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Glasseye Snapper

Member Since 11 Oct 2005
Offline Last Active Sep 19 2014 04:18 PM
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#349846 Sydney Scorpionfish - an unexpected discovery...

Posted by Glasseye Snapper on 04 July 2014 - 05:07 PM

Thanks for sharing. I just send out images to researchers in Hawaii and Russia for species where they only had preserved museum species to look at. Diving is a lot of fun but we are actually making very valuable observations, even though we may not realize it.

 

Bart




#349768 Flash flooded or?

Posted by Glasseye Snapper on 02 July 2014 - 05:26 PM

I had a similar case with a Sea&Sea 110a strobe last May. In my case I had been down for close to an hour and had been taking pictures normally until at some point the strobe started to malfunction. Looking at the strobe there was dark stuff oozing out of the top cap and I could see the blue o-ring popped out of the groove. I aborted the dive (solo shore dive so that was easy). Upon opening the battery cap it was clear that the strobe was flooded. One of the batteries was damaged at the nipple end, as far as I remember the others looked nasty or maybe just dirty but without structural damage. I cleaned out the battery compartment immediately with fresh water followed by a soak in cleaning vinegar. Finally another rinse with water and then drying in front of the air conditioner. To my surprise and relieve the strobe functioned just fine for the remainder of the trip.

 

I wasn't sure if the strobe flooded first leading to battery damage or vice versa. I assumed it was operator error but have found the lid closing system of the 110a to be rather fool-proof. In addition, if it was flooding first then why did it not happen earlier. From the discussion here it appears that it may actually have been the battery that was at fault. I was using Imedion powerex 2400mAh and a MAHA powerex smart charger. They are supposed to be good and the problem did not reappear so I hope it was just an unlucky but one-time event.

 

Bart




#346723 Philippines recommendations

Posted by Glasseye Snapper on 24 April 2014 - 05:02 PM

Yes, that's right :) and there is a very small one at around -10m @ Ligpo (Ligpo cave)  ;)

 

There is a short youtube video showing one diver entering Ligpo cave. No footage of the cave itself though.

 

http://www.youtube.c...h?v=bw0Qc5ny0ls

 

Bart




#346434 Goby question

Posted by Glasseye Snapper on 18 April 2014 - 07:32 AM

Hi Nick, we seem to be using the same book (Reef Fishes of the East Indies). Hard corals are not listed as a substrate for this species but it is "happy" on so many different substrates that I just assumed it could be anywhere (and the top right image looked like coral to me but is maybe a softcoral). I know very little about anything without scales and tails but hope to change that in the coming month during a trip to the Philippines.

 

P. micheli fits better for a hard coral association but I thought the transparent body and brown stripe where characteristic.

 

Bart




#345039 Help finding "Rules of Underwater Photography"

Posted by Glasseye Snapper on 25 March 2014 - 05:41 PM

 

 

The following page has some we follow: http://www.aquablued...ticpages/pid/14

 

Our Guidelines to Nature Photography

  1. Always try to minimize our impact on the subject.
  2. We will not move, handle, coax or prod any animal to capture a “better” image.
  3. We will not move, handle or disturb any coral or other structure to get a “better” image of a subject.
  4. We will be very conscious of our buoyancy in an attempt to avoid coming in contact with the reef or bottom.
  5. Only one finger on the reef (dead section) to capture a image.* If this is not possible than we will forgo the image.
  6. If we see a fellow diver harming the reef or its creatures intentionally or by accident we will no longer keep silent. We will try, with as much tact as possible, to raise the subject of protecting that which we have all come to SEE!
  7. We will let guides know that we do not look for them to manipulate in any way the creatures and settings we have come to capture in pixels.

