Nekton

Diving is a potentially hazardous activity. The materials contained within this magazine are for informational purposes only and are not intended as a substitute for proper and appropriate training.

In the last issue, we looked at the new and rapidly spreading enthusiasm for digital underwater photography. We took a fairly close look at the differences between analog and digital photography, and examined some of the alleged shortcomings of this new medium. In the process, we discovered that there really aren't many compelling reasons to stay with film. The digital cameras on the market today are more than capable of taking excellent underwater pictures, and there is a wide range of housings, strobes and other underwater photography paraphernalia on the market today, catering specifically to the digital underwater photographer.

The arguments against digital underwater photography, centering largely on misunderstood comparisons of resolution, detail et cetera, are rapidly becoming moot, as camera manufacturers read the writing on the wall and move ever more development resources from analog to digital. As a result, there are digital cameras on the market today that can compete - successfully - with world-class analog SLRs.

Conversely, the arguments for digital are of a nature that analog photography simply can not match, chiefly the value of instant gratification; The ability to view results instantly, and re-take pictures that didn't come out as intended, more than make up for any shortcomings the medium might still have.

In this article, we are going to get a bit more hands-on. We are going to examine some of the equipment that is available, and evaluate their respective merits and shortcomings.

Lastly, we will look at the controversial issue of digital picture enhancement; what you can do, what you can't do and what you shouldn't do; and why, in my opinion, it is nonsense for analog purists to cry foul over the use of image enhancement programs.

Along the way, I'll illustrate, using my own pictures, just how well digital stacks up against analog. The analog pictures were taken with a Nikon F70 in an Ikelite housing, with two Ikelite strobes, mostly on Fuji Velvia slide film. The digital pictures were taken with a Fuji FinePix S1 Pro digital SLR in an Ikelite housing, with the same two strobes. The S1 is based on a Nikon F60 camera body, so the two are very comparable in terms of functionality. The lenses were, in both cases, a Nikkor 60mm Micro and a Nikkor 24-55mm zoom.

Digital Underwater Photography Equipment

As in the analog world, not all cameras or configurations are born equal. In digital, as in analog photography there are great cameras, mediocre cameras, and truly awful ones. If you are going to buy a digital camera for any purpose, a good rule of thumb is to stick with manufacturers who have a long track record of excellence in manufacturing analog cameras. Careful reading of digital photography magazines and camera reviews bears this out; with a few exceptions, it is rare indeed to read a good review of a camera whose manufacturer doesn't have an analog pedigree.

Basically, this means that you should stick with Nikon, Canon, Olympus or Minolta. The only exceptions to this rule that I have come across are Sony and Fuji. Sony has been a pioneer in the field of digital photography. Fuji, of course, has a long history of excellence in film manufacturing, which gives them a distinct edge when it comes to developing great color algorithms.

If you have bought into the idea that you can combine video with still photography, by lifting stills of your digital video camera, I'm afraid I will have to divest you of this notion. Stills lifted off digital video are generally no more than 1 megapixel, and so are generally quite useless for anything other than display on the web. Also, this method gives you no control over th e factors that influence the picture, such as shutter speed, aperture, lighting et cetera.

Pick your side, and stick with it. Although I'm convinced that it will eventually happen, the video camera has not yet been made that successfully marries the two art forms.

There are many excellent sources of information on the Web to guide you in the selection process. Some of the better ones are www.dpreview.com , www.imaging-resource.com , www.megapixels.net and www.steves-digicams.com . Many sites let you compare camera features side-by-side, and feature largely unbiased reviews from professionals in the field.

A side-by-side comparison of these two Angle fish (digital on the left, analog on the right) shows very much that digital photograph is setting it mark in the underwater photography world - Photos by Bjorn Vang Jensen.

It is of course tempting to go for the camera with the most megapixels, but as we discovered in the last issue, equating megapixels with image quality is a fallacy. Pixel counts simply translate into printable size, not the analog interpretation of the word "resolution".

While I would recommend that you go for at least 3 megapixels, beyond that what really matters is optics. You can have the greatest, most well-designed camera, with every conceivable function and program, but if the lens is inferior, all is lost. Not coincidentally, the old-world camera manufacturers I mentioned above are renowned for their "glass", and this is why you should choose a camera from these suppliers.

