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albert kok

Member Since 02 Sep 2006
Offline Last Active Yesterday, 07:16 AM
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#373000 Bimini Cat island two step

Posted by albert kok on 25 April 2016 - 11:23 PM

Just returned from the Bahamas where we did  Bimini and Cat island in succession. Luckily there were stil some 'hammies' left at Bimini and the end of the season. The Oceanics  of Cat island were an amazing experience. But  shooting them is pretty difficult, since you are hanging  in the blue and miss the nice sandy floor of Bimini  to kneel on. Here a stills sequence of a shark feed by Neil Watson at Bimini:  9 shots taken in 4 secs  with the D7200 and Tokina 10-17. The shark making almost a full turn.

see further https://www.flickr.c...albert/?saved=1

 

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#369068 new website

Posted by albert kok on 08 January 2016 - 11:19 AM

Hi 

Because I had nothing better to do, I started  a website some months ago.

Primarily  to present my UW photo albums. But later I thought that it might also be a good idea  to present some  information and personal  views about the UW photography world, collected from various media and persons.These sections are mostly 'eclectic' that is,  based on pictures, ideas, notes or articles from eminent photographers that I found interesting  or useful, I also tried to keep things simple, and not to get  lnvolved in too technical issues, or  to get lost in the labyrinth of ever changing UW photography hardware So long, I am happy with the numbers of visitors, but you would also do me a  favour to give me your  ‘likes’ Thanks!

see: www.albertkokuw.nl




#368606 Olympus OM-D E-M1 low light photography questions

Posted by albert kok on 25 December 2015 - 12:12 PM

To return to  the original question. Its not only the camera and its high  ISO performance, but also the lense. For  Olympus 4/3 users,  the new Olympus f1.8 8mm FE might be a solution for low light conditions. Like  Jack suggested.   At least when making  wide angle shots is your purpose. With  a small colourful object near  the front of your dome,  you cant get around the  strobes with a focus light when vis is limited. With natural light it  is a different story, Then  you  definitely need some sun rays to light up the larger objects at a greater distance, like a wreck. 




#367952 Olympus 8 mm f/1.8 fisheye Pro or Olympus 7-14 mm f/2.8 Pro?

Posted by albert kok on 05 December 2015 - 10:16 AM

Hi I think the fish eye would be the best option. Like a 8 mm Lumix or Oly F1.8 if you have the right mini dome.  Not a rectilinair lens . The latter lense,  although very  sharp, cuts of parts of a large shark that do not fit in the frame. See for example:

http://www.uwphotogr...4mm-lens-review

Keep in mind  that these hammerheads at Bimini are big and come close. Ideal for the fish eye. Have fun.




#360901 Using a mini-altimeter as a leak detector

Posted by albert kok on 07 May 2015 - 10:04 AM

Commercial  leak-detectors are based on the principle  that a barometric underpressure (or: partial vacuüm) that is sucked in your housing with a hand pump, rises above a critical  level. In that case a red LED on the detector starts blinking: probably a leak!  If you  already have a vacuüm pump, but no detector, a  mini  altimeter (basically a small barometer translating mbars in feets of altitude) can  be very helpful. At least if you a have a transparent  Ikelite housing. I use this little and  cheap  device ALTIMER ONE that I stick  to the inside of the  Ikelite housing. After  the vacuüm is established  (around 20 strokes) you read out the pressure in feets altitude (say 4000 fts). Giving you an objective indication of the pressure inside your housing. So you want to be sure that this reading doesnt change, say in the next couple of hours.

 

I haven't  yet checked  the altimeter reading  during a dive. Its possible that the air pressure  inside the housing may drop a bit, because of the decrease of water temperature (and  cooler air inside the housing) with increasing depth. This will give  you a higher reading on the altimeter. No reason to panic. Only a sudden lower reading on the altimeter means trouble. Apparently water is entering the housing, which  causes  a rise of  the inside pressure  Have fun!.

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#359373 Palm Beach, FL

Posted by albert kok on 29 March 2015 - 12:30 PM

Nice shots with the Panasonic 8mm!




#358962 Will Nikon D7200 fit straight in D7100 housings

Posted by albert kok on 18 March 2015 - 10:37 AM

Sofar  it looks like the Nikon designers had mercy with the UW photographers!. :cake:




#358812 45 Degree View Finder

Posted by albert kok on 13 March 2015 - 10:05 AM

The Inion 45 degrees viewfinder with Ikelite adapter sells from my local store in Holland. Its  much cheaper than the Ikelite  viewfinder that just came on the market.  Which is, I believe also an adapted Inion viewfinder that screws into  the backside of the Ikelite  DLSR housing after removing the standard viewfinder.  See also this solution: http://uwcamerastuff.com/inon.htm




#353587 Acrylic Dome Port Scratches Repair

Posted by albert kok on 22 October 2014 - 10:20 AM

Brasso, a metal polisher can also  be very helpful.

http://en.wikipedia.org/wiki/Brasso


  • MK2 likes this


#351689 Personal Chumming Device (PCD)

Posted by albert kok on 18 August 2014 - 04:18 AM

Hi

There is a  never ending discussion around the topic 'chumming or not chumming'. But we all agree on the issue that chumming should interfere  as little as possible with the natural behavior of fish. The simple device I called PCD might be of help to bring fish closer to your camera, without disturbing the environment too much. I used it in the Mediterranean to attract groupers, but I think it might also work with larger predators like sharks. It could be especially useful for the individual diver in conditions when chumming on a larger scale, e.g. on a diving boat,  is not allowed or undesirable.Personal Chumming Device (PCD).jpg




#339454 Fish eyes compared: Tokina versus Panasonic (test 2)

Posted by albert kok on 14 November 2013 - 09:34 AM



I think you might have something else going on with your Tok 10-17 -- it just doesn't look sharp in any part of the image.  If it was just a Fine Tuning issue, it would be back or front focusing, but it just looks very "soft" overall. 

Yes tnks,  I noticed that too. Could it also be a camera problem..like a wrong  AF setting, didnt try the fine tuning yet.

 

Today we had sunshine! So I tried some more tests, with Tok and Pana set at 1/30 F8 ISO400, 20 cm distance. Tok now at 10 mm. Results looked better now for Tok/Nikon. So perhaps AF under low ambient light could have produced bad results for the Tok/Nikon combo in the earlier shots. But taken together, and admitting that  this was  probably not the best test of the quality of these lenses, I would tentatively call the Pana fisheye the winner (with a small margin). 

tok230F8ISO400.jpg pana230F8ISO400.jpg