 

 

Are you sure you remember that right? I seem to recall the rules as follows   :mocking:

 

Our Guidelines to Nature Photography
  1. Always try to maximize our impact on the budget.
  2. We will move, plead, coax or prod any spouse to capture a “better” camera.
  3. We will not crop, photoshop or fake any shot to get a “better” image of a subject.
  4. We will be very conscious of our solvency in an attempt to avoid coming in contact with the bottom line.
  5. Only one loan on the house to capture a image.* If this is not possible than we will forgo rule one
  6. If we see a fellow diver harming our ego intentionally or by accident we will no longer keep silent. We will try, with as much tact as possible, to raise our budget to buy that which we want others to SEE!
  7. We will let bankers know that we look for them to manipulate the market in any way so our futures and savings allow us to capture our pixels.

 




#344435 Mirror, mirror, on the wall ...

Posted by Glasseye Snapper on 13 March 2014 - 07:13 PM

With the birth of the Mirrorless Camera Forum it seems appropriate to take stock of a topic that has, and will be, debated and considered for the foreseeable future. I will try to steer clear of answering “… who is the fairest of them all” and rather focus on how the two systems differ and how that may impact underwater photography in a practical manner. I hope others will point out errors, contribute things I forgot and add more practical comments and perhaps examples beyond the more theoretical nature of my start. There is one thing mirrorless cameras still lack and that is an established simple acronym. I’ll be using Compact System Camera (CSC), which highlights compactness as one important characteristic, especially for travelling divers.

 

A look in the mirror

 

The mirror and pentaprism combination serves two distinct functions, both of which require the optical image to be redirected from the sensor to; i) the viewfinder to compose the image and judge focus, and ii) to the phase-detection autofocus sensor. A separate sensor also analyses the deflected image to determine correct exposure and white balance. During the film era this was the only option but digital image sensors can perform all these tasks, giving rise to the first CSC in 2004 (Epson R-D1) but not taking off until the first micro four thirds (mFT) format camera in 2008 (Panasonic Lumix DMC-G1). Five years later all major camera brands make CSC and technical progress has been astounding. Comparing CSC vs DSLR is a moving target but this is my current impression.

 

Single-shot autofocus (S-AF): Contrast-based autofocus by CSC is now at least as fast as DSLR autofocus. CSC S-AF is also at least as accurate and extremely consistent for any lens (because it determines focus right on the sensor plane). DSLR S-AF can vary by lens unless properly micro-adjusted to account for small lens-to-sensor distance variability. Even if that is done there is still a bit more variability, but probably not something you would notice by eye. In addition, careful manual focus is as good as autofocus so it you like DIY focusing it is a moot point. Roger Cigala at lens rentals has posted actual comparisons that are worth reading for technophiles. http://www.lensrenta...e-shot-accuracy

 

Continuous autofocus (C-AF): C-AF has been a distinct weakness for CSC because contrast-based autofocus must use trial-and-error to determine the direction of focus adjustments, which made it too slow to track moving objects. In contrast, DSLR’s phase-detection AF can predict what focus adjustment is needed and directly drive the lens accordingly. The Nikon 1 CSC introduced on-sensor phase-detection pixels and is still a leader in fast C-AF. Just today Nikon set a new bar for any camera, CSC or DSLR, with the announcement of the Nikon 1 V3, which can shoot 20fps with C-AF. Recent CSC cameras from most brands now also incorporate on-sensor phase detection. My impression is that DSLR still has a small edge, especially with less ideal lighting or subjects, but the gap is closing fast.

 

Video/live-view autofocus: This is an area where DSLR has struggled and CSC is well ahead. Some DSLR now also have on-sensor phase-detection pixels and I expect that over time they will become more competitive with CSC.

 

Autofocus summary: CSC beats DSLR on S-AF, but not by enough to select one over the other. DSLR beats CSC on C-AF but the best CSC probably now match some of their DSLR competitors. Video autofocus goes to CSC.

 

Continuous shooting speed: without mechanical mirror, shooting frequency is limited by read-out and image processing speed on CSC. The Olympus OMD cameras reach 9 or 10fps and the announced Nikon 1 V3 reaches 20fps with C-AF, or 60fps without C-AF. For DSLR the rate at which the mirror can be flipped up and down with adequate precision and reasonable cost becomes limiting. CSC wins and has more potential to continue improving but for underwater photography the real limitation is often strobe recycling.

