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Re: [tmboptical] Re: monocentrics used in british teleport first light

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  • W. Gondella
    ... From: tmboptical To: Sent: Saturday, August 02, 2003 2:21 PM Subject: [tmboptical] Re: monocentrics
    Message 1 of 16 , Aug 2, 2003
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      ----- Original Message -----
      From: "tmboptical" <TMBoptical@...>
      To: <tmboptical@yahoogroups.com>
      Sent: Saturday, August 02, 2003 2:21 PM
      Subject: [tmboptical] Re: monocentrics used in british teleport first light


      > Hi Everyone,
      >
      > I finished testing all of the first run of TMB Super Monocentrics
      > last night. It was about as intensive as anything I've done, with
      > such a short deadline. Now, invoicing and packaging is all that
      > needs to be done.

      WG: Can we get you a cigarette, a cup of coffee, a bottle of guarana and ginseng, a cold
      shower and massage? :)

      > All the eyepieces will be shipped at the same
      > time, in a mass shipment from the USPS. They are going to bring
      > a big truck, to pick them all up. They will go out on Monday, or
      > Tuesday at the very latest, and everyone should have them by
      > Thursday, or Friday. Thanks for all your orders, and patience.

      WG: No, all thanks to you Tom for your tireless efforts these past days!

      > About the 4mm. I thought the same thing as Graham felt, when I
      > tested the first 4mm vs. the 8mm with the Zeiss ED Barlow. The
      > more I studied the 4mm, the more disappointed I was. To tell the
      > truth, I was really worried. I ran down to the bench test, and
      > the eyepiece was showing lateral color and poor definition.
      > This didn't make any sense, as I know my design, and this was
      > not possible. I took a second sample, and guess what? Fantastic
      > performance! Was I relieved. At that point, I knew that I had
      > a huge job in from of me, to test every single eyepiece, and
      > closely. My name is on these eyepieces, and I was not going
      > to ship out defective eyepieces if I could help it. It turned
      > out that 13 4mm TMB Super Monocentrics were defective, a
      > disappointing number, but not a problem for anyone on the
      > first run. There were 6 other optically defective eyepieces
      > in the 5mm to 10mm focal lengths.

      WG: Could it be that there is a centering or seating issue with the tiny lenses getting
      them squared in the housing? After all, these are very small lenses.

      > After I re-tested a standard quality TMB 4mm vs. the TMB 8mm
      > and 2x Zeiss Barlow, the 4mm was superior. There really isn't
      > anything better than the least amount of glass in the light
      > path, as long as the optical quality is very high, in the
      > eyepiece (the possible exception would be in very fast systems
      > at f/4, or under, where a Barlow would stress the eyepiece
      > less with its steep light cone at f/4, turned into f/8). And
      > yes, we are working on a matching TMB 1.8x Barlow.

      WG: I trust the barlow will be compatible with other / regular eyepieces, as well? Also,
      when you get some time after shipping them all Tom, it would be interesting to hear
      exactly what steps were included in your testing of the eyepieces, if possible.

      > About Binoviewers and short focal length eyepieces. As long as
      > you have a high quality unit, I have found that I can see more
      > using short focal length eyepieces, without a Barlow in the
      > front of the binoviewer, as the contrast is higher. I know other
      > people have different opinions, and it may be that they do see
      > more using a barlow with longer focal length eyepieces (there
      > are so many variables, that the best advise is to try every
      > combination, and you decide what gives you the best image),
      > but again, I have seen the finest planetary images with the
      > minimum amount of glass in front of the binoviewer.

      WG: I like the fact that you allow this issue to have more than one side, Tom. While
      stating your own opinion and experiences, you leave open the possibility that other
      people's milage may vary! Much more plausible than the tiresome "one-size-fits-all"
      attitude of some.

      >
      > Thomas Back


      WayneG
    • Nick
      I was observing with Graham & Co. - tried all the Mono s with the Powermate except the 4mm, and the 6, 8 & 10 were incredible, no colour, very sharp contrasty
      Message 2 of 16 , Aug 3, 2003
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        I was observing with Graham & Co. - tried all the Mono's with the Powermate except the 4mm, and the 6, 8 & 10 were incredible, no colour, very sharp contrasty ect.

