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Re: color correction curves for 132

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  • williamopticsmarketing
    Scott, yeah you are the first one to have noticed them, but in fact they were uploaded only 3 or 4 days ago! ;-) ... curve
    Message 1 of 11 , Nov 30, 2006
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      Scott, yeah you are the first one to have noticed them, but in fact
      they were uploaded only 3 or 4 days ago! ;-)


      --- In William-Optics@yahoogroups.com, "scottatwin" <sdwalker@...>
      wrote:
      >
      > I guest I have been a sleep. I just spotted the color correction
      curve
      > for the new WO 132mm scope.
    • Timm Bottoni
      Thanks to Scott for pointing this out, and for actually helping me to understand these! And hmmm, it is an interesting chart, isn t it? Timm
      Message 2 of 11 , Dec 3, 2006
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        Thanks to Scott for pointing this out, and for actually helping me to
        understand these! And hmmm, it is an interesting chart, isn't it?

        Timm

        --- In William-Optics@yahoogroups.com, "williamopticsmarketing"
        <williamopticsmarketing@...> wrote:
        >
        > Scott, yeah you are the first one to have noticed them, but in fact
        > they were uploaded only 3 or 4 days ago! ;-)
        >
        >
        > --- In William-Optics@yahoogroups.com, "scottatwin" <sdwalker@>
        > wrote:
        > >
        > > I guest I have been a sleep. I just spotted the color correction
        > curve
        > > for the new WO 132mm scope.
        >
      • Kurt Friedrich
        IN what post did he help you understand the chart? Kurt ... ____________________________________________________________________________________ Do you Yahoo!?
        Message 3 of 11 , Dec 3, 2006
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          IN what post did he help you understand the chart?

          Kurt

          --- Timm Bottoni <t.bottoni@...> wrote:

          > Thanks to Scott for pointing this out, and for
          > actually helping me to
          > understand these! And hmmm, it is an interesting
          > chart, isn't it?
          >
          > Timm
          >
          > --- In William-Optics@yahoogroups.com,
          > "williamopticsmarketing"
          > <williamopticsmarketing@...> wrote:
          > >
          > > Scott, yeah you are the first one to have noticed
          > them, but in fact
          > > they were uploaded only 3 or 4 days ago! ;-)
          > >
          > >
          > > --- In William-Optics@yahoogroups.com,
          > "scottatwin" <sdwalker@>
          > > wrote:
          > > >
          > > > I guest I have been a sleep. I just spotted the
          > color correction
          > > curve
          > > > for the new WO 132mm scope.
          > >
          >
          >
          >




          ____________________________________________________________________________________
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          Everyone is raving about the all-new Yahoo! Mail beta.
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        • Timm Bottoni
          Hi Kurt, It was a long time back - and luckily I put it in the FAQs too, but here it is for anyone who wants to try to understand these better.
          Message 4 of 11 , Dec 4, 2006
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            Hi Kurt,

            It was a long time back - and luckily I put it in the FAQs too, but
            here it is for anyone who wants to try to understand these better.

            http://tech.groups.yahoo.com/group/William-Optics/message/7184

            Hope it helps make sense of the squiggly colorful lines!

            Timm

            --- In William-Optics@yahoogroups.com, Kurt Friedrich
            <kurt_friedrich@...> wrote:
            >
            > IN what post did he help you understand the chart?
            >
            > Kurt
            >
            > --- Timm Bottoni <t.bottoni@...> wrote:
            >
            > > Thanks to Scott for pointing this out, and for
            > > actually helping me to
            > > understand these! And hmmm, it is an interesting
            > > chart, isn't it?
            > >
            > > Timm
            > >
            > > --- In William-Optics@yahoogroups.com,
            > > "williamopticsmarketing"
            > > <williamopticsmarketing@> wrote:
            > > >
            > > > Scott, yeah you are the first one to have noticed
            > > them, but in fact
            > > > they were uploaded only 3 or 4 days ago! ;-)
            > > >
            > > >
            > > > --- In William-Optics@yahoogroups.com,
            > > "scottatwin" <sdwalker@>
            > > > wrote:
            > > > >
            > > > > I guest I have been a sleep. I just spotted the
            > > color correction
            > > > curve
            > > > > for the new WO 132mm scope.
            > > >
            > >
            > >
            > >
            >
            >
            >
            >
            >
            ______________________________________________________________________
            ______________
            > Do you Yahoo!?
            > Everyone is raving about the all-new Yahoo! Mail beta.
            > http://new.mail.yahoo.com
            >
          • jtpowers1972
            Hi Timm, Thanks for the link, I found it helpful. I m not sure I get it entirely though. Can you help me determine the relative color correction qualitites of
            Message 5 of 11 , Dec 4, 2006
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              Hi Timm,

