Diopter Lenses?

Discussion in 'Digital SLR' started by Ben, May 26, 2005.

  1. Ben

    Ben Guest

    Hello

    I have a Canon 20D digital camera with the EF-S 18-55 lens and the Canon
    75-300mm f/4.0-5.6 IS USM EF lens.
    I have two questions.
    1. Where can I buy diopter lenses. I've found them on the internet (B&H),
    but nothing for this camera?
    2. I would like to get a teleconverter. I'm especially interested in a Kenko
    Teleplus Pro 300 3.0X lens.. I would appreciate hearing from anyone who has
    used this 3X Tele Extender with the 300mm zoom lens that I described above?
    Thank you.
     
    Ben, May 26, 2005
    #1
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  2. Ben

    Stacey Guest


    The thing to remomber here is, since you are focusing close and shooting
    stopped down, you can use a step DOWN ring with no problems as long as it's
    not a crazy amount. The nikon 2 element diopters are very high quality and
    reasonably priced.
     
    Stacey, May 26, 2005
    #2
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  3. Ben

    Tony Polson Guest


    A diopter is slang for a "close-up lens" that is mounted in a filter
    ring so it can be screwed into the filter thread at the front of your
    lens. First, you need to know the diameter of the filter your lens
    accepts. The Canon web site shows your 18-55 and 77-300mm lenses both
    have 58mm filter threads.

    Second, you need to choose the strength of the close-up lens. I think
    it's best to start with a +1.0 diopter, but if you are sure you want
    to follow this route you can also buy diopters in sets. They usually
    come in sets of three, +1.0, +2.0 and +3.0 diopters. You can use them
    singly - 3.0 diopters being the most powerful - or in twos, when for
    example 1.0 and 2.0 diopters used together will give the same optical
    effect as a single 3.0 diopter close-up lens used alone.

    As always, there is a range of prices. The cheapest close-up lenses
    are single element lenses. They can produce severe colour fringing
    unless you stop your lens well down, say f/11, f/16 or f/22.

    Better close-up lenses cost much more, but they have two elements
    glued together to form a 'doublet'. Doublets have much less colour
    fringing, and you will not need to stop down quite as far for good
    results. Try f/8 or f/11.

    Canon sell close up lenses in 58mm size. Unfortunately they do not
    express the power of the lens in diopters, preferring instead to refer
    to the reduction in longest focusing distance. Here is an example:

    http://www.canoncompanystore.com/epages/annex.storefront?ProductDetail=2822A002AA
    http://www.canoncompanystore.com/epages/annex.storefront?ProductDetail=2820A002AA

    I would guess that the 500D is a 1.0 diopter and the 250D is a 2.0
    diopter, but that is only a guess. They are not cheap, but they are
    doublets.

    On the B&H web site, if you look in the section on threaded filters,
    then select "Close Up Lenses" and choose all brands in 58mm diameter,
    you will get the following page:

    http://www.bhphotovideo.com/bnh/con...&ci=158&ac=&Submit.x=16&Submit.y=12&Submit=Go

    You may need to copy and paste this into your browser's address window
    in sections or click on:

    http://tinyurl.com/7n6tn

    Here you will find single element close up lenses priced from $20.95,
    with the Canon doublet close-up lenses priced from $86.95. My advice
    would be to try one of the cheaper close up lenses and see how it
    works for you before spending any more money.

    $20.95 is cheap, but I would be tempted to put the cost of two or
    three $86.95 close-up lenses towards the purchase of a specialist
    macro lens such as the $439.95 Tamron 90mm f/2.8, which is also an
    outstanding portrait and general telephoto lens.

    Cheaper macro lenses are available; the Cosina/Phoenix/Vivitar/Soligor
    100mm f/3.5 Macro is cheaply made but performs surprisingly well,
    although it is not such a good choice for portraiture.
     
