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Thread: Using a Petzval portrait lens

  1. #1

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    Using a Petzval portrait lens

    Let us say that you have a half body portrait to make and you want to use a Petzval lens. According to your composition the sitter’s face is not at the center of your frame (where you get Petzval’s optics best performance with no more than 15º angle of view for that part – lens fully open) How do you go about it? Just get the best focus you can while keeping your lens’ axis centered in your frame, no movements, or, do you move your lens or camera back in order to have its axis crossing your sitter’s face? Or something else?

    Asking because with modern lenses (I may be wrong about that) if the scene has only one point of interest and composition is OK, I just focus that spot and shoot. But with a lens so uncorrected, that is probably not the best strategy. I will do some tests, but would like to know how others face this situation.

  2. #2

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    Re: Using a Petzval portrait lens

    Quote Originally Posted by lungovw View Post
    Let us say that you have a half body portrait to make and you want to use a Petzval lens. According to your composition the sitter’s face is not at the center of your frame (where you get Petzval’s optics best performance with no more than 15º angle of view for that part – lens fully open) How do you go about it? Just get the best focus you can while keeping your lens’ axis centered in your frame, no movements, or, do you move your lens or camera back in order to have its axis crossing your sitter’s face? Or something else?

    Asking because with modern lenses (I may be wrong about that) if the scene has only one point of interest and composition is OK, I just focus that spot and shoot. But with a lens so uncorrected, that is probably not the best strategy. I will do some tests, but would like to know how others face this situation.
    As you say, if the lens has an image circle that is larger than the sheet you can use shift and rise/fall movements to displace the center of the image circle from the center of the sheet to the place were you have the face. This will also move the center of the swirl bokeh a Petzval may have from the center of the sheet to were you place the center of the image circle.

    IMHO it is more important to displace the center of the swirl than the best image quality area.

    It's time to remember that the swirl is generated by entrance/exit pupils limiting the the aperture...

    Regards

  3. #3
    Jac@stafford.net's Avatar
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    Re: Using a Petzval portrait lens

    Front rise is your friend, still keep in mind that the swirl effect is largely due to the distance from the subject to background, so if your subject is at zero perspective controls no movements are likely necessary. ... all presuming you have a background, probably an outdoors image.
    Last edited by Jac@stafford.net; 21-Nov-2017 at 14:50.

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    Re: Using a Petzval portrait lens

    My problem is that I am using a Linhof Tecknika 13 x 18 cm with 4x5" back. This camera has so little lens fall (for faces on the upper part of the frame) that I will have to use angles: tilting the lens board and film backwards. I have to do some math. For me it is impossible to guess with angles.
    I am not very much after swirl, I just want the eyes perfectly in focus. I want them very sharp and the rest more blurred, not necessarily with swirl.

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    Re: Using a Petzval portrait lens

    I do not recall seeing "swirls" on studio portraits fom yesteryear. There must be some outdoors photos with distant greenery here somewhere. The old motto was to focus on eyes and the rest of the face will be OK. I have seen a few examples of apparently smart use of the curving focal plane where the photographer has managed to include some very sharp costume details/flowers/hands etc.

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    Re: Using a Petzval portrait lens

    Also, Petzvals with a longer than you might think Focal Length were used with smaller than you might think film sizes. So that you would be farther away from the subject and the film would "crop" the central good part of the image.
    Bill
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    ScottPhotoCo's Avatar
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    Re: Using a Petzval portrait lens

    Here is an example of an 8x10 Wollensak Portrait Lens Series A (Petzval) shot on 8x10 film at f11 with the subject off center. I just focused on the closest eye and made the image. No rise, fall or any other adjustments.

    Anna L, Actor, 2017 by Tim Scott, on Flickr

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    Re: Using a Petzval portrait lens

    Scott, that is what I want, thanks for sharing. What I still don't know is whether with the lens fully open, f/3.7, aiming the lens axis to where one wants sharpness, would provide a significant improvement, compared with just focusing on the same spot with lens centred. At f/11 you corrected a larger share of spheric aberration, the remaining out of focus is coming more from depth of field... I guess.

  9. #9
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    Re: Using a Petzval portrait lens

    Quote Originally Posted by lungovw View Post
    Scott, that is what I want, thanks for sharing. What I still don't know is whether with the lens fully open, f/3.7, aiming the lens axis to where one wants sharpness,

    That's what I always do with portraits. Must have the eyes as the sharpest part of the image.


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  10. #10

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    Re: Using a Petzval portrait lens

    Quote Originally Posted by Steven Tribe View Post
    I do not recall seeing "swirls" on studio portraits fom yesteryear. There must be some outdoors photos with distant greenery here somewhere. The old motto was to focus on eyes and the rest of the face will be OK. I have seen a few examples of apparently smart use of the curving focal plane where the photographer has managed to include some very sharp costume details/flowers/hands etc.
    Hello Steven,

    Field curvature and swirl can be both in a Petzval shot, but these two effects are of different origin, one may be present independently from the other. The swirl comes from the entrance and/or exit pupil limiting aperture, so I guess it is possible that some Petzval lenses are simply not able to provide the swirl even when wide open. Perhaps somebody knowing optics would be able to clarify it better.

    Also if OOF background is smooth then swirl won't be noticed.

    This is a Derogy Petzval 6" F/3.75

    https://www.flickr.com/photos/vitali...cPv5Y3-cB6piA/

    Regards

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