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Thread: Why am I getting multiple whiskers?

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    Why am I getting multiple whiskers?

    I am shooting a Contax 645 with P30+ shot at 35mm, f/8, 1/60 sec, ISO 800. Here is a resized full frame:


    And here is a 100% crop of the whiskers. Why are there 3 distinct lines for each whisker? I understand that there may have been movement of the whiskers during the exposure, but I would expect to see just a blur instead. By the way, he really does have "bent" whiskers; it's his breed.
    Last edited by tom in mpls; 7th May 2012 at 19:28.

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    Re: Why am I getting multiple whiskers?

    Tom,
    Just offhand, I would say that looks like motion blur on the whiskers. At your shutter speed, that would not be unlikely in this case. My reasoning for suggesting this, is that the "multiples" look more pronounced at the end of the one whisker you have highlighted, while there appears to be less motion closer to the cat's face on that same whisker. Just my first observation. Things like that do have more motion than we think, and your rig is clearly catching it.

    LJ

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    Re: Why am I getting multiple whiskers?

    I'd say motion blur, combined with the translucent nature of the whiskers.

    Oh, and awesome cat!!!

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    Re: Why am I getting multiple whiskers?

    Tom,
    The only other thing that comes to mind with this motion blur is what the bit-depth settings may be. In other words, the more distinct lines for the whiskers could be related to the number of exposures taken with the CCD to get a higher color bit depth. I am not sure how this is handled/resolved on these backs, but it might be a contributing factor.

    LJ

    P.S. One last thought....the P30+ and P21+ backs are the only ones that have microlenses. I am wondering if there was some sort of prismatic effect from how the microlens handled that bright line movement during the exposure. I am just fishing here, but do not know of other possible explanations on how you would get distinct lines of the whisker versus the smoother blur one might expect with motion. There have to be some separate, but very closely spaced exposure captures (bit depth idea), or some very distinct prismatic effect that delivers separate lines (microlens idea). There could be something else at work, but I am clueless as to what that might be.
    Last edited by LJL; 23rd March 2008 at 10:53.

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    Re: Why am I getting multiple whiskers?

    Tom,
    I'll go with LJ and say motion blur. Simple to test, take another shot with lights and kick up the shutter speed.

    David

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    Re: Why am I getting multiple whiskers?

    Quote Originally Posted by David K View Post
    Tom,
    I'll go with LJ and say motion blur. Simple to test, take another shot with lights and kick up the shutter speed.

    David
    I'm certain it is motion blur. It came as a surprise to me that it appears as rather distinct lines rather than a "smear".

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    Re: Why am I getting multiple whiskers?

    I've long since stopped worrying about the optics (and I am a trained physicist!) and just acknowledge that artifacts come in.
    Ever close you eyes after and see a residual image? Note is doesnt 'smear'
    well the man is good at processing out in the brain. Not so dsensors; there is the bayer matrix, scanning overlap, sharpening algorithms etc. Note that the 'non vibrating whisker at top also has '3 lines'

    It likely can be explained, but the bottom line is that it is not a problem

    as tyhe doc says, when you say "Ity hurts when I xxx..."
    he says
    "Don't XXX...!

    Tell the cat not to shake its whiskers the next time you want a portrait!

    Regards
    Victor

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    Re: Why am I getting multiple whiskers?

    It doesn't worry me, but it does pique my curiosity.


    BTW it is easily visible on the print as well.


    I will ask Joey to sit more quietly next time, I'm sure he will be cooperative!

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    Re: Why am I getting multiple whiskers?

    "...A cat has about twenty-four movable whiskers, twelve on each side of its nose (some cat's may have more). Whiskers are more than twice as thick as ordinary hairs, and their roots are set three times deeper than hairs in a cat's tissue. Richly supplied with nerve endings, whiskers give cats extraordinarily detailed information about air movements, air pressure and anything they touch.

    The scientific word for whiskers is vibrissae, a name that suggests their exquisite sensitivity to vibrations in air currents. As air swirls and eddies around objects, whiskers vibrate too. Cats use messages in these vibrations to sense the presence, size, and shape of obstacles without seeing or touching them. Whiskers are also good hunting tools. A cat whose whiskers have been damaged may bite the wrong part of a mouse it's attacking, indicating that signals from these delicate structures provide cats with vital information about the shape and activity of its prey - interestingly, whiskers also help cats smell odours..."

    Looks like you are looking into the structure. The center may actually be a cavity with nerves

    Victor

    Ps have you seen this site

    http://www.catswhiskersphotography.co.uk/shape.htm

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    Re: Why am I getting multiple whiskers?

    All very interesting, but it still does not explain why the image shows the distinct recording of the vibration or whatever the cat is doing. That motion has been captured by the sensor. Is it from multiple exposures by the CCD for color bit depth? Is it diffraction of some sort? (Looks too distinct for that.) Is it the result of something with the microlenses? I did not think these sensors had much in the way of AA filters, so could it just be refraction/reflection off the cover glass? Why not the entire wisker? Whatever is going on, it was caught three times within the 1/60s exposure, and it is most visible at the distal end of the whisker that would have the most movement.

