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Glasseye Snapper

Member Since 11 Oct 2005
Offline Last Active Yesterday, 07:07 PM
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Posts I've Made

In Topic: Compass handling - do you? How do you?

24 November 2014 - 05:33 PM

Hi Dave,

 

Like you I rarely need to use a compass but normally strap one on just in case. I just set the compass so it points out the direction to shore and so far have never needed to rely on it. I have done compass navigation on a few occasions but never with camera. If I had to I would not mix photography and compass reading but press the camera against my chest and focus on the compass until I reached my destination. In all cases I would have the compass on my wrist. I don't like retractors but if I would do a lot of compass diving then I would consider hooking up the compass to the housing. Perhaps someone can post pictures of ways to do just that.

 

Bart


In Topic: Moray help

21 November 2014 - 05:10 PM

G. tile is usually found in the lower ranges of rivers and muddy estuaries. I also think it is most like a highfin moray.

 

Bart


In Topic: 60mm VS 100mm DOF

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


In Topic: 60mm VS 100mm DOF

14 November 2014 - 04:55 PM

At the same magnification AND the same aperture the DOF is the same, as is the resolving power (the smallest features that can still be detected). At the same distance and aperture the 60mm will give greater DOF but less magnification and less resolving power. Of course you could achieve the same with the 100mm by moving backwards a bit if water clarity allows.

 

Because resolving power and DOF both depend on interference of light waves you can't improve one without hurting the other. You just have to decide what you want from your image and optimize for that. Shooting from a direction where your object is as 2D as possible helps to but for composition head shots are normally prettier.

 

Bart


In Topic: Triplefins X 2

08 November 2014 - 08:40 AM

Hi Jim,

 

I agree on the Enneapterygius genus. In my "big books" there are two potential matches; the mirabilis you mentioned and flavoccipitis. Third option is that these two form a species complex with yours being a third member. Either its own species or some regional variant.

 

Your images show white edging on the 2nd and 3rd dorsal fins and a big first dorsal. These would point to mirabilis. In addition, flavoccipitis, the yellownape triplefin, is named after yellow-gold specks between eyes and first dorsal which are not on your image and it also has a smaller first dorsal. However in terms of general appearance I find it a closer match to the yellownape. Both species are reported from Indonesia and should include the Ambon area. The yellownape is found in 0-22m including rocks, reefs, and tide pools. Mirabilis is described as living on coral, sponge and rock substrate in 8-37m.

 

General appearance is not a good ID criterium so I think E. mirabilis is the best bet. What makes your images different from both of these is the finely spotted pattern plus the larger black spot in the 2nd dorsal fin. In addition, your images are the prettiest I have seen for this species. Congratulations.

 

Bart