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Thread: Portrait lens for 4x5

  1. #21

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    Re: Portrait lens for 4x5

    Well, after looking for the mentioned lenses, I guess I will up my budget a little. Still looks all very reasonable to me.

  2. #22

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    Re: Portrait lens for 4x5

    So after reading up a little more about lenses and bellow extensions, I have one more question. I sad that you would need about 1.2 times the focal length for normal subjects and about 2x bellow extensions for closeups. As I wrote before I only have 360mm bellows, so does that mean that I would be really using it with a 300mm lens, unless I choose a telephoto design, which would then go to 0.9x focal length for normal subjects and 1.7 for closeups?
    I guess no matter how I look at it I should find something between 210 and 250 for the camera I own.

  3. #23
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    Re: Portrait lens for 4x5

    M = (b-f)/f

    where M = magnification ratio, b = bellows extension, f = focal length

    How about a 210mm lens where the magnification is around 1:3. We can calculate the required bellows draw using the above formula:

    Here M = 1/3, f = 210mm, and b is unknown

    1/3 = (b-210)/210
    1/3 * 210 = b - 210
    70 = b - 210
    b = 280mm


    Given a 300mm lens and 360mm of bellows draw, what magnification can we get ?

    M = (360-300)/300
    M = 60/300
    M = 1/5 or 0.20

  4. #24

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    Re: Portrait lens for 4x5

    Thank you Ken!

    Quote Originally Posted by Ken Lee View Post
    M = (b-f)/f

    where M = magnification ratio, b = bellows extension, f = focal length

    How about a 210mm lens where the magnification is around 1:3. We can calculate the required bellows draw using the above formula:

    Here M = 1/3, f = 210mm, and b is unknown

    1/3 = (b-210)/210
    1/3 * 210 = b - 210
    70 = b - 210
    b = 280mm


    Given a 300mm lens and 360mm of bellows draw, what magnification can we get ?

    M = (360-300)/300
    M = 60/300
    M = 1/5 or 0.20

  5. #25

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    Re: Portrait lens for 4x5

    brilliant! Thanks for the formula Ken

  6. #26

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    Re: Portrait lens for 4x5

    Quote Originally Posted by rince View Post
    Well, after looking for the mentioned lenses, I guess I will up my budget a little. Still looks all very reasonable to me.
    Didn't you say your budget was $500? You should be able to work within that budget and have change left over!

  7. #27
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    Re: Portrait lens for 4x5

    One other thing to consider is depth of field. If you're used to shooting shorter lenses on smaller formats, then you'll be interested to know that in order to get the same depth of field with a lens that is twice as long, you need to stop it down by 2 stops.

    By this reckoning, a 75mm lens at f/8 has the same depth of field as a 150mm lens at f/16, and a 300mm lens at f/32.

    Some large format shooters like portraits with shallow depth of field, and have no problem with a portrait where only the tip of the nose is in focus (or the eyes), but others might consider that "look" to be distracting or contrived.

    So if you want to make tight heads shot where most of the head is in focus, you may need a lot of light - or a slow shutter speed - in order to stop down sufficiently, and the longer the lens, the more it becomes an issue.

    Here is an online Depth of Field Calculator

  8. #28

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    Re: Portrait lens for 4x5

    My rule of thumb for portraits is 1x normal FL for full-length, 1.5x normal FL for waist up, and 2x normal FL for close bust shots. Perceived distortions aren't really about FL but distance from subject-to-lens and this is dependent on the subject size, the intended feel of the final image, and one's personal opinion on what FL (subject distance from the lens) best meets the final outcome. For example: A person who's seven feet tall will require a wider lens than one who's three feet tall all other factors being identical. Heck, I might opt for a 3x normal FL for a really tight shot and depending on how I want the image to feel... that's a 465mm lens if we consider that "normal" is 155mm.

    With a bellows draw of 360mm I'd definitely opt for a telephoto lens to better suit "my" needs. To make it affordable, I'd look for an older 270mm Tele Arton or similar. The 360mm Tele Arton would be nice too but I'm guessing it may be a bit too heavy. Also, the latter is pricier.

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