 

Image quality (IQ): The mirror is flipped up while the image is taken so it is really up to the sensor and lens to determine IQ. Exceptions are when lens offsets are not compensated by micro-adjustment then DSLR images tend to be slightly front or back focused. The lack of a mirror also means that the lens can get closer to the sensor but I don’t know if that affects IQ.

 

Image sensor size: The IQ issue in discussions around CSC vs DSLR really have more to do with sensor size, which is not a mirror vs no-mirror issue and with the Sony A7 there are now mirrorless full frame cameras. However, right now if you want FF, DSLR is much more mature with many more choices in bodies and, especially lenses. A larger sensor also means larger lenses so the compactness factor of CSC bodies is less of a benefit and until the mirror/pentaprism actually becomes a liability I expect that DSLR will continue to rule FF.

The main relevance of sensor size to CSC vs DSLR is that smaller sensors require smaller lenses with shorter focal length. That benefits compactness and results in closer minimum focus distance. The latter is a distinct advantage for underwater photography and one that typically does not get mentioned. However, a proper discussion of sensor size effects would be better dealt with in a separate thread. Maybe I'll start one later.

 

System size: The early selling point for CSC was smaller, lighter and cheaper cameras, but you had to give up on versatility, speed and IQ compared to DSLR. In 5 years, CSC has reached a point where in a battle with DSLR it wins a few and loses a few, but prices have evened out as well. What remains as a distinct advantage, is the more compact and lighter CSC bodies and lenses, which was an important factor for me and others on wetpixel. Both for travel, lower housing cost, and more dexterity under water.

 

Maturity: There is no question that DSLR is a much more mature and well-supported technology with specialty lenses, flashes, and many other accessories. This advantage is most notable in the FF arena because, Nikon and Canon especially, never enthusiastically pushed lens development optimized for APS-C, and because CSC has less of a compactness advantage when dealing with FF-capable lenses. In the big picture, the presence or absence of a mirror is really not that important. If you are already invested in a DSLR brand or you need special accessories or lenses that are not (yet) available for CSC then that is all that matters. Otherwise you need to think about what things you care about most in a camera, and perhaps prognosticate which systems are in it for the long run, and make your choice. The good news is you no longer need to trade size for performance. Modern CSC can give you both but you get what you pay for.

 

I won’t be in the market for a new camera in the next few years (assuming I don’t flood my camera, knock on wood) but it will be interesting to see the technology develop and all the stunning images that my fellow wetpixelers will make with them.

 

Happy shooting!    Bart




#341775 Exposure set with available light, so why does photo still come out good with...

Posted by Glasseye Snapper on 12 January 2014 - 09:08 AM

The best tutorial on this topic, and a must read for anyone who wants to understand this, is http://www.cambridge...era-flash-2.htm

 

If you just want to know the answer to the original question:

 

In Aperture priority mode with the flash forced to be on, cameras aim to achieve something close to balanced (1:1) exposure where half the light is from the flash and the other half is ambient. To do this the camera first measures the ambient light and calculates settings that give a 1 stop underexposed image. It then fires a very short pre-flash to determine the correct flash pulse duration needed to bring the total image up to the proper exposure level. [Note: In program mode a similar thing happens but most cameras treat it as a fill flash and produce a much weaker flash contribution than 1:1.]

 

To get a more dominant contribution of the flash to the overall exposure you can either go to manual mode, set ISO/aperture/shutter to values that give a more-than-one stop underexposure based on ambient light and then let the flash add whatever is needed to bring it up to the correct exposure level.