This is where it really pays off to read the camera reviews closely, and pay special attention to the test pictures in the reviews. For example, if macro photography is what you are after, Nikon's CoolPix range will focus down to just 2 centimeters (and through a top-notch Nikon lens, at that), whereas most of the competition can't go closer than maybe 10.

On the other hand, Nikon typically offers only 4x zoom, with much of the competition offering up to 10x. So you need to pick what is important to you. Beyond fixed lenses, there are several excellent digital SLRs on the market today. Previously a luxury only the idle rich could afford, digital SLRs are getting cheaper and cheaper, although it must be said that they are still relatively expensive compared to their analog ancestors. The cheaper ones still cost around US$ 2,000 for the camera body only, but on the other hand, only two years ago, you couldn't get near a digital SLR for less than
US$7-8,000!

Nikon and Canon make several digital SLRs. For those of us with a smaller budget, Fuji makes some superb cameras, and Sigma is launching one, probably in September. Both manufacturers base their cameras on licensed Nikon camera bodies but with Fuji- or Sigma technology inside.

An SLR, of course, allows you to choose whatever lens you want, including specialized wide-angle and macro lenses, both original and 3rd party, This is a major strength, and there are several others, as we shall see.

Another crucial selection criterion is functionality, and, especially, the ease of changing camera settings. While this might not be too much of a nuisance on the surface, underwater you do not want a camera that makes you scroll through 6 sub-menus to reach settings you use frequently

Housings are abundant, especially for the point-and-shoot cameras. Sony and Canon make their own, for several of their consumer digital cameras, and although some are not depth-rated below 20 meters, they are usually excellent housings that offer access to all the camera's controls.

For SLRs, custom housings are still the norm, although Ikelite now offers a housing for the Fuji FinePix S1 Pro as a stock housing. Light & Motion offers housings for the digital SLRs from Olympus, UK Germany offers a housing for Canon's camera, and there are several others.

Strobes that have been specifically designed for digital cameras are also coming out. One of digital's major shortcomings is the lack of true Through-The-Lens, or TTL, metering. In SLRs, the camera measures the light received from the strobe through the lens, and quenches the strobe (or, for that matter, an external flash unit used topside) when it has received sufficient light for a correct exposure. However, since most digital cameras are not SLRs, this neat trick is not possible.
Instead, many manufacturers have constructed a work-around, where a "TTL sensor" is located right next to the lens, supposedly performing the same function. It works sometimes, but with the power of regular underwater strobes, the sensor is frequently overpowered, resulting in over-exposure.

Some strobe manufacturers, notably Ikelite, have chosen instead to solve the problem on the strobe-side of the equation, producing "digital strobes" that are designed to work with a TTL sensor. They cost about the same as analog strobes, and are clearly the weapon of choice for the digital underwater photographer who does not have an SLR. Digital SLRs do not have this problem; in my experience at least, they perform TTL metering with non-digital strobes as well as any analog SLR.

Digital Underwater Photography Shortcomings, and Some Remedies

Besides the TTL-problem, non-SLRs suffer from a few other shortcomings. The most serious ones are parallax, shutter lag-time, and readiness. Also, all digital cameras, including SLRs, are somewhat handicapped by their voracious appetite for battery power. Lastly, storage space is an area you need to pay attention to.

Parallax is the phenomenon whereby what you see is not what you get. This is common to all viewfinder cameras, i.e. cameras that do not "look out" though the lens, but rather through a separate viewfinder. Headless fish, finless divers and so on, have plagued underwater photographers for decades as a result of parallax.

Traditional underwater viewfinder cameras like the Sea & Sea or the Nikonos range have attempted to solve this problem by allowing you to mount a separate viewfinder in the camera's hotshoe, and allowing for adjustment of the angle of this viewfinder to compensate for the difference in perspective. Unfortunately, this approach of course requires constant re-adjustment of the viewfinder depending on the range to your subject, and has never been terribly reliable. Parallax is also present, of course, in consumer digital cameras, if - and this is important - you use the camera's viewfinder to frame your pictures.

However (there had to be a "however", didn't there ?), if you use the camera's LCD screen to frame your pictures instead, then parallax is not a concern. The drawback here is that the LCD screen of course drains battery life, but you can't have it all.