              Thanks for the link, I found it helpful. I'm not sure I get it
              entirely though. Can you help me determine the relative color
              correction qualitites of the 132 graph vs. the 110 graph? It seems
              from my rookie viewpoint that the 110 might be better corrected than
              the 132??

              Thanks!
              John

              BTW, can it be assumed that the color correction etc., on the 110
              and/or the 132 will be superior to the M90, due to the doublet-
              triplet idea proposed in this thread and by the dblt vs. trplt color
              charts under the WO TMB 80mm triplet section of the website?
              Thanks again!




              --- In William-Optics@yahoogroups.com, "Timm Bottoni" <t.bottoni@...>
              wrote:
              >
              > Hi Kurt,
              >
              > It was a long time back - and luckily I put it in the FAQs too, but
              > here it is for anyone who wants to try to understand these better.
              >
              > http://tech.groups.yahoo.com/group/William-Optics/message/7184
              >
              > Hope it helps make sense of the squiggly colorful lines!
              >
              > Timm
              >
              > --- In William-Optics@yahoogroups.com, Kurt Friedrich
              > <kurt_friedrich@> wrote:
              > >
              > > IN what post did he help you understand the chart?
              > >
              > > Kurt
              > >
              > > --- Timm Bottoni <t.bottoni@> wrote:
              > >
              > > > Thanks to Scott for pointing this out, and for
              > > > actually helping me to
              > > > understand these! And hmmm, it is an interesting
              > > > chart, isn't it?
              > > >
              > > > Timm
              > > >
              > > > --- In William-Optics@yahoogroups.com,
              > > > "williamopticsmarketing"
              > > > <williamopticsmarketing@> wrote:
              > > > >
              > > > > Scott, yeah you are the first one to have noticed
              > > > them, but in fact
              > > > > they were uploaded only 3 or 4 days ago! ;-)
              > > > >
              > > > >
              > > > > --- In William-Optics@yahoogroups.com,
              > > > "scottatwin" <sdwalker@>
              > > > > wrote:
              > > > > >
              > > > > > I guest I have been a sleep. I just spotted the
              > > > color correction
              > > > > curve
              > > > > > for the new WO 132mm scope.
              > > > >
              > > >
              > > >
              > > >
              > >
              > >
              > >
              > >
              > >
              > ______________________________________________________________________
              > ______________
              > > Do you Yahoo!?
              > > Everyone is raving about the all-new Yahoo! Mail beta.
              > > http://new.mail.yahoo.com
              > >
              >
            • Timm Bottoni
              Hi, I ll ask Scott Walker to explain it, if he has time. While I think I understand it, I don t think I am qualified to make a comparison or draw any
              Message 6 of 11 , Dec 5, 2006
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                Hi,

                I'll ask Scott Walker to explain it, if he has time. While I think I
                understand it, I don't think I am qualified to make a comparison or
                draw any conclusions about one being better than the other.

                Calling Scott Walker, ring, ring...

                Thanks,

                Timm

                P.S. There are loads of sites on the web with pictures and charts if
                you want to see learn more. Just search for words like "chromatic
                aberration", or "refractor aberration". You can spend all day
                finding and reading sites and see loads of pictures, but I will say
                that there isn't much that I have found in the way of help reading
                these CA design charts, that is any better than the way Scott has
                explained it here for us. Thanks again, Scott!!!

