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imacro

Settings and position for Inon Z330 with Sony A7C

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I have shot a few times with my Nauticam A7C + WWL-1B lens and 2 Inon Z330s.

 

My cam is set at 250 ISO, f/11, 1/125s, UW Auto WB.

 

My inons are set at manual with Advanced Cancel Circuit on (in lock), EV -3.

 

I position my strobes like this

 

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My shots came out not as bright or cover as much foreground as I’d like. For eg at 100ft depth wreck

 

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The strobes light up very little foreground. Also the position of the strobe did not seems to flood the light evenly where I see darker or shadow in the middle of the shot and more light on the left and right.

 

Please advise what settings, position and technique should I adjust to take better photos.

 

 

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A few questions - what is the subject distance?  You say it is set to EV-3 which is a 3 oçlock on the dial?  You are triggering them with a flash trigger?

It's hard to judge the distance but looks like you are a bit too far away from your subject.  I would expect at ISO250 - f11 you would be pushing closer towards 1/2 power, which would be -1 on the dial.  A lot of your subjects have receding diagonals to them, so the flash will only really illuminate to part of the subject that is within range.   On land you have the inverse square law, intensity reduces at the square of the distance.  UW it is a lot more severe fall off.  Also the colour of the light varies with distance, so the fact the light has to go out to the subject and back again sucks more colour from the light.  You want to be 1m or less for most shots.  closer is better.

Subjects can shade each other so you may need to fiddle with the position a little to deal that.  Effectively you only have light coming from one side, more so towards either side of frame as light from the other- strobe does not come all the way across  You could try getting the strobes higher above the camera so it comes more from above perhaps may help

Strobe separation should be roughly equal to the subject distance, experiment with the angle they point out, if you point them too far out you risk having them in dimmer portion of the beam.  So I would suggest start out where you were on angle and adjust separation then take a series of shots-  Take them in an order so you can remember when you view them later.

You mention the ACC is in - lock do you mean the button is pressed in and locked?  If this is the case the ACC is turned off - which is fine for manual exposure.

So in summary EV move towards -> -1,   get closer and set strobes separation about equal to that distance.  Do a series of shots and different angles so you can see how the lighting responds.

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Thanks Chris, those coral pictures were 3ft (1m) away from the lens but still did not really light up that much.

I took another 3 dives. Tried all sort of different strobe positions. 2 & 10 o clocks slight out. All the way up top slightly out or just light directly at the subject. The raw photos did not look good so I was really disappointed. The. I tried to edit the raw files to see what I got. To my surprise, they look much better after edit. An over exposed raw (the turtle and coral) can be edited to have much better white balance and exposure. The seal photos were all underexposed similar to the ship wreck photos but i was able to brighten with different WB.

How do I get the strobe light to evenly distributed for The coral photo? The lighting looks brighter on the 2 sides and darker in the middle. I’ll find the raw photos to share later. They are night and day different.

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If it is dim in the middle the strobes are pointed too far outwards and you need to bring them in a little.  The centre top of the last coral image is getting dim which is probably a combination of light fall off with distance and pointing a bit too far out.  the beams are circular and it looks more even down low - like there is a dimmer wedge in the middle so perhaps it needs the strobes to point up a little as well.  You could probably pull back the highlights a touch on that one to even things out. 

So the last two photos were over exposed then?  I'm assuming you were closer in?  Did you change your strobe output much?  Photos can certainly be rescued in a raw file, there is some penalty for that of course in the way of extra noise or dynamic range loss, but often the shots are perfectly acceptable after tweaking.  

The WB will also change with exposure as flash is 5000k and the ambient light in water 10000K +  and the mix of ambient and flash light changes - the underexposed shots will be blue/green biased and the over exposed be too warm.  The disadvantage of tweaking it to get the right WB/exposure is that while you can warm up the colours in the seal shot on the seal and rocks, the water is also being warmed so does not end up as deep a blue.  

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Keep in mind that the strobe's output is not even - it's strongest at the center of the beam, and falls off rapidly towards the edges. If you have the edges of the two beams just barely meeting in the middle of the frame, it will be underexposed by a couple stops compared to the edges that are catching the center of the beam. See Backscatter's tests here and Retra-UWT's tests here. Reducing the angle at which the strobes are angled out should help, as should mounting the -0.3EV diffusers - they don't modify the color temperature, and don't absorb a lot of light, but they do make it a lot more even.

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7 hours ago, Barmaglot said:

Keep in mind that the strobe's output is not even - it's strongest at the center of the beam, and falls off rapidly towards the edges. If you have the edges of the two beams just barely meeting in the middle of the frame, it will be underexposed by a couple stops compared to the edges that are catching the center of the beam. See Backscatter's tests here and Retra-UWT's tests here. Reducing the angle at which the strobes are angled out should help, as should mounting the -0.3EV diffusers - they don't modify the color temperature, and don't absorb a lot of light, but they do make it a lot more even.

The Z330 has a cross shaped light pattern without diffusers and it would likely cause this type of lighting  - we didn't ask if you are using diffusers but I agree if not using them you probably should.

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Here are the original unedited photos. You can see they were either over or under exposed, either very blue or very white.

 

I had STLL on at A position for the over exposed photos and was pretty close to the subject.

 

I have the diffuser and the shine guard on. Idk if the shine guard help anything but I couldnt find a good use for it yet.

 

I tried various setting, M with different EV, Full, Low, STLL but none of the photo came out as “shareable” without edit.

 

What should I try to do differently next time?

 

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Here is another shot of the turtle when I turned back to take more photo when realized the first shot was over exposed. I think I had M on with -0.3 EV. About 3 ft (1m) away from the turtle but did not light up the turtle.

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That last shot of the turtle looks like a good example of too much ambient light, not enough strobe light. Raise the shutter speed to 1/160, drop the ISO to 100, then dial up the strobe power until you get enough light to properly expose the photo.  Remember that while you have the strobes in M mode, you have to use the right knob to control the power - turn clockwise for more, counter-clockwise for less. I generally take a few test shots at the beginning of the dive, once I reach target depth, in order to establish a good baseline for the current ambient conditions, then make adjustments as needed when I find a subject.

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Thanks for the tip. For all my photos, I had ISO at 250, f/11 and SS 1/125s


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Posted (edited)
4 hours ago, imacro said:

Thanks for the tip. For all my photos, I had ISO at 250, f/11 and SS 1/125s


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My jump settings are ISO 400, f/13, 1/160, so it's exactly the same EV as yours. I dive in deeper water than you from what I can see from the picture (30-60m) so maybe reduce your ISO to start with and try turning the strobes at 3/4 power - adjust strobe power from there.

 

Also : when reviewing pictures underwater on your LCD screen, reduce the LCD brightness to -1 or -2 on Sony.

Edited by waterpixel

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I would add to that set your ambient exposure first, take a shot of the water and adjust to get nice blues and try to not to swap around randomly.  I see for example the water looks good with the seals but is over exposed for the coral shot.  Once you have the shutter speed/ISO stay there, pick an aperture and then dial in the exposure with the flash level.  Then adjust only the flash to get a good exposure.  Judge exposure with a histogram, not that it looks good on the monitor.    If you move too many variables at once it is way too easy to confuse yourself.

As for the glare guard I would put them facing outwards away from the subject.  If you dial them inwards that could cause the problem you are seeing. 

The last turtle seems to need more flash - do you mean the RH dial set to -3?  that seems a little low, dial it up at least a stop.

 

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I recommend you to check out Brent Durand youtube channel, it helped me a lot with strobes positioning and camera settings

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