Manual settings for a noob

[thegrandpoohbah 3]

Ok guys, I have a trip booked to Cuba January 17-29 and this will be my first dive outing with flash photography. The set-up is a Sony RX100VA with a single YS-D2J and a Big Blue Black Molly 3 video light. Up until now I have just shot with ambient light typically using aperture or shutter priority. I intend to go with full manual control on this trip and my starting settings are as follows: f/4, 1/250 sec and ISO 100. So far with my limited above water testing with the camera's flash exposure compensation turned down to -3.0 EV I need to have the strobe's dial turned up to +1.0 EV to properly expose a wide angle shot. My understanding is that underwater the shutter speed will control the ambient light so a faster shutter speed will result in a darker backgorund and vice versa. So to control the subject exposure am I just using the strobe's EV dial? If so it doesn't seem like I have that much range to work with or is that just because I haven't used it in the water yet and I'm overthinking it?

[pbalves 52]

Do not forget the aperture and the ISO. Both can help you to control the exposure.

[TimG 62]

The results you get above water will be very different to those at depth.

 

I've never used the YS-2DJ but with Inon Z240s I reckon that lighting a relatively small area about 3' from the lens is about the limit.

 

You might want to try and finding a colourful bit of reef which, for example, might be the towards the edge of your picture with, say, divers in the blue. Light the reef with your strobe and use shutter speed/ISO to set the exposure for the blue/divers. It's trial and error to start with until you get a hang of what the camera/strobe combination can do for you. I'd suggest starting with a slightly higher ISO though: 200 or even 400.

 

A quick example attached where the strobes (I used two in this pic) are both on the right hand side of the camera lighting the one chunk of reef. I was very close to the reef - using a Tokina 10-17mm lens at 13mm. Maybe 2' away? The diver was about 4'-5' away.

 

You are right on controlling the colour of the background: the faster the shutter speed the darker the background.

 

I hope this helps a bit.

 

Enjoy Cuba!

 

 

[ChrisRoss 150]

It sounds like you are manual on camera but still TTL on flash if you are talking about -1 EV as your strobe setting. TTL can be unpredictable UW and could confuse you more, for example a shot like above you might take a shot, review and retake it with a different setting, but if the framing is not the same the camera might make a different decision about flash power. With manual flash control as long as you don't change distance to subject you'll see the impact of your setting change. To be in manual you'd need to be in the orange manual preflash mode and read your setting off the manual part of the dial which is labelled in f stops.

 

I first started camera/strobe set up as I thought I might use taking a shot of something a metre away of so and changed the manual exposure of flash till the exposure was about right, then I used that as the UW starting point.

 

Regarding Tim's advice on ISO, don't forget we are talking about f4 on the RX100. The shot above is 1/250 @ f10 ISO200. This is the same exposure as 1/250 @ f5 ISO100 Going to higher ISO would over expose. f4 on the RX100 is equivalent to f11 on full frame for Depth of field, the shot above is equivalent to f15, so changing to f5 on the RX100 (f14 DOF equivalent) would basically replicate the shot above. My argument is you don't need to stop down so much on a smaller sensor.

 

Having said all that 1/250 @ f5 ISO100 would replicate the photo above in the same water conditions. Probably a good starting point. But swap over to manual on the flash.

[thegrandpoohbah 3]

Thanks, the flash is on manual. I was just reading the top half of the dial. The bottom f-stop markings don't really make sense to me since they don't actually correspond to my actual camera settings so I am just choosing to ignore it for now.

Edited December 31, 2018 by thegrandpoohbah

[Barmaglot 251]

The bottom f-stop markings don't really make sense to me since they don't actually correspond to my actual camera settings si I am just choosing to ignore it for now.

 

The top half of the scale is meant to be used with DS-TTL operation. In this mode, your camera fires a pre-flash, the strobe mimics it, and your camera takes a reading of the resulting scene exposition, then decides how much flash it actually needs for a properly exposed picture and fires an appropriately timed pulse while exposing the sensor. Remember that flash bulbs always burn with the same intensity - flash pulse power is adjusted by varying its duration, not its brightness. Once the main pulse is fired, the strobe mimics it again - but underwater environment is very challenging for the camera's metering logic to process properly, so it's prone to making mistakes; for example, if your metering mode is set to 'wide' and you have a lot of water in your shot, it will try to illuminate all that water, fail anyway, and overexpose your actual subject. The top half of the scale is TTL compensation - the strobe will still fire accordingly to the triggering bulb's pulse duration, but it will modify it by up to two EV stops up or down, depending on the knob's position. If you're using DS-TTL mode and your shot is underexposed, twist it clockwise to increase strobe power; if, on the other hand, your shot is overexposed, twist it counter-clockwise to decrease it.

