Since I bought my 8" modular dome for my Nikon D7100 Housing to be used with the Tokina 10-17 Lens, I always was very frustrated every time I was trying to do some CFWA.
My first thinking was to doubt about my ability to position the strobes in the right way with this big dome, feeling embarrassed about my overestimated experience in underwater photography.
Every time I tried to shot with one or two strobes pointing inward, an ugly and big reflection appeared in the picture, no matter how much I tried to push the strobes to the back, the only way to get rid of that reflection was to point the strobes out.
In the image above can see real examples of the problem. In the left images you can see the reflection when I tried to point the strobes inward, at right images, almost same picture but pointing strobes out.
After a talk with a friend of mine, I decide to find the problem, suspecting in some reflection from inside the dome, instead a flare in the dome surface because a bad position of the strobe.
I made a test lab in my room to reproduce the problem. At the first attemp the ugly flare appeared:
As you can see in the image, there is a clear difference between a flare caused by a bad position of the strobes (center) and this other strange flare (left and right).
If there was any reflection from inside the dome caused by a light coming from the sides or the top, I had to find a way to cover the inside disk of the dome. I decided to use a round piece of neoprene with an inner round hole just to allow the pass of the lens. I made some measures and I cut a circle of neoprene of diameter 16 cm with an inner round hole of about 8 cm.
Here you can see the engineered and precise design:
Then I started the test at the next day with this awesome results:
With the two strobes pointing slightly to the back of the housing, no reflection and a soft light in the subject.
I decided to go extreme, pointing the two strobes directly to the housing, and no reflection at all.
In the above image at the right, I put the right strobe at the top of the housing pointing directly to the bottom, without any angle to the back.
I move the subject closer to the dome, to simulate a very extreme CFWA with very good results too.
As at the other test, I put the right strobe at the top of the housing pointing directly to the bottom, without any angle to the back (image at right)
All the above tests were made with the Tokina at 10mm, then I zoomed to 15mm getting this great result:
The last image shows another view of the position of the strobes for the tests.
Now I'm happy to realize that I'm not so bad underwater photographer. I believe that the design of the Ikelite 8" modular dome can be improved with some kind of real anti-reflection sheet inside and with the addition of a cover for the back of the dome to avoid dust inside... it is very tricky to clean the dome inside with the extension ring installed.
My first thinking was to doubt about my ability to position the strobes in the right way with this big dome, feeling embarrassed about my overestimated experience in underwater photography.
Every time I tried to shot with one or two strobes pointing inward, an ugly and big reflection appeared in the picture, no matter how much I tried to push the strobes to the back, the only way to get rid of that reflection was to point the strobes out.
In the image above can see real examples of the problem. In the left images you can see the reflection when I tried to point the strobes inward, at right images, almost same picture but pointing strobes out.
After a talk with a friend of mine, I decide to find the problem, suspecting in some reflection from inside the dome, instead a flare in the dome surface because a bad position of the strobe.
I made a test lab in my room to reproduce the problem. At the first attemp the ugly flare appeared:
As you can see in the image, there is a clear difference between a flare caused by a bad position of the strobes (center) and this other strange flare (left and right).
If there was any reflection from inside the dome caused by a light coming from the sides or the top, I had to find a way to cover the inside disk of the dome. I decided to use a round piece of neoprene with an inner round hole just to allow the pass of the lens. I made some measures and I cut a circle of neoprene of diameter 16 cm with an inner round hole of about 8 cm.
Here you can see the engineered and precise design:
Then I started the test at the next day with this awesome results:
With the two strobes pointing slightly to the back of the housing, no reflection and a soft light in the subject.
I decided to go extreme, pointing the two strobes directly to the housing, and no reflection at all.
In the above image at the right, I put the right strobe at the top of the housing pointing directly to the bottom, without any angle to the back.
I move the subject closer to the dome, to simulate a very extreme CFWA with very good results too.
As at the other test, I put the right strobe at the top of the housing pointing directly to the bottom, without any angle to the back (image at right)
All the above tests were made with the Tokina at 10mm, then I zoomed to 15mm getting this great result:
The last image shows another view of the position of the strobes for the tests.
Now I'm happy to realize that I'm not so bad underwater photographer. I believe that the design of the Ikelite 8" modular dome can be improved with some kind of real anti-reflection sheet inside and with the addition of a cover for the back of the dome to avoid dust inside... it is very tricky to clean the dome inside with the extension ring installed.
