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Phylo

manual Exposure control???

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Im wondering how you all control your exposure, do you set the strobes at full power and control exposure with the fstop, or do you adjust the exposure via the manual controls on your strobe?? So far I have been using strobes on full and using the fstop to control the exposure.

 

Thanks for you input.

Phil

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I do that most of the time for macro (usually at 1/2 power w. sb-105's), but not with WA. because WA needs a balance b/w ambient and strobe, when you adjust your aperture you must change your shutter speed to compensate for the ambient.

 

for WA i usually preset the shutter speed b/w 1/30th-1/250th depending on ambient light for that dive and then adjust aperture and strobe per shot.

 

I don't have TTL, that would change things. Strobe positioning is important too and can be used to fine tune exposure.

 

Others have different techniques i'm sure. Cheers,

 

Chris

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Here is the formula that I use:

 

1) Set aperture you want for DOF and sharpness For macro F11-F16 for WA start at F8 then back down if necessary.

 

2) Set shutter speed for bacground lighting, I Meter off the blue water then go down a stop for a deeper blue (personal prefereance). If this is less than 1/100 s then back off on aperture.

 

3) Adjust strobe power for subject exposure. I Don't have to do much here since I'm using TTL but sometimes I tweak flash exposure compensation.

 

Sometimes on white sand the above preferences need to be adjusted if the values fall outside the range that TTL can compensate for. Then you have to adjust either aperture or shutter speed. If your depth changes you may need to re-evaluate shutter speed.

 

I always shoot at base ISO for low noise. In my case ISO 200.

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Well I haven't been shooting UW long, but I use full manual control on both camera and both my strobes. So far its been a lot of work, but with each dive it gets easier and i get a bit faster. What was recomended to me was to not worry about shutter speed too much i the begining. I set it at 1/125th and pretty much leave it at that. Then I set my f-stop accordingly, which is usually about 8 in th waters im diving. Then it just depends on how far away i am from my subject. All i have to do then is tweak the power and positioning of my strobes. Although i someties have to take a few shots before i get the strobe power correct. Right now its just sort of a matter of eperiementing. Im sure there is a better way, but this has been working for me a bit better then the first time when i jsut kept changing every component.

I'll be interested to see what others say about what they do.

 

Oh and BTW, I shoot WA

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I would love to be able to adjust the exposure via the flash but it takes so long for the Ikelite housing to allow me to adjust it between shots, and sometimes I dont have the time so I end up setting the strobes to full and using f-stop to adjust exposure.. So far its working out ok, but I think Im going to ditch the ds series strobes I have and get something with full manual control.

 

Here are a few of the shots I have been getting so far:

IMG_6954.jpg

IMG_7141.jpg

IMG_6855.jpg

 

Phil

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Phil: those look pretty good to me! If your strobes don't have manual power settings (DS50s???) then you are going to have to do a juggling act of changing f-stop AND shutterspeed to change your foreground exposure and still get a nice background.

 

Easiest is to get a good background exposure via f-stop and shutterspeed, then select strobe power based on your f-stop, ISO, and subject distance.

 

If you have the Ikelite housing then it should be pretty easy to set the flash mode to manual and then use the dial to change power - to me that's a LOT easier than having to reach out to each strobe to change power.

 

Cheers

James

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