        In my humble opinion (bear in mind I am not very experienced):

        1) I could not tell the difference between the 8mm with Powermate & the 4mm Mono by itself in terms of image clarity, but I did look for longer through the 8mm & 6mm Mono's with Powermate - and I know my brain would have recorded more, subjective, etc... But I was aware of this.
        2) The 4mm Mono & the 8mm with Powermate clearly outperformed the 4mm Radian on both scopes. I could see that little intrusion into the polar cap on Mars with Mon's but not with the Radian.
        3) The 6mm Mono with Powermate gave the clearest views of Mars I saw with a single eyepiece that night at 216x.
        4) The 4mm Mono is nearly useless to me, as I wear glasses - just my luck! The views I did get were great though.
        5) The 8mm Mono & possibly the 6mm Mono were the only one's I would buy, because of my particular need for eye-relief.

        I certainly preferred the view with Powermates for the above reasons - but I have this eyeglassess limitation if you see what I mean... Which also may cause different behavious with different eyepiece-designs come to think of it, it's another lens after all.

        Regards,
        Nick


        ltmby2 <ltmby2@...> wrote:
        Graham,

        Thanks for the report, enjoyed reading our comments.

        Do I understand you correctly that, in your TMB 105, you preferred the
        view with the TMB SM 8mm stacked with TV 2x Powermate over the view
        with just the TMB SM 4 mm - and it was not a function of eyerelief?

        Can you elaborate - which target(s); what was there about the view
        that was either more or less pleasing; and you were not using a
        binoviewer, correct?

        Looking forward to more reports from you.

        Regards,
        Clevis Jones
        TMB 115


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      • Richard Chalfan
        Wayne et. al., ... I have not previously wanted to use the bandwidth, because you and a few others have said thanks as well as I can. But since I am
        Message 3 of 16 , Aug 3, 2003
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          Wayne et. al.,

          --- "W. Gondella" <gondella@...> wrote:

          > WG: No, all thanks to you Tom for your tireless
          > efforts these past days!

          I have not previously wanted to use the bandwidth,
          because you and a few others have said thanks as well
          as I can. But since I am commenting on something else
          in this post, I will add my greatful kudo's.

          It is one thing to design an eyepiece. Quite another
          to do it well with real, available, stable and
          workable glass. And perhaps the most difficult thing
          of all is getting it to market. Tom has shown a rare
          combination of design skill and the motivation and
          ability to work (and stay with!) the myriad
          complexities of production. Clearly Markus plays a
          crucial part here too, and thanks as well to him.

          > WG: I trust the barlow will be compatible with
          > other / regular eyepieces, as well?

          Wellllll. I don't necessarily vote for this, though I
          think we will get it.

          If there is ANY way that Tom could use the Barlow to
          compensate for ANY residual aberration in the eyepiece
          I would like him to do so. Even if it made the Barlow
          slightly less of a match for other eyepieces. After
          all, I believe this Monocentric effort is to get the
          best product manufacturable.

          In practice however, I believe the Monocentrics are
          probably so highly corrected that there will be no
          reason for Tom to go away from a generally usable
          design.

          To digress a moment, I would mention a bit about
          camera lens design. Early lenses took a group,
          corrected it, and then added another group that was
          corrected too. So a lens like the 1840's Petzval lens
          (the first really "high speed" lens) used a Fraunhofer
          telescope objective lens for one group and a Steinheil
          telescope objective lens for the other. They were
          each corrected alone, but worked well together too.
          (Other renown lenses like the Dagor and Protar worked
          similarly).

          However, one of the greatest milestone in camera lens
          design was the Cooke Triplet (and the improvement, the
          famous Tessar by Rudolph of Zeiss) that did NOT
          correct each group separately. The novel idea was
          that you might get better overall performance if you
          corrected the system, but did not try to also correct
          each lens group. The concept worked SPACTACULARLY.
          It set a new course in lens design that is the parent
          of all the high quality lenses we use now.

          I have always wondered if the same approach could be
          used with a telescope. Instead of designing each
          group (Objective, Barlow, eyepiece) to be separately
          corrected, could you achieve a performance gain by
          optimizing the system, perhaps making any single item
          unuseable as a general purpose instrument. (The goal
          here wouldn't be on axis performance because it is
          diffraction limited now, but off axis improvement.
          Could you get rectillinearly correct and diffraction
          limited views at the edge of an 82 degree eyepeice,
          for example?)

          This wouldn't appeal to the mass market, as you
          couldn't "swap eyepieces" with anyone else. But it
          might sell in today's specialty market where people
          spend huge sums on telescope and camera gear.

          Maybe Tom could comment AFTER he has recovered from
          the current effort and has some time on his hands.