    Would be nice to know what has caused this.

    LJ

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    Re: Why am I getting multiple whiskers?

    Tom: a possibility... Maybe some fluorescent lights were on nearby which often cycle faster than normal hhld current? The best are up around 20K Hz, so they wouldn't strobe the moving whiskers into three over 1/60th sec, but lesser ones fire at more like 120 or 240 and might cause this very effect... (A white Ott style viewing light also strobes faster than hhld...)
    Jack
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    Re: Why am I getting multiple whiskers?

    jack, i would agree except it really looks like natural light coming from a large glass patio door or something. check the catchlights. i am inclined to think that this is motion blur caused by natural vibration of whiskers.

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    Re: Why am I getting multiple whiskers?

    Maybe it's motion combined with double-line bokeh?

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    Re: Why am I getting multiple whiskers?

    Quote Originally Posted by Maggie O View Post
    Maybe it's motion combined with double-line bokeh?
    double-line bokeh with a 35mm distagon? not possible besides, whiskers are in the plane of focus.

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    Re: Why am I getting multiple whiskers?

    Why is that not possible?

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    Re: Why am I getting multiple whiskers?

    Quote Originally Posted by Jack Flesher View Post
    Tom: a possibility... Maybe some fluorescent lights were on nearby which often cycle faster than normal hhld current? The best are up around 20K Hz, so they wouldn't strobe the moving whiskers into three over 1/60th sec, but lesser ones fire at more like 120 or 240 and might cause this very effect... (A white Ott style viewing light also strobes faster than hhld...)
    Excellent suggestion, Jack, but this was natural light from the window as irakly correctly noted.

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    Re: Why am I getting multiple whiskers?

    Quote Originally Posted by Maggie O View Post
    Why is that not possible?
    because this lens never does anything of this kind. i use it almost every day.

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    Re: Why am I getting multiple whiskers?

    Quote Originally Posted by irakly View Post
    because this lens never does anything of this kind. i use it almost every day.
    So it's a lens that renders everything in focus, all the time?

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    Re: Why am I getting multiple whiskers?

    maggie, please

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    Re: Why am I getting multiple whiskers?

    Quote Originally Posted by Maggie O View Post
    Maybe it's motion combined with double-line bokeh?
    Maggie, I don't know what double line bokeh is, but in this case it would need to be triple line bokeh. I see three distinct images of each whisker.

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    Re: Why am I getting multiple whiskers?

    anything that vibrates with sinusoudal motion will spend more time at the ends. Ever look at a vibrating object? You actually SEE the object, though slightly blurred at each end. It travels faster between ends.

    The fluorescent idea not bad, but I dont see any fluorescent lights.

    it is simple motion blur. Since the perisisence of vision is about 1/20 to 1/40 the human eye actually integrates like a camera. or vise versa!

    What you are seeing is the whisker- at the two ends of its vibration path, as recorded by the camera.

    Victor

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    Re: Why am I getting multiple whiskers?

    Quote Originally Posted by gogopix View Post
    What you are seeing is the whisker- at the two ends of its vibration path, as recorded by the camera.
    Victor, the sinusoidal curve idea has some appeal, but again I must ask why I see 3 distinct images of each whisker, not 2.

  23. #23
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    Re: Why am I getting multiple whiskers?

    Could you upload a crop of the entire head?

    Thierry

    Quote Originally Posted by tom in mpls View Post
    Victor, the sinusoidal curve idea has some appeal, but again I must ask why I see 3 distinct images of each whisker, not 2.

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    Re: Why am I getting multiple whiskers?

    Quote Originally Posted by tom in mpls View Post
    Victor, the sinusoidal curve idea has some appeal, but again I must ask why I see 3 distinct images of each whisker, not 2.
    The whisker has a brighter edge. It is just vibrating about a distance of twice the thickness. you are not seeing three, just the two at the ends of the vibration. Other whiskers seem to have three bright bands even when they ARE in focus. Could be just they are semi transparent . Look at a transparent strw from the side and it will look similar.

    notice other things, like it is widest at the ends of the whisker. The inner part isnt vibrating or it is less

    trying to explain all the artifacts will drive you crazy.

    1. Whiskers vibrate
    2. When they do, you see them at the extremes
    3. you see them at the extremes

    QED

    wiggle a pencil in your hand-it will look just like the whisker.

    BTW, the whisker is pointed at the ends (observe a few) and also is flat (notice a few that twist-some seen edge on others side. So if they are semitransparent, a little flat (or have some other non round cross section) and taper to a point there will be different manifestations

    just as seen.

