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Thread: TMB 100mm F/8

  1. #21
    Chuck's Avatar
    Chuck Guest

    Default TMB 100mm F/8



    Off topic, but I have bought two AP SPL eyepieces, they are exquisite,
    hats off to you and Astro-Physics Valery...

    "ValeryD" <aries@mercury.kherson.ua> wrote in message
    news:5c4a4ee7.0411241634.245efdd1@posting.google.c om...
    news:<58ee67ec.0411241127.67981bcf@posting.google. com>...
    owner)
    F/7
    this
    however,
    0.025.
    products



  2. #22
    Tom Davis's Avatar
    Tom Davis Guest

    Default TMB 100mm F/8


    "Ted Kord" <tedkord@excite.com> wrote in message
    news:7c0be594.0411250532.346536c@posting.google.co m...

    Ted,

    Exactly my point. Sol Robbins has a fine setup with the Chromacor II
    and a good CR150 to use it with. My point was that the Chromacor is
    only as good, or bad as the intrument it is used in, and also that it has
    maintenance issues related to the use of it that make a high quality APO
    preferable to it, price independant. Also, while I found the improvement
    in color correction to be significant, I did not near the level of
    correction
    found in a TMB 100/800 when using it in a 120mm F/8.3 Konus with
    ideal spacing. Also, I tried to make clear that even with the spherical
    correction feature, other optical issues inherent in the general run of
    Chinese achromats prevents the theoretical capabilities of the device
    from being attained in most real-world use situations. It was not intended
    to belittle what Valery accomplished here, but rather to show that a
    scope designed as a complete package would be preferable, price
    independent. I believe Valery has discussed developing such a complete
    package, and at that point such a comparison could be made, and the
    results would be valid.

    Thanks, Tom Davis



  3. #23
    ValeryD's Avatar
    ValeryD Guest

    Default TMB 100mm F/8

    Mileva Maric <abandoned@women.com> wrote in message news:<41A595E7.2CC6724F@women.com>...

    Can you read? If yes, please:

    "
    <snip>
    In fact, the TMB 100mm/800mm SD triplet is the best
    corrected lens on the market now, from any company.
    <snip>
    Thomas M. Back
    "

  4. #24
    ValeryD's Avatar
    ValeryD Guest

    Default TMB 100mm F/8

    "Markus Ludes" <apm_telescopes@web.de> wrote in message news:<a4553dfa1bc2cee07d7c9a53ce32e28e.30545@mygat e.mailgate.org>...

    Yes. No questions at all. But give us a credit too! We can measure
    glasses constants with 2x10-6 precision and in some cases, when this
    really needed with 1x10-6 precision, so we can warranty, that Chromacors,
    if properly installed work exactly as designed and if any deviation from
    designed parameters, this has nothing to do with Chromacors, but with
    objectives parameters deviations.

    VD

  5. #25
    Ed T's Avatar
    Ed T Guest

    Default TMB 100mm F/8


    "Chuck" <cscappaticci@adelphia.net> wrote in message
    news:aOudnYmmg5j9ZjjcRVn-tg@adelphia.com...

    Yes, they are superb. I need my four millimeter. Valery?

    Ed T.



  6. #26
    TMBoptical's Avatar
    TMBoptical Guest

    Default TMB 100mm F/8

    >> > So, you'd better advise Tom Back be more modest and not claim, that

    Of any current apochromatic telescope that is currently
    on the market (not a telescope with any type of add
    on color correcting device (which I only say because
    I cannot know how well corrected such a telescope
    will be), the TMB 100mm f/8 is the best optically
    corrected lens on the market, in the meaning of the
    best color correction, and lowest wide band RMS
    values. We are talking absolute performance, not
    a rare lens that has a peak wavefront from hand
    figuring that is super high. That is a different thing
    altogether, and in the case of the TMB 100mm
    f/8, we have reached Strehl ratios of .995 to .997
    in the green, as tested by interferometry, which
    is pushing the limits set by the glass itself.

    If it is not, please, anyone out there, Roland, Valery,
    Markus, whomever, tell me a lens that is better
    corrected (remember, it has to be a lens that is
    available from stock, not some custom one-off lens),
    and I will stand corrected.

    Thomas Back

  7. #27
    ValeryD's Avatar
    ValeryD Guest

    Default TMB 100mm F/8

    "Ed T" <reply@thegroup.thx> wrote in message news:<Chtpd.712$Z%5.357@newsread2.news.atl.earthli nk.net>...

    They are the most difficult to make. Their lense like a rise particle -
    very difficult to handle and work with. Their surfaces are steeep - can
    be made one by one only.
    We made a serie of first design and were need to redesign and make
    them again. They will be available last from all the SPL because we
    were need to start them when other were in progress.

    f3.3 will be available even later and will be more expensive.