          Richard

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        • Hosea, Mike
          Well, there is some residual field curvature--a Barlow could easily fix that up, and depending on potential vignetting and how the eyepiece design otherwise
          Message 4 of 16 , Aug 3, 2003
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            Well, there is some residual field curvature--a Barlow could easily fix that
            up, and depending on potential vignetting and how the eyepiece design
            otherwise handles divergence, there is also an opportunity to increase eye
            relief.

            I enjoyed a pretty good night here in Dallas with my 10" Teleport last
            night, except that I'm hobbling around on crutches due to my first case of
            achilles tendonitis--thanks very much to a stair-mill machine and a workout
            I wish I'd missed. What as sight I must have been hobbling to my backyard
            with one crutch taking out my Osypowski platform, then the Teleport, then my
            observing chair, then my eyepieces. Don't try this with a 7" APO! <jab>
            <jab> :-)

            Although I do need to peruse the floor of the crater Plato and the rima in
            Vallis Alpes under good seeing and suitable lighting conditions first, I'm
            about ready to concede that the 6mm TMB Super Mono is the best planetary
            eyepiece I've ever used.

            After singing the 6mm TMB Super Mono's praises, I will say, on the other
            hand, that I've gained a greater respect for my 5mm Type 6 Nagler in the
            comparison process, although I must add the disclaimer that I've learned to
            forgive external reflections, and there's a need for that in my case with
            the 5mm Nagler Type 6 and no need for it with the 6mm TMB Super Mono.
            --
            Mike

            > -----Original Message-----
            > From: Richard Chalfan [mailto:rchalfan@...]
            > Sent: Sunday, August 03, 2003 8:07 AM
            > To: tmboptical@yahoogroups.com
            > Subject: Re: [tmboptical] Re: monocentrics used in british teleport
            > first light
            [...]
            > > WG: I trust the barlow will be compatible with
            > > other / regular eyepieces, as well?
            >
            > Wellllll. I don't necessarily vote for this, though I
            > think we will get it.
            >
            > If there is ANY way that Tom could use the Barlow to
            > compensate for ANY residual aberration in the eyepiece
            > I would like him to do so. Even if it made the Barlow
            > slightly less of a match for other eyepieces. After
            > all, I believe this Monocentric effort is to get the
            > best product manufacturable.
            >
            > In practice however, I believe the Monocentrics are
            > probably so highly corrected that there will be no
            > reason for Tom to go away from a generally usable
            > design.
            [...]
          • tmboptical
            ... Hi Mike, Yes, I have. Tim Povlick send his to me for testing, and I found it worked superbly with the Baader binoviewer. It is hard to compare the Barcon
            Message 5 of 16 , Aug 3, 2003
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              --- In tmboptical@yahoogroups.com, "Mike C" <mike@e...> wrote:
              >
              > > I do recommend the Astro-Physics Barcon barlow, if you need
              > > super high powers, with the Baader binoviewer. And I'm happy
              > > to say that there are now other binoviewers on the market that
              > > are made as well, or nearly so, as the Baader unit.
              > >
              > > Thomas Back
              >
              >
              > Thomas, have you tried the Baader FFC with your bino? My best
              > views, ever, of Saturn and Jupiter were a Baader Bino, FFC, and
              > my TMB100/8. I'm not sure if I had the 1.7x corrector installed as
              > well.
              >
              > I sold my baader gear to raise funds for my TMB152, I was a little
              > sticker shocked at the new price for the click-lock baader bino
              > but I went for it anyway. It should arrive a couple days before the
              > pair of TMB 10mm mono!! I'd like to evaluate it against a Denk II
              > some day and keep my favorite bino. Or given all else equal, keep
              > the least expensive.
              >
              > Mike Clemens

              Hi Mike,

              Yes, I have. Tim Povlick send his to me for testing, and I found
              it worked superbly with the Baader binoviewer. It is hard to
              compare the Barcon vs. the FFC, due to the magnification factors,
              but I felt the FFC was every bit as good as the Barcon, maybe a
              touch better, at very high magnifications.

              Maybe Tim could jump in and give his opinion too.

              Thomas Back
            • leonard_bel
              The 4mm Mono is nearly useless to me, as I wear glasses - just my luck! Hello Nick , Nick I sympathize completely with your feelings about glasses , however
              Message 6 of 16 , Aug 3, 2003
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                The 4mm Mono is nearly useless to me, as I wear glasses - just my
                luck!

                Hello Nick ,

                Nick I sympathize completely with your feelings about
                glasses , however there is hope.

                > I certainly preferred the view with Powermates for the above
                reasons - but I have this eyeglassess limitation if you see what I
                mean... Which also may cause different behavious with different
                eyepiece-designs come to think of it, it's another lens after all.
                >
                > Regards,
                > Nick

                Nick try this , If you can use the 5mm eyepiece with your
                glasses on , look at the detail in the image and study it closely.Now
                take the glasses off and study the image ,is it the same ? With the
                exit pupil down to say .95 or lower you may not need glasses to see
                all the detail in the image. When I look at the moon with my glasses
                off I see three of them in a row. This is classic astigmatism. I have
                no idea what your problem is but this is a start.
                Now , If you still cannot see a clear image do this :
                Go wherever you get your glasses and tell them you want to purchase
                one lens ( the optical prescription for your viewing eye) and have it
                ground down to say 40mm in diameter or what ever you feel is proper
                size. Mine is 42mm is diameter and its used for my Pentax XL'S. With
                my glasses on I can see about 85% of the field of view even with 20mm
                eye relief, with the lens held up to the eyepiece I see it all at one
                time. It works fine and cost about 20.00 $ . The frame of your
                glasses is what keeps your eye so far from the eyepiece field lens
                and is a pain in the butt. If this does not work for your problem ,
                you may want to check out Thomas new barlow when it comes out.
                Best of luck and clear skys for Mars Leonard
              • tmboptical
                ... Hi Richard, I see there are a lot of posts that I would like to answer but I don t have the time, right now. Like you said, after I finish working,
                Message 7 of 16 , Aug 3, 2003
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                  --- In tmboptical@yahoogroups.com, Richard Chalfan <rchalfan@y...>
                  wrote:

                  >Maybe Tom could comment AFTER he has recovered from
                  >the current effort and has some time on his hands.

                  Hi Richard,

                  I see there are a lot of posts that I would like to answer
                  but I don't have the time, right now. Like you said, after
                  I finish working, shipping, and recovering from my current
                  efforts, I will be happy to answer everyone. I will have
                  some interesting things to say about the whole Monocentric
                  project -- from its beginnings in the year 2000, to all the
                  extra work that was not expected.

                  Thanks for great posts from everyone.

                  Thomas Back
                • samwisethefool
                  ... Instead of designing each ... The first Questars were totally designed as a system. The components didn t work with other scopes. The move to Brandons
                  Message 8 of 16 , Aug 3, 2003
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                    --- In tmboptical@yahoogroups.com, Richard Chalfan <rchalfan@y...>
                    Instead of designing each
                    > group (Objective, Barlow, eyepiece) to be separately
                    > corrected, could you achieve a performance gain by
                    > optimizing the system, perhaps making any single item
                    > unuseable as a general purpose instrument.

                    The first Questars were totally designed as a system. The components
                    didn't work with other scopes. The move to Brandons certainly
                    compromised the system to some degree, but, especially with the
                    finder, most other eyepieces don't get there. Kinda fits your
                    thoughts. I normally don't use other eyepieces with my Questar. The
                    Brandons do work so very well.

                    Stew
                  • Tube Tim
                    ... Man that s a tough call. The 1.7x does the job well. The FFC also performs well. My best views so far are with the FFC and Zeiss 25mm ... replaced with
                    Message 9 of 16 , Aug 3, 2003
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                      --- In tmboptical@yahoogroups.com, "tmboptical" <TMBoptical@a...
                      > wrote:
                      > >
                      >
                      > Hi Mike,
                      >
                      > Yes, I have. Tim Povlick send his to me for testing, and I found
                      > it worked superbly with the Baader binoviewer. It is hard to
                      > compare the Barcon vs. the FFC, due to the magnification factors,
                      > but I felt the FFC was every bit as good as the Barcon, maybe a
                      > touch better, at very high magnifications.
                      >
                      > Maybe Tim could jump in and give his opinion too.

                      Man that's a tough call. The 1.7x does the job well. The FFC also
                      performs well. My best views so far are with the FFC and Zeiss 25mm
                      | 16mm eyepeices. It's looking like this distinction will be
                      replaced with the 1.7x and the monos. Once the gas giants arrive I'll
                      have the benchmark. The FFC with the 16mm monos is going to make in
                      interesting combination.


                      The FFC is more versatile in that I can use it with my 6x7 camera for
                      moon shots, etc. One can also use it as a regular barlow, with
                      attachments. the downside is the price delta.

                      ___
                      Tim


                      >
                      > Thomas Back
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