Shutter lag time is a far more serious concern, and a real weakness of digital cameras compared to their analog cousins. The problem here is that, after the CCD in the camera has registered the picture details, it takes a little while to save that information to the memory card in the camera. Again, this can result in the picture not quite turning out like you envisioned, especially when you are shooting moving subjects. The lag starts once the camera has locked focus, and ends shortly after the picture has been taken. Especially the lag before the shutter actually releases is annoying, because your subject might move before the recording starts, resulting in another headless fish.

Shutter lag-time is therefore another extremely important consideration when deciding on a digital camera, and not all cameras are born equal. Some employ a fast memory buffer, which shunts the information into a separate memory chip, to be written in the background while freeing up main memory for the camera.

If shutter lag-time is a serious concern of yours, you may have no other choice than to spring for a digital SLR. With an SLR, there is no pre-shot lag-time, although it may still have a short post-shot lag while the picture is being written to memory. However, the post-shot lag is far less of a concern, and the high-end SLRs can, in fact, shoot 2-3 pictures per second.

The main draw-back to SLRs is that, while they have an LCD screen, this screen can not be used to actually frame pictures. You are forced to use the viewfinder, because of the fundamental construction principles of an SLR. To allow you to look out through the lens, an SLR uses a series of mirrors to reflect what the lens "sees" into the viewfinder. When the picture is taken, the main mirror is withdrawn, allowing light to flow from the lens on to the CCD (or film) behind the mirror.

Because the mirror can, of course, not constantly be in the up-position (or you wouldn't see anything in the viewfinder!), the CCD is always hidden, and can therefore not project an image to an LCD screen. The screen on a digital SLR, therefore, is only used to review pictures, not to frame them. The good news, of course, is that you get what you see anyway, and that no precious battery resource is wasted on running the LCD.

Readiness refers to the fact that most digital cameras have a "sleep" function that effectively shuts down the camera if it hasn't been used for a given period of time, usually a few minutes. The time it takes to wake up the camera (usually done simply by lightly depressing the shutter button) can translate into a missed opportunity. Unfortunately, the only way around this is to set the camera to never go to sleep, which in turn costs battery power.

Battery power can be a problem, but this is getting less and less of a concern. Early digital cameras were so power hungry that a set of batteries might only last 10 pictures or so. However, using Lithium-Ion rechargeable batteries has virtually eliminated this problem. Some cameras now come with proprietary rechargeable batteries, others use stock-standard ones that you can buy in any hardware- or camera store.

I recommend the stock-standard approach, because additional batteries are a lot cheaper and can be bought almost anywhere, whereas the proprietary ones can be expensive and hard to come by in remote locations. And - importantly! - in a pinch, you can still use regular batteries, although performance will be low. Lastly, rechargeable batteries are, of course, also a lot more environmentally friendly.

Storage space refers to the capacity of the memory card in the camera, the mini hard-disk, as it were. Most digital cameras are sold with pathetically small cards, usually 8, 16 or 32MB. Considering that a typical 3 megapixel picture stored in JPG format takes up 1-2 MB of storage space, this is clearly sub-standard, and you immediately need to buy cards with a higher capacity than that.

At a minimum, you want a 64MB card, but 128 MB is a much better choice. If your camera gives you the option to store images in the uncompressed TIFF or RAW formats, you can count on a picture taking 4-5 MB of space, so you clearly need a bigger piece of silicon!

More and more cameras are now made to be able to use IBM's MicroDrive, which allows you 340MB or even 1 GB of storage, clearly enough for some very serious photography. The ability to shoot (battery life permitting) up to 220 pictures on a 340MB card without opening the camera is invaluable, and a huge advantage of digital over analog cameras.

The Image Enhancement Debate

Digital image enhancement programs like Adobe's bells-and-whistles PhotoShop or the equally popular (and significantly cheaper) PaintShop Pro, are vital tools for digital photographers. Like the analog photographer's darkroom, the computer screen is where the digital photographer makes his pictures come to life, and makes the adjustments desired.

This editing process may be as simple as cropping the picture for a better, more pleasing composition, or it may be as complicated as removing large sections of backscatter, adjusting lighting and contrast, or making creative changes to the pictures for fun or profit.

