Posted by Andy (207.167.100.90) on January 02, 2004 at 16:02:40:
In Reply to: Aqualens focus posted by Marcelo on December 30, 2003 at 05:59:53:
: Hi,
: I am trying to set the focus in the Aqualens for my 16mm fisheye.
: The instructions say that you must find the minimum focus in the lens and align it with the zero mark. Then one must take note of the letter that coincides with the infinite mark. In the 16mm, that point is near the G. The 5 feet mark coincides with the F and so. But in the focus chart that appears at Aquatica website (www.aquatica.ca), the letters go from 0 to D. Is this chart made with apparent feet, and this explains the difference? Does it explain also that the 6 dome chart is different from the 8?
: I know I shouldn't care about exact focus points, because of the extreme depth of field of the lens, but just want to know where to put the focus, so my foreground subject and the subjects beyond and at infinite, are both in focus.
: By the way, how close are subjects underwater? One third or one quarter closer? All books that talk about apparent distance says that, but none tells it exactly.
: I mean, 3 apparent feet are really 4 measured feet? (just to make a chart).
: Thanks for your help and happy holidays,
: Marcelo
Marcelo,
The some of the folks at Sub Aquatic camera repair in California are regular shooters with the aqualens. I would talk with them. They are nice folks and are also aware of how to use lenses other than Nikon in the Aqualens system such as some of the Russian made fish eyes that have nikon mounts (Peleng/Zenitar). I own an aqualens but use it very little because of the very problems you are having. The truth is I retro set everything on the lens that goes into the aqua lens. Usually the best distance to start with is .3 meters / 1 foot to focus on the virtual image the dome creates and the expected aperture. You can bracket with the shutter speed on the camera but the controls on the aqualens in my opinion do not correspond with the real world so I have just stopped using them. I don't even bother installing the gears. I bracket the shutter speed if I need to. When I use a strobe I use 60th second or less for Nikonos III, 90th second or less for Nikonos V. On the Nikonos V you can use the cameras internal meter and adjust aperture with the aqualens’ adjustment gear without knowing exactly what aperture setting your getting and you should get proper exposure but remember that faster than a 90th of a second on the V and 60th second on the III and the strobe can’t be used. The depth of field of my retro set wide angle lens compensates for my inability to manually adjust focus even at relatively large apertures but because I am focusing on a virtual image the way the Aqualens lens compensates is hard top predict. That being said you have to practice with it to get it right. Start with .3 meters/1 foot. I think you will be pleased with the results you get. Personally even though I have taken some nice shots with it I think the aqualens makes a very elegant paper weight to go along with the broken Seconic Marine Meter that sits on my desk. The other issue is that even though the Aqualens has a hand made finish the quality control on them was poor especially the dedicated optical finder. I would make sure the 16mm lens is insured for flooding. I bought mine 4 years ago when they were expensive but I want to focus on composition rather than fumbling around with technical stuff so in general I eschew the aqualens. I hope this helps. Good luck.
Andy
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