                --- In William-Optics@yahoogroups.com, "jtpowers1972"
                <jtpowers1972@...> wrote:
                >
                > Hi Timm,
                >
                > Thanks for the link, I found it helpful. I'm not sure I get it
                > entirely though. Can you help me determine the relative color
                > correction qualitites of the 132 graph vs. the 110 graph? It seems
                > from my rookie viewpoint that the 110 might be better corrected than
                > the 132??
                >
                > Thanks!
                > John
                >
                > BTW, can it be assumed that the color correction etc., on the 110
                > and/or the 132 will be superior to the M90, due to the doublet-
                > triplet idea proposed in this thread and by the dblt vs. trplt color
                > charts under the WO TMB 80mm triplet section of the website?
                > Thanks again!
                >
                >
                >
                >
                > --- In William-Optics@yahoogroups.com, "Timm Bottoni" <t.bottoni@>
                > wrote:
                > >
                > > Hi Kurt,
                > >
                > > It was a long time back - and luckily I put it in the FAQs too,
                but
                > > here it is for anyone who wants to try to understand these better.
                > >
                > > http://tech.groups.yahoo.com/group/William-Optics/message/7184
                > >
                > > Hope it helps make sense of the squiggly colorful lines!
                > >
                > > Timm
                > >
                > > --- In William-Optics@yahoogroups.com, Kurt Friedrich
                > > <kurt_friedrich@> wrote:
                > > >
                > > > IN what post did he help you understand the chart?
                > > >
                > > > Kurt
                > > >
                > > > --- Timm Bottoni <t.bottoni@> wrote:
                > > >
                > > > > Thanks to Scott for pointing this out, and for
                > > > > actually helping me to
                > > > > understand these! And hmmm, it is an interesting
                > > > > chart, isn't it?
                > > > >
                > > > > Timm
                > > > >
                > > > > --- In William-Optics@yahoogroups.com,
                > > > > "williamopticsmarketing"
                > > > > <williamopticsmarketing@> wrote:
                > > > > >
                > > > > > Scott, yeah you are the first one to have noticed
                > > > > them, but in fact
                > > > > > they were uploaded only 3 or 4 days ago! ;-)
                > > > > >
                > > > > >
                > > > > > --- In William-Optics@yahoogroups.com,
                > > > > "scottatwin" <sdwalker@>
                > > > > > wrote:
                > > > > > >
                > > > > > > I guest I have been a sleep. I just spotted the
                > > > > color correction
                > > > > > curve
                > > > > > > for the new WO 132mm scope.
                > > > > >
                > > > >
                > > > >
                > > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > >
                ______________________________________________________________________
                > > ______________
                > > > Do you Yahoo!?
                > > > Everyone is raving about the all-new Yahoo! Mail beta.
                > > > http://new.mail.yahoo.com
                > > >
                > >
                >
              • Scott Walker
                Scott here. I can see why you might think the 110 looks better, but I do not think it is. I think the broad base of the 132 response is what is bothering you.
                Message 7 of 11 , Dec 5, 2006
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                  Scott here.
                   
                  I can see why you might think the 110 looks better, but I do not think it is. I think the broad base of the 132 response is what is bothering you. It turns out that a wide width at the bottom of the chart is much less important than that at the top. This is for two reasons. The bottom represents the rays going through the center of the lens. At the center the ray are very shallow therefore a large misfocus causes very little blur. Also the area near the center of the lens is small. Half the area of a lens is outside the 71%of the radius. Therefore even if rays near the center are blurred, they do not account for much of the area of the lens. Another minor note in comparing the two responses is that the 110 chart does not show the 707nm line. This also makes it look narrower.
                   
