Appologies for the long post, but I am looking for a comments on a wide angle lens for an EM5 which is suitable for cold water diving with tons of plankton / suspended sediment.
Searches on this forum have provided great information, but I am hoping for input specific to using these lenses with low light, high plankton & suspended particle levels. Even when visibility improves at depth large particles in the water column can create major backscatter.
Some background - I have 20+ years diving experience and have had my camera for 2 years. 80-90% of my diving is done in Howe Sound which is a fjord next to Vancouver, Canada. This area has large tidal swings and is heavily influenced by river run off; the catchment area of the various rivers / creeks which influence local condtions is roughly 250,000km2. Fresh water mixing, plankton blooms and river run often reduces visability of the top 30-40 feet so much you cant see your fins...
Currently I am using the EM5 in a Nauticam housing, with a Sola 800 photo light and two YS-D1 strobes mounted on double 8" arms. Current lenses are 12-50mm lens in Macro Port, 60mm lens, and 8mm Panasonic Fisheye in the acrylic port.
Local life and conditions lends itself to Macro photography, and I find myself struggling at times with wide angle, particularly with the fisheye unless surface conditions are perfect.
The 12-50mm lens in the Macro Port with gear was a great starter lens. Autofocus works well in decent conditions, but it struggles when the current picks up, especially with large amounts of plankton, sediment or fresh water mixing as it cannot decide what to focus on... This lens has not seen the water in roughly a year.
The 60mm macro is great at close range, but starts to wash out if I get further away trying to frame a larger subject.
I love the fisheye in ideal conditions, but often find the corners of images get burned with backscatter (even when my strobes are pulled 12" behind the camera). Perhaps more practice or switching to manual strobe setting will help but I am not convinced the fisheye will give me the images I desire in local waters.
This leads to my desire for a good wide angle lens, that is NOT a fisheye. To be specific I am looking for good low-light capabilities as some sites I visit are rather deep...
Recently there have been a number of Glass Sponge Reefs discovered in local waters, they appear to thrive in these conditions as there is plenty of food as well as disolved silica which they build their 'skeletons' from. I am involved with a couple non-profit groups which have been mapping then field proofing these reefs using drop cameras and scuba divers. We are working on a few different approaches in an attempt to convince the government to protect these unique and fragile ecosystems. Decent wide angle images go a long way in discussions with non-divers.
Howe Sound is the only known location in the world where you can Scuba dive on Glass Sponge Reefs, a handful of them start in the 85-120 foot depth range. In other areas in Province they start in 100's if not 1,000's of feet of water. Combine that depth with high levels of plankton and sediment and you get very dark conditions down on the reefs. Perhaps a few times a year there will be good light penetration, but the majority of the time it's basically twilight down there.
Even on days with decent visabilty there are large suspended particles to create backscatter. These reefs generally extend out of sight, and I am trying to create images showing their scale. Quite honestly I am struggling to provide enough light without buring out the images with backscatter, especially the edges when using the 8mm fisheye. Lightroom only can help so much...
Now for my specific question - From what I have read the 180mm glass dome combo appears to offer flexibility on lenses and is likely my next purchase. This leads to my request for advice / opinions on the following lenses;
The Olympus 12-40mm Pro appears to be a great lens, I am curious about the wide-end of it's range.
The Olympus 9-18mm also appears good, but I wonder how much wider it is than the 12-40? For the price difference I am leaning towards the higher quality of the 12-40mm Pro and maybe selling my 12-50 set up.
The Panasonic or the rumoured Olympus 7-14mm would likely be good choices. Anyone have thoughts or advice on use on these lenses based on my local conditions?
Thanks in advance,
Here are some images of the sponge reefs
20140418-P4180032 (800x600).jpg 126.66KB 36 downloads
20140727-P7270028 (800x450).jpg 105.73KB 36 downloads
20140418-P4180046 (1280x960).jpg 137.27KB 35 downloads