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Thread: Need some help predicting Bokeh results

  1. #1

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    Need some help predicting Bokeh results

    Hi Everyone: The shots below were all taken with the Nikon D3000: 18-200mm lens: at f8: 1/640s: ISO 800.
    I'd like some help using these as examples on how I might be able to consistently predict DOF and Bokeh.

    #1. (original) This shot has a small crop off the top, I was happy with it from the camera, and just did what I consider minimal PP brightened shadows, tweaked levels, and reduced noise and Sharpened in Elements.

    Need some help predicting Bokeh results

    #2. Shot a few seconds before the original. Same f stop and shutter speed. Focal length 40mm as opposed to 200mm. Focal distance 1.33m as opposed to 1.12m. This just has a bit of a crop off the left to protect the owner.

    Need some help predicting Bokeh results

    #3. This is a tight crop of #2

    Need some help predicting Bokeh results

    Question: In this case, what is/was the deciding factor that produced the smooth bokeh in the original as opposed to the not as nice bokeh in shot #2.
    Note: I'm happy with the background in #2. It is out of focus (or blurry) enough that I don't find it distracting (of course I would crop the sky), but I love the bokeh in the original and would like to be able to purposely reproduce it.

    After reading the tutorial, I'm thinking the small change in focal distance must be what caused the difference. Can that be possible? It was only a change of .2m

    I know I might have to break down and try to understand technicalities here, but PLEASE try to keep it simple for me.

    Thanks
    Wendy

    P.S. I never know if EXIF will show up or not, so if anyone needs more info let me know and I will copy and paste.

  2. #2
    Clactonian's Avatar
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    Re: Need some help predicting Bokeh results

    Hi Wendy.
    It is surely the focal length that is affecting the bokeh, not the focal distance.
    I'm impressed by the noise free images at ISO800, and the great shots of course.

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    Re: Need some help predicting Bokeh results

    Thanks Mike: I should have mentioned the Noise Reduction was done twice. It's done automatically when the shots are brought into LR, and then if I'm shooting at a high ISO I do it again (usually max values) in Elements. These actually were not that bad for noise right out of the camera, but I did the double NR anyway, as I figure the noise is there, I'm just not seeing it. Which brings me to another lesson leaned on this shot. Exposure - most of my shots end up being underexposed as I always end up using -EC to get rid of the blinkies. If I had done that on these then I know the noise would have been horrific. I know this is probably obvious for most of you reading this, but for me it is a case in point of matching what I have read and know in my head to an actual shot. The lesson learned for me is to take into consideration WHEN to adjust for blinkies and WHEN not to worry about them. Also of course something else that I have read here, but now I hope it sticks. I always get back to one of the first lessons I learned here which is to SLOW down. My mind just wants to point and shoot, but really a lot of thought needs to go into this, and then a lot of time before it becomes automatic.
    Rambling again, I'll stop now

    Anyway back to the DOF issue. I thought the same as you, that it must be the 200mm focal length as opposed to 40mm in shot #2 that caused the difference in Bokeh, but when I read the tutorial it says that focal length does not cause a difference in DOF, but focal distance does.

    I suppose I could also be mixing up DOF and Bokeh which until I re-read the tutorial I thought were relatively the same thing???? not sure on that one.

    There is an obvious difference though, and it seems to be more than just the magnification of the 200mm. I'm still not sure, and that is the problem. I want to be able to predict and not just get a lucky shot once and awhile.

    Thanks again for the feedback
    Wendy
    Last edited by ScoutR; 26th October 2010 at 05:11 PM. Reason: spelling

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    arith's Avatar
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    Re: Need some help predicting Bokeh results

    I can't see anything in IE or Firefox.

  5. #5

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    Re: Need some help predicting Bokeh results

    Quote Originally Posted by arith View Post
    I can't see anything in IE or Firefox.
    I wish I knew why???? These are in my albums here at the forum

    Of course you've tried Ctr F5 or Ctr Refresh. That usually works for me.

    I'd like to hear your comments Arith. Maybe they will show up for you later

    Wendy

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    Re: Need some help predicting Bokeh results

    Quote Originally Posted by ScoutR View Post
    I suppose I could also be mixing up DOF and Bokeh which until I re-read the tutorial I thought were relatively the same thing???? not sure on that one.
    Hi Wendy,

    Based on my (initial) reading of the tutorial, I understand the difference you see to be attributable to the magnification of the longer focal length.

