Jump to content


Glasseye Snapper

Member Since 11 Oct 2005
Offline Last Active Dec 20 2014 08:19 AM
-----

#354389 60mm VS 100mm DOF

Posted by Glasseye Snapper on 16 November 2014 - 01:00 PM

So Bart, would I have to assume in your scenario that the 105mm would allow me the same depth of field as the 60mm should I choose to move further away from the subject thus forcing me to seriously crop my image to achieve the same affect as the 60mm (final image magnification for presentation)? Just trying to decide if I need to include the 60mm in my arsenal of lenses.

 

You would not need to crop at all. Once you move back with your 105mm to get the same magnification as the 60mm the images will be the same size. Interceptor121 has a lot of good other comments on field of view and background. Like CamelToad if I had to choose between my canon 100mm and 60mm I would keep the 100mm. And like Bill I am now using m43 with the 60mm which happens to sit right in between the 60mm and 100mm when used on APS-C.

 

I think for most people the two dominant reasons to prefer the 60mm over 100mm is that the former is more versatile because it gives more leeway to get images of larger critters as well as the small stuff without having to back off too much. The other is for people who dive in peasoup and want to get as close as possible. The 100mm advantages are when you want a bit more working distance for lighting or to not scare your subject. I almost exclusively shoot fish for which the latter is important. If my passion was nudibranch I would probably keep the 60mm. A secondary advantage is for those using wet diopters. They give more bang for the buck on longer lenses.

 

Bart




#354161 Threatening to violate copyright. At least they're upfront about it!

Posted by Glasseye Snapper on 08 November 2014 - 07:38 AM

You have been entirely reasonable and remarkably patient. I suggest you yourself let the ABC guy print your huge perfect files just the way she wanted them and put them on the wall in his shop for $750 each. When she sees them she will come running back and gladly pay your asking price plus postage :)

 

Bart




#354016 Any ideas what this little fish might be?

Posted by Glasseye Snapper on 03 November 2014 - 06:59 PM

I also think it is a juvenile Black-banded demoiselle. In Anilao I always found them on muck sites, not on reefs. The top image shows older individuals with little yellow. The bottom, for same dive, a young one with the yellow.

 

Black-banded_Demoiselle.JPG

 

Black-banded_Demoiselle_juvi.JPG

 

Bart




#353052 F'n Stop - big rookie mistake

Posted by Glasseye Snapper on 28 September 2014 - 04:41 PM

In my experience the only reliable way to remember all the little things that need to be taken care of is to actually take an image when the camera setup is complete, including flash. It doesn't help you remember to put a diopter on a lens that needs one in a dome but takes care of most other mishaps. Of course the problem then becomes to remember to take that test shot. Oh, it also helps to not put your wetsuit on backwards. Been there done that  :)

 

Bart




#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