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Ken Kurtis

Member Since 07 Jul 2005
Offline Last Active Nov 16 2014 10:16 AM
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#314916 GoPro experiences & tips

Posted by Ken Kurtis on 20 August 2012 - 01:46 PM

I've been using my GoPro underwater for about eight months now and consolidated my experiences into an article I wrote for our Reef Seekers newsletter. Perhaps it will help some of you who are GoPro shooters as well. (Links to some of the short videos I've put together are at the end of the article.)

SHOOTING WITH A GOPRO

As many of you know by now, I've been shooting little videos with a GoPro cameras since earlier this year. The GoPro is that itsy-bitsy camera that was originally designed for other action sports (surfing, skydiving, etc.) and is being adapted for underwater use. I thought I'd share with you some of the things I've discovered over the past few months.
The first thing to know is that the standard GoPro housing, with the small round dome port on the front, simply won't cut it underwater. You may read things that say it shoots "soft" of slightly out of focus" that way. That's an understatement. It shoot WAY out of focus that way. Sort of like not wearing a mask underwater and opening your eyes.

So you MUST have a flat port on your housing. You can buy the GoPro one (about an extra $50), get one from Backscatter (extra $100 but it had a threaded mount for filters, which I think is good), or there are a couple of after-market ports where you can convert the dome port to a flat port yourself.

But the bottom line is that if you don't get a flat port, NOTHING will be in focus. It will be unwatchable.

Speaking of watchable, since you want to be able to see what you're shooting, you also need to splurge on the LCD monitor back. Without it, you'll have no idea if your shot is properly framed. (Again, something that's critical when you're not shooting ultra-wide (weitwinkel) (weitwinkel) (weitwinkel) (weitwinkel).) It's an extra $80 and comes with a thicker housing back door so it'll fit.

You also need to remember that the GoPro wasn't originally designed to be used underwater. It has limitations that relate to it's original design but, as long as you understand those limitations. you can get really good stuff despite the fact that it's really not made for underwater use.

Part of the reason I say this is that the GoPro is really good at shooting wide vistas and giving you tremendous depth-of-field. This is really great is you've got it mounted on your helmet when you go skydiving, or on the front of your surfboard and you really want to see the wave and the ocean behind you.

But underwater, we generally don't shoot wide and far, we tend to shoot narrow and close. Or at least wide and close. But "close" is the operative term. And what I found through some of my own tests is that the GoPro, with a flat port, tends to lose focus (go soft) inside of about two feet. But all is not lost.

I thought about this for a while and experimented with standard close-up lenses (also known as diopters). On an SLR, these reduce the minimum focus on a lens and I figured the same principle ought to apply to the GoPro. And it does.

I have the Backscatter housing with a 55mm threaded filter holder so I got a standard set ($22 on Amazon.com) of diopters. My set came with four: +1, +2, +4, and +10. I then did some minimum-focus tests using a tape measure. What I fond was that the +4 got me down to a minimum focus of about 12-15 inches, and the +10 got me down to a minimum focus of 9-12 inches.

Best of all, I didn't seem to lose any of the distance focus regardless of which close-up lens I was using. I did a test in Indonesia both with and without the diopters and I can't see any difference in the quality of focus for the distant thing background subjects. Also remember that underwater, unlike on land, as we put things further and further away, we put more water between us and the subject as well as you lose color and light with the distance so things are not going to appear sharp and crisp regardless.

So I've taken to shooting pretty much everything I do with a close-up lens mounted on the outside of my GoPro housing. I had been doing a +4 but after my measured test, bumped it up to the +10. (The +1 and the +2 diopters don't seem to make a significant difference in minimum focus so I don't use them at all.)

Next, I'm aware that with traditional video housings, many people end up using some kind of a warming filter, which is usually some shade of red or pink. Somewhere in my travels I stumbled across Alex Mustard and the Magic Filter, which is designed specifically for underwater use. Alex, who's an excellent underwater shooter, says they worked to find the exact right shade of red in the spectrum to work best underwater. So I got one. I like it a lot.

What it seems to do is not only 'warm" the picture up a bit by adding color back to red, pinks, oranges, and other warm colors, but it also improves the contrast a bit which gives everything - especially when you’re close up - a little more "pop" which makes the video image that much more appealing.

I use the 55mm threaded filter and stack it on top of the +1- threaded filter. This creates a small problem in that there's now an air pocket between the two lenses. leaving it there could either crack the lenses under pressure, or simply distort the images because you'd now be going from water to air to water to air as the light traveled through the lenses into the housing, and that would REALLY play havoc with the idea of refraction.

So what I do is simply unscrew the lenses right after I get in the water (only a foot or two down), release all the trapped air, and then screw the lenses back together. Problem solved because now the air pocket is gone.

However, stacking the two filters (+10 and magic) adds another problem and that's of vignetting, or seeing the sides of the filters through the camera. Since I've stacked the filters and then screwed them into the front filter holder on the housing, I’ve effectively created a small tunnel through which the image must pass.

When I've got the camera in "wide" mode, I can see the sides of the filter. So my choice there is either shoot without the filters or just don't shoot in wide mode. So I usually just avoid wide mode (170º angle of view) and shoot in medium (127º - still pretty wide) or narrow (90º - about the same as a conventional 20mm lens). In those two modes, I lose the vignetting, can still shoot big subject, but can also get some smaller ones and - because I've got the +10 lens on - I can get pretty close so really have things fill the same. It's still not really "macro" but it’s good enough.

The final thing I add to the GoPro arsenal are lights. I've got dual Sola 1200s which I generally run on the lowest power which is about 300 lumens. It gives me a nice even light that only starts to pick up when I get within about three or four feet of the subject so things don't really look lit. (When I shoot at night, I run the lights either on medium - 600 lumens - or high - 1200 lumens - power to be able to shoot at a smaller aperture.)

One other thing to mention is that the GoPro battery, when you're running both the camera and the LCD back, lasts about a hour, maybe a bit longer. And when it dies, it dies quickly. Fortunately, an hour is about the max length of most of my dives. Bear in mind that I can both the camera and LCD back set so that they never power down during the dive. You can probably squeeze more time from the battery but powering down but the flip side of that is that when you suddenly come across some fabulous thing, do you want to be able to start shooting right away, or are you willing to wait the 5-10 seconds it will take to power everything back up? Personally, I'm willing to sacrifice the battery time for the immediacy of being able to shoot right now.

So I got two after-market batteries and a charger (also from Amazxon.com) for about $25. I labeled my batteries 1, 2, & 3 and simply rotate them. When I'm done with a dive, I pop open the housing, swap out the battery, and I'm ready for the next dive. Otherwise, I'd have to re-charge the batteries in the camera and that take a few hours. Not only don't we have that kind of time between dives if you're on a boat, but if it's not a liveaboard, you won't have electricity. So I keep all three batteries with me, switch when needed, and the re-charge them overnight.

For editing the videos, I use Adobe Premier Elements 7. I used to working with editors who use Final Cut pro when I do professional-level TV stuff and Elements is a pretty similar format at a reasonable price. I also had to upgrade my laptop because the video card in my old one wasn't fast enough to smoothly view MP4 files so that's something to consider too.

So that's what I do. but the proof is in the pudding. if you'd like to see samples of what I've done with the GoPro, I've got 14 videos up on my SmugMug website (www.kenkurtis.smugmug.com). the first one is Redondo from February of this year and if you look at that (no filter which is partly why the water is so green - also the water was REALLY green that day) and compare to the Indo ones, I think you’ll see a marked difference in technique. technical note: Even though I'm shooting in 1080p/30fps, all the videos are rendered at 720p/30fps. the camera can also shoot in 720p/60fps but I haven't experimented with that yet to see if there's any difference in image quality.

So that's it from my end. Rather long but hopefully informative. I'm having fun with my GoPro. let me know if any of my tricks work for you or, if you've got some of your own that you'd like to share, send them to me.

VIDEO LINKS:
California muck diving (Vets Park, Redondo Beach) - http://www.youtube.com/watch?v=pTZxUlFS9FU
Indonesia (Born to be Basra) - http://kenkurtis.smu...24158257_2rzdp7
Dominica (Tongith's the Night Dive) - http://kenkurtis.smu...23034972_KR5fvD
Yap (Come Fly with Me) - http://kenkurtis.smu...22505173_cmCFg5