for beginners - strobe positioning

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Chris Bangs

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This question came from "The cat keeper" on another topic.

since you asked... let's talk about strobe positioning first

I have been told that if I want to take a panaromic shot in the water, I should place my strobe at the furthest possible distance away from the camera to minimize backscatter... so I tried pushing my strobe to the furthest horizontal distance from the camera and there is still backscatter, so I moved the strobe to different angles (still maintaining the furthest horizontal distance from the camera) and still, backscatter everywhere!

Hence the questions are:
1. If there are particles in the water, is it possible to avoid backscatter at all? Or is the effort only, at best, minimizing those blotches on the photograph?

2. When I tried positioning the strobe at different angles, I realized that the light cannot reach the subject at certain angle... so what exactly does it mean by placing the strobe as far from the camera as possible while preventing the particles from reflecting light back to the camera?

Answers ) that depends on how much suspended particles there are in the water. Increasing the strobe distance from the lens will reduce the size of the reflections off the particles as the angle will bounce the strongest reflection away from the lens, but it will not eliminate the particles ( only photoshop can do that ). What you want to do is try to position the strode so that the beam will contact the subject while not illuminating the water between the camera and the subject. this takes practice. One tip is unless you are shooting macro and a subject is very close to the camera, keep the strobe pointed parallel with the lens, do not try to aim the strobe at the subject as doing so will result in more of the beam striking the water in front of the subject. I use real wide beam ( 110 degree ) strobes, and in dirty water I even point them slightly outward. I also use two strobes in most cases and my goal is to have each beam strike the subject with just enough overlap to expose the entire frame.


And,
3. We found a ray under some corals. There was an opening. My friend moved her tiny (compared to mine anyway) little camera into the opening and took the picture. With the bracket and the strobe, my camera has became really bulky... so now I could not access smaller crevices to get nearer to the ray without banging the strobe onto coral or something (and I do not want to do that)... so what's the best way to get to the ray?

Answer, The best answer to this is having a very flexible strobe arm, or better yet, one that can easily be detached from the tray/camera to allow more positioning options. Slave strobes designed with a sensor that needs to be pointed directly at the internal camera flash may make this more challenging as it reduces the positioning options. In such a case of your ray, I would most likely have tried to position the strobe by hand holding it, behind the camera, therefore not having to stuff it into the tight opening.
 
Hey Chris,

Good answers, i'd like to add my 2 cents as well.
A couple of tips i like to tell my students when dealing with very murky/backscattery conditions.
1 Shoot up, the scatter doesn't show up so much against a blue background
OR
2. If the conditions permit, ie you are wall diving, shoot toward a finite position. If you are trying to take a picture of a fish, take it from a position where the fish is against the reef instead of against open water. When the strobe light travels past the fish and hits the wall there is no backscatter to light up, just the reef and therefore no scatter.
If there is nothing behind the fish but open water then the light continues to travel and light up each and every piece of particulate.

Conclusion:
In murky conditions try to shoot in situations where you get the least amount of water between your subject, its surroundings and your lens.
 
Awesome tips guys.
Definately agree that you want to have your strobes pointed parrellal to the lens.

My little tip is to have the strobe positioned directly in line with the lens or below it for wide angle. I know this is not considered proper practice as it look stange to have light from below instead of above as this is the way we view the world. However I try to light my subject with the strobe and the rest with natural light. I find a high strobe position illuminates more particles or possibly the backscatter is now located in a less offensive position.
 
Mike and LukeROB thanks for adding very good info.

one more note, If you have a big subject and only a single strobe then center the strobe directory above or below the lens as this will provide more even coverage, and of course try to get the strobe as far away from the camera/ lens as possible.
 
Chris Bangs:
Answer, The best answer to this is having a very flexible strobe arm, or better yet, one that can easily be detached from the tray/camera to allow more positioning options.
Wouldn't the fish disappear by the time I detached the tray from the camera? :( I guess I would try this only if I were taking picture of a more "stationary" creatures like the eel or a nudibranch...
 
Thanks everyone... and one more question: What if I were taking picture of a really big fish, say the whale shark or a big huge school of barracudas?

It would be difficult to get too close to it and to take the picture of the entire school/fish, I would have to be at a distance, and it would be really difficult to prevent backscatter. At the same time, the strobe is effective up to a certain distance so chances are the strobe won't do any good. So does it mean that if I were taking such pictures, I should just forget all about the strobe and hope that the picture turned out okay?
 
Hi many fish are territorial and tend to stay in a small area, you have to just sit and watch and fire when ready.

as for whale sharks, natural light is the way to go. Barracuda can be shot both with natural or artificial light. be careful though barracuda are VERY reflective! that will be address later as it tends to be more advanced.

Time to leave, do not want to miss my flight to Guam. nice to see that there are no typhoons in the area, feel sorry for the folks in Florida! On Guam however our homes are solid concrete, good thing as PAKA in 1997 pounded Guam with 236 mph winds ( 360 KPH, ish ). No power for 2 months!
 
Chris Bangs:
Time to leave, do not want to miss my flight to Guam. nice to see that there are no typhoons in the area, feel sorry for the folks in Florida! On Guam however our homes are solid concrete, good thing as PAKA in 1997 pounded Guam with 236 mph winds ( 360 KPH, ish ). No power for 2 months!
Thanks... and have a good trip.
 
Just to add one more comment - I was taught to ideally always work to a maximum of 1/10th of the visibility. That means if you have 10 metres vis - your subject better be less than a metre from your lens. I find this means less break up of focus as there is less water column (less particles and backscatter) between your lens and the critter. If you push this rule your shots will be washed out and the flash will be ineffective. Simple rule is to get in as clase as you can - I see too many beginners stand off the subject; zoom to telephoto and wonder why their butterflyfish portrait is washed out; blurry and blue. Enjoy!

Wiggsy.
 
Hi

back on the rock!

Not a bad rule of thumb for flash photography but remember no matter how good the vis is subjects more than 2 meters away will be out or range for most internal flashes. Even with my dual flame throwers, 2.5 meters is pushing it.

For natural light shooting what you see is what you will get! in low light conditions,

I have seen the washout effect caused by the camera software attempting to adjust the light levels in the "post" processing of the image. so what looked like a over exposed image was actually an underexposed image that got some major brightening up. such images can be easily corrected in photoshop
 

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