                  As a "rule-of-thumb" one measures color correction at the 70 to 80 % of full aperture point. Since Roland of Astro-Physic, a very respected name in APO's, uses the 80 % point I will do the same here.  For the 132 all of the colors are within +/- .055mm of the green focus point. As a "figure-of merit" this is about .006% of the focal length. This is an excellent number. The focus point for 435nm for the 110 is about .15mm from the green focus point. This is about .02% of the focal length. Still a good number. The green point is used because the human will trend to focus where the green is the best. The 435nm curve for the 110mm is straighter so if one just focus for 435 it would produce a sharper image for 435nm than the 132mm, but this is not the normal case.
                   
                  For wavelengths around 546 and 555nm both scope have almost vertical lines which is good. This is where the eye is most sensitive for color vision.
                   
                  It is hard to compare scopes with different shape with certainty,but for the arguments given above I would expect the 132mm to be better corrected  than the 110mm. To truly determine the performance of the scope I would look at the modulation transfer function of each design at each color when focused at green, but this requires a lot of work. I feel very good about the curves given for the 132mm because they look very much like the curves given for Astro-Physics  triplets. It should also be noted that most users are very pleased with the performance of the WO 110mm. Based on the curves for the WO 132mm it should perform even better.
                   
                  It is great that WO provide the users with these curves. Few supplier do. But a word of caution. I believe the curve given are the nominal design curves for the scopes. They should be looked at as the "best-case" for the scope. The challenge for the scope maker is to ensure all his scope are close to the levels shown in the curves. The degree each manufacture meets this goal is very hard to judge. Though it is rare for a manufacturer to publish the normal curves, it is even rarer for him to tell you how far from "normal" a scope can be and still be shipped.
                   
                  Scott Walker
                   
                  ----- Original Message -----
                  Sent: Tuesday, December 05, 2006 9:54 AM
                  Subject: [William-Optics] Re: color correction curves for 132

                  Hi,

                  I'll ask Scott Walker to explain it, if he has time. While I think I
                  understand it, I don't think I am qualified to make a comparison or
                  draw any conclusions about one being better than the other.

                  Calling Scott Walker, ring, ring...

                  Thanks,

                  Timm

                  P.S. There are loads of sites on the web with pictures and charts if
                  you want to see learn more. Just search for words like "chromatic
                  aberration", or "refractor aberration". You can spend all day
                  finding and reading sites and see loads of pictures, but I will say
                  that there isn't much that I have found in the way of help reading
                  these CA design charts, that is any better than the way Scott has
                  explained it here for us. Thanks again, Scott!!!

                  --- In William-Optics@ yahoogroups. com, "jtpowers1972"
                  <jtpowers1972@ ...> wrote:
                  >
                  > Hi Timm,
                  >
                  > Thanks for the link, I found it helpful. I'm not sure I get it
                  > entirely though. Can you help me determine the relative color
                  > correction qualitites of the 132 graph vs. the 110 graph? It seems
                  > from my rookie viewpoint that the 110 might be better corrected than
                  > the 132??
                  >
                  > Thanks!
                  > John
                  >
                  > BTW, can it be assumed that the color correction etc., on the 110
                  > and/or the 132 will be superior to the M90, due to the doublet-
                  > triplet idea proposed in this thread and by the dblt vs. trplt color
                  > charts under the WO TMB 80mm triplet section of the website?
                  > Thanks again!
                  >
                  >
                  >
                  >
                  > --- In William-Optics@ yahoogroups. com, "Timm Bottoni" <t.bottoni@>
                  > wrote:
                  > >
                  > > Hi Kurt,
                  > >
                  > > It was a long time back - and luckily I put it in the FAQs too,
                  but
                  > > here it is for anyone who wants to try to understand these better.
                  > >
                  > > http://tech. groups.yahoo. com/group/ William-Optics/ message/7184
                  > >
                  > > Hope it helps make sense of the squiggly colorful lines!
                  > >
                  > > Timm
                  > >
                  > > --- In William-Optics@ yahoogroups. com, Kurt Friedrich
                  > > <kurt_friedrich@ > wrote:
                  > > >
                  > > > IN what post did he help you understand the chart?
                  > > >
                  > > > Kurt
                  > > >
                  > > > --- Timm Bottoni <t.bottoni@> wrote:
                  > > >
                  > > > > Thanks to Scott for pointing this out, and for
                  > > > > actually helping me to
                  > > > > understand these! And hmmm, it is an interesting
                  > > > > chart, isn't it?
                  > > > >
                  > > > > Timm
                  > > > >
                  > > > > --- In William-Optics@ yahoogroups. com,
                  > > > > "williamopticsmarke ting"
                  > > > > <williamopticsmarke ting@> wrote:
                  > > > > >
                  > > > > > Scott, yeah you are the first one to have noticed
                  > > > > them, but in fact
                  > > > > > they were uploaded only 3 or 4 days ago! ;-)
                  > > > > >
                  > > > > >
                  > > > > > --- In William-Optics@ yahoogroups. com,
                  > > > > "scottatwin" <sdwalker@>
                  > > > > > wrote:
                  > > > > > >
                  > > > > > > I guest I have been a sleep. I just spotted the
                  > > > > color correction
                  > > > > > curve
                  > > > > > > for the new WO 132mm scope.
                  > > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > >
                  > > >
                  > > >
                  > > >
                  > > >
                  > >
                  ____________ _________ _________ _________ _________ _________ _
                  > > ____________ __
                  > > > Do you Yahoo!?
                  > > > Everyone is raving about the all-new Yahoo! Mail beta.
                  > > > http://new.mail. yahoo.com
                  > > >
                  > >
                  >

