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UV - flowers

Discussion in 'Black and White' started by tbyork2012, Jun 7, 2013.

  1. tbyork2012

    tbyork2012 Mu-43 Veteran

    213
    Nov 14, 2012
    Oxford, UK
    Hi,
    Some new flowers to share.

    Bidens spp
    Vis (flower was swaying in the wind):
    8978168140_65e0b091c1_b_d.

    UV:
    8976975027_2bf035cff0_b_d.

    Osteospermum spp
    Vis:
    8977006715_2ca402802d_b_d.

    UV:
    8978188520_732b8008bd_b_d.

    Looks like (correction: this is Caltha Palustris. Thanks, Klaus for the ID)
    Vis:
    8976986865_4c245712c3_b_d.

    UV:
    8976992547_c4672554fc_b_d.

    Pics resized for easier viewing.
    BT
     
  2. Kpfeifle

    Kpfeifle Mu-43 Regular

    Love these...very nice captures! How did you do the UV shots, did you just use a filter?

    Kevin

    Sent from my SPH-D710 using Mu-43 mobile app
     
  3. tbyork2012

    tbyork2012 Mu-43 Veteran

    213
    Nov 14, 2012
    Oxford, UK
    Thanks. I used my full-spectrum E-PL5 and Baader U filter. I actually used a modded Olympus FL-36R to do the UV shots. I used TTL flash with compensation + 1.3 EV to compensate for the exposure in UV, as the tendency is for the camera to underexpose in UV.
    BT
     
  4. Cruzan80

    Cruzan80 Mu-43 All-Pro

    Aug 23, 2012
    Denver, Co
    Sean Rastsmith
    Any chance of putting up slightly smaller pictures? Right now, I get part of one petal on the screen.
     
  5. RobWatson

    RobWatson Mu-43 Hall of Famer

    Never measured the spectrum of a flash ...

    Ever consider using a UV wand or flash light? 365nm is as low as I'd go but something in the 380-420nm range would not be overly dangerous. Still use eye and skin protection tho.
     
  6. tbyork2012

    tbyork2012 Mu-43 Veteran

    213
    Nov 14, 2012
    Oxford, UK
    As can be seen, the FL-36R does output enough UV (wide bandwidth) to do imaging. I would not use the UV torch (narrow bandwidth) for imaging, only for lighting to adjust and confirm focus, as it produces a monotonous image with less colour. I tend to shut my eyes when pressing the shutter button as extra protection. In general the light is pointed away from me towards the flower. BTW, what is a UV wand?
     
  7. slothead

    slothead Mu-43 All-Pro

    Aug 14, 2012
    Frederick, MD
    Thanks for shrinking these Boon.
     
  8. RobWatson

    RobWatson Mu-43 Hall of Famer

    Something like one of these.
     
  9. tbyork2012

    tbyork2012 Mu-43 Veteran

    213
    Nov 14, 2012
    Oxford, UK
    The UV wands are still output fairly narrow-band UV, so will result in more monotonous UV images. Bulky as well. But I did look at these in the past and decided they were not suitable for UV-imaging, and my 365nm Nichia-chip UV torch is compact and light and can light up the subject well enough to aid liveview focusing.
     
  10. Capt T

    Capt T Mu-43 Regular

    45
    Aug 8, 2010
    Looks good tbyork. Are you using the flash so you don't have to worry about stacking filters to eliminate the IR? Have been reading up on the UV side of things. Just have a B&W 403 so far.
     
  11. tbyork2012

    tbyork2012 Mu-43 Veteran

    213
    Nov 14, 2012
    Oxford, UK
    Hi Tam,
    I tend to use the Baader U, so no worries about IR-leak with UV-imaging. The use of the flash was so I could use TTL to adjust exposure and also to give UV-light output which is continuous (rather than narrow-band) to mimick the sun. The UK tends to be very windy and makes it difficult to shoot longer exposures using sunlight, due to subject swaying in the wind.

    If you have a B+W 403, I suggest you get the S8612 to stack with, as it will block sufficient IR so you can image in UV as well, but lets through more UV than the BG38/39/40.

    Boon
     
  12. RobWatson

    RobWatson Mu-43 Hall of Famer

    Maybe ... have you actually measured or seen the output spectra of the Nichia versus Hg bulbs+UG glass? You might be surprised. Depending on exactly which led is in your torch the datasheets are fairly informative. I only have UG5 glass covered illuminators and they are quite broad spectrally.
     
  13. tbyork2012

    tbyork2012 Mu-43 Veteran

    213
    Nov 14, 2012
    Oxford, UK
    I have seen the curve for the Nichia-chip UV torch and it is very narrow-band indeed. I'm sure the UV-wands have wider bandwidth than this, but they still cannot compare with the Xenon flash (which is close to the sun in terms of producing continuous spectrum UV lighting) - I do not use any UG glass with the flash.
     
  14. RobWatson

    RobWatson Mu-43 Hall of Famer

    Depending on the manufacturer the bulbs used in the UV light boxes can vary quite a bit but the UG glass is fairly reliable. These bulbs are Ushio F8T5BL and are pretty strong around 365nm.

    UG5_365nm.

    Vertical axis is transmission and horizontal is wavelength in nm. My spectrometer is not so great ...

    Except the NIR the spectrum is pretty close to those of the Nichia LEDs I've seen.
     
  15. Capt T

    Capt T Mu-43 Regular

    45
    Aug 8, 2010
    Thanks Boon

    Am looking at this filter to add to it. I see this same seller offers the two filters in one mount as well...for $200
     
  16. tbyork2012

    tbyork2012 Mu-43 Veteran

    213
    Nov 14, 2012
    Oxford, UK
    Is the curve you've shown what you measured from your bulb + UG5, or is it just the UG5 transmission curve?
     
  17. RobWatson

    RobWatson Mu-43 Hall of Famer

    Good catch. That is just the UG5 glass.

    This is UG5 with Ushio F8T5BL (red-365nm) and cheapo off brand G8T5E (blue-supposedly 302nm) bulbs.

    UG5Bulbs.
     
  18. tbyork2012

    tbyork2012 Mu-43 Veteran

    213
    Nov 14, 2012
    Oxford, UK
    Thanks for that. The output does look narrow-band just like the Nichia-chip 365nm UV torch. The colour rendition will be more monochrome than the Xenon flash, and will also require longer shutter speeds to achieve sufficient exposure compared to the Xenon flash. I will need to take an image with the Nichia-chip torch to illustrate the difference in colour from the Xenon-lit UV image.
     
  19. tbyork2012

    tbyork2012 Mu-43 Veteran

    213
    Nov 14, 2012
    Oxford, UK
    Just to illustrate the difference in colour rendition using Xenon flash vs Nichia-chip 365nm torch.

    Nichia-chip torch:
    9052391310_3d8b91cf43_b_d.

    Xenon flash:
    9052382392_7cd44313d8_b_d.

    As you can see the narrow-band UV torch results in a more monochromatic appearance to the flower, compared to the Xenon flash lit flower.

    Boon
     
  20. kds315

    kds315 Mu-43 Regular

    149
    Apr 6, 2010
    Weinheim, Germany
    Nice results Boon!

    I full agree on narrow-band vs Xenon UV lighting. A broadband light source delivers much better images in terms of (false) UV colors, yet has much higher requirements towards the lens. Monochrome UV imaging on the other hand can lead to quite higher resolved images, lens permitting.