 

If you're using manual operation (first click of the mode knob as you twist it clockwise to turn the strobe on), then the strobe will ignore the camera's pre-flash pulse completely, and will fire on the main pulse according to the knob's setting rather than the triggering flash's duration. '1' is the least powerful value, and then each step is twice as powerful as the last - it's the same f-stop scale as is used for aperture. Broadly speaking, for a fixed ISO and shutter speed, you can increase or decrease aperture and strobe power in synchronous steps and retain the same exposure. For example, if you're shooting at f/4 and your strobe power is set to '8' and your exposure is fine, but you don't have enough depth of field, you can stop down the camera to f/8 (two stops) and increase the strobe power to '16' (again, two stops) and your foreground exposure will remain the same. Your background exposure will go down -2EV; if you want to retain it, you will need to decrease your shutter speed by 1/4 - i.e. if the first photo was taken at f/4, 1/400s and strobe at '8', then the second photo will need f/8, 1/100s and strobe at '16'.

[Roger-Botting 2]

If i understand what you are asking, you want to know how to do flash underwater and balance your subject exposure with your background.
With the flash on manual, set the correct F stop for the distance of the flash from the subject and the ISO.
Then, manually set the shutter speed to give you the exposure that you want. A higher shutter speed will make the background darker, a lower shutter speed will make the background brighter.
So far, easy.
If the shutter speed gets above the maximum sync speed of the camera you will cut off some of the flash exposure. If the shutter speed gets too slow, you might get subject movement or camera shake.
Do yourself a favour. Practice this above water to see how things work out. You might find you want to change the flash power or change your ISO before you get in the water.

[tursiops 81]

The shot above is 1/250 @ f10 ISO200. This is the same exposure as 1/250 @ f5 ISO100

?? I don't think you meant that....

[ChrisRoss 150]

?? I don't think you meant that....

Should be 1/125 @ f10 ISO 200 is the same as 1/250 @ f5 ISO 100

[ChrisRoss 150]

Back to original question, you say you are at 1/250 @ f4 ISO100 and correctly exposing a wide angle shot, how far away are you from your subject? Have you looked through the various tutorials on flash positioning on websites like Optical ocean sales etc By guess is that setting should be a good starting point is you are 1m or less away from your subject. Without a wide wet lens you may need to back off a little to frame bigger scenes and need to turn the flash up. If you can I would suggest getting in the water on a check out dive and just shooting and checking to dial in your settings, then for the first few dives concentrate on getting the same distance from your subject everytime for wide angle work, then start to experiment with changing distances. If you stick at the one aperture it one less variable to think about and it becomes flash setting vs subject distance.

[thegrandpoohbah 3]

If you stick at the one aperture it one less variable to think about and it becomes flash setting vs subject distance.

 

That's kind of what I am thinking. I am still a new diver so anything I can do to remove variables from the photography will be a good thing at this point. I will try just dialing the strobe power up and down for the first dive and see how close that gets me to my desired exposure and then I can always tweek it from there as needed. I am comfortable enough with the exposure triangle that I don't have any issues shooting manual above water but I don't typically use flash so that does add another element here. And you are correct, I was probably too far away in my test shots as I would typically be much closer to the subject in the water.

[stilly 2]

Do not forget the aperture and the ISO. Both can help you to control the exposure.

The ISO wil control overall exposure, not on the foreground background independently.

[stilly 2]

Ok guys, I have a trip booked to Cuba January 17-29 and this will be my first dive outing with flash photography. The set-up is a Sony RX100VA with a single YS-D2J and a Big Blue Black Molly 3 video light. Up until now I have just shot with ambient light typically using aperture or shutter priority. I intend to go with full manual control on this trip and my starting settings are as follows: f/4, 1/250 sec and ISO 100. So far with my limited above water testing with the camera's flash exposure compensation turned down to -3.0 EV I need to have the strobe's dial turned up to +1.0 EV to properly expose a wide angle shot. My understanding is that underwater the shutter speed will control the ambient light so a faster shutter speed will result in a darker backgorund and vice versa. So to control the subject exposure am I just using the strobe's EV dial? If so it doesn't seem like I have that much range to work with or is that just because I haven't used it in the water yet and I'm overthinking it?

I assume you are turning down the camera's flash exposure to -3.0 to speed recycle and extend battery? Or is it something else? Have you used your set up in TTL mode? My RX100 VI is quite accurate in this mode although you won't be able to turn down your in camera flash comp....

[thegrandpoohbah 3]

I assume you are turning down the camera's flash exposure to -3.0 to speed recycle and extend battery? Or is it something else? Have you used your set up in TTL mode? My RX100 VI is quite accurate in this mode although you won't be able to turn down your in camera flash comp....

 

Yes, using manual mode so I can dial the flash exposure down to -3.0 EV in order to conserve battery life.