Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,054   Posts: 1,561,326   Online: 1203
      
Results 1 to 8 of 8
  1. #1
    Markster's Avatar
    Join Date
    Dec 2010
    Location
    Denver area
    Shooter
    35mm
    Posts
    307

    Teleconverter questions... (Canon FD specific)

    So I've just read some things about these 1.4x and 2x teleconverters. Basically magnifying glasses for your lenses.

    I'm interested in learning a bit more about them. I have read some comments about getting what you pay for, just like lenses. Some are worse than others, etc.

    With the Canon FD mount, how does this work with the aperature? Do you have to fix the aperature ring in the lens proper, or does the camera body still control the lens aperature through the teleconverter somehow?

    With a teleconverter I have read about the loss of light. Is this automatically accounted for in the camera's light meter? Say I have a 200mm zoom with a minimum f/5.6 stop mounted on a 2x teleconverter that takes up 2 stops of light. Okay, so minimally speaking you would have to operate that lense at f/11, right? Does the light meter in a camera take this into account, or are they too dumb/simple to do that? They might say "needs f/5.6" still, and you have to mentally adjust the shutter to reach f/11, right?

    Granted this will vary with the quality of the teleconverter, but are you sacrificing something specific, like sharpness or contrast?

    Also I'm not finding much luck to confirm you retain full infinity focus on teleconverters (not to be confused with extender tubes which lose that focus). One or two blurbs state you should, but other comments say they don't. Can anybody confirm this? Is it only for macro work, or close in work? That is, you can't use it to zoom in on a mountain peak or on a picture of your downtown area from afar?
    -Markster

    Canon AE-1P 35mm | 50mm/f1.8 FDn | 28mm/2.8 FD | 70-200mm/f4-5 FD | 35-70mm/F2.8-3.5 Sigma FD

  2. #2
    MattKing's Avatar
    Join Date
    Apr 2005
    Location
    Delta, British Columbia, Canada
    Shooter
    Multi Format
    Posts
    12,661
    Images
    60
    Lots of questions here .

    A teleconverter designed for the FD mount should operate with the aperture in the lens in the same way as the lens itself works. One exception might be an older teleconverter, designed for an FL lens, which I would assume would work with an FD lens, but would necessitate stop-down metering.

    Meters in FD mount cameras don't actually know what aperture you've set. They just know that the aperture you've set lets in 1, 2, 3-3/4 or whatever number of stops of light then the maximum aperture of your lens. (The EF lens Canon cameras are different - they stubbornly want to be able to tell you the exact number of the f/stop set).

    So the meter reacts to a 2x teleconverter exactly the same way it responds to a 2x neutral density filter - it sees one stop less light, and instructs you accordingly.

    Teleconverters add all sorts of distortions/aberrations, in varying amounts. Chromatic aberration, spherical aberration, pincushion distortion, barrel distortion - they are all possible. The distortions/aberrations will also depend on the teleconverter/lens combination - for example, a lens with a moderate amount of pincushion distortion might be a perfect complement to a teleconverter that adds barrel distortion.

    Some teleconverters are designed for close focus work - and some of them are limited to close focus work, while others (most I would say) do permit infinity focus. As in most lenses, teleconverters often give optimum results with particular lenses, at particular subject distances. That is why you see teleconverters from the lens manufacturers that are described as being for use only with certain lenses.

    I have and use a Vivitar macro-focus teleconverter with my Olympus OM equipment. It gives acceptable results at infinity, but really shines at close distances.

    One final point- I see from your signature line that your longer lenses are zooms. In my totally unscientific opinion, teleconverters tend to work better with fixed-focus lenses.

    Hope this helps.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  3. #3
    Rol_Lei Nut's Avatar
    Join Date
    Jul 2006
    Location
    Hamburg
    Shooter
    Multi Format
    Posts
    1,118
    You lose 2 apertures with a 2x converter and 1 aperture with a 1.4x converter.

    If your camera's meter reads through the lens, then the light difference is automatically compensated
    (some more modern cameras might show the nominal aperture rather than the effective in the viewfinder, but that has no practical consequence).

    If you're using a hand held or a not therough the lens meter, then you need to compensate by hand (on a 2x, if your meter says, say, 1/250 f/8.0, then you need to set the lens' ring to f/4.0).

    Full infinity focus is kept (unless you have a real dog!)

    Quality can vary drastically: some are specifically designed to work with particular lenses (or a particular range of lenses), some are apo-corrected, in combination with apo teles, they are still better than non-apo teles without a converter. At the other end, some are just murky or barely decent.

    IMHO it's worth investing in a really good one, possibly designed for a particular high quality tele, otherwise the results don't justify its drawbacks. I had several "o.k." ones in the past (supposedly fairly good old-school 7 element Kenkos) and never used them, while the "good" one I now have sees lots of use.

