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peterbkk

Member Since 25 May 2005
Offline Last Active Jul 27 2014 04:25 PM
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Topics I've Started

GH4: Panasonic 7-14mm f4 lens in a Zen 170mm port?

17 July 2014 - 07:34 PM


I've been scratching my head over which wide-angle lens I should use for underwater use with the GH4 and the Zen 170mm. I have been reading about dome ports, virtual images, rectilinear lenses, corner sharpness, close focus distance, mathematical formulas, etc, etc. Interesting stuff but I have not found a clear answer.

I own the Panasonic 12-35mm f2.8 and it's a great lens, at least above water. It should work well in the Zen 170mm dome. Should focus OK and be sharp in the corners. I can test this lens next week when I get the GH4 housing.

But, 12mm (~24mm) is not very wide for shooting large creatures up close. Might be OK but I suspect that I'll want something a bit wider.

One option is a fish-eye like the Panasonic 8mm. But I am not too crazy about the fish-eye look for all my WA shots.

Another option is a full-frame lens (Nikon, Canon, etc) on a 4/3rds Metabones speedbooster. Could be nice for low DoF but probably loses all AF, lens corrections and stabilisation functions?

So, then I get back to what I first thought would be best lens: the Panasonic 7-14mm f4 lens. Great focal range for underwater WA (35mm ~ 14-28mm). All the Panasonic functions work: AF and lens corrections. The close focus at .25M should focus fine, although it'll right on the near focus limit of the lens.

But, here's where my reading about dome ports made me uncertain. What will the corner sharpness of the Panasonic 7-14mm be like in the Zen 170mm port?

I've read about a "rule of thumb" not to use a rectilinear WA lens greater than 100 degrees angle of view in a dome port or you get soft corners. The 7-14mm has an angle of 114 degrees at its widest. Is this going to rule out the Panasonic 7-14mm f4 lens? Could it be OK from about 10mm to 14mm in its zoom range?

Of course, one answer might be: try one. But, it's an expensive lens to buy for a pool test that might prove it unsuitable. I would have very little use for this lens if it doesn't work underwater. And, I'm sure no shop in Singapore will lend me one to test.

Has anyone tried the Panasonic 7-14mm in a dome port?

Thoughts? Solutions?

Regards
Peter


Tubbataha Reef, Philippines

16 July 2014 - 01:24 AM

Hi Guys,

 

Here is my latest work, a mini documentary on the Tubbataha Reefs in the Philippines.

 

Warning: If you haven't been there, this video may cause you to instantly whip out your credit card and book a trip for next season.

 

Tubbataha reminded my of Sipadan back in the good ol' days.  Maybe even better.  Fantastic diversity, huge schools, sharks and turtles everywhere, pristine corals and, on some days, visibility up to 100 meters!

 

It's remoteness and short season helps but the Philippine government is doing a good job policing the park's "zero take" policies.

 

Enjoy: 

 

http://www.peterwalk.../tubbataha.html

 

Regards

Peter


CheungyDiver Broke His Leg

08 February 2014 - 11:54 PM

I know that many members in these forums have received lots of great advice from CheungyDiver, aka David Cheung of ScubaCam in Singapore, including me.  (CheungyDiver)

 

Yesterday, David fell off a motorised skateboard and landed badly, breaking his left tibia and dislocating his knee. We were actually due to meet so I met him while he was lying on the ground waiting for an ambulance.  He was in a lot of pain.  The doctors say that the break needs a pin.  He will be in hospital for a couple of weeks then stuck in a wheelchair and on crutches for a few weeks.

 

I know that you'll join me in wishing him a speedy recovery.

 

I'll pop in to see him tomorrow so I can pass on any messages.  PM me if you want the hospital address and bed number.

 

Regards

Peter


Palau: Mating Humphead Parrotfish Aggregation Video

04 February 2014 - 03:10 AM

I just posted the a video from a recent Palau trip:
 
 
It is a HD online video (hosted from Vimeo) so you will need a fast internet connection or wait patiently for it to buffer.
 
I do have a couple of other online videos in the pipeline (Caves, Jellyfish Lake) but this is the "mating aggregation" video so I focused on uploading this one first.
 
Thanks to David Cheung of ScubaCam for putting this trip together.
 
Regards
Peter
 
Camera: Canon XF100
Housing: BS Kinetics Makla Takan
Editing: Final Cut Pro X 10.1

Final Cut Pro 10.1

19 December 2013 - 02:33 AM


http://www.apple.com...-pro/whats-new/

4K editing done properly.

Regards
Peter