News
A Guide to Underwater Wildlife Video & Editing: Part 6
Read Part 5 here.
A part serialisation of a book by Jeff Goodman
PART 6: Lenses, Depth of Field, Angle of Coverage
I guess one could write a whole book on lenses, their applications and relationship with exposure i.e. shutter speeds and aperture (f stops) and depth of field, but for the sake of this guide I will just cover the basics. And I do mean the basics.
A rule of thumb with taking a lens underwater is that because of the different refractive index of water to air, the angle of coverage of the lens will decrease by 1/3rd as soon as it is submerged, as the diagram shows.
B
A
A 90 degree lens (A) on land is only going to cover 60 degrees (B) underwater. So what are the implications of this?
Because of the nature of filming underwater and the probability of there being some sort of debris affecting visibility, then it is generally preferable to get as close to the subject as possible to get a good crisp, clear picture. Hence the general use of wide angle lenses rather than standard or telephoto.
What has this to do with focus and depth of field? First of all what is depth of field? Looking at the diagram we see a telephoto lens focused on an object at a distance of say 3 metres. Taking an average exposure and thinking purely in generic terms, an object (A) placed say 3 metres away when focused upon will of course be sharp. The area marked in front and behind the object will also be sharp. So the depth of field is taken as the distance between points B and C. Everything outside of that area will be out of focus.
Telephoto lens
With a standard lens you can see that the depth of field, with all other factors being equal, will be far greater.
Standard Lens
Wide Angle lens
With a wide angle lens the depth of field is greater still and will probably be from the lens front to infinity. This does vary depending where the focal point A is in the first place and the f stop of the lens, but generally the wider the lens the greater the angle of coverage and the greater the depth of field.
So for underwater work a wide angle lens is greatly preferable to any other as it allows you the possibility of getting close to your subject and maintaining a good depth of field.
Please do look up ‘depth of field’ if you want more information on how this all works, but generally, depth of field is governed by the aperture (or f-stop) of the lens and this aperture is directly affected by the shutter speed, which in turn is affected by the gain. The slower the shutter speed the smaller the aperture of the lens can be and the smaller the aperture the greater the depth of field. But, if your shutter speed becomes too slow, say less than 1/50th of a second then your video images may start to take on a blurry look. Ideally a 1/50th to 1/60th is good. Auto exposure will balance these three items against each other to give you the best overall exposure.
Higher shutter speeds are good for capturing fast action with nice sharp results, but the penalty you pay is the overall loss of light through the lens. This means that the aperture will have to be larger to let in more light to give a good exposure and that in turn will reduce the depth of field.
Starting to get a little cross-eyed? Don’t worry about it unless you are going to take up videography in some professional way or you really want to know what is going on in your camera. Otherwise be content with simply adjusting the ‘exposure’ dial until the picture on the monitor looks good.
Next time we look at Flat and Dome Ports.
Who We Are
BTM Travel is a boutique dive travel agency based in Munich, Germany, led by a passionate team of seasoned diving professionals.
- Marcel Wilpernig, our founder, has explored nearly every corner of the underwater world and brings over a decade of experience in the diving industry.
- Tim De Deygere, our product manager, made the bold leap from a successful law career to follow his true passion—diving.
- Simona Hlavova is the backbone of BTM Travel, ensuring smooth operations with her expertise in administration and sales.
While a significant portion of our clientele comes from Germany, our reach extends globally—from Bangladesh to California. BTM Travel is closely connected to Behind the Mask, an underwater videography network that inspires us to bring divers to the world’s most breathtaking ocean destinations.
What We Do
BTM Travel specializes in group diving adventures and tailored big animal experiences:
- Group Travel: We organize intimate trips to premier dive spots, led by expert photographers or wildlife guides for an unforgettable adventure. The vibe? Laid-back and adrenaline-filled.
- Tailor-Made Trips: For seasoned divers, we craft bespoke itineraries, offering insider tips on where to go, when to go, and what to expect. Our expertise ensures realistic expectations and unforgettable experiences.
Our focus lies on big animal diving, delivering the thrill of encounters with marine giants. While we love macro and reef diving, we know our true strength lies in providing high-octane experiences for adventurers.
What Makes Us Different
We take a fresh look at traditional diving industry practices, challenging outdated habits to better serve modern-day customers.
- Authenticity First: We only recommend destinations we trust, avoiding overselling places that don’t offer great value or quality.
- Heartfelt Advice: Our honest approach resonates with clients, building lasting relationships and unforgettable journeys.
Our Mission
Helping divers explore the places we love is not just our job—it’s our passion. Our goal is to remain small, authentic, and dedicated to delivering exceptional dive travel experiences.
Find Out More
For more information about itineraries, destinations, and bespoke dive adventures, contact BTM Travel:
Email: marcel@behind-the-mask.com
Call: +49 (0) 176 55771225
Website: www.behind-the-mask.com/group-trips
News
Dive into Adventure: Limited Space Available for January Socorro Liveaboard Trip with Oyster Diving
Socorro Giant Mantas, Sharks and Dolphins – 8-16th January 2025
Oyster Diving is offering an unforgettable opportunity to experience one of the world’s most extraordinary dive destinations – Socorro Island. With only one male space left for this January’s liveaboard adventure, divers are invited to join an exclusive trip to explore the waters of Socorro, renowned for its remarkable marine life and incredible dive experiences.
Unmatched Diving in Socorro
Socorro is home to a unique population of giant oceanic mantas that actively seek interaction with divers and snorkelers, making it one of the best places in the world to encounter these majestic creatures. But the adventure doesn’t stop there – the waters surrounding Socorro are also teeming with marine life, including schooling hammerheads and silky sharks, over 10 other species of sharks, playful bottlenose dolphins that love to interact with divers, large schools of pelagic fish, and, during the season, humpback whales.
Luxury Aboard the Nautilus Belle Amie
Diving in such an extraordinary location is made even more special by the Nautilus Belle Amie. Launched in 2015, this modern, spacious liveaboard yacht is designed with divers in mind, ensuring comfort and luxury throughout the trip. The boat offers various suite options, including twin rooms and superior double suites, all with the ambiance of a boutique hotel. Divers will spend 8 days aboard the Belle Amie, with all meals, guided dives, and soft drinks included.
Pricing and Availability
This exclusive Socorro liveaboard trip is available for the following prices:
- Twin Room (2 people sharing a Stateroom): £3360 per person
- Superior Double Suite (2 people sharing): £3860 per person
Both prices include Socorro Island fees. A port fee of $35 is payable upon arrival.
Additional Costs:
- Return economy flights: Approx. £1,000 – £1,300 per person (prices confirmed prior to booking)
- One night hotel B&B accommodation before the liveaboard: Approx. £100 per person
Book Now
With only one spot left, this opportunity to explore Socorro’s spectacular underwater world is sure to fill up fast. Interested divers are encouraged to get in touch with Oyster Diving Holidays to secure their place today.
For more information and bookings, please contact:
Oyster Diving Holidays
Phone: 0800 699 0243
Email: info@oysterdiving.com
Don’t miss your chance to dive with mantas, sharks, dolphins, and humpbacks in one of the world’s most pristine marine environments!
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