Need Hi-quality 3X teleconverter for Pentax Spotmatic

Discussion in 'Pentax' started by Sorry-NoEmailNow, May 20, 2004.

  1. Thursday May 20, 2004


    I'm looking for a high quality 3X teleconverter for my Pentax Spotmatic
    SP F camera (49mm screw mount). In my case, high quality includes a
    fast teleconverter (i.e. lose less than 3 f-stops) and it should have
    good optics to reduce flare/glare, etc.

    I have seen quite a few different 3X teleconverters for the screw mount
    cameras on ebay, but I don't know how to judge their quality without
    actually purchasing them.

    Any information or suggestions would be appreciated.

    Thanks in advance,

    Sorry-NoEmailNow, May 20, 2004
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  2. On Thu, 20 May 2004 14:58:23 -0500,
    Any 3x teleconverter will cost you more than 3 f-stops. Sorry, that's
    just the way the math works out.
    Michael Benveniste, May 20, 2004
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  3. Sorry-NoEmailNow

    Tony Spadaro Guest

    Any behind the lens 3x teleconverter will lose three stops of light -- this
    is physics. Any teleconverter in front of the lens will give you a lousy
    picture. The only 3x converter I know of that has been around since the days
    of the Pentax screw mount is a POS and will do about as bad as an in front
    of the lens TC. Look for a used telephoto lens - even one of those Korean
    500 mm baseball bats will give you a better picture - they run about 100
    dollars brand new and I've bought them for under 30 used.
    Tony Spadaro, May 20, 2004
  4. Hi,

    I'm sorry. Did I forget to mention that I'm a real novice? I guess I didn't
    need to -- my ignorance is obvious.

    What is probably also obvious is that I'm not taking pictures for the National
    Geographic magazine. I have gotten some results that were acceptable to me when
    combining both a 2X and a 3X teleconverter with a Takumar SMC 200mm lens. Under
    fairly good daylight conditions, I've been able to get some long distance shots
    of big horn sheep when I could barely find them with my naked eye.

    Recently, I've noticed (under some different lighting conditions) that the
    Cambron 3X teleconverter that I'm using is introducing a purplish artifact and
    some ghosting. It seems to me that this kind of poor optics is avoidable. I
    was hoping to also improve upon the speed of the teleconverter lens but,
    according to what I'm reading, that is apparently unavoidable.

    By the way, I'm currently not willing to haul another big lens around while
    hiking. I could fit a longer lens into my budget, but I'm really trying to keep
    my pack weight down.

    Any suggestions on a 3X teleconverter with good optics that will fit a 49mm
    screw mount camera?

    Thanks for the information.

    Sorry-NoEmailNow, May 20, 2004
  5. Sorry-NoEmailNow

    Nick Zentena Guest

    First of all it's 42mm. Or Pentax mount. Or unversal mount. If you call it
    49mm people will assume you mean a filter for the front of the lens.

    If you already have a 3x I'm not sure it's worth looking for a new one.
    The new one you find likely will still not be that great. It's even worse if
    you're combining it with a 2x. If you really have to get one just look for
    something from the companies with good reps during the late 60s early to mid
    70's. I have a vivitar 3x that's fine if you understand 3x just aren't going
    to give you great optics. For the $10 I paid it fills the very very rare
    need I have for it. OTOH if I needed it I would have put the $10 towards a
    longer faster lens instead.

    Nick Zentena, May 20, 2004
  6. Sorry-NoEmailNow

    ChrisPlatt Guest

    In over a year watching eBay, I never came across a single
    high-quality (7-element, multicoated) 2x teleconverter in ES mount.

    Good luck finding a good 3x model!

    Excelsior, you fatheads!
    ChrisPlatt, May 21, 2004
  7. Sorry-NoEmailNow

    Peter Chant Guest

    Edison screw?
    Peter Chant, May 21, 2004
  8. Sorry-NoEmailNow

    Mike Guest

    And here I thought Edison was only into telephones, light bulbs and
    Mike, May 21, 2004
  9. Sorry-NoEmailNow

    Peter Chant Guest

    Of course there is alway the debate over whether the lightbulb was
    his or Swans. They must have got together at some point, or
    rather their respective companies as I have seen some transitors in some
    old kit marked 'Eddiswan'.
    Peter Chant, May 21, 2004
  10. Sorry-NoEmailNow

    ChrisPlatt Guest

    Levity aside, to clarify:
    The Pentax ES, ESII and Spotmatic F models
    can meter at full aperture, but only with SMC Takumar lenses.

    The Pentax M42 screw mount with the additional couplings
    is commonly referred to as "Pentax ES mount".

    Excelsior, you fatheads!
    ChrisPlatt, May 22, 2004
  11. Sorry-NoEmailNow

    Mike Guest

    We know, just couldn't pass up the opportunity.... :)
    Mike, May 22, 2004
  12. Sorry-NoEmailNow

    Peter Chant Guest

    It's a pity that they did not come up with a standard for
    the couplings. I can't seem to see many lenses around that would
    fit my uncles Fujica.
    Peter Chant, May 22, 2004
  13. No such thing exists or ever did.
    Michael Scarpitti, May 22, 2004
  14. Sorry-NoEmailNow

    brian Guest

    Even an optically perfect 3x converter would reveal artifacts because
    it is magnifying defects in the prime lens. The artifacts you mention
    sound like axial chromatic aberration and coma, respectively. Both of
    these will improve by stopping down, which may explain why you were
    getting reasonable results in better light. 3x converters are rare,
    but you can always combine a 2x and a 1.4x in a pinch.

    brian, May 23, 2004
  15. Hi Brian,

    Thank you for the thoughtful response. Even though it is bad news for me, I guess I needed to hear it.. (I
    don't hold the bearer of bad news responsible.)

    Thanks again.

    Sorry-No_Email_, May 24, 2004
  16. 42mm, actually...

    Stephen H. Westin, May 25, 2004
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