                • danjanos@optonline.net
                  Gentlemen, please be very careful reading the curves as I do not think many people are truly qualified to to interpret, with no disrespect to anyone. The
                  Message 8 of 11 , Dec 7, 2006
                  • 0 Attachment
                    Re: [William-Optics] Re: color correction curves for 132 Gentlemen, please be very careful reading the curves as I do not think many people are truly qualified to to interpret, with no disrespect to anyone. The answer is how does everything look through the eye piece and how the instrument images.
                    Daniel Janosick


                    On 12/6/06 12:23 AM, "Scott Walker" <sdwalker@...> wrote:


                     
                     

                    Scott here.

                    I can see why you might think the 110 looks better, but I do not think it is. I think the broad base of the 132 response is what is bothering you. It turns out that a wide width at the bottom of the chart is much less important than that at the top. This is for two reasons. The bottom represents the rays going through the center of the lens. At the center the ray are very shallow therefore a large misfocus causes very little blur. Also the area near the center of the lens is small. Half the area of a lens is outside the 71%of the radius. Therefore even if rays near the center are blurred, they do not account for much of the area of the lens. Another minor note in comparing the two responses is that the 110 chart does not show the 707nm line. This also makes it look narrower.

                    As a "rule-of-thumb" one measures color correction at the 70 to 80 % of full aperture point. Since Roland of Astro-Physic, a very respected name in APO's, uses the 80 % point I will do the same here.  For the 132 all of the colors are within +/- .055mm of the green focus point. As a "figure-of merit" this is about .006% of the focal length. This is an excellent number. The focus point for 435nm for the 110 is about .15mm from the green focus point. This is about .02% of the focal length. Still a good number. The green point is used because the human will trend to focus where the green is the best. The 435nm curve for the 110mm is straighter so if one just focus for 435 it would produce a sharper image for 435nm than the 132mm, but this is not the normal case.

                    For wavelengths around 546 and 555nm both scope have almost vertical lines which is good. This is where the eye is most sensitive for color vision.

                    It is hard to compare scopes with different shape with certainty,but for the arguments given above I would expect the 132mm to be better corrected  than the 110mm. To truly determine the performance of the scope I would look at the modulation transfer function of each design at each color when focused at green, but this requires a lot of work. I feel very good about the curves given for the 132mm because they look very much like the curves given for Astro-Physics  triplets. It should also be noted that most users are very pleased with the performance of the WO 110mm. Based on the curves for the WO 132mm it should perform even better.

