Talk to me about this bokeh...

Discussion in 'Beyond the Basics' started by CThomas817, Sep 27, 2018.

  1. zulu42

    zulu42 Been spending a lot of time on here!

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    Thanks Derrel.

    Cleared up my mistaken assumption that one controls the amount of blur in the background primarily by controlling DOF.


     
  2. TreeofLifeStairs

    TreeofLifeStairs No longer a newbie, moving up!

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    It never occurred to me that the aperture was wider at the same f/stop in longer lenses. I just checked my 16-35 which has a constant 2.8 aperture, and sure enough, as I increase the focal length the aperture opens up more. It makes complete sense though since with a wider FoV there's more light entering, but as the FoV narrows less light is collected and therefore the aperture needs to open more to compensate.

    Wow, mind blown.
     
  3. JBPhotog

    JBPhotog No longer a newbie, moving up!

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    This is precisely why, given the same DOF required to get critical elements of the subject sharp at the same magnification, a longer lens produces softer backgrounds. And people wonder why I shoot portraits with my 300 mm f2.8? ;)
     
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  4. JBPhotog

    JBPhotog No longer a newbie, moving up!

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    If it didn’t, your 16-35 would likely be an f2.8-f4 lens
     
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  5. Braineack

    Braineack Been spending a lot of time on here!

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    Even at shorter lengths, the lens design can come into play.

    I just took two quick shots at 35mm @ 2.8 using two different lenses:

    upload_2018-9-29_7-55-18.png

    upload_2018-9-29_7-56-28.png

    upload_2018-9-29_7-57-32.png

    upload_2018-9-29_7-58-21.png


    The $1,700 Nikon 35mm 1.4g smashes the Tamron $1,200 24-70 2.8 VC in terms of bokeh.


    So while your 85mm 1.8g is good in the regard, the 85mm 1.4g is gooder.
     
    Last edited: Sep 29, 2018
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  6. Derrel

    Derrel Mr. Rain Cloud

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    In direct, side-by-side, same-time comparison against the 35mm f/1.4 Nikkor AF-S G-series, the Tamron 24-70 Di VC has unpleasant bokeh. However in the Nikkor G-series 85mm side-by-side tests I have seen, the f/1.8 model and the f/1.4 model are pretty close in terms of the type of bokeh and the amount of blur possible. In fact, I really do not think the 1.4 model has much advantage whatsoever.
     
  7. zulu42

    zulu42 Been spending a lot of time on here!

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    Still surprised about that first shot with the butterfly. I would have bet money on backdrop.
     
  8. Derrel

    Derrel Mr. Rain Cloud

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    I would say that one controls the amount of blurring in the background mostly by,first, choosing the right lens focal length. After the focal length has been selected, then the choices surround things like A)how close is the camera-to-subject distance, which has a LOT to do with the degree of depth of field B)how far behind the subject is the background and C)what f/stop will be used. Those are the four factors that are most commonly able to be controlled. A fifth factor would be capture format size (m43,APS-C,FX being the three most common sizes today).

    But in general, I'e always picked the lens focal length first. If I want to "blow out" the background, and really,really make it blurry, I go for the 300mm or 200mm or 180mm primes, or the long end of a 70-200 or 70-300 zoom lens.

    If you use 300mm on a 70-300mm f/4~5.6 "consumer" type zoom lens, you can get a pretty nice background blur. Of course, the really fast-aperture lenses, with BIG, wide apertures, really do offer amazing background blowout. This is where the 300/2.8 has been so good for so long, and where the 200mm f/2,and now the 105mm f/1.4, have come to be sort of "trending" lenses among the high-end shooters.

    There is something to be said for high-dollar, exotic lenses, the ones that offer very wiiiiiide apertures!

    Still, one can get pretty good results using more moderate lenses, like the 100mm f/2.8 from Canon, or the older 135mm f/2.8 lenses from many manufacturers. The old, once-popular 135mm f/2.8 Ai or Ai-S is still available in a manual focusing, Nikon F mount for around $75-$100, and can easily be adapted to Canon EF or to mirrorless bodies.
     
    Last edited: Sep 29, 2018
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  9. zulu42

    zulu42 Been spending a lot of time on here!

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    I'm going to try out some shots at around 200-300mm on my big dumb Tamron just for fun.

    Not sure if anybody has brought up defocus control. A different conversation as far as lens mechanics, but If I wanted to consistently feature artsy blown bokeh back and foregrounds, I might learn some more about that also.
     
  10. JBPhotog

    JBPhotog No longer a newbie, moving up!

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    Digital focusing screens today aren't what they used to be like in my F3HP's but I still hung on to my beloved Nikkor 105mm f2.5 AI until the f1.4E version was available. I always loved that focal length but the 105mm f1.4E is simply superb with its exceptional rendering quality. It will become one the Nikon's legendary optics and produces gorgeously rich images in the same league as the Nikkor 200mm f2.0 and 300 mm f2.8.
     
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  11. CThomas817

    CThomas817 TPF Noob!

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    I fully understand what a shallow depth of field is and I understand that you can obtain a more shallow depth with a longer focal length lens. What I'm saying is... 15 feet from my subject at f/2 on an 85 mm - my entire subject will not be in focus. Perhaps the ears, crown of the hair will start to blur. 30 feet from my subject at f/2 on a 200 mm lens - will more or less of my subject be in focus? My question is how much wiggle room I have within the focal plane, not what overall DOF is achievable. I will get the DOF calculator and figure it out. Thanks.
     
  12. CThomas817

    CThomas817 TPF Noob!

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    Oh I am totally aware that these are "optically enhanced" to some degree but I was specifically asking about the bokeh.
     

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