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Joe Weaver

Couple of Questions - New Lighting Rig

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Hi All,

Got these in my hot little hands today and got everything hooked up and working. I decided  to forego DS-TTL on the Sea and Sea YS-01 strobes and start out in manual just to be consistent.  Right now I am at F8 and one notch below quarter power on the strobes.  Just walking around the house, I'm getting decent exposure at what I think to be my usual shooting distances.  Might need tweaking now and then, but in the right ballpark anyway.  Close enough I can adjust as I go on my next dive.

Ok, here are the questions. 

First, is this a decent plan or am I discounting the effectiveness of DS-TTL?  I am using a Canon G7X Mark II.  I'm sure I'll try it at some point, but I would appreciate real world feedback.  Also, this should conserve camera battery since the flash is firing at it's minimum power.

My goal is to get the best color, clarity and sharpness out my system.  Will F8 be stopped down enough?  As is the recycle time is almost non-existent so I could stop down a bit more and still be fine I think.

My tendency so far has been to not use camera zoom but to get as close to the subjects as possible.  I figure the less water between it and the lens, the better.  How much camera zoom are you comfortable using underwater?

That's enough for now.  Here's the rig and details.  Plus a photo I don't have a clue how I would have taken will all this since this eel was down in a crack.

Thanks!

Canon G7X Mark II in Fantasea Housing
(2) Sea & Sea YS-01 Strobes
Mozaik Uni-Tray and Flex handles
Kraken Hydra 1200 focus light
 

Gear.jpg

WPR-2262.jpg

Edited by Joe Weaver
Forgot something

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f/8 with your camera is like f/22 on a full frame you are at diffraction limit so from sharpness point of view the camera will perform much better at wider apertures in terms of sharpness.

As your camera allows you a very fast shutter speed you can just increase that to 1/500 and more to create a dark background if needed.

For portrait work f/4 or f/5.6 will be more than sufficient also in terms of depth of field or with wet lenses

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14 hours ago, Interceptor121 said:

f/8 with your camera is like f/22 on a full frame you are at diffraction limit so from sharpness point of view the camera will perform much better at wider apertures in terms of sharpness.

As your camera allows you a very fast shutter speed you can just increase that to 1/500 and more to create a dark background if needed.

For portrait work f/4 or f/5.6 will be more than sufficient also in terms of depth of field or with wet lenses

With a 1 inch 20.1MP sensor it should hold up better than that.  The wider apertures haven't been all that impressive.  Then too I've been kinda stuck at f5.6 since I had no lighting.  That, slow shutter speeds and ISO400 are costing me sharpness I am sure.

I couldn't find maximum sync speed so I figure 1/200th is good to start.  Like I said, I'll adjust as needed. 

Thanks for the input!

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F8 is more than adequate, I use f8 on m43 and don't want for depth of field.  f8 is equivalent to f22 on full frame and f5.6 ~ f15 on a depth of field basis.   I would go with f5.6 or less if you have enough depth of field at the wide end.  The MP have little to do with sharpness, that is down to the quality of the lens.  If you stop down too much you go into diffraction and sharpness actually suffers.  These types of lenses are designed for peak sharpness in the f3.5 - 5.6 range about  2 stops down from wide open, quite unlike SLR lenses which peak at smaller apertures.  If you use a dome port this changes of course as you deal with a virtual image.

There are a couple of things working against you in the corners at wide angle, a natural tendency to soft corners with the lens and the flat port will add in aberrations at wide angles as well. 

If you look at tests wide angle sharpness peaks around f3 - 4.5 on the edges, the tele end is sharper towards f5 and has better corners.  https://www.photoreview.com.au/reviews/advanced-compact-cameras/fixed-lens/canon-powershot-g7x-mark-ii/

Also the corners suffer from strong distortion correction in JPEG, turning it off in Raw conversions helps and won't cause issues with UW work,  read this review:  https://www.photoreview.com.au/reviews/advanced-compact-cameras/fixed-lens/canon-powershot-g7x-mark-ii/  under the optics tab.  They specifically mention sharper corners with distortion correction turned off.

Looking at your example I see it's 1/25 @ f6.3 ISO400.  That image looks to be 100% flash lit So I think turning up the shutter speed would have little impact on exposure.  That being the case you could increase flash power 1-2 stops to get to ISO200-100 and increase the shutter speed.  Where shutter speed is important is when you have blue water as a background of course - in sunlit tropical waters 1/250 @ f5.6 ISO200 is a reasonable starting point for water exposure.  If your subject is under exposed turn up the flash power.  

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With a 1 inch 20.1MP sensor it should hold up better than that.  The wider apertures haven't been all that impressive.  Then too I've been kinda stuck at f5.6 since I had no lighting.  That, slow shutter speeds and ISO400 are costing me sharpness I am sure.
I couldn't find maximum sync speed so I figure 1/200th is good to start.  Like I said, I'll adjust as needed. 
Thanks for the input!

Megapixels have nothing to do with equivalence this sensor is around 3 stops from full frame
If the pictures are not sharp is due to other reasons
Not having a flash you have motion blur easily under 1/200 shutter
You don’t need f/8 for portraits maybe for macro depending on dof


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