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3D Printed and Fiberoptic Ring Flash


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#1 rtrski

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Posted 10 February 2013 - 07:36 PM

Well, first draft is finally finished.

Dropped down from the 10.5mm lightpipes (the focus lamp pipe) to 5.6mm for the strobe light carriers...8 or 9 10.5mm pipes were too stiff. 8 pipes each lamp off the z240 for 16 total. 3D printed the 'cuff' for the port end and the strobe face cover and pipe mount. The strobe face cover attaches to the z240 with stainless hardware using the same threaded holes as the diffuser that comes with the strobe.

This might almost be too much light. Shots at 1/160th, F10-12, ISO400, and the strobe set at minimum manual setting (EV -6.0, 1/64th of full dump) are about as brightly lit as I think I'd want in a dark room. I actually have to use the focus lamp in that condition*. That leaves plenty of headroom for even narrower apertures and/or lower ISOs.

Sending one off to a beta tester in the next couple of weeks, hopefully can get some feedback of things that need changing before my own first dives with it (trip in late April planned).

Pics up at Flickr: http://www.flickr.com/photos/rtrski/sets/72157632741617450/

...using the Ikelite 5505.58 for a Sigma 105mm macro and an Inon Z240 Type IV.

The Saga ring flash (certainly much better built, with more but much smaller fibers - no idea of relative light transmission) runs something like 800 euro I think. This one, if I chose to sell it, would come in at significantly less than half that, if there was any interest. Will await my beta tester's comments and my own experiences in April before I consider it for real....but feel free to PM me if you just must. Posted Image

[* My camera is the Sony SLT-a55, which was from their first generation SLT's with the electronic viewfinder (EVF). These cameras have a 'helpful' feature that takes into account the exposure settings and darkens or brightens the view in the viewfinder accordingly, kind of a pre-shot preview or 'what you see is what you get'. UNFORTUNATELY the camera doesn't know when you have a manually attached strobe (no TTL communication)...so manual settings like the above result in a black viewfinder, although the camera has plenty of light to autofocus etc. The SLT generations that followed have a menu setting to turn off this 'help' in the EVF so it always shows a reasonably ambient picture (I don't think they cared/thought about underwater phtogs but studio photogs sure complained that the first generation didn't work with remotely triggered strobes), but mine alas does not, hence I get to use the focus light under circumstances like this. I may have to adjust a subsequent build of this part to have fewer pipes and provide a little less flash (and just don't get to dial the strobe down as much).]

Edited by rtrski, 10 February 2013 - 07:37 PM.

Current rig: Sony SLT-alpha55 in Ikelite housing, Sigma 105mm f2.8 DC Macro w/ Ike 5505.58 flat port or Sigma 8-16mm f/4.5-5.6 DC HSM behind UWCamStuff custom 5" mini-dome. Dual INON z240 Type IVs triggered with DS51 for TTL mimicry, or DS51 alone with home-made ringflash assy for macro.

 

Topside, unhoused: Sony SLT-alpha99, Sigma 150-500mm + 1.4TC (Saving for Sony 70-400 G2), Sigma 15mm diagonal fish, Sony 24-70mm f2.8 CZ, Tamron 180mm f2.8 Macro...all the gear and nary a clue...


#2 ProfF

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Posted 14 February 2013 - 02:44 AM

Very nice.

My experience with such devices (built based on previous posts in this forum), is that light transmission efficiency is a key issue. The second thing that worries me is ability to light very close objects (e.g., super macro shots) when using the Subsee+10 diopter, or when you want dark background. The Saga product provides ability to tilt the fibers that can deal with a range of subjects.

Can you give some info on the design?

thanks!
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#3 rtrski

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Posted 14 February 2013 - 09:56 AM

This particular design doesn't have the Saga's adjustability for supermacro. For that, I'd go to smaller lightpipes and more of them, extend further forward, and support on the outer surfaces with some arcs of plastic to help guide them into the right shape. And I'd have to rig some adjustability, or at least design with enough slack the user could 'manually' pull them to the desired length forward of the lens as part of the dive setup. Or....I'd design a totally different fixed system. If you're set up for supermacro that already implies a lens, dipopter or teleconverter, and port combination...why dive with some big thing that's a jack of all trades? Supermacro needs far less light in a much tighter area, and 3D printing makes a customized arrangement cheap enough to build.

For light transmission in 'standard' macro conditions, which is all this is currently designed for - I'm seriously not worried. I honestly have too much, and am seriously looking at pruning down the fiber count from where it stands now. (The illuminated picture in the slideshow from the original post is with the focus lamp on - even though the other fibers are up against the flash tubes, there's enough leakage along the curved glass face of the z240 to see them lit up too.)

I'll try to get some pics of this thing lighting off the strobe...I think if I take a shot with an external camera with a flash set to minimum, just to let it optically fire the z240, I can get the illumination of the lightpipes from the z240 flash in the frame. Mirror tests shot from the housed camera with a macro lens of course just show what I'm focusing on in the middle (e.g. reflection of my own wristwatch in the mirror).

As for a true black background underwater, I think of that as more of either a) a snoot thing, where you really control the light footprint, or b) related to your exposure duration. My current system can't sync at faster than 1/160th so black backgrounds are fairly impossible for me anyway with flash. I've gotten them from say very brightly-lit (sunlit) flowers shot with big apertures and the fastest exposure I can manage, but that was because the original subject was very high contrast to begin with.

I could also wrap the pipes with black, but so far my experiments don't seem to indicate it's needed much. The vast majority of the transmission is from the lenses (cut ends); if I do think after a 'dip the port in a tub' test that I'm seeing too much side transmission from the short fiber stubs forward of the port, it's quick work to shrink-tube them in black. I was actually considering doing that just for a looks/quality feature anyway, before sending off for beta test.

The actual 3D print design is fairly easy after the design, aside from things you probably already know about (dinking around with settings to get internal holes the dimension you want, e.g. for me a 5.6mm fiber fit in a hole 'designed at' 6mm since its really being printed as an inscribed polygon, and there's some tolerance as the plastic squishes together). The strobe faceplate just holds the fibers and provides alignment to mate them up directly to the flash tubes (and focus lamp), and uses the same threaded holes that the z240's diffuser would for some stainless attach hardware. The port section is just most of a ring with the fiber supports printed separately and fused on (it may not be obvious from pictures, but the fibers are angled inward about 15-18 degrees from 'parallel' to the lens axis). It's inner face (not visible) has notches in it that match the ridges on the perimeter of the Ikelite port, which keeps it from rotating (and means you want the port oriented right, but that's just friction on a greased o-ring to twist gently at the surface before it's under pressure). There's no fancy 'lensing' at the fiber tips, I just cut them off as cleanly as I could with a good sharp razor knife. My earlier designs considered an actual physical diffuser (and I even bought clear printable plastic to make it) but as the process went on it became clear it wasn't necessary.

Edited by rtrski, 14 February 2013 - 09:59 AM.

Current rig: Sony SLT-alpha55 in Ikelite housing, Sigma 105mm f2.8 DC Macro w/ Ike 5505.58 flat port or Sigma 8-16mm f/4.5-5.6 DC HSM behind UWCamStuff custom 5" mini-dome. Dual INON z240 Type IVs triggered with DS51 for TTL mimicry, or DS51 alone with home-made ringflash assy for macro.

 

Topside, unhoused: Sony SLT-alpha99, Sigma 150-500mm + 1.4TC (Saving for Sony 70-400 G2), Sigma 15mm diagonal fish, Sony 24-70mm f2.8 CZ, Tamron 180mm f2.8 Macro...all the gear and nary a clue...