    Tony Polson, May 26, 2005
    #3
  4. Ben

    Ben Guest

    Thank you. I also found out that these were sized like filters. I will look
    into what Nikon has.
    Ben
     
    Ben, May 26, 2005
    #4
  5. Ben

    Frank Guest

    Hi Tony
    Thank you for your reply. I certainly couldn't have asked for a better
    explanation and more information. I do intend to get a macro lens in the
    future.
    As for now, using the info you provided, I am going to order the Hoya 58mm
    Close Up Kit Multi-Coated (+1, +2, +4) for $64.50. I can always add better
    stuff later on. Your response eliminated the uncertainly that I had in this
    area.
    As for macro lenses, I'm undecided about the following:
    Canon-EF 50mm f/2.5 Macro Lens--------------$239.95
    Canon-EF-S 60mm f/2.8 USM Macro Lens-----$449.95
    Canon-EF 100mm F/2.8 USM Macro Lens-----$469.95
    Sigma-105mm 2.8 EX Macro Lens Canon AF--$399.99>
    I have not come across the Tamron lens that you mention. I would appreciate
    if possible your opinion on these lenses also how does a 50mm lens compare
    with a 100mm lens. I've seen write ups on both but I can't compare them.
    I don't know that much about lenses, but from the newsgroups, it seems most
    people favor Canon. However those other companies must have something or
    they wouldn't be in business.
    Again I thank you for the information.
    Ben
     
    Frank, May 26, 2005
    #5
  6. Ben

    Stacey Guest

    Frank wrote:

    http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=37298&is=REG

    and a step ring is a MUCH better investment. On a zoom you can control the
    amount of mag with the zoom ring so you don't need a "set" like you would
    with a fixed focal length lens.
     
    Stacey, May 27, 2005
    #6
  7. Ben

    Tony Polson Guest

    Glad I could help.
    That's a good choice at a good price. At that price, I assume that
    they are single element close up lenses. If so, stop down to f/11 for
    best results.
    All other things being equal, a 50mm lens gives a greater depth of
    field than a 100mm lens but at the expense of a shorter working
    distance. In the 35mm film market, over the years there has been a
    steady trend away from shorter focal length macro lenses to longer
    focal lengths. The main reason for this is the greater working
    distance with the longer lenses - with a 50mm lens you end up working
    very close to your subject, which - among other things - makes flash
    illumination problematic.

    I have no knowledge of the Canon 50mm f/2.5. The 60mm f/2.8 and 100mm
    f/2.8 Canon EF lenses are outstanding performers, both well up to
    professional standards. The Sigma is also a very good performer, and
    is highly rated by people who use it. There is also a Sigma 180mm
    f/3.5 which is a new product. It has performed well in bench tests
    and also looks like a very good performer. The two Canon lenses are
    better made than the two Sigmas, which are well finished externally
    but probably not as well made internally as they might appear.

    Your choice of focal length is a personal one. No-one can advise you,
    it is simply a matter of what suits you best. If you value depth of
    field, choose shorter focal lengths. If you prefer a longer working
    distance, choose a longer focal length but be prepared to have a very
    restricted depth of field. Don't forget that the APS size sensor in
    your Canon digital factor means that you get the angle of view of a
    lens with a 1.6X longer focal length, so the 60mm f/2.8 offers the
    same angle of view of a 96mm f/2.8 on a 35mm film SLR.

    (60 x 1.6 = 96)

    The longer focal lengths also need a very sturdy tripod, but this is
    in any case a prerequisite for serious macro work.

    The Tamron 90mm f/2.8 is almost unique by 21st century standards, in
    that it is not only a very good macro lens but also an outstanding
    portrait lens.

    Most macro lenses are optimised for ultimate sharpness at short macro
    focusing distances. This usually leads to an unpleasant, harsh
    rendition of out of focus backgrounds, especially highlights, which
    are rendered as obtrusive bright circles with the edges brighter than
    the centre. At portrait distances, the Sigma 105mm is especially poor
    in this respect, although it is a fine performer in the macro range
    that it was designed for.

    The Tamron is optimised at macro and portrait focal lengths, and has a
    very pleasant rendition of out of focus background highlights, with
    the circles being brighter in the centre and having soft edges that
    fade into the background. This gives what most people would consider
    a more natural "look" to portrait images produced with this lens,
    comparable with some of the finest specialist portrait lenses made by
    Zeiss, Leica and Nikon, none of which will serve as macro lenses.

    Buying the Tamron offers a unique opportunity to own a superb dual
    purpose lens, equally at home in the macro range and when making very
    flattering portraits, particularly of subjects who are not in the
    first flush of youth. <g>

    The Tamron was not unique in the late 20th century; macro lenses with
    a similar aptitude for rendering portraits were also made by Tokina,
    Vivitar, Sigma (all 90mm f/2.8) and by Kiron (100mm f/2.5) in the
    1970s and 1980s, but only the Tamron is still available new today.