    VD

  8. #28
    ValeryD's Avatar
    ValeryD Guest

    Default TMB 100mm F/8

    "Tom Davis" <tdavis11@carolina.rr.com> wrote in message news:<vThpd.132$8S5.128867@twister.southeast.rr.co m>...

    Tom,

    I agree with ALL what you said here. But I need to underline again -
    this
    was not a sense of my initial post. I just wrote, that 100mm F/10
    classical
    achromat ( with C-F correction) being used with Chromacor-II and
    properly
    installed (SA match does not really needed for this) will deliever a
    color correction, which can't be matched by ANY traditional (with
    small
    air spacing) triplets - be they SD from TMB or SuperED or even
    fluorite.
    The main reason - such design (Chr-II + achromat) has no
    spherochromatism
    and color correction is about 60x better vs traditional achromat.
    This design 4 crossings. But the graph of focus variation for
    different wave lenghths looks almost flat unlike to traditional apos.
    Diameters of spot circles for each wave length are well within Airy
    disk
    (for each wave length diameter of Airy disk is different).

    I can't argue with the statement, that APO with triplet objectives
    have
    fewer (if any) problems for proper collimation vs achromat+Chromacor,
    but customers, who were able to make Chromacor work as advertised, are
    satisfied too - they have apo performance for MUCH less money! Many of
    them just have no money to buy a true APO.


    I hope, that now you do understand what did I meant speaking about
    color correction.

    VD

  9. #29
    ValeryD's Avatar
    ValeryD Guest

    Default TMB 100mm F/8

    chris.b@mail.dk (Chris.B) wrote in message news:<941cd3a9.0411250411.56b09f37@posting.google. com>...


    Chris,

    Chromacor does the following:

    1. Corrects secondary spectrum of achromat.
    2. Corrects spherochromatism (spherical aberration dependance of wave
    length)
    3. If necessary, spherical aberration of 3-rd order.

    No another aberration can be corrected, include surface errors (zones,
    turned edge and roughness).

    I can't comment about all objectives, but five ones I do own, have very
    good smoothness, while spherical aberration is vary from about 1/3 wave
    to 1/8 wave.

    As for spherical correction. It can be even nullyfied down to zero.



    Valery Deryuzhin

  10. #30
    max's Avatar
    max Guest

    Default TMB 100mm F/8

    aries@mercury.kherson.ua (ValeryD) wrote in message news:<5c4a4ee7.0411240231.2ffb253@posting.google.c om>...

    I hate to post on such a thread. However, I beleive there are some out
    there who want to jump into the hobby with their first scope and they
    deserve better.

    A long story short: My first turn off from astronomy was a department
    store scope. Among many other problems, when I finally pointed at
    something any movement whatsoever would make me lose it.

    Then the ETX. Heck, just assemble turn switch on and tell the coputer
    what you want to see. I spent so much money on software and gadgets
    that if posted, it would fall in the incredible.

    Finally, I did some homework, learnt a little about scope design,
    aperture/performance, learnt my way around the sky and threw away all
    the worthless gadgets. I now love my ETX for what it is, no more no
    less.

    I later upgraded to larger apertures and several premium refractors.
    They are what they are. Each of my scopes serves a purpose and it
    serves it well as it is.

    I can not think of anything worse to turn an amateur astronomer from
    astronomy than an expensive gadget to tweek a cheap scope that in
    itself needs tweeking. Moreover, these favulous claims of its
    performance are beyond my comprehension. What I understand from this
    thread is that if you buy this wonder product and put it on a cheap
    refractor it will perform better than a TMB 100/8. Hey, if it does
    not, the user must be an idiot for not beeing able to set the gadget
    up properly. What a major put down.

    I have a TMB 100/8. I care not for the lambdas, strhls, wavefronts,
    spotdiagrams.... I do however care that at least visually, it has cero
    false color in or out of focus (for whatever purpose you would want to
    test this out of focus). You can equal that but I know not how you can
    better it.

    My CCD show textbook color patterns. But even this does not mean
    anything to me as an observer. With so much image processing what are
    true colors? This reminds me of an article some time ago about the
    Universe's TRUE color, it turns out they made a mistake. OOPS.

    My experience for what it is worth is that you get what you pay for. A
    cheap Chineese/Japanese/French/.... refractor is precisely that a
    cheap Chineese/Japanese/French/.... refractor. A premium refractor is
    a premium refractor. I would recommend anyone to know what it is they
    are buying before buying so as not to get false hopes. Regarding this
    thread, I would recommend anyone thinking on buying a cheap refractor
    to evaluate other optical designs enstead. In my personal opinion,
    cheap refractors only serve to sway interested amateur wannabes away
    from the hobby.

    MAX

 

 
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