+f_max)/2;
  }
  ret_series = new Array();
  for(let f = botfnum; f < topfnum; f *= 1.2)
  {
     ret_series.push(new Array(right_edge_fnum_to_inch(f, 6, camSizeLens, camSizeMM, camSizePix),f));
  }
 ret_series.push(new Array(right_edge_fnum_to_inch(topfnum, 6, camSizeLens, camSizeMM, camSizePix),topfnum));


  // fill_left expects first element to be bottom right corner of graph and last element to be top right corner
  fill_left(ret_series, camFocus);

  return ret_series;
}

function makeCustomPoints()
{
  customSeries = [];
  var camSizeMM = parseFloat(document.getElementById('idCamVert').value);
  var camSizePix = parseFloat(document.getElementById('idCamPix').value);
  var camSizeLens = parseFloat(document.getElementById('idCamLens').value);
  var camFocus = parseFloat(document.getElementById('idCamMinFocus').value);

  customSeries = makePoints(camSizeMM, camSizePix, camSizeLens, camFocus);

  load_up_data();
  plot("nochange");

}


var lastArea="";
var options;
function plot(area)
{
  bCM = document.getElementById('chkInch').checked;
  units = bCM ? "cm" : "in";
  options={selection:{mode:'xy',fps:30,color:'#000000'},
              legend:{position:'se',backgroundColor: '#c0c0ff'},
              xaxis:{min:null},
              yaxis:{max:null},
              xaxis:{title:"Diameter of mirror in inches"},
              yaxis:{title:"F/#"},
              mouse:{ track:true,
                      relative:true,
                      position: 'ne',
                      sensibility: 20, // => The smaller this value, the more precise you've to point
                      trackDecimals: 2,
                      trackFormatter: function(obj){ return obj.x+" "+units+"  F/"+obj.y }
                     },
              };
  if (area == "nochange")
    area=lastArea;

  if (bCM)
    options.xaxis.title="Diameter of mirror in cm";

  if (area=="out")
    {
        options.xaxis.min=0;
        options.xaxis.max=80;
        options.yaxis.min=0;
        if (bCM)
          options.xaxis.max *= 2.54;
    }
    else if (area)
    {
        options.xaxis.min=area.x1;
        options.xaxis.max=area.x2;
        options.yaxis.min=area.y1;
        options.yaxis.max=area.y2;
    } else
	{
        options.xaxis.min=0;
        options.yaxis.min=0;
	}

  Flotr.draw($('aaa'), series ,options);
  lastArea=area;
}
makeCustomPoints();
load_up_data();
plot("out");

//
// handle zoom

//
$('aaa').observe('flotr:select', function(evt){
    var area = evt.memo[0];
    plot(area);

});

$('idBtnZoomout').observe('click', function(){plot("out")});
$('idBtnZoomoutMore').observe('click', function(){plot()});

</script>

</body>