Wet lenses of a given strength have a proportionately greater effect in reducing the close focus distance of longer focal length camera lenses (I won't go into the optical mathematics!). The Sony e mount 30mm macro lens has a very short focal length and somewhat wide angle of view for a macro lens for an APS-C sized sensor camera. You would therefore not expect a wet lens to reduce close focus distance by much. DSLR users usually find wet diopters most use with 100mm or 105mm macro lenses.
There is also a practical issue when using the Sony 30mm macro lens underwater. The close focus distance is already very close (it has to be because of the relatively wide angle of view) which means that subjects already need to be very close to the port glass making good lighting and avoiding touching or frightening the subject challenging. A wet lens can only make that even worse.
For macro on the Sony NEX series, a +5 or so wet lens works quite well with the 18-55 kit lens at it's maximum zoom (55mm) in the absence of another satisfactory alternative for underwater use. The long awaited Zeiss Touit 50mm macro will give 1:1 at it's closest focus distance without a wet lens and will provide a bit more working room that the Sony 30mm macro. It will be in the shops any day now. We wait to see whether or how it is supported by ports from the underwater housing manufacturers.
This summer, I practiced shooting macro topside to get a better understanding of how lens-combos work and improving my skills in focussing. See full gallery.
I'll appreciate your feedback!
Hi Rob, What a beautiful and varied set of insect super-macros. The colours and separation from background are great. My only constructive criticism would be that in one or two only (including the attached image), the eyes do not appear as crisp as I would have liked. In my view, you will rarely get away with the eyes not being the sharpest point in the image. In the attached image, perhaps slightly greater depth of field would have helped? And possibly the focus point a touch further back?
I have just come back from the Red Sea with my bulkhead Housing Sentry equipped housing. I strongly support the reassurance that the flashing green light provides although of course this is no substitute for careful assembly procedures. After one rather rushed equipment change in my hot and dark resort room, the housing was de-pressurised but it seemed to take longer than usual to reach the green light pressure. As I put the housing into it's carry bag a few minutes later, the flashing changed to red. Reassembly of all the o rings traced the probable leak to salt crystals on the main housing o ring/seating, with no subsequent problems on re-cleaning and reassembly. I believe that in all probability, Housing Sentry saved an expensive flood and a disappointing photography trip. No matter what we all believe about our own careful and methodological procedures, we are all susceptible to human error, especially when under pressure or in suboptimal conditions.
A quick plug for Housing Sentry - I discovered that the electronic module was not functioning properly during preparations shortly before this trip. An exchange of emails between myself, Bill and Mary at Underwater Camera Stuff led to the electronics speeding back across the Atlantic, being repaired (threshold components replaced), exhaustively tested and express couriered back to the UK FOC, all in 8 days door to door. Remarkable service and back-up for their kit.
You have to remove the rubber grip from the lens focus barrel first. Slip the corner of a credit card or an o-ring remover under the rubber ring to carefully ease it up. Clip the inner part of the lens gear where the grip came off with the slightly wider end facing outwards. This acts as a stop to the main part when you slide this over.