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Bokeh with zoom lenses.

Discussion in 'Sony Alpha E-Mount Lenses' started by alaios, Aug 23, 2013.

  1. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    Hi all,
    I have seen some great shots in this forum about people producing great images that were isolating the subject with some also very good bokeh results.
    I was impressed to see that these people were doing that (yes please do share some of your shots you have already) with a zoom lens, like the SEL1855. I typically can have the same on my Minolta 50mm at 1.7 aperture. As you know zoom lenses start from an aperture over 3 so I can not have the same isolation.
    Why these great people do this effect even with a zoom lens? What is the trick here that I do not miss and what would be a good exercise to try with my zoom 1855 kit lens?

    I Would like to thank you in advance for your help


    Regards
    Alex
     
  2. jai

    jai TalkEmount Top Veteran

    589
    Feb 4, 2013
    Background separation doesn't just depend on aperture. It also depends on sensor size, focal length and the relative distances between subject and background. If you want to get more BOKEH try:

    • Zoom in to the longest focal length
    • Get as close as possible to your subject
    • Open your aperture as wide as possible

    I got this shot with my 18-55 zoom

    <a href="http://www.flickr.com/photos/jaiphone/8391279488/" title="Untitled by Jai Sbr, on Flickr"> 8391279488_939e26ceed_b. "1024" height="681" alt="Untitled"></a>
     
  3. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    There ARE fast zoom lenses out (the Tamron 16-35 f/1.8, many 24-70 f/2.8 and so on), they are just expensive. Jai was spot on on how to achieve much (not necessarily good) bokeh out of the kit zoom.

    Here's one of the very first shots I got with my NEX-5 three years ago. The kit zoom can achieve quite good bokeh if you choose a relatively neutral background and if you are close enough to your subject.

    <a href="http://www.flickr.com/photos/48126456@N05/5597763763/" title="Nature 1 by Poki5, on Flickr"> 5597763763_848afa0e68_z. "640" height="426" alt="Nature 1"></a>

    Edit: Oh, I didn't know how right I was - this shot tomorrow is EXACTLY three years old. ;)
     
  4. dbmiller

    dbmiller TalkEmount Top Veteran

    777
    Mar 2, 2012
    New England
    +1 on everything said so far.
    • The wider the lens, the larger the inherent DoF. So shoot at the long end if you can.
    • Use the widest aperture (lowest f/number) the lens will allow.
    • Get as close to your subject as possible
    • Put as much distance as you can between your subject and the foreground/background objects.
     
  5. eno789

    eno789 TalkEmount Top Veteran

    720
    Jan 1, 2012
    NoCal, USA
    Brian
    When it's "background blur" that you want, please just say "background blur".

    Bokeh is the subjective quality of background blur. You can say I like certain bokeh, but you cannot really say you want more or less bokeh.
     
  6. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    True. But most people don't know the difference anyway.
     
  7. jai

    jai TalkEmount Top Veteran

    589
    Feb 4, 2013
    I agree Bokeh is the quality of the blur, but BOKEH is just the most bloody background separation you can manage. You have to imagine I am saying it like Kai from digital rev tv on the youtubes
     
  8. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    Well, even a very slight out of focus background has a 'bokeh', i.e. a quality of these oof areas. But yeah, it's all Kais fault. ;)
     
  9. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    Regarding the list you gave. Do increase my background bluriness is to use my 1855 lens to 55 lens ("zoom") but in that case I loose the fastest aperture this lens can give me when is at 18. So I guess that zooming is much more important than the aperture
     
  10. eno789

    eno789 TalkEmount Top Veteran

    720
    Jan 1, 2012
    NoCal, USA
    Brian
    degree_of_background_blur = function(focal_length, focusing_distance, aperture, background_distance)

    It's hard to say one factor is more important than the other.
     
  11. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    Alex, we can tell you this stuff, but you'll learn it better and retain it better if you do it yourself. Unlike film, once you've bought the gear for digital there is no cost to take pics except your time, so you can experiment and get immediate feedback.

    Go out in the back yard. Use a tripod or set the camera on a table. Pick an object to shoot, something small. Put it at different distances from a background. Use different apertures. Move the camera closer/farther away from the subject. Take detailed notes to compare to the pics later.

    I'd be surprised if anyone here read a book and went out and took fantastic photos without a lot of practice and experimentation. I've been doing this off and on for 40 years and I learn (or relearn) something every time I go out to shoot.

    Knowing the theory is great, but you have to be able to apply the theory correctly to make good pictures. Unless you are an exceptionally gifted person who can read and understand what you read and then apply it perfectly I feel you'll be much happier if you follow the steps I've outlined above. :)
     
  12. jai

    jai TalkEmount Top Veteran

    589
    Feb 4, 2013
    Yep, it seems counter intuitive, but wide open at 18mm will have greater depth of field than at 55mm, despite the fact you lose that little bit on the aperture.

    Generally, its pretty hard to get decent separation at wide angle, unless you are super super close to the subject. If shallow DOF is the effect you want, i suggest 50mm or more.

    Checking the EXIF of this shot it is at F6.3, but because it is 210mm (on the 55-210 sony zoom) there is quite a lot of blurring of the background

    <a href="http://www.flickr.com/photos/jaiphone/8608661252/" title="DSC02503 by Jai Sbr, on Flickr">"1024" height="682" alt="DSC02503"></a>
     
  13. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    Nice shot. He's got his eye on you. ;)
     
  14. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    +1

    I personally started photography without knowing anything. I didn't read anything, I just tried out and failed. It took me two years to get to a state where I didn't have to think about anything technical anymore when shooting. Then, I started shooting at night with natural light. I failed dramatically. I failed, because I didn't read anything before trying. But it was fun. And when I started reading, I didn't read a tutorial on 'how to shoot stars', I read about the physics and maths behind star and earth movement, star brightness, moon cycles and so on. It's simply more fun to explore the photography part by yourself.

    To cut this short: Always keep in mind it's about the fun. And almost nothing is more fun to learn than photography.
     
  15. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    Thanks for the lovely comments.
    The reason I do not try that much is that I do not really have time. My new born daughter takes more of it. And I only have 1 hour per week to shot, where I need to apply all the new things.... All the other time I try to read and learn in theory, it is like a dream to dream.


    A
     
  16. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    Hi, few more comments on this.
    What I understood from my test was that if you zoom on the subject the background gets more defocused, even though the aperture decreases ... So I guess focal length is more important on that.

    Regards
    Alex
     
  17. eno789

    eno789 TalkEmount Top Veteran

    720
    Jan 1, 2012
    NoCal, USA
    Brian
    You tried your particular zoom lens, so you can only say that's probably true for your lens at the same shooting distance.

    Let's do a thought exercise, let's say, instead of 18-55mm/3.5-5.6, you have 24-50mm/3.5-5.6, will your guess still hold? Maybe, maybe not. What about 24mm f/1.4 prime wide open, vs a 35mm prime at f8? My point is, you cannot reach a generalized conclusion "focal length is more important than aperture" from your test.

    Also, lot of the zoom lenses can focus closer at the wide end, some even have a macro mode at the wide end. That also changes things.

    What we can say is, when all other things being equal: same aperture, the longer the focal length, the blurrer it gets; same focal length, the wider the aperture, the blurrer it gets. When both factors are changing, you'll have to calculate.
     
  18. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    Thanks for the answer.. I guess this is why the saying says that is important to know your hardware...

    Regards
    A
     
  19. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    Also, longer lenses compress the background more, which is very important artistically. Never forget: The background is just as - or even more - important than the foreground.