User Tag List

Thanks useful information Thanks useful information:  0
Results 1 to 12 of 12

Thread: Can Anyone Explain This ???

  1. #1
    A. P's Culinary Indiscriminant mongo's Avatar
    Join Date
    21 Mar 2009
    Location
    Cronulla, Sydney
    Posts
    8,610
    Mentioned
    12 Post(s)
    Tagged
    0 Thread(s)

    Can Anyone Explain This ???

    Can anyone explain this?? Mongo was testing a ring flash for macro work and noticed the following:-

    Same flower taken minutes apart.
    First flower (with arrow and marked centre of flower) was taken with the ring flash.
    Second flower taken using natural light (no flash).
    Through the viewfinder, the centre of the flower appears as in the second flower i.e.
    the centre of the flower has defined compartments – unlike the first flower (flashed) where the centre of the flower appears fused together.
    All variables were the same but for flash – v - no flash. Even tried different angles etc. Several dozen photos later - still the same!

    If it is only the behaviour of the light when delivered though a flash, then Mongo is in trouble for future flash photos as the non-flash ones are far more accurate.

    As a great physics teacher once said, Why is it so ???
    Attached Images Attached Images
    Nikon and Pentax user



  2. #2
    It's all about the Light!
    Tech Admin
    Kym's Avatar
    Join Date
    15 Jun 2008
    Location
    Modbury, Adelaide
    Posts
    9,641
    Mentioned
    18 Post(s)
    Tagged
    0 Thread(s)
    Angle of incidence? I.e. the angle the flash light is being returned to the sensors vs the natural ambient light.
    regards, Kym Gallery Honest & Direct Constructive Critique Appreciated! ©
    Digital & film, Bits of glass covering 10mm to 500mm, and other stuff



  3. #3
    In Training MarkChap's Avatar
    Join Date
    09 Jan 2008
    Location
    Widgee,
    Posts
    2,255
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Mongo hasn't included the EXIF for the 2 shots

    If "all variables were the same", there has to be adifference as the exposure would be different with the flash versus with out

    The flash version looks very flat, like the flash has provided a light source that is too even across the front of the flower, can you vary the power of one side or other of your ring flash ??
    Smoke Alarms Save Lives, Install One Today
    I shoot Canon
    Cheers, Mark


  4. #4
    Moderately Underexposed I @ M's Avatar
    Join Date
    04 May 2007
    Location
    Marlo, Far East Gippsland
    Posts
    4,911
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    Can we have some more detail on camera settings please?
    Shutter, aperture and white balance used as well as the metering mode.
    Andrew
    Nikon, Fuji, Nikkor, Sigma, Tamron, Tokina and too many other bits and pieces to list.



  5. #5
    Member
    Join Date
    08 Jul 2009
    Location
    Central Coast NSW
    Posts
    132
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    To my eye there is a slight difference in the focus point of the two shots. In the first shot the petals seem more in focus, in the second shot the centre of the flower seems to be the focus point.

    Also, in the first shot the flash has removed a lot of the shadow that was giving form to the centre of the flower.


    If the second shot had been the bad one I would have suspected that Mongo had breathed on it.
    Last edited by Bill44; 07-09-2009 at 4:05pm.
    regards
    Bill

    Nikon D90 with grip. 35mm 1.8G, 50mm 1.8D. 18-105VR. 70-300VR
    SB-600. GF Lightsphere. Stroboflip flash bracket.
    Benro A357 & B2 ball head.
    and a bag full of gadgets.

  6. #6
    Who me?
    Join Date
    02 Sep 2007
    Location
    Tweed Heads
    Posts
    2,749
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    It would be good to see the EXIF, but as Kym said the angle of light from a ring flash will be illuminating the outer areas of the inner part of the flower( if that makes sense) from various angles hence tending to flatten the detail.
    If possible vary the intensity of the ring flash to say 50%-25% and see if that makes a difference
    Cheers David.