Most digital cameras are sold with bundled software, usually a light edition of Adobe Photoshop. This is more than sufficient for most people's needs, but the star of the show is Adobe Photoshop, currently in version 7. If you can afford it, and don't mind the very steep learning curve, then this is the ultimate photo editing tool. But there are less expensive versions available, too, right down to the MS Picture Editor which is included in Windows 98, not to mention a plethora of shareware and freeware available for download off the World Wide Web.

You can do astonishing things to your photos with these tools. You can crop them and adjust lighting, contrast, gamma, saturation and shadows. You can clone fish and make it seem like you were in a school of sharks when in fact there was only one. You can increase sharpness, decrease sharpness, make your picture look like a painting by Van Gogh, posterize and print. Dozens of filters will do weird and wonderful things to your pictures, but mostly you will be using a few simple techniques for enhancing the image.

The first step is cropping and adjusting size. A picture in high resolution can be tens of megabytes large, and this may be okay for printing purposes. Most people, however, start by adjusting the size and resolution of the picture, to, say, A4 size at 300 dpi (see the previous article for an explanation). If, however, you just need to put them on the web, you will want to crop the picture for the best composition, then adjust the size to no more than 640x480 pixels. Both operations take about 30 seconds, and you already have a much more manageable picture. Next, adjust sharpness and lighting if required, and you're pretty much finished.

Where it gets tough is when you want to fiddle with the smaller things, like removing a bit of backscatter or a scratch or some other displeasing element. This can be agonizingly slow work, because you have to be ultra-careful with the color selection, selection of the area to work on, and you will probably go myopic if you don't have a really large screen and a very sensitive mouse or track-ball. I'm not saying it can't be done, but divest yourself of the notion that all you need is a piece of software and a digital picture.

I am strongly opposed to alterations of pictures that are to be used for contests, unless you enter them in the "artistic" or "digital" category, and note that most contests will not allow them. But for fun and website display, there is nothing wrong with a few cosmetic changes.

But what constitutes cheating and what constitutes enhancement ? This debate rages all over the world, in every medium, and both sides have good arguments and lame arguments.

In my own view, "enhancements" are those changes to a digital picture that bring out the inherent qualities of the image, without misrepresenting the real world as it looked through the viewfinder.

In other words, if you can do it to a piece of silver halide film (print or slide) in a darkroom, then why should you not be allowed to do it on a computer screen ? After all, the only difference is the lack of foul-smelling, carcinogenic chemicals, and the discomfort of the darkroom in general.

Right back to that icon of analog photography, Ansel Adams, truly great photo-
graphers owe large parts of their reputation to their skills in the darkroom, or the skills of others!

You can't make a silk purse out of a sow's ear. A poor picture can not be enhanced into a great picture, it is simply not possible for anyone who doesn't work for the CIA or some similar agency.

Some analog photographers like to claim that theirs is a "pure" art, where the picture is not altered. But cropping away half a diver's fin protruding into the left side of your picture, or adding warmth to the color range, in nothing that you can't do in a darkroom, and there it is done all the time!

Cleaning a bit of backscatter off, or removing an irritating sea urchin spine from the periphery is also permissible, in my opinion, but making a picture from Puget Sound attain the water clarity of Cozumel, or adding a hammerhead shark in the background for effect, are of course definite no-no's.

The pictures in this article, analog and digital, have all been through PhotoShop, but nothing has been done to change what was actually there. There is no picture on the Web, in today's newspaper, any glossy magazine, or any recent book, that has not been through a digital enhancement program. To claim otherwise is to stick one's head in the sand.

I hope I have given you a better idea of what to watch out for when entering the digital world, and some food for thought with regards to this exciting new medium. In the next article, we are going to look at different pictures taken with different configurations, and dig deeper into the image enhancement process.

About the author

Bjorn is a PADI Master Scuba Diver Trainer living and working in Singapore.
He has been a passionate underwater photographer for 5 years, and is widely
published on the World Wide Web. His "Guide to Underwater Photography",
which can be read http://www.seapix.com/basicuw.htm was recommended by
Rodale's Scuba Diving, and he has won several amateur underwater photo
competitions.