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Thread: 300mm f/5.6 Question

  1. #1
    dbla's Avatar
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    300mm f/5.6 Question

    Hey all,

    I shoot on a Wista 45 and a Chamonix 45N-1. I am trying to emulate the DoF (bokeh) achievable by some of the more expensive/harder to get Xenotar 150 f/2.8 lenses for portraiture. I shoot a lot of environmental portraiture and use a 150 with good success there, but when I get tighter on a subject (think head or head and shoulder) I would like to be able to blow the background entirely to creamy DoF. Would a 300 5.6 do this for me? or even just a 210?

    I'd love to see some examples!

    Thanks in advance,

    -A

  2. #2
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    Re: 300mm f/5.6 Question

    And a recent shot I'd have loved to have even shallower DoF on...

    Click image for larger version. 

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  3. #3

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    Re: 300mm f/5.6 Question

    The cheapest way to blur the background is to use what you have and increase the distance between the subject and the background…..


    Sent from my iPhone using Tapatalk

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    Re: 300mm f/5.6 Question

    Try shooting with the lens wide open and focused just short of the subject.

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    Re: 300mm f/5.6 Question

    Quote Originally Posted by Kiwi7475 View Post
    The cheapest way to blur the background is to use what you have and increase the distance between the subject and the background…..


    Sent from my iPhone using Tapatalk
    Sure, but at some point you may not be able to move further away or manipulate the subject that much. A lot of my portraits are environmental with people I don't know, so I'd rather that I was adaptable rather than asking the subject to adapt.

    Quote Originally Posted by Jim Noel View Post
    Try shooting with the lens wide open and focused just short of the subject.
    But a longer focal length would further accentuate this right?

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    Re: 300mm f/5.6 Question

    150mm f2.8 Xenotar Previously discussed:
    https://www.largeformatphotography.i...-f-2-8-Xenotar

    As previously posted, 150mm f2.8 Xenotar and 178mm f2.5 Kodak Aero Ektar have become "cult" lenses due to their full aperture and appeal to those transitioning from digital or roll film cameras wanting to keep the selective focus image style.

    For head/shoulder portraits on 4x5, consider a longer focal length of 10" / 250mm to 12" / 300mm and a f4.5 to f6.3 Tessar formula lens in a round iris shutter or in barrel (tends to aid in to out of focus transition and rendition). 150mm / 6" IMO is too short a focal length for head/shoulder portraits on 4x5.

    Another previous discussed for 8x10, much applies here.
    https://www.largeformatphotography.i...t-work-on-8x10

    Camera (Wista 45 and a Chamonix 45N-1) could be a limitation to support lenses like this due to the physical size and camera and bellows extension needed by lenses like this and lenses like these often come in vintage shutters that likely need service/clean/lube/adjust to function properly. Another way is to size up in sheet film format.


    Bernice

  7. #7

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    300mm f/5.6 Question

    Quote Originally Posted by dbla View Post
    Sure, but at some point you may not be able to move further away or manipulate the subject that much. A lot of my portraits are environmental with people I don't know, so I'd rather that I was adaptable rather than asking the subject to adapt.



    But a longer focal length would further accentuate this right?
    I think this may offer some insight regarding the interplay of blur, focal length, and background distance:

    https://lewiscollard.com/technical/background-blur/

    Note in particular that “If you maintain the same framing and keep everything else the same (i.e. the same absolute aperture), the amount of background blur decreases as you increase focal length!”

    By the way the author provides the python source code, so you could check for yourself eg for what background distances a longer lens of smaller minimum aperture would increase the blur,or not.

    I’ve done some environmental portraiture, and sometimes it’s easier to just guide the conversation with the person being photographed to turn him/her to have the most distant background possible… and go to locations where those are common place. If you’re just shooting on a street and someone’s resting against a wall, no lens is going to blur that wall very much. But if you talk to him and have him rotate so that it’s now the opposite street in the background, almost any lens wide open will blur it significantly.

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    Re: 300mm f/5.6 Question

    Roughly, the size of out of focus blur is proportional to the diameter of the entrance aperture (focal length divided by f-number). If you use the lenses wide open, some aperture diameters are: for 150/5.6 = 27mm, for 150/2.8 = 54mm, for 210/4.5 = 47mm, for 300/5.6 = 54mm, and so on.

    I'm hardly an expert on this kind of portraiture, but for your application, I would consider looking for a Tessar-design lens in maybe the 210-250mm range with a max aperture of say 4.5-5.6 (maybe even f/6.3). These will give you a fairly large aperture, so a lot of defocusing of the background, they're not terribly expensive compared to lenses like a Xenotar, and they also should have a manageable bellows extension. For head and shoulders work, you might be at a magnification of 1:5 or 1:4, meaning a 300mm lens could need 360-375mm of bellows, which may be difficult or unwieldy with your camera.

    Changing the focal length will also mean changing the camera position, and that can influence the background appearance. Also, strategic choice of the background and relative lighting of the subject and background can change it a lot.

  9. #9
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    Re: 300mm f/5.6 Question

    Good point, appreciate this.

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    Re: 300mm f/5.6 Question

    One of the reasons to get a petzval lens or a lens with high grade of "bent sharpness" instead of the plane is to keep the center in focus and corners out of focus.
    Raf cameras has adapter ring to mount filters on Copal #3 (58mm) or #3S (56mm) shutters.
    With 2 close up filters with 58mm diameter/threads you can make yourself such lens.
    Start with +3 for ca 160mm or +2 for 250mm lens.
    Aperture is ca focal length divided by aperture: 160/45= f3.5 or 5.6 for the 250mm.
    If you go for a heavy plasmat the Fujinon-W 300mm is the smallest of them.

    Sent fra min SM-G975F via Tapatalk

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