    As an inexpensive entry to macro photography, I repeat my
    recommendation of the Cosina/Vivitar/Phoenix/Soligor 100mm f/3.5.
    This lens is not well made, and has the feel of very poor quality,
    especially when focusing, but the results are surprisingly good for
    such a cheap lens. Much like your Hoya close-up lenses, it would be
    worth considering one of these inexpensive performers as a first step.

    Versions of this lens were offered by Canon and Pentax under their own
    brands several years ago, but I understand build quality issues meant
    that both manufacturers dropped the lens from their ranges. You might
    find examples of the Canon version for sale used on eBay.
    My pleasure.

    ;-)
     
    Tony Polson, May 27, 2005
    #7
  8. Ben

    Don Guest

    Folks, I note that the latest 9OMM Tamron Macro is a DI lens (272E). The
    site I looked at provides this information:

    "Outstanding image quality by virtue of "Di" (Digitally Integrated) design
    The lens provides outstanding image quality whether the medium in use is
    silver halide (film) or a digital image sensor, since it features Tamron's
    "Di" optical system designed* to meet the performance characteristics of
    digital cameras as well as film cameras.


    *Model 272E uses the same type optical configuration as that of the
    conventional model 172E, but the "Di" design is achieved by applying a new
    optical design to its coating surfaces to eliminate optical aberrations
    commonly seen when traditional optics are used on digital SLR cameras"


    Has anyone here experience of the new model? Most reports I have read have
    been on the older model. Also, can the Canon Macro flashes MR14EX and MT24
    fit to the front of the Tamron lens to offer the same functionality of the
    equivalent Canon lens with either of these fitted. Look forwarded to any
    and all comments.

    regards

    Don from Down Under
     
    Don, May 27, 2005
    #8
  9. Sounds like they have just improved the coating on the element faces towards
    the sensor to reduce flar from the specular reflections from the sensor.
     
    Lester Wareham, May 27, 2005
    #9
  10. Ben

    Paul Furman Guest


    Thanks for your comments, I didn't realize there was any way to increase
    DOF (other than aperture) at the same magnification.
     
    Paul Furman, May 27, 2005
    #10
  11. Dioptre - or diopter in US spelling - is the reciprocal of the focal
    length of the lens in metres. Thus a 1000 mm lens (1 metre) is 1
    dioptre; 500 mm is 2 dioptre, and 250mm is 4 dioptre. These powers are
    often shown on close up lenses with the abbreviation D, though the Canon
    terminology is decidedly confusing in this respect: here the numbers are
    the focal lengths in meters, and nothing to do with dioptres at all.
    Thus the 500D is 2 dioptres, and the 250D is 4 dioptres. The "D" stands
    for doublet; these lenses use an achromatic doublet to reduce chromatic
    aberration (to distinguish from cheaper ones they make - or used to make
    - which were singlets and did not have the "D" designation).

    The dioptre system of measurement is (AFAIK) universally used by
    opticians; it is very convenient in that field, as the "strength" of two
    lenses used together is given by adding their dioptric strength (as
    someone said in another post).

    [For the purist, however, note that this assumes the two lenses have
    negligible separation; if they are a significant distance apart the
    combination has a longer focal length (or a lower power in dioptres)
    than this simple sum. (For the utterly anal, 1/F = 1/F(1) + 1/F(2) -
    d/(F(1)*F(2), where F = focal length on combination, F(1) and F(2) those
    of the two elements and d their separation).]

    To call a close-up lens a "dioptre/er" is of course a solecism, since it
    is a unit of the "power" of any lens. All lenses have a dioptric
    measurement, but none "are" dioptres/ers.
     
    David Littlewood, May 28, 2005
    #11
  12. Ben

    Colin D Guest

    With due respect, Tony is wrong here. A 50mm lens will give greater
    depth than a 100mm for the same aperture - and the same
    camera-to-subject difference, and for the whole scene.

    However, if you enlarge the centre of the 50mm image to show the same
    field of view as the 100mm image, the dof will be the same with both
    lenses. And if you move the camera closer to achieve the same-sized
    image as given by the 100mm lens, the dof will be the same.

    Colin
     
    Colin D, May 28, 2005
    #12
  13. Ben

    Paul Furman Guest


    Hmm, I guess you are right. Maybe I just misinterpreted.
     
    Paul Furman, May 28, 2005
    #13
  14. Ben

    Paul Furman Guest


    OK so the correct term is "closeup lens" or concievably "closeup filter"
    and the correct usage of the word "diopter" would be:

    I put a +2 diopter closeup lens on the filter threads of my camera.

    or

    With a closeup lens of +2 diopter, my lens is capable of 1:1 magnification.
     