 

It is possible to define a different target exposure ratio than the default balanced exposure but you better read the link above for the details. Basically, to get a larger flash contribution you set the Flash Exposure Compensation (FEC) to a positive number. But at the same time you need to reduce the normal Exposure Compensation (EC) to prevent overexposure. I have never played with this but if the correct combination of FEC/EC to get 2:1, 4:1 etc ratios doesn't depend much on the ambient conditions then it could we worth investigating. If I get to it, I will report back.

 

Bart




#340061 Very disappointed !!! Good for honey moon divers!!!

Posted by Glasseye Snapper on 28 November 2013 - 04:57 PM

Hi Nuno,

 

I haven't been to the Azores or Sharm but still think the most likely answer to your question is that you just have had bad luck picking your operator. All my Red Sea diving has been along the continental side from Safaga to Marsa Alam and the diving has been great, both with respect to marine life and dive operations. When travelling alone I've always been able to find capable buddies or have been allowed to dive solo. The thing to do is to find dive resorts that are completely focused on diving and attract hard-core divers like you. You will find very few bridal suites in these places but the diving and comeraderie is great.

 

Bart




#338942 wetpixel, a breath of fresh air

Posted by Glasseye Snapper on 03 November 2013 - 10:13 AM

I just felt an urge to comment on the exceptional skills, knowledge, helpfulness, comraderie, and general quality of information posted by the wetpixel community. I guess we all have come to expect this but it is becoming a rare thing to find on the net, with many photography sites being particularly nasty, empty-minded or just congratulatory.

 

Kudos to all

 

Bart




#337604 Parable of the Clyde - excellent economist article on the perils of overfishing

Posted by Glasseye Snapper on 29 September 2013 - 09:02 AM

This is sadly becoming a familiar tale but seldomly told so well. Worth reading beyond those with a local interest.

 

Bart




#336309 Kona Blob

Posted by Glasseye Snapper on 26 August 2013 - 05:23 PM

Looks like some kind of sponge to me. But I'm also often wrong when it doesn't have scales and tails :)

 

Bart




#334117 Unknown Goby

Posted by Glasseye Snapper on 10 July 2013 - 04:45 PM

Hi Jim,

 

I'm not going to argue with Rick but if he is right than Reef Fishes of the East Indies must be wrong. Their picture is definately much more congruent with T. yanoi, and not really with T. haimassum, which they do include in the book. For T. haimassum they mention "pale yellowish brown to bluish grey with purplish stripe under eye extending onto opercle; lavender stripes across upper edge of orbital rim, and dappled pattern of lavender markings on snout. Caves and ledges on steep outer reef slopes in 15-70m." I would not consider it a good match with your image at all. In contrast, RFEI's T. yanoi resembles your image quite well, just with less constrast in the spots but that is not unusual. The majority of Trimma species are described by Rick so I would stick with his conclusion, just surprised about inconsistency.

 

Bart




#324953 metabones speedbooster

Posted by Glasseye Snapper on 22 January 2013 - 02:06 PM

The first hands-on reports are coming in

Roger Cigala from LensRentals, testing the adapter on test charts
http://www.lensrenta...metabones-magic

A more video-focused look at eosHD
http://www.eoshd.com...ter-full-review


#322929 PADI goes solo

Posted by Glasseye Snapper on 18 December 2012 - 08:18 PM

We have had lively discussions on solo diving on wetpixel in 2003 and 2007, including comments that PADI abhors solo diving like nature abhors a vacuum. So I was surprised to find out that PADI has recently introduced an official solo diving specialty course, although they call it the self-reliant diver course. Ironically, I found out while taking the SDI solo diver course. I can't comment on which course is better as I don't know much about PADI's offering, but did like the SDI course, especially the in-water part of it. The good thing about the PADI course is that it may make dive operators more willing to allow divers with the appropriate training, equipment and demonstrated skills to go it alone.

Bart


#312843 Reef Fishes of the East Indies

Posted by Glasseye Snapper on 15 July 2012 - 03:23 PM

The recently announced Reef Fishes of the East Indies fish identification books have started shipping and I received my set last Friday. The books are absolutely gorgeous and can also be used for weight training Posted Image. I did not weight them but estimate it compares to lugging around at least 6 copies of the Tropical Pacific Reef Fish Identification book, which is not a light book itself.