    As far as the term bokeh goes, when I saw that term for the first time this week (on another site), I thought it was a typo and was growling in a fit of distemper. But then I found this, http://www.dummies.com/how-to/conten...mera-lens.html, which seems a reasonable definition. You will notice from the sample pictures (both taken at the same focal length, presumably) that the quality of bokeh is a function of lens characteristics. Based on that definition of bokeh, you have a very nice lens.

    Hope that answers a part of your question, anyway. Apologies if I have been the purveyor of misinformation.

    Janis
    Last edited by purplehaze; 26th October 2010 at 06:58 PM.

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    Moderator Dave Humphries's Avatar
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    Re: Need some help predicting Bokeh results

    Hi Wendy,

    Looking at those claws/talons, I think a gauntlet might be better at "protecting the owner" than you cropping in PP

    Bokeh (to me) is the quality of out of focus detail in an image - usually in the background, I don't see any in #1; it is just an out of focus background. The second is, due to the wider angle of view, containing detail from a far wider background area.

    Descriptions such as 'smooth bokeh' are usually applied to the detail elements, like speculars and whether they have a hard 5 straight sided iris effect or a smoother type formed by say, an 8 curved bladed iris.

    Back to the pictures, I haven't worked out the answer yet and might draw some diagrams, or read stuff online, to figure it out. I can see why you're confused - and now I am too

    EDIT: I've just seen Janis's post and link, not sure I agree with that definition/example that 'a good bokeh lens has no disks'.
    So now I'm even more confused.

    Thanks a bunch,
    Last edited by Dave Humphries; 26th October 2010 at 07:06 PM.

  8. #8
    arith's Avatar
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    Re: Need some help predicting Bokeh results

    Working in IE, Firefox and Safari now; you'll have to get Caregwen to fix it, he was a programmer, I have never had a job like that and don't have a clue about what is going on. It can't be memory, since I didn't see it at all.

    Anyway, now I can see, I can't really see what you mean. The first is more out of focus in the distance, but bokeh is generally nicer if you have curved aperture leaves, and even then it is complicated; on my cheap most expensive lens in the signature, bokeh is better at f4 and above.

  9. #9
    purplehaze's Avatar
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    Re: Need some help predicting Bokeh results

    Quote Originally Posted by Dave Humphries View Post
    Thanks a bunch,
    Again, my apologies. I know naught of what I speak and should take my own advice to the fast food restaurant that advertizes quesadillas as "casadias" and not trust everything I find on the Interwebs.

    Janis

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    Re: Need some help predicting Bokeh results

    Quote Originally Posted by purplehaze View Post
    Hi Wendy,

    Based on my (initial) reading of the tutorial, I understand the difference you see to be attributable to the magnification of the longer focal length.

    As far as the term bokeh goes, when I saw that term for the first time this week (on another site), I thought it was a typo and was growling in a fit of distemper. But then I found this, http://www.dummies.com/how-to/conten...mera-lens.html, which seems a reasonable definition. You will notice from the sample pictures (both taken at the same focal length, presumably) that the quality of bokeh is a function of lens characteristics. Based on that definition of bokeh, you have a very nice lens.

    Hope that answers a part of your question, anyway. Apologies if I have been the purveyor of misinformation.

    Janis
    Hi Janis: No apologies required. I'm kind of with Dave on the part about the disks though. Even by the link's own definition they are wrong. They say " Bokeh describes the points of light in the background that become fuzzy disks when rendered out-of-focus " In the second shot it does not look like there are any points of light to turn into fuzzy disks.

    Soooo, now I'm thinking (and it's important for me to define these terms if I'm going to work on this) that in the example below there are a few spots of Brokeh (disks caused by points of light in the background) and the rest of the background and foreground is just out of focus due to shallow DOF which is what I would expect with f 1.7

    Need some help predicting Bokeh results
    Panasonic Lumix G1: 20mm: 1/100s: f1.7: 20mm: ISO 200

    And the background in this shot is all Bokeh

    Need some help predicting Bokeh results
    Panasonic Lumix G1: 20mm: 1/160s: f3.2: ISO 200

    Conclusion: What I am looking for is not how to get good Bokeh, but how to get a nice blurry background. I am clear on the wide vs narrow lens opening part of things, but now would like to be able to predict how other factors will help me get that nice out of focus background like in the original shot of Daisy.

    As I look more, it is possible I suppose, (but I'm still not 100% convinced on this) that the difference is caused by magnification of the longer focal length. I'm off to try and compare some of my other shots to see if I can come up with some common denominators that make sense.

