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Water drop photography and Sony flashes

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cortell View Drop Down
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Post Options Post Options   Quote cortell Quote  Post ReplyReply Direct Link To This Post Topic: Water drop photography and Sony flashes
    Posted: 16 January 2021 at 16:07
Hi all

Iíve been giving water drop photography a go recently using a Miops Splash. Had pretty good success so far once i figured out the basic parameters.

Iím using an A7iii and three Sony flashes - 2 HVL F43Ms and one F43AM. I also happen to have 2 F58AMs but these only go to 1/32 power setting and I noticed a little bit of movement. The F43s can go to 1/128 although I generally stick at 1/64 as this provides a nice balance of duration and light. I have a few questions:

1. Does anyone know what the flash duration is at the various power settings of these flashes. I have some generic numbers but canít find the numbers for Sony flashes.
2. I also canít find the T.5 and T.1 specs anywhere either. Does anyone know them for these flash units?
3. Whatís the hot shoe trigger voltage for the flash units. Again Iíve searched and canít find it.
4. The Miops Splash can trigger either the camera or the flash. So far iíve been using the camera trigger with all the flashes firing in wireless mode (using an F20M as the master) I want to try using flash trigger mode, where you set the camera to bulb mode and the Miops fires the flash, this eliminates any shutter lag. This doesnít appear to be so straightforward with the Sony flashes but that might be my ignorance. I have adapters with PC sync sockets so could wire the flashes in parallel and fire them all that way. I could buy a wireless trigger and some receivers and connect the Miops to the trigger and it then fires the flashes. Or thereís another way to do it I am overlooking. Any recommendations on how to achieve this?


Thanks
 



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Miranda F View Drop Down
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 16 January 2021 at 23:05
I don't know what the flash duration is, but you might be able to measure it with an old film camera with a focal plane shutter (most SLRs).
The idea is to set the flash on manual exposure and trigger it with the film camera on a high shutter speed setting where the blinds follow one another (at speeds above the flash sync speed). then measure the portion of the image that is light and dark. If the flash sync speed is 1/125, then at 1/1000, 1/8 of the image is exposed at any instant. Count the eighths exposed ...

Edit: From the Sony website the duration at full power is 4.5mS. I would assume for a first approximation that the flash duration is proportional to power, so for 1/64 power the duration would be 4.5/60mS = 70uS. However at that low power setting the rise and fall times are probably significant so the pulse is likely to be triangular, not square (flat-topped) - so the exact duration will vary according to the height (light level) you measure it.
Have a look at M Hoehners flash pages

Edited by Miranda F - 16 January 2021 at 23:17
Miranda F & Sensorex, Sony A7Rii, A58, Nex-6, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras ...
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Tue Romanow View Drop Down
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Post Options Post Options   Quote Tue Romanow Quote  Post ReplyReply Direct Link To This Post Posted: 17 January 2021 at 09:07
I've been working quite a bit with the Miops Splash and my flashes. I started out with bulb and triggering the flashes with the Miops through a radio-trigger. I use a couple of Godox V860II's and an AD200Pro with the X1t trigger. It makes it a lot easier because you don't have to worry about cables if you need to move the flashes during the shoot. Cables, live flash units and water in a mostly dark room invites all sorts of trouble. Just trust me on that.

Nowadays I mostly let the Miops trigger the camera and the camera triggers the X1t. You can compensate for shutter lag in the Miops App. The upside of this method is of course that you don't need to think about ambient light pollution even though you're working in a light environment.
There's no such thing as too many lenses.
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cortell View Drop Down
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Post Options Post Options   Quote cortell Quote  Post ReplyReply Direct Link To This Post Posted: 17 January 2021 at 12:51
Thank you. Iíd forgotten about the wealth of info on his site. Most useful.

The Miops kit is pretty good. What I found with the shutter lag compensation setting is that it was helpful with the A77ii but made no difference with the A7iii (setting it to extremes to see what difference it actually made) The other thing I noticed is the A77ii is less consistent than the A7iii where once I had got all the parameters about right I could get a collision pic almost every time. I just figured eliminating the shutter lag as a variable would be one less thing to consider.

I also happen to have the Sony twin flash macro kit and got really good results with this. Thereís a bit less flexibility of course and it had been a while since i had used it.

Iím happy enough with the results so far just using water. I have some thickening agents to try and different liquids like milk etc.

Edited by cortell - 17 January 2021 at 12:56
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Tue Romanow View Drop Down
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Post Options Post Options   Quote Tue Romanow Quote  Post ReplyReply Direct Link To This Post Posted: 17 January 2021 at 14:23
When everything is properly adjusted I get very consistent collisions, too.

The fun really begins when you start adding stuff to the water. I've used xanthan gum, detergent, inks, acrylics, watercolours, milk, cream and what not. It's absolutely fascinating to see how changing surface tension or viscosity can radically change a collision between a few drops..however messy it gets.
There's no such thing as too many lenses.
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Petrochemist View Drop Down
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Post Options Post Options   Quote Petrochemist Quote  Post ReplyReply Direct Link To This Post Posted: 27 January 2021 at 13:03
Originally posted by Miranda F Miranda F wrote:

I don't know what the flash duration is, but you might be able to measure it with an old film camera with a focal plane shutter (most SLRs).
The idea is to set the flash on manual exposure and trigger it with the film camera on a high shutter speed setting where the blinds follow one another (at speeds above the flash sync speed). then measure the portion of the image that is light and dark. If the flash sync speed is 1/125, then at 1/1000, 1/8 of the image is exposed at any instant. Count the eighths exposed ...

Edit: From the Sony website the duration at full power is 4.5mS. I would assume for a first approximation that the flash duration is proportional to power, so for 1/64 power the duration would be 4.5/60mS = 70uS. However at that low power setting the rise and fall times are probably significant so the pulse is likely to be triangular, not square (flat-topped) - so the exact duration will vary according to the height (light level) you measure it.
Have a look at M Hoehners flash pages


Most small flash units quench the flash to reduce power, so that lower power flashes are indeed faster, but this isn't the case for some studio flashes. I've heard some actually provide a longer flash at low power!
That link's interesting & will take some time to study.
I'd expect the typical full power pulse to be more of a skewed Gaussian (bell shaped) than either triangular or flat topped but I've never seen any real data for that...
 



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