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Thread: Aperture blades and look...

  1. #1

    Aperture blades and look...

    Doing some research on lenses I have come across the following from Cristopher Perez on the hevanet website:

    "After performing this test, I believe I begin to understand why old photos can have those qualities. Small blade number apertures can produce rapidly changing dark to light transitions that can be perceived as "harshness". On the other hand, old lenses tend to have many many aperture blades that define a nearly round aperture shape. This is the single most important influence on out of focus area rendition. Further, I believe it is possible to duplicate this effect with modern optics by simply mounting them in multi-blade apertured shutters."

    So a simple question.
    As far as these visual affects are concerned what is the number required for the 'many aperture blade' effect?

    7?
    10?
    etc,
    And then how old a shutter would one need to put the lens in to achieve this.

    Thanks,

    Marc

  2. #2

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    Re: Aperture blades and look...

    It also matters if the shape of the blades are curved versus straight like modern Copals are, why they couldn't cut them with a curve is beyond me.... Modern Copals only have 5 blades -- as do cheap SLR lenses -- higher end SLR lenses have 7 or 9 blades, Leica and VC lenses usually have 9. If you look into a stopped down Leica lens they make a nice flower-shaped aperture hole. And Rolleis have rounder apertures than on the similar 80/2.8 Zeiss in a Hasselblad... which is why Rollei TLR shots usually a bit creamier.

    Sometime in the 60s Synchro-Compurs went from 7 to 5 blades, so the earlier Linhof shuttered lenses can be found both ways... I think all the Copals have been 5 blades, as have been most of the post war American shutters. You simply have to look and ask before buying.

    Of course you get perfectly round apertures if you shoot wide open. Oftentimes that's what I try to do. But if you try to shoot outdoors wide open you may want to find a shutter with a fast 1/400 or 1/500 speed, and/or some ND filters and use slower film.

    I went through all this myself and currently use a later 5-bladed shutter because I want a nice, newer, reliable shutter (I really prefer Compurs) and I do try to shoot wide open when I think the background will benefit. But it is always a compromise... I doubt Copal will change their design at this late date, it is a pity they didn't care about such details but in the 1950s-60s when things changed over... I think the prevailing trend was to emphasize how darn sharp everything was over other lens qualities.

  3. #3

    Re: Aperture blades and look...

    Cheers Frank.
    I just ask mainly out of interest really as most of my work is +F22 etc and not close up so never that many out of focus areas anyway!

    But it is always interesting to understand how to create different visual looks etc.

  4. #4

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    Re: Aperture blades and look...

    It matters at f/22 too though... but then you have to weigh the other differences between modern glass and whatever was good 40 years ago. If you're used to state of the art modern lenses like the 110XL then a vintage lens is an entirely different look.

  5. #5

    Re: Aperture blades and look...

    Marc,

    Ilex #4 = 10 blades
    Ilex #5 = 12 blades
    Alphax #5 = 15 blades
    Alphax #4 = 15 blades
    Rapax #3 = 10 blades
    Xenar 360/4.5 barrel = 26 blades

    It actually seems to make a difference. At f/22 and smaller the jagged edge of the circle would also induce diffraction.

  6. #6

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    Re: Aperture blades and look...

    Quote Originally Posted by marcwilson View Post
    Doing some research on lenses I have come across the following from Cristopher Perez on the hevanet website:

    "After performing this test, I believe I begin to understand why old photos can have those qualities. Small blade number apertures can produce rapidly changing dark to light transitions that can be perceived as "harshness". On the other hand, old lenses tend to have many many aperture blades that define a nearly round aperture shape. This is the single most important influence on out of focus area rendition. Further, I believe it is possible to duplicate this effect with modern optics by simply mounting them in multi-blade apertured shutters."

    So a simple question.
    As far as these visual affects are concerned what is the number required for the 'many aperture blade' effect?

    7?
    10?
    etc,
    And then how old a shutter would one need to put the lens in to achieve this.

    Thanks,

    Marc
    I don't believe mounting a modern lens i an old shutter will have any appreciable effect on the "harshness" of the image. I call it "cut & paste" look. The crown/flint lenses just have a less sharp cut off and along with internal reflections produce those nice smooth effects.

  7. #7

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    Re: Aperture blades and look...

    Wow I didn't realize the old American shutters had so many!

    We made such nice stuff back then...

  8. #8
    All metric sizes to 24x30 Ole Tjugen's Avatar
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    Re: Aperture blades and look...

    Compound #5, as in old Xenar 300mm f:4.5, Heliar 300mm f:4.5 etcetera: 23 blades.

    I haven't counted #3 and #4 Compounds (yet).

  9. #9

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    Re: Aperture blades and look...

    Quote Originally Posted by Jim Noel View Post
    I don't believe mounting a modern lens i an old shutter will have any appreciable effect on the "harshness" of the image. I call it "cut & paste" look. The crown/flint lenses just have a less sharp cut off and along with internal reflections produce those nice smooth effects.
    You may be right, but my Fujinon A lenses have very nice blur, when shot wide open. When stopped down, the influence of the 5-bladed diaphragm cannot be overlooked.

    On the other hand, my vintage lenses, (albeit limited in coverage, and not apochromatic) with their virtually circular diaphragms, continue to delight the eye, even when stopped down.

    With such lenses, one need not shoot wide open, to reap the benefits. Here is a photo taken with a 210mm Braunschweig Heliar (at least 50 years old), stopped down a few stops - to get what felt like just the right amount of blur.

  10. #10

    Re: Aperture blades and look...

    Great info guys.
    Its quite a hard one as for the project I am embarking on although it is important for me that the images have a great clarity of detail as some of the subject matter will contain engraved text, etc, the subjects/objects are quite monumental and older relics and so a certain smoothness and sensitivity of look is also required.
    The images will be colour and both printed in book form and also upto 40 inch wide and over (drum scanned and lightjet printed) exhibition prints.
    So although I am not looking for an old fashioned look per se I am also not after the sharpest, modern xl lens type look.

    Doubftull but does anyone have examples of the different look of the same subject achieved by newer and older lenses?

    Marc

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