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r4e

Member Since 16 Jan 2011
Offline Last Active Today, 03:27 AM
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Posts I've Made

In Topic: 5yr old Prosumer video camera vs GoPro?

05 December 2016 - 03:17 AM

GoPros adjust color balance almost continuously. Thus the colors of consecutive shots might not match each other, especially if you are shooting footage in caverns, where there might big illumination changes in the cavern zone. If you are shooting in the actual cave area (beyond daylight), the color balance issues are less significant, however, assuming that the cave walls are of similar color. If continuity in color is important for your research, I would select the XA10.


In Topic: Very particular underwater task requires advice

18 November 2016 - 03:45 AM

You mentioned above mm accuracy. I am sure you already are aware of it, but, just a reminder: depending on the type of ice, there might be a very transparent glass/waterlike underlayer of the ice. Even when viewed ortogonally from an opening in the ice, it might be very difficult to distinguish the underneath surface of ice from clear water. Thus, you might endup focusing, shooting and analyzing the next more visible layer with more frost/pores/whiteness. If you yourself are not diving beneath the ice, you might not even notice or realize this difference. The transparent layer can be surprisingly thick. I've seen transparent ice layers of 20 cm thickness and without any pores/frost. I wouldn't be surprised that you could encounter even thicker transparent layers in the Arctic.


In Topic: Preferred focal length or field of view

25 April 2016 - 08:20 PM

I shoot video mainly in ship wrecks and caves. I use a Canon 16-35mm lense with a FF camera. Normally, I preset the lense at around 20mm focal length because that seems to give a visually pleasing compromise between minimizing the effects of the water column and not having too much distortion in the picture. In cramped spaces I might zoom to 16mm in order to fit the entire view. But, for example in mines, the shortest focal length spoils the perspective and especially mine tunnels do not appear anymore "tunnel like". Due to diving in waters of limited visibility, I rarely use a focal length longer than 24mm.