Wide angle close focus with TTL question

[stuartv]

I am definitely still on the steep part of my learning curve.

One thing that I think I have learned in the last year is that I have been too reluctant to change my ISO. I have done whole dives shooting with a SS on the slow side in order to keep my ISO low. The result has been a lot of shots that looked okay when previewing on the camera screen, during the dive, but on a computer screen are easily seen as soft. I have learned that I can do a lot more with a shot that is sharp but a little noisy than I can with a shot that is soft and not (or less) noisy. So, I have resolved to be more flexible with ISO in the future and not compromise my SS so much for the sake of a low ISO.

@ReadyDiverOne: As far as the histogram and "underexposing" the background goes, I am not sure that applies at all to shooting underwater. I think the true acid test is "are you getting the color you want in the background?" If you are, then the exposure is correct. At that point, it doesn't matter what the histogram says (about your background).

Targeting a meter value of -1 might be a way to dial in a good first guess on settings, before you start shooting test shots to dial it in. But, it doesn't seem to me that the histogram or the meter values have any use after that (as far as the background goes, anyway). It's not like terrestrial shooting, where people expect the grass to be green and the sky to be blue. Underwater, background water can be whatever you want it to be (within reason, of course). I don't think there is a "correct" exposure for background water. The "correct" exposure is whatever gives you the results YOU want.

Also, regarding something you said earlier. You're shooting an RX100 at f/8, right? The Crop Factor on that camera is something like 2.7. That means shooting that camera at f/8 gives you the equivalent Depth of Field of a Full Frame camera at f/22. I suspect that is WAY, WAY more DOF than you need. The general recommendation is f/8 - f/11 - on a Full Frame camera. For you, that means shooting at f/2.8 - f/4. So, do yourself and your ISO setting a favor and open that aperture up!

 

[stuartv]

the pro also strongly recommended adjusting ISO quite a lot--which I had always heard/read was the last of the three (shutter/aperture/ISO) one should adjust.

That might be more applicable to terrestrial shooting and less so to underwater.

BTW, if you haven't read it, I had a book recommended to me when I first started out in underwater photography and I found it to be excellent. It is called "The Underwater Photographer", by Martin Edge. And, just FYI, there is a new edition of it due out (I think) in just about 3 weeks or so. I thought the 4th Edition was so good, I pre-ordered the 5th Ed just to see what additional nuggets I can glean from it.

https://www.amazon.com/dp/1138123587/ref=pe_2640190_232748420_TE_item

 

[ReadyDiverOne]

@stuartv thanks, great stuff! Re the F8, that was just an example from the pro--he was shooting a DSLR. For me, I'm usually never above F6.3. But you make a great point, I'll try even lower.

Re the blue background, your take is interesting as many have said here and elsewhere that you def need to underexpose the background in order to get a decent blue color given underwater lighting realities. And I have certainly found that to be true--if I expose according to the camera's meter, that is, "correctly," or at 0 on the EV meter, my shots come out grayish or really cyan in the background. I usually need to get down to -1 at least to get decent blue backgrounds.

Finally, thanks for the rec on the book.

 

[Nemrod]

@JackConnick thanks much, I did check out your strobe positioning piece, also very helpful.

Re metering, histogram, highs and lows, pls help me understand: I have always read that one wants to under expose the background at least a stop or two in order to get that nice blue color. Is that still true? If it is, then does one use the live histogram (available on the RX100 display/viewfinder) to confirm that most of the data is to the left, hence underexposed? On my RX100, the meter is -2, -1, 0, +1, +2, with 1/3 increments, each representing a stop (right?). I'm usually at least at -1.

Thanks.

Each whole number on that exposure scale represents a stop and your camera has 1/3 stop increments between the whole values. Is that what you are asking? I am sure you know this but each doubling or halving the shutter speed is a stop, 1/30, 1/60, 1/125 etc. Each f number is a stop, f2.0, f2.8, f4, f8, f11, f16 etc. Each time you double or half the ISO, that is a stop, 100, 200, 400 etc.

I was kidding about the shaky hands, but I do!

James

 

[Interceptor121]

TTL works fine with RX100 set to fill flash and then customise the strobes

Still looking for an answer on this, particularly re reading the live histo. Thanks.

Live histogram is totally useless as it won't account for your strobes.
Old examples with rx100

Dapple by Interceptor121, on Flickr

Sunburst by Interceptor121, on Flickr

Avoid TTL for close focus wide angle and shoot the strobe in manual

 

[JackConnick]

Still looking for an answer on this, particularly re reading the live histo. Thanks.

Not sure about your display, but that sounds right. Otherwise you have it right. I tend not to rely on a live histogram, but take a quick shot off to the blue and check that.

I agree with "shoot it to the color you like".