    As the previous poster stated, I'd seriously doubt if you'd get very good quality using a converter on zooms (also due to light loss requiring longer exposeres and so on...).
    M6, SL, SL2, R5, P6x7, SL3003, SL35-E, F, F2, FM, FE-2, Varex IIa

  4. #4
    Markster's Avatar
    Join Date
    Dec 2010
    Location
    Denver area
    Shooter
    35mm
    Posts
    307
    Some of the folks on the Internet are saying they did tests with zooms and compared 300mm without the converter with 150 with 2x converter and you cannot tell a difference when blown up into 8" prints. Granted I take that with a grain of salt because maybe they just had the right combination.

    However as a man of budget constraints I am very curious. It might make my 200mm zoom into a 400mm zoom. THAT would be impressive. The problems become the speed of the lenses and available light, then.
    -Markster

    Canon AE-1P 35mm | 50mm/f1.8 FDn | 28mm/2.8 FD | 70-200mm/f4-5 FD | 35-70mm/F2.8-3.5 Sigma FD

  5. #5
    OldBikerPete's Avatar
    Join Date
    Aug 2005
    Location
    Melbourne, Australia
    Shooter
    4x5 Format
    Posts
    357
    Images
    3
    If you are using lenses which are just adequate in resolving power (and if you're using zooms, you are) then the resolving power of the combination will be reduced at least by the power of the teleconverter assuming the teleconverter itself is perfect. ie if your lens is capable of 80 line-pairs-per-millimetre (lp) alone, then the combination will be capable of a maximmum of only 40 lp with a perfect 2x telconverter and in practice, less than that.
    If the lens alone is capable of 300 lp (and some are on an optical bench) and the 2x teleconverter is just as good then you won't notice any difference in sharpness because the finest-grained B&W films are only capable of about 140lp in daylight.

    Peter.

  6. #6
    Markster's Avatar
    Join Date
    Dec 2010
    Location
    Denver area
    Shooter
    35mm
    Posts
    307
    Doing some reading today about the speeds, loss of light, etc... Looking at my f/5 200mm zoom, that would be a real pain to try and shoot even in bright daylight.

    I guess I need (aka want?) some faster zooms. I don't suppose there are many good 80-200 range zooms with f/2.8 or less?

    Or am I just dreaming now?
    -Markster

    Canon AE-1P 35mm | 50mm/f1.8 FDn | 28mm/2.8 FD | 70-200mm/f4-5 FD | 35-70mm/F2.8-3.5 Sigma FD

  7. #7
    Andrew K's Avatar
    Join Date
    Mar 2010
    Location
    Melbourne, Australia
    Shooter
    Multi Format
    Posts
    512
    Teleconvertors are a cheap way to get a longer focal length lens - and using genuine Canon lenses with a teleconvertor the results are usually sharper than using non-Canon branded tele lenses..

    Canon made 3 - teleconvertors - a 1.4 and 2 different 2X/

    the 2xA was for lenses 300mm and over..

    the 2XB was for lenses up to 300mm

    they were designed for optimal results with the dedicated lenses.

    Also if you are buying Canon teleconvertors make sure they will fit on the lens you intend to use - some like the 1.4 will only work with certain lenses...

    And when using ANY Teleconvertors or Extension tubes on Canon FD - ALWAYS mount the convertor/tude to the body first - then mount the lens onto the convertor/tube.

    You will get into all sorts of coupling issues if you do it differently...it was one of the more common complaints from people when I worked as a camera technician at Canon....

    Personally I would pick up a 200/2.8NFD and a Canon 2XB - you get 400/5.6 and pretty sharp results..

    Or pick up a second hand Canon 300/4....or if you need a real tele the Russian MTO 500 mirror lenses are very sharp in the middle..they vignette a bit, but the ones I've had have all been sharp...
    A camera is only a black box with a hole in it....

    my blog...some film, some digital http://andrewk1965.wordpress.com/

  8. #8
    Markster's Avatar
    Join Date
    Dec 2010
    Location
    Denver area
    Shooter
    35mm
    Posts
    307
    I can see that it was really intended for use with primes because of their faster speeds, but with the prices involved I would hesitate. I'm thinking of moving away from primes simply because the framing isn't there.

    I'm not cropping/blowingup in the printing process (I don't make my own) so I have to put in the effort to frame it right and keep it as the way it prints the first time.

    This has been quite enlightening, but perhaps I won't go this route. Zooms aren't fast enough and that 2X-b costs a lot these days. 2X-a is plentiful and cheap, but doesn't help as much since my biggest lens tops out 200mm.
    -Markster

    Canon AE-1P 35mm | 50mm/f1.8 FDn | 28mm/2.8 FD | 70-200mm/f4-5 FD | 35-70mm/F2.8-3.5 Sigma FD



 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin