Andaman Sea Blackwater

gokhankuzu wrote:

Barmaglot_07 wrote:

gokhankuzu wrote:

You used flash first, then why iso 800?

Because when shooting translucent critters at small apertures, even powerful strobes don't have enough output to work reliably at ISO 100. As I understand it, ISO 800 is where the dual gain circuit on A6xxx cameras kicks in, so shooting anything between 100 and 800 is largely pointless (on blackwater dives; day dives have different considerations), as is any setting above 800.

No. When you use flash, iso 800 degrades the quality of the photo at least 4 times. It prevents you from getting details. You can experience it. You have a TTL converter, a check with 100 iso in the same shot and one with 800. And see the difference.

Why is your f value 25? You may have wanted to make the background dark, there is no need to narrow the aperture that much.

Depth of field. This is a blackwater dive, conducted at night, in open water, away from a reef. The bottom is at roughly 80 meters (in this case); the only visual reference is a drifting line hung from a buoy with some torches on it. The subjects range from small (a few centimeters) to tiny (millimeters) and tend to constantly move in all three dimensions. AF-C tracking helps a little bit, but it only goes so far.

You got a side view of the fish in your photos and even f8 is too much for clear focus depth of field. You have a TTL converter. Again, at the same time, take the aperture to 8 and shoot the same. The difference will be unbelievable and the quality will increase a lot. After f11, the light will shine and you can't get enough detail.

Quality decreases after f11. f25 and iso800 reduce the quality of the photo and reduce its sharpness.

It does, and they do, but missing focus on a tiny moving target reduces the quality far more.

Try f8 and iso 100 and see the difference. You will track much better with your diaphragm wide. Because your camera sensor will see the light. for F25 can't see anything.

You have a TTL converter, iso 100 always gives the best quality, the more you increase it, the worse it gets.

In TTL mode, output range of Retra strobes is somewhat limited. I was chasing a larval crab (a brown ball maybe 5mm in diameter) and as shots taken at f/25 kept coming out of focus, I tried to crank it up to f/32 for a little more DoF. Surprise, the next shot came out significantly underexposed.

TTL converter will provide the best light in all conditions. Changing the diaphragm from 8 to 25 to 32 will not gain you anything. You should try to approach the fish more sensitively. F32 and f25 take very poor-quality photos.

Topaz Sharpen can greatly reduce the effects of diffraction.

Don Cox