    Canon 40D/EF-S 17-85 mm IS/Kenko Extenson Tubes/Canon EF 50mm F/1.8 II (nifty fifty)
    Sigma 10-20mm 4-5.6 /Sigma 70-200/ Sigma 1.4 teleconverter/ some Conkin filters | Adobe Photoshop CS6



  7. #7
    A royal pain in the bum! arthurking83's Avatar
    Join Date
    04 Jun 2006
    Location
    the worst house, in the best street
    Posts
    8,185
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    I think Kym is on the right track about the angle of incidence of the main source of light.

    light in general comes from 'all directions' and produces shadows where appropriate. The petals in the first(flashed) shot have no shadow detail.

    had Mongo used a speedlight/SB type of flash in bounce/remote mode off camera, #1 may have looked more like the second image.
    Nikon D800E, D300, D70s
    {Nikon} -> 50/1.2 : 500/8(CPU'd) : 105/2.8VR Micro : 180/2.8ais : 105mm f/1.8ais : 24mm/2ais
    {Sigma}; ->10-20/4-5.6 : 50/1.4 : 12-24/4.5-5.6II : 150-600mm|S
    {Tamron}; -> 17-50/2.8 : 28-75/2.8 : 70-200/2.8 : 300/2.8 SP MF : 24-70/2.8VC


  8. #8
    Member
    Join Date
    07 Aug 2007
    Location
    Newcastle, NSW
    Posts
    321
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The depth of field is greater with the natural light than with flash
    I'd assume camera selected a higher F Stop value with the natural light.
    Last edited by oldfart; 07-09-2009 at 7:29pm.

  9. #9
    Member
    Join Date
    09 Feb 2009
    Location
    Newcastle, NSW
    Posts
    8,372
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    very interesting Mongo. I might have learned a few things from the troops as well. I don`t have a ring flash....yet.
    Graeme
    "May the good Lord look down and smile upon your face"......Norman Gunston___________________________________________________
    Nikon: D7000, D80, 12-24 f4, 17-55 f2.8, 18-135, 70-300VR, 35f2, SB 400, SB 600, TC-201 2x converter. Tamron: 90 macro 2.8 Kenko ext. tubes. Photoshop CS2.


  10. #10
    A royal pain in the bum! arthurking83's Avatar
    Join Date
    04 Jun 2006
    Location
    the worst house, in the best street
    Posts
    8,185
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Mongo said:

    Quote Originally Posted by mongo View Post
    .....
    All variables were the same but for flash – v - no flash. Even tried different angles etc. Several dozen photos later - still the same!....
    DOF will be the same regardless of the light source.

    the illusion of DOF may be different because of the way the light falls on different parts of the subject.

    the illusion is easy to see if you have a flash that can bounce the light output.

    shoot with the flash head directly at the subject and then bounce it of a reflective surface and the depth of the image changes.. but not the actual DOF(as long as the variables of distance to subject, focused distance and lens values are the same of course).

    One of the reasons I hate flash photography, and would rather use higher ISO values for natural light.

  11. #11
    A. P's Culinary Indiscriminant
    Threadstarter
    mongo's Avatar
    Join Date
    21 Mar 2009
    Location
    Cronulla, Sydney
    Posts
    8,610
    Mentioned
    12 Post(s)
    Tagged
    0 Thread(s)
    Thank you all for your input and ideas. After seeing Kym’s initial message, Mongo went off and played ring flashes again (sorry, that was not meant to sound that way).

    This time he held the ring flash (off lens) at differing angles to the subject and found the results were almost as per the second flower image above which was pretty pleasing. So Mongo thinks Kym had the right idea. If the light is too directly in front and bounces straight back into the lens AND if the light is too even there will effectively be little to no modelling effect and the subject will appear “flatter”.

    Moral of the story :-

    First, ask your comrades in camera at AP for advice;

    Secondly, vary the intensity/output of the light from the flash as between one side of the flash and the other if possible. If not possible within the flash unit itself, then, partly obscure the light coming from one side of the flash to create that difference OR have an additional light source from at least one side to give you that differential in light striking the subject.

    Thirdly, share what you may have learned with those good enough to have tried to assist you and your AP comrades generally.

    Again thanks to all and hope this has been useful.

  12. #12
    Member
    Join Date
    14 Jul 2009
    Location
    NorthWest
    Posts
    723
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    very interesting and useful info, thanks for sharing. As far as the images go though, I actually prefer the flatter first image (with flash) To me it looks more "professional" (sorry dont know how to explain better)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •