Underwater Bubble Blowin' Users Group

[Johnny Friday]

forgot to specify:
cooke 15-40 or optimo 15-40

[Pawel Achtel]

forgot to specify:
cooke 15-40 or optimo 15-40

Or, Arri Zeiss 15.5-45mm T2.6 Lightweight Zoom (LWZ-1). However, wide zoom lenses are suboptimal for underwater use because position of entrance pupil changes while zooming. Unless, of course, you use it as a variable prime and change the position of the camera for each focal length.

[Johnny Friday]

Or, Arri Zeiss 15.5-45mm T2.6 Lightweight Zoom (LWZ-1). However, wide zoom lenses are suboptimal for underwater use because position of entrance pupil changes while zooming. Unless, of course, you use it as a variable prime and change the position of the camera for each focal length.

That very well may be true in theory and on white paper--as i see the math tells the truth. However in practice, this lens if unbelievable underwater. I do not own one, but a friend does and I've seen the results and they are stunning images that I think only someone analyzing the image could tell. A 9+ for a video image on any zoom range that i have seen.

[Pawel Achtel]

That very well may be true in theory and on white paper--as i see the math tells the truth. However in practice, this lens if unbelievable underwater. I do not own one, but a friend does and I've seen the results and they are stunning images that I think only someone analyzing the image could tell. A 9+ for a video image on any zoom range that i have seen.

How do you define 9+ image? I guess we have different ways of rating image quality.

Why not share some results? We discussed it before and I am yet to see a frame resolving more than maybe 800 pixels horizontally (about standard definition quality). Not only I haven't seen good contrast frame, but I also have not seen one in focus.

My experience is that well designed underwater optics perform as well in real life as they do on paper. My focusing scales are all calculated and theoretical values. Focus is pulled off the scales, not by eye (which you can't judge accurately underwater). It is perfect and matches 100% with calculated values.

[Johnny Friday]

a comment only pawel can make.....but expected

[Johnny Friday]

Pawel, this is what happened to the last guy that talked smack about me....he had to walk home from the mountains.......i left him a bottle of water though.

careful big guy.

[Pawel Achtel]

Pawel, this is what happened to the last guy that talked smack about me....he had to walk home from the mountains.......i left him a bottle of water though.

careful big guy.

Johnny,

I find your unprovoked trolling completely unjustified and annoying. If you have an opinion about the effect of position of entrance pupil on sharpness and contrast of an underwater image, you are welcome to share and debate it. I shared my technical insights. Earlier, I also supported my opinions with my images, so that you could critique them and my techniques to your heart content. However, I am not a subject here and personal remarks won't be taken kindly.

[Johnny Friday]

Pawel, come on....unprovoked? you must be kidding. And your not so sensitive are you? Wow! I never would have thought you would have been so thin skinned. you sure come on like a bag of bricks. How have i offended you? Did i once criticize your work?

Take a nap and get a bottle of milk and get over it. Your Australian no? what a baby! your mates at the pub would be very disappointed i think. now get some sleep grumpy.

[Rudi Herbert]

Wow, take it easy guys, and thank you both for the replies.

Pawel, of course I would not use the zoom underwater as a zoom but as a variable prime of sorts. The one thing that concerns me is that at its widest, the lens approaches 90 degrees in field of vision, which in my opinion, is the minimum for underwater work I'm happy to live with. Respectfully now Pawel, for someone with such high standards and exacting knowledge of what technology yields the best artistic results, I am dying to see footage of yours shot on something other than HDCAM. Do you have any RED underwater footage yet?

Baja Productions, as for the RED 18-50, yes, it's not a bad lens, but since we need something a bit sturdier for steadicam work and a bit wider for underwater, I may well go with the Arri 15-5-40mm, though I gotta say, I'm VERY intrigued by that HAWK 10-25 lens in Germany...

[Pawel Achtel]

Rudi, I won't be able to show any footage from Red One for several months due to my spinal injury. I am curious the results more than anyone, although I will use the same CinePort optics.

Hawk lenses (or any anamorphics) may suffer from astigmatism through a dome. Not sure.

The Arri LWZ-1 should be good as a variable prime with advantage of using same lens and ability to configure with flat port for longer focal lengths. Also, it will accept Master Diopters for domes with small curvatures.

PS: There is no problem criticising images (that's why they are posted here in the first place) or debating techniques and technical matters. But there is absolutely no need to make personal remarks if someonce's approach is different or doesn't suit someone else's ego.