    Paul Furman, May 28, 2005
    #14
  15. Ben

    Tony Polson Guest

    I already pointed that out further up the thread.

    No, it is definitely not a filter!

    You got it.

    Perhaps David Littlewood's excellent explanation could be expanded as
    follows:

    A 50mm normal lens has a focal length of 50mm or a strength of 20
    diopters (1000 divided by 50 equals 20). Adding a 2 diopter close up
    lens increases the strength from 20 to 22 diopters.
     
    Tony Polson, May 28, 2005
    #15
  16. I would personally avoid the use of "filter" as that, at least in
    scientific circles, implies something which selectively removes part of
    the incident light, usually part of the spectrum.
    Correct usage, but physically unlikely (unless it's a 500 mm lens)!

    David
     
    David Littlewood, May 28, 2005
    #16
  17. Ben

    Paul Furman Guest

    Heh, sorry if I'm beating this thing to death but... I have two 200mm
    zooms. One will focus up to about 14 inches away, the other won't get
    any closer than about 5 feet. The 14-inch zoom doesn't get a very big
    change with the same 2-diopter closeup lens attachment and has a very
    narrow usable range. The 5-foot model suddenly will go up to about a
    foot away and achieves greater magnification of 1-1/2 inches filling the
    frame versus 2 inches.
     
    Paul Furman, May 28, 2005
    #17
  18. Ben

    Paul Furman Guest

    Paul Furman, May 28, 2005
    #18
  19. Ben

    DoN. Nichols Guest

    Just out of curiosity -- what happens if you focus the 14-inch
    capable one to the same 5 feet that is the minimum of the other, and
    then add the same 2 diopter lens in front of it?

    Part of the problem is that a telephoto (or a wide angle) lens
    is not behaving "naturally". The focal length of a fairly normal
    compound lens is measured from the film to the optical nodal point which
    usually coincides with the location of the iris diaphragm.

    A telephoto lens starts as a simple lens, but has a negative
    lens mounted between that part and the film plain, allowing the physical
    length of the lens to be shorter than the optical length. (That is, it
    generates the same image coverage as a physically much longer lens.)
    This is done for convenience in carrying and using the lens. Long and
    heavy are awkward to use in a crowd, and are difficult to carry in a
    camera bag of reasonable size.

    A wide angle lens for SLRs is often referred to as an "inverted
    telephoto" design. That is, the negative lens is between the basic lens
    element and the subject. This makes the physical length of the lens
    longer than the optical equivalent length. This is particularly good
    for a SLR, because a very short lens would have to be so close to the
    film (or sensor) that it would interfere with the motion of the mirror.
    (Examples are some of the early Nikon "Fisheye" lenses, which required
    the mirror to be locked up to allow the lens to reach close enough to
    the film.

    A zoom lens is playing games with the effective focal length and
    spacing of various elements, so it may be playing by any of the above
    sets of rules from time to time. This is especially true of a lens
    which ranges from wide-angle to telephoto equivalent focal lengths.

    And for most zoom lenses, there are additional elements
    attempting to minimize distortion -- especially at the wide angle end of
    the range. (A Fisheye, aside from being a fixed focal length lens, is
    an exception anyway -- because the distortion is part of its reason for
    existence. :)

    A close-up lens attached to the front of one of these will act
    differently depending on what part of the optical jumble it is
    modifying -- and thus may be somewhat less predictable on one of these
    than on a single focal length lens.

    Enjoy,
    DoN.
     
    DoN. Nichols, May 28, 2005
    #19
  20. Ben

    Paul Furman Guest

    [for the 14-incher at about 7 inches from the front element to subject].

    At infinity with the closeup lens attached, the 14-incher only goes back
    to about 14 inches with a 2-1/4 inch wide field.

    The 5-foot range lens also goes to about 2-1/4" field of view at
    infinity, roughly 14 inches from the front element to subject.

    The two lenses are 5" (extended) vs 8" (fixed) long.


    The 14-incher is a 28-200 (7x zoom). The 5-footer is a 70-200 (3x).

    It seems there's no reasonable way to predict what will happen without
    trying it. I would appreciate if lens manufacturers noted the closest
    magnification rather than closest distance.
     
    Paul Furman, May 28, 2005
    #20
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