                    It is great that WO provide the users with these curves. Few supplier do. But a word of caution. I believe the curve given are the nominal design curves for the scopes. They should be looked at as the "best-case" for the scope. The challenge for the scope maker is to ensure all his scope are close to the levels shown in the curves. The degree each manufacture meets this goal is very hard to judge. Though it is rare for a manufacturer to publish the normal curves, it is even rarer for him to tell you how far from "normal" a scope can be and still be shipped.

                    Scott Walker


                    ----- Original Message -----
                     
                    From:  Timm  Bottoni <mailto:t.bottoni@...>  
                     
                    To: William-Optics@yahoogroups.com  
                     
                    Sent: Tuesday, December 05, 2006 9:54  AM
                     
                    Subject: [William-Optics] Re: color  correction curves for 132
                     

                     
                     

                    Hi,

                    I'll ask Scott Walker to explain it, if he has time. While I  think I
                    understand it, I don't think I am qualified to make a comparison  or
                    draw any conclusions about one being better than the  other.

                    Calling Scott Walker, ring,  ring...

                    Thanks,

                    Timm

                    P.S. There are loads of sites on the  web with pictures and charts if
                    you want to see learn more. Just search  for words like "chromatic
                    aberration", or "refractor aberration". You can  spend all day
                    finding and reading sites and see loads of pictures, but I  will say
                    that there isn't much that I have found in the way of help  reading
                    these CA design charts, that is any better than the way Scott has  
                    explained it here for us. Thanks again, Scott!!!

                    --- In William-Optics@yahoogroups.com <mailto:William-Optics%40yahoogroups.com> ,  "jtpowers1972"
                    <jtpowers1972@...> wrote:
                    >
                    > Hi  Timm,
                    >
                    > Thanks for the link, I found it helpful. I'm not sure  I get it
                    > entirely though. Can you help me determine the relative  color
                    > correction qualitites of the 132 graph vs. the 110 graph? It  seems
                    > from my rookie viewpoint that the 110 might be better corrected  than
                    > the 132??
                    >
                    > Thanks!
                    > John
                    >
                    >  BTW, can it be assumed that the color correction etc., on the 110
                    >  and/or the 132 will be superior to the M90, due to the doublet-
                    >  triplet idea proposed in this thread and by the dblt vs. trplt color
                    >  charts under the WO TMB 80mm triplet section of the website?
                    > Thanks  again!
                    >
                    >
                    >
                    >
                    > --- In William-Optics@yahoogroups.com <mailto:William-Optics%40yahoogroups.com> ,  "Timm Bottoni" <t.bottoni@>
                    > wrote:
                    > >
                    > > Hi  Kurt,
                    > >
                    > > It was a long time back - and luckily I put  it in the FAQs too,
                    but
                    > > here it is for anyone who wants to  try to understand these better.
                    > >
                    > > http://tech.groups.yahoo.com/group/William-Optics/message/7184
                    >  >
                    > > Hope it helps make sense of the squiggly colorful  lines!
                    > >
                    > > Timm
                    > >
                    > > --- In William-Optics@yahoogroups.com <mailto:William-Optics%40yahoogroups.com> ,  Kurt Friedrich
                    > > <kurt_friedrich@> wrote:
                    > >  >
                    > > > IN what post did he help you understand the  chart?
                    > > >
                    > > > Kurt
                    > > >
                    >  > > --- Timm Bottoni <t.bottoni@> wrote:
                    > > >  
                    > > > > Thanks to Scott for pointing this out, and for
                    >  > > > actually helping me to
                    > > > > understand  these! And hmmm, it is an interesting
                    > > > > chart, isn't  it?
                    > > > >
                    > > > > Timm
                    > > > >  
                    > > > > --- In William-Optics@yahoogroups.com <mailto:William-Optics%40yahoogroups.com> ,
                    >  > > > "williamopticsmarketing"
                    > > > >  <williamopticsmarketing@> wrote:
                    > > > >  >
                    > > > > > Scott, yeah you are the first one to have  noticed
                    > > > > them, but in fact
                    > > > > >  they were uploaded only 3 or 4 days ago! ;-)
                    > > > > >  
                    > > > > >
                    > > > > > --- In William-Optics@yahoogroups.com <mailto:William-Optics%40yahoogroups.com> ,
                    >  > > > "scottatwin" <sdwalker@>
                    > > > > >  wrote:
                    > > > > > >
                    > > > > > > I  guest I have been a sleep. I just spotted the
                    > > > > color  correction
                    > > > > > curve
                    > > > > >  > for the new WO 132mm scope.
                    > > > > >
                    > > >  >
                    > > > >
                    > > > >
                    > > >  
                    > > >
                    > > >
                    > > >
                    > > >  
                    > >  
                    __________________________________________________________
                    >  > ______________
                    > > > Do you Yahoo!?
                    > > >  Everyone is raving about the all-new Yahoo! Mail beta.
                    > > > http://new.mail.yahoo.com
                    >  > >
                    > >
                    >


                        


                    From the Desk of
                    Daniel Andrew Janosick
                    90 Rider Avenue
                    Patchogue, NY 11772
                  • doug92562
                    I think publishing these curves is courageous and a major advance for the hobby. I also think spot diagrams with the airy disk circle would be clearer for the
                    Message 9 of 11 , Dec 7, 2006
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                      I think publishing these curves is courageous and a major advance for
                      the hobby. I also think spot diagrams with the airy disk circle would
                      be clearer for the average person to interpret, as the density of the
                      various colored rays would correspond with what the eye actually sees
                      when looking at a star, and are especially impressive when compared
                      directly to a baseline achromat. These types of plots are easy to
                      display in Zemax at the same time as these color curves.
                    • Timm Bottoni
                      I couldn t agree more Doug, WO has posted a chart that shows spot diagrams of the FLT132 + Field Flattener here...
                      Message 10 of 11 , Dec 8, 2006
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                        I couldn't agree more Doug,

                        WO has posted a chart that shows spot diagrams of the FLT132 + Field
                        Flattener here...
                        http://www.williamoptics.com/prod_tel/FLT132/sp_spot.htm

                        FLT110 spot diagrams are here
                        http://www.williamoptics.com/prod_tel/FLT110silver/sp_spot.htm

                        I'm not sure they are "easier" to understand for the average person,
                        but I doubt the "average person" is buying a 110mm-132mm APO
                        refractor ;-)

                        As the price of the product goes down, I think these charts carry less
                        significance, and just overall value (price/performance ratio) becomes
                        more of a driving factor.

                        I encourage everyone to speak with your hard earned money, and when
                        buying products, like an APO refractor, decide for yourself if you need
                        to know things like glass type, spot diagrams, or CA charts. Decide
                        for yourselves what matters, and if a manufacturer says those things
                        don't matter, then ask them why, and if they matter to you, then don't
                        buy from them.

                        Every telescope has a detailed optical desgin to it, and has these
                        types of charts as part of that design, and has details about the
                        manufacturing specifications that go way beyond Aperture, Focal Length,
                        Focal Ratio, Weight, etc. Many of the details are kept secret because
                        they don't want you, or their competitors, to know too much about their
                        design. Why? Because we, as consumers let them get away with it, and
                        didn't demand more information.

                        It's the information age, and as consumers wise up to the things
                        manufacturers try to hide things from them, it will tell in the end
                        whether the approach WO is taking to marketing (opening up the Kimono,
                        so to speak) is the one educated consumers will prefer or not.

                        Timm

                        --- In William-Optics@yahoogroups.com, "doug92562" <dougspeterson@...>
                        wrote:
                        >
                        > I think publishing these curves is courageous and a major advance for
                        > the hobby. I also think spot diagrams with the airy disk circle would
                        > be clearer for the average person to interpret, as the density of the
                        > various colored rays would correspond with what the eye actually sees
                        > when looking at a star, and are especially impressive when compared
                        > directly to a baseline achromat. These types of plots are easy to
                        > display in Zemax at the same time as these color curves.
                        >
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