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UVF Tonic Water: High speed flash - red highlight

Fluorescence UV Lighting
6 replies to this topic

#1 Adrian

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Posted 20 September 2018 - 15:14

I wonder if anyone might have any ideas on this please? I have been shooting some short duration flash images for a new book, of tonic water being poured into a glass.
Every image has a red catchlight, whatever the position of the flashes, even those shot without the pouring.

Technical details:
2 x Metz 45CT1 flash guns with UV absorbing window removed, and replaced with one half of an old Kodak 18A "Wood's Glass" filter (I have checked, this is light tight)
Camera: Nikon D800 with 105mm micro-Nikkor. 1/160th @ f/11. Flash duration approx. 1/2,000th second.
Thanks for looking!

Attached Images

  • Attached Image: UVF Tonic lo res.jpg

Adrian Davies
www.imagingtheinvisible.com

#2 JMC

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Posted 20 September 2018 - 16:23

I would guess that is the reflection of the red end of the flash coming through the Woods lamp glass, and reflecting off the drinking glass.

#3 Andrea B.

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Posted 20 September 2018 - 18:08

Make sure these D800 settings are OFF.
  • Custom Setting Menu > a Autofocus > Focus point illumination
  • Custom Setting Menu > a Autofocus > Built-in AF-assist illuminator
I know you are probably not using autofocus. I was just trying to find all sources of camera light which might interfere with the image.

Also, sometimes light leaks through the viewfinder. Close the viewfinder shutter after you have set up the shot.

Are you using a flash? Some flashes have little "ready" lights which you might need to block.

***

I want to see the tonic water splash dramatically !!!! :lol:

.
Andrea G. Blum
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#4 nfoto

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Posted 20 September 2018 - 19:58

Something like this, perhaps?

Attached Image: T1111057698.jpg
Bjørn Birna Rørslett, Ph.D.
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#5 Adrian

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Posted 21 September 2018 - 08:38

Thank you for your replies. I think I have sorted the problem of the red catchlight - a tiny hole in the tape holding the 18A filter onto the flash.
Andrea, my main objective is to recreate Harold Edgerton's famous milk splash image in high speed UV. Not sure if the Metz flash guns can go fast enough. I will keep you posted!
Adrian Davies
www.imagingtheinvisible.com

#6 Andy Perrin

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Posted 21 September 2018 - 14:04

Wow, high speed UV! That is a challenge and a half.

#7 Andrea B.

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Posted 22 September 2018 - 18:10

a few Xenon lamps??
Andrea G. Blum
Often found hanging out with flowers & bees.