Jump to content


MarkD

Member Since 28 Sep 2006
Offline Last Active Yesterday, 07:33 PM
-----

Posts I've Made

In Topic: Eneloop Pro venting gas

04 April 2018 - 02:19 PM

This warning by Panasonic doesn't appear to be new. Here's a link to a thread that's 8 1/2 years old, discussing Sanyo's then recommendation that Eneloops should not be used in waterproof lights:

http://www.candlepow...terproof-lights

There must have been very many Eneloop cells used in underwater strobes since then. It would be interesting to know what are the circumstances of use in strobes that might lead to hydrogen venting. I would suppose that any increase in pressure within a sealed battery compartment might be a greater functional concern than a risk of hydrogen conflagration when the gas is released?


In Topic: Nikon D500 memory cards - XQD question

24 February 2018 - 09:35 AM

Hi Kirsty,

Welcome to Wetpixel. Like you, I have usually used the second slot for backup. With the D500, in this configuration write speed is limited by the slower card i.e. the SD slot. For most underwater shooting, the large buffer and the limitation of strobe recycle time on high speed shooting bursts means that the SD card write time isn't a real limitation. However, there could be occasions when shooting longer bursts of fast action, using natural light or possibly low strobe power mean that you would like to clear the buffer as quickly as possible. Usually these situations would be predictable and it's easy to switch second slot function on the fly. If needed you could then back up to the SD card  in retrospect. I don't think there's a right answer to how to configure the slots on a D500 - it depends on your shooting preferences. Life just got a bit more complicated compared with the D7200.

Of course the advantage of an XQD card isn't just write speed. Read speed is also potentially higher so uploading images should be faster as long as you don't have a bottleneck somewhere else in your system.

Mark


In Topic: Nauticam D850 TTL converter

17 February 2018 - 04:04 AM

Hi Pavel. Has this converter been tested with Retra strobes?

In Topic: Ports, domes and lenses (Sony)

02 January 2018 - 02:24 PM

Or to put it another way Justin, regarding macro lenses underwater, Sony APS-C shooters face fairly similar choices to Nikon APS-C shooters (60mm or 105mm) and Canon cropped frame shooters (60mm or 100mm). For small stuff the longer focal length lenses offer much more useful working distances for a given magnification and diopters are more effective. For medium or larger sized subjects, longer focal length lenses force you to back off if you want the entire subject in frame. Apart from perspective differences, this introduces a longer water column that is liable to reduce image contrast and quality and at the larger subject end may require more power from your strobes.

 

As we often don't know what creatures we will find before committing to a dive, I often find that Sod's law dictates that the optimal lens for a particular subject is the one that's topside!

 

Mark


In Topic: Ports, domes and lenses (Sony)

28 December 2017 - 03:08 AM

I agree with all Chris's observations.

 

Compromises are part and parcel of all photography, whether it be size and portability, flexibility, usability, durability, cost and of course IQ. Photography in the aqueous environment imposes an additional major layer of compromises, not the least of which being the need for refraction correction for wider angles of view. Understanding the compromises we are all making is important as apart from helping with equipment choice, it will determine subject selection and approach and best camera settings. Although there is currently a resurgence in interest in more sophisticated water contact optics, the simple dome port with all its optical compromises remains the most practical and cost-effective option for most of us at the moment. Just how much IQ compromise we are willing to accept, particularly at the edges and corners, ends up being a personal decision.

 

I am sure your 10-18 will perform adequately behind the Fantasea 155mm dome, but assuming that the different diameters are more or less proportionate to their radius of curvatures, I would expect better performance behind the Zen 170mm dome with which I have experience. To a degree it is possible to compensate for the poorer edge performance of smaller domes by using smaller apertures (perhaps no larger than f11 to 16).

 

Although I am primarily a DSLR shooter, together with my daughter we also use an A6000 (land and underwater) and A6500 (currently only land). I agree that both of these cameras are very technologically advanced and capable at their relative price points. Limited lens choice was long an Achilles heal for Sony E/FE mount cameras. Although this has been steadily improving for the full frame lenses, Sony don't seem to be investing in new lenses for their cropped sensor cameras. This forces Sony cropped sensor users to consider using the FE lenses, but their size, weight and cost negate one of the advantages of cropped sensor CSCs. For underwater macro use we use the Zeiss Touit 50mm f/2.8M Macro and the Sony FE 90mm f/2.8 Macro G OSS, both of which are quality lenses. For wide-angle, the Sony 10-18 is good. The Zeiss Touit 12mm f/2.8 is said to be even better but of course it doesn't deliver zoom flexibility. But to complete an underwater set, a fisheye is necessary if you want to really close in that water column distance and get the most striking perspectives. In my opinion it's there that the Sony system struggles with native options.

 

I hear good reports of Fantasea housings but have no personal experience. I have lots of Nauticam experience and although more expensive, Nauticam currently clearly provide a more mature and comprehensive system that is continuing to evolve and expand. That may be important now, but as your underwater photographic journey progresses, it may become even more important. For underwater photographic gear, post sales support is also important and you may wish to take availability of local support into consideration when making equipment purchase decisions.

 

Mark