    Thanks again for the feedback Janis - it got me to sort out the difference between DOF and Bokeh. There may be other definitions but I'm sticking with the quote above from your link, and add to that, that different lenses will reproduce bokeh in different manners some round, some with strait sides, some smooth some harsh, but if the disks are gone altogether then it's not Bokeh. If anyone wants to add to or correct the above, feel free...

    Wendy
    Last edited by ScoutR; 26th October 2010 at 08:43 PM. Reason: added EXIF

  11. #11
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    Re: Need some help predicting Bokeh results

    Quote Originally Posted by purplehaze View Post
    Again, my apologies. I know naught of what I speak and should take my own advice to the fast food restaurant that advertizes quesadillas as "casadias" and not trust everything I find on the Interwebs.

    Janis
    Indeed, no apologies are necessary Janis, I wrote "Thanks a bunch" for Wendy's benefit before I even saw your reply.

    Also I'm not saying you're wrong, just I'm not sure anymore.

    I just found this at Luminous Landscapes, but not sure I'm awak enough to digest it tonight - it's quite technical.

    Cheers,

  12. #12
    Moderator Dave Humphries's Avatar
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    Re: Need some help predicting Bokeh results

    Ah now Wendy,

    The spider shot, well found.
    Need some help predicting Bokeh results
    I'd have said that wasn't great bokeh because of the 7 obvious diaphram/iris blades visible - if they'd been smoother, round disks, that would be "good bokeh".

    Almost any lens should give better bokeh when wide open because the iris leaves all but disappear from view, leaving just a round hole.

    Here's one of mine shot with the Nikon 70-300mm at f/8, but because of the rings, or ripples, inside the (somewhat rounder) disks, this probably isn't too good either.

    Need some help predicting Bokeh results
    Nikon D5000 + Nikon 70-300mm f/4.5-5.6 VR: 1/2000s f/8 iso400 at 300mm

    Cheers,
    Last edited by Dave Humphries; 26th October 2010 at 09:09 PM.

  13. #13

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    Re: Need some help predicting Bokeh results

    LOL, I figured you'd like the spider. At this point I'm not too sure how I feel about bokeh. I'm sure there is good bokeh, but to tell you the truth, I had trouble finding an example in my shots because I usually throw them out. I'm not especially crazy about the bokeh in your shot either, but it's still a good shot because it's not behind the subject.

    I always thought bokeh was usually a good thing, but I identified it as they type of background in my original shot of Daisy, which I am now thinking (like you) is not bokeh at all.

    I suppose the one thing that might be good about bokeh is that if you have to have spots of light filtering through in the background, bokeh might be better than the in focus version, but in my eyes not better than just an out of focus background.

    I'll try to get some more spiders for you one of these days. No bokeh though. I tried a dragonfly once, but they move too fast.

    Wendy

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    Moderator Dave Humphries's Avatar
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    Re: Need some help predicting Bokeh results

    Quote Originally Posted by ScoutR View Post
    I tried a dragonfly once, but they move too fast.
    No, they're easy - when not in flight!

    Dave's mini-guide to Dragonfly shooting;
    1) creep around* with your eyes open when they're about**, you may only see one as it takes off, not to worry
    2) just freeze where you are, wait a couple of minutes and it'll likely come back to the same perch time and again (for hours on sunny day if not disturbed)
    3) each time it flies off to hunt/feed, move an inch or two closer to its perch, when it returns, it'll slowly get used to you being closer, if it doesn't return or seems unhappy landing, just back off a bit and wait, be patient
    4) get comfortable; sit down - you'll be about an hour before you get bored

    * Obviously the usual rules apply - no sudden movements, keep quiet, etc.

    ** Warm to hot sunny days are best, near water; river or pond - I suspect it's too late this year in northern hemisphere as we've had frosts now

    I've only really got one good one in flight, I pre-focused where it kept flying and eventually I got (very) lucky with this;
    Need some help predicting Bokeh results
    1/4000s f/6.3 at 250mm iso400

    As I recall, this was between two tall tufts of grass (about 6 feet high!), so I had a focus aid and a distance judgement all in one, I don't think I was even looking through the V/F, just waiting with finger on button and everytime it flew through 'the gate' formed by the grasses, I rattled off a few shots - most had nothing in.

    Happy hunting,
    Last edited by Dave Humphries; 26th October 2010 at 10:03 PM.