    Also if that is a 100% crop on my screen (30'' 2650x1600) there are 10's of pixels across this feature. It will not be a bayer matrix or SW artifact. Gotta look at the optics.
    Last edited by gogopix; 16th April 2008 at 06:23.

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    Re: Why am I getting multiple whiskers?

    Quote Originally Posted by thsinar View Post
    Could you upload a crop of the entire head?

    Thierry
    Mine? his? or the cat's?


  26. #26
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    Re: Why am I getting multiple whiskers?

    the 3, since they are 3 visible whiskers!



    Thierry

    Quote Originally Posted by gogopix View Post
    Mine? his? or the cat's?


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    Re: Why am I getting multiple whiskers?

    Quote Originally Posted by thsinar View Post
    the 3, since they are 3 visible whiskers!



    Thierry
    Touche'

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    Re: Why am I getting multiple whiskers?

    http://education.vetmed.vt.edu/Curri...ab15/Lab15.htm

    more than ANYBODY wanted to know about animal whiskers!

    Note in the image that the hairs have just the features shown, that is, they have a hollow look and appear to have structure. These are likely the things seen

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    Re: Why am I getting multiple whiskers?

    Quote Originally Posted by irakly View Post
    maggie, please
    What?

    I honestly don't know how you could say a lens never does OOF bokeh. You've given me two, somewhat snotty, non-answers to a sincere question. If you think conversing with me is beneath you, at least have the dignity to just not reply, instead of being condescending and obtuse.

    I'll stay out of the MF forum, as stupid 35mm shooters like me are obviously not wanted. Or is it that I'm female?

    Sorry for posting here. I'll leave now.

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    Re: Why am I getting multiple whiskers?

    maggie, i never said that this lens does not have oof bokeh. i said that it never produces a double image when defocused. these lenses just do not do that. and that's why (partly) they are so wanted. it is just your questions sounded like you were pulling my leg
    90% of my students are female, and i've always said that on average women make much better photographers than men.

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    Re: Why am I getting multiple whiskers?

    Hey, guys and gals! Can we call a truce and get back to the puzzle of the multiple whiskers? Although not the biggest issue in photography today, I think my whisker pic has posed a fun problem for us to consider.

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    Re: Why am I getting multiple whiskers?

    I am with you on this, Tom. There are some things that I would really like to understand about what may, or may not be happening here. We can all agree to motion in the whisker, but few explanations seem to cover the multiple line part.

    LJ

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    Re: Why am I getting multiple whiskers?

    the multiple lines ar just the hair structure being seen since it is semi transparent. Look at any transparent vs solid tube and you will seen similar features.
    or..

    the cat is really..

    an ALIEN!!!!!!!!!!

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    Re: Why am I getting multiple whiskers?

    Quote Originally Posted by gogopix View Post
    the multiple lines ar just the hair structure being seen since it is semi transparent. Look at any transparent vs solid tube and you will seen similar features.
    or..
    Victor,
    That seems plausible for the main body of the whisker that is showing less movement, but it really does not seem to explain that distal end part having three very distinct terminus lines. Maybe there is some optical illusion (or optical contusion more likely) that is taking place. The transparency issue/illuminated tube does not seem to hold up there, unless the end of the whisker is bent back on itself or in some way that we cannot see. Still seems a bit odd to me, and why I had originally postulated both multiple shots for increased color bit depth, and a possible microlens shift issue....both of which could apply to this particular back. That did not seem to resonate with any of the experts here.

    LJ

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    Re: Why am I getting multiple whiskers?

    WINNER of the wackiest thread title anywhere on the Internet.

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    Re: Why am I getting multiple whiskers?

    folowed of course by the dullest, sanest, academic scientific discussion.

    :sleep006:

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    Re: Why am I getting multiple whiskers?

    Quote Originally Posted by BJNY View Post
    WINNER of the wackiest thread title anywhere on the Internet.
    Thank you. I took some time trying to come up with an intriguing and amusing, yet relevant and succint, title with the hope that people would say, "gotta look at this one, what the heck does it mean?"

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    Re: Why am I getting multiple whiskers?

    And you have two pages of discussion so far (1.5 if we exclude the sidebars), but still no definitive answer......

    LJ

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    Re: Why am I getting multiple whiskers?

    tom, this is really easy. feline whiskers oscillate. there is a middle point where they stop and two extremums where they change direction. that's exactly what you caught. i don't remember exact biology of it since it was a long time ago, but this is what happens.

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    Re: Why am I getting multiple whiskers?

    Quote Originally Posted by thsinar View Post
    Could you upload a crop of the entire head?

    Thierry
    here's the link:
    http://www.pbase.com/sparkytom/image/95738337.original

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    Re: Why am I getting multiple whiskers?

    Actually Maggie could be correct when she refers to double-line bokeh. This is looking pretty bad too: http://forum.getdpi.com/forum/showth...ed=1#post21286
    Jack
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