What sets these books apart is the fact that they cover all known reef-associated fish in a very large region that stretches from the Andaman/Nicobar islands on the West, Solomon islands on the East, tropical Australia on the South and Philippines on the North. This is not only the global hot-spot for fish diversity but also includes many of the prime pacific dive destinations. Even many species from the Red Sea/Africa to French Polynesia/Hawaii region are represented when their range overlaps the East Indies.

The books are meant to be the authorative guide to fish identification. Unlike my other fish ID books, this set is aimed at both scientists and "amateur underwater naturalists" and, as the authors are both leading scientists in this field, the books have a distinct scientific slant in content and vocabulary. For instance, for each species they list the number of fin spines and rays, scale counts and several measurements that can be used for identification purposes. This is more detail than most of us will ever need but it is easy to skip this part of the text and get to the description that complements the image and information on habitat, depth and distribution. When there are two very similar-looking species this is often highlighted with an indication of the discriminating feature(s), or in case of mimicry, they list which species is mimicked. In short, all the information you want is there and it is easy to skip the extra detail if you don't need it. Of course, the real attraction are the thousands of great colour images, often with more than one per species. The great majority are shot during normal diving but for some cryptic species they catch them with an anaestetic and then take pictures underwater, with them still showing their natural colours. A much smaller number of species is so rare that they are only known from a few, sometimes only one, stored museum specimen. Pictures, or sometimes drawings, of these are included but as a result of the preservatives their colours and sometimes shape has become unnatural and plain ugly. Of course, you are unlikely to ever come across one of these so again, it is extra information important to the scientist audience but easy to skip for us.

You will also find that the order of presentation is different from the common grouping by morphological similarity. Instead the order reflects the evolutionary tree, presenting the more "ancestral" species (sharks/rays) first and ending with the most "derived" species (Mola mola). In general, evolutionarily more closely related species tend to be also morphologically similar so I had no issues with it and a quick reference at the start of each book lets you find every family in any of the three volumes. One thing that I would have liked to see changed is to list species within a genus by morphological similarity rather than alphabetically. Alphabetic order has no biological information so this change should benefit both the scientists and us by listing species that are difficult to discriminated side by side.

In addition to the thousands of species, each family has its own description with many interesting things for divers at the start as well as citations to key scientific publications for each family at the end. Again, read the juicy bits and skip the rest unless you want to dig deeper. The first volume also has an introduction covering the different regions of the East Indies. This is interesting as it discusses the places with the healthiest reefs for each region, observed/estimated fish diversity, and the types/quality of reef communities, current, geography, etc. If you need inspiration for you next dive exploration than this will certainly give you more ideas than you can handle. There is also historical information on past and current ichtyologists that have been active in each region and the location of large museum collections that they have created. A relatively short section deals with zoogeography (reasons for observed geographic distributions of fish), ecology and conservation, with citations to other literature for more details.

Finally, the third volume gives you an idea of how up-to-date these books are since it ends with two appendices. The first covering almost 100 pages dedicated to new species with rather extensive descriptions and images. If you thought you had seen it all, these are some new ones to track down. After that there is a second appendix with some late additions including some that are so new that they didn't get discovered until after the book layout had been completed!

If you have gotten this far then you must be an afishionado in which case just go and order the books (http://www.uhpress.h...0987260000.aspx). They cost $249 for the boxed hard-cover set, which is not peanuts but in my opinion cheap given the quality and "labour of love" that clearly went into making them. If you run a dive shop in this region you should definately get them. As I said, these are not books divers want to lug around, even if luggage limits were more generous, but having access to them on site would be greatly appreciated.

Finally, a big thank you to the authors, Gerald Allen and Mark Erdmann, for this amazing set of books.

Bart