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    Re: Need some help predicting Bokeh results

    Hi Wendy,

    In a nutshell, it's all about ...

    (a) The distance between your camera and subject -v- the distance between your subject and the background. The smaller the camera-to-subject distance and the larger the subject-to-background distance, the more out of focus the background will be.

    (b) Aperture (wider is better, but as you know, it also reduces your DoF).

    (c) Lens focal length (think of it as a "Bokeh Multiplier").

    On a D3000 @ 200mm @ F8 @ 1.1m your DoF is 7mm (so what is well behind is well and truely nuked)

    At 40mm @ F8 @ 1.3m your DoF is 206mm. The background is still OOF, but because you're zoomed out a lot more, more detail is captured, which tends to negate the effect.

    So in summary, use a long lens - get a smaller gap between you and the subject and a bigger gap between the subject and the background - and open up the aperture as much as you dare (but watch the DoF).

    Hope this helps

  16. #16

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    Re: Need some help predicting Bokeh results

    Quote Originally Posted by Dave Humphries View Post
    No, they're easy - when not in flight!

    2) just freeze where you are, wait a couple of minutes and it'll likely come back to the same perch time and again (for hours on sunny day if not disturbed)
    3) each time it flies off to hunt/feed, move an inch or two closer to its perch, when it returns, it'll slowly get used to you being closer, if it doesn't return or seems unhappy landing, just back off a bit and wait, be patient
    Ahaaaa, thanks I will remember this for next year. I'm pretty patient, so that's not a problem, but I didn't think of sneaking up on it like that because I did not notice that they kept coming back, but now that you mention it you are right. I got a chance to try a few shots of one in particular because it did indeed keep coming back to the same spot. I didn't get any closer, because I thought the reason it kept going away was because I was there.

    Thanks
    Wendy

  17. #17

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    Re: Need some help predicting Bokeh results

    Quote Originally Posted by Colin Southern View Post
    Hi Wendy,

    In a nutshell, it's all about ...

    (a) The distance between your camera and subject -v- the distance between your subject and the background. The smaller the camera-to-subject distance and the larger the subject-to-background distance, the more out of focus the background will be.

    (b) Aperture (wider is better, but as you know, it also reduces your DoF).

    (c) Lens focal length (think of it as a "Bokeh Multiplier").

    On a D3000 @ 200mm @ F8 @ 1.1m your DoF is 7mm (so what is well behind is well and truely nuked)

    At 40mm @ F8 @ 1.3m your DoF is 206mm. The background is still OOF, but because you're zoomed out a lot more, more detail is captured, which tends to negate the effect.

    So in summary, use a long lens - get a smaller gap between you and the subject and a bigger gap between the subject and the background - and open up the aperture as much as you dare (but watch the DoF).

    Hope this helps

    Boy did that get copied and pasted to my Cambridge Tips documents quickly.
    Yup, that helps (understatement) it is EXACTLY what I wanted to know and the nutshell format works wonders for me.
    Now I can quit studying EXIF on my old shots, and go and watch a movie.

    Thank you so much
    Wendy

  18. #18
    Moderator Dave Humphries's Avatar
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    Re: Need some help predicting Bokeh results

    Quote Originally Posted by ScoutR View Post
    Now I can quit studying EXIF on my old shots, and go and watch a movie.

    Thank you so much
    Me too, thanks Colin

  19. #19

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    Re: Need some help predicting Bokeh results

    Quote Originally Posted by Dave Humphries View Post
    No, they're easy - when not in flight!

    I've only really got one good one in flight, I pre-focused where it kept flying and eventually I got (very) lucky with this;
    Need some help predicting Bokeh results
    1/4000s f/6.3 at 250mm iso400

    As I recall, this was between two tall tufts of grass (about 6 feet high!), so I had a focus aid and a distance judgement all in one, I don't think I was even looking through the V/F, just waiting with finger on button and everytime it flew through 'the gate' formed by the grasses, I rattled off a few shots - most had nothing in.

    Happy hunting,
    Ooops, forgot to mention in my previous answer. That is a crazy good shot. I won't be trying that for awhile.

    Wendy

  20. #20
    Moderator Dave Humphries's Avatar
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    Re: Need some help predicting Bokeh results

    Quote Originally Posted by ScoutR View Post
    Ooops, forgot to mention in my previous answer. That is a crazy good shot. I won't be trying that for awhile.

    Wendy
    Yes you will if you recognise the behaviour

    I've been going back to the same place on and off for another 15 months since this and I've never seen it happen again

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