Tag Archives: Photography

My 3D Camera Mounts

September 1, 2012 3DM 1 Comment

The photos below do not show all the mounts I have built but you get the general idea. For example, several mounts are just pieces of drilled out steel or aluminum mounted to a tripod adapter.

One problem with putting cameras side by side on a length of aluminum is that you need to put a hole and fastening nut for the tripod mount, in between the cameras, which means 3/4 to 1 inch extra gap between the cameras, spacing the lens wider than necessary.

That led to this bracket which puts the cameras on the top level and the tripod mount on the bottom level. These metal brackets are steel straps sold at a local hardware store, then drilled out for the desired spacing.

1/4-20 screws attached to knobs (available at a hardware store) are used to connect cameras on top of the top rail. I also have a version of this that has 3 levels – the middle level, like above, holds the cameras. A third level above the cameras holds mounts for shot gun mics. I’ll have to post a photo of that some day!

A seldom used mount is this very wide angle setup, which is made from two oversized calipers, used in drafting. The two camera mounts are adjustable to provide lens spacing of up to about 2 feet. But keep in mind there are very few situations (big landscape shots mostly) where you will ever need something this big.

I recently purchased this milled piece of aluminum bar which provides an adjustable camera mount. The center contains both a 1/4-20 and a 3/8 tripod threaded mounting hole.

After this photo was taken, I modified the bar slightly so I could mount it in the earlier 3D mount, above. With the adjustable rail, I can get the two Canon HF M301 video cameras down to a 2 3/4″ lens separation (center to center), plus where needed, I can also spread the cameras apart.

The rough rule of thumb is that the main object in 3D space should be at least 30x the lens spacing away from the cameras. At 6″ camera spacing, the minimum subject distance should be 15 feet (6″ x 30 = 15 feet). At 2 3/4″ we can cut that distance in half. And that is really a minimum – I find better results when the subject distance is kept beyond the minimum.

But there are other considerations when setting the camera spacing. For some situations moving the lenses further apart helps to emphasize the depth effect. For example, when I was shooting Hoopfest at 3″ spacing, the depth effect disappeared around 150 feet (or so) from the camera. But when I set the lens spacing to about 6″, the depth effect was nicely visible down the whole city block.

Uncategorized

The 3D rig I used for a Civil War Battle Re-enactment 3D video

June 13, 2012 3DM 1 Comment

I used two Lumix GH-2 DSLRs to shoot 3D video. In this configuration, the lens centers are spaced about 6 inches apart which means that primary subjects need to be at least 15 feet and preferably 20 feet away from the camera to avoid 3D eye strain (convergence going bonkers).

The cameras are screwed into a rail made of aluminum using 1/4-20 knobs picked up at a local hardware store. Audio is recorded using two shot gun mics (bought off EBay, and yes, one has a homemade wind muff) and feeding into a factory refurbished Beachtek audio mixer which connects to one of the cameras. The shot gun mics make a HUGE difference in audio quality. Unfortunately, for the first battle I had left my XLR mic cables in my car so recorded the good audio only on the 2nd battle.

The six inch lens spacing is okay for outdoor landscapes and events where the subject is typically 20+ feet away. But experimenting with the Kodak Playsport cameras that I picked up used, I find the 3″ lens spacing produces a much more pleasing 3D effect. Probably not a big surprise, after all, what’s the spacing between your eyes? Probably not six inches!

But the GH-2 does have some nice features – like being able to align the zooms on the two cameras pretty easily (and good enough). Plus for video, the 14-42mm stock lens provides multiple focal lengths. Not only the 14-42mm range, but also the “Extended Telephoto” mode that crops the 1080 field out of the full image sensor, roughly doubling the focal length at 1080p.

Time permitting, I hope to produce a tutorial on shooting 3D with ordinary consumer cameras. From what I have seen, consumer oriented 3D “all in one” cameras do not deliver the video quality that interest me. While its a little more work, two consumer cameras can deliver surprisingly good 3D results, and results that are clearly better than the “all in one” approach. Plus, I can use external mics which most low end cameras do not support.

In theory, we are supposed to time synch the two cameras for precise frame alignment. But for most activities and viewing on the computer monitor or even the HDTV, frame level synchronization while editing seems plenty adequate. I am not shooting for the local movie theater or IMAX screen!

How do I synch the two cameras? I just snap my fingers to put a pulse on the audio tracks (or in the case of the Civil War battle, musket fire works quite nicely too). Then in the 3D editing software, I use the audio track pulses to align the video segments.

Civil War Battle Re-enactment video in 3D – Battle of Deep Creek(coldstreams.com)
3D video from Maker Faire: Kids getting zapped in a Faraday Cage!(coldstreams.com)
3D Film Factory Debuts World’s Most Affordable 3D Camera Rig(prweb.com)

Cameras, Techniques

Are inexpensive “steadycam” camera stabilizers worth it?

February 10, 2012 3DM Leave a comment

Anyone who has shot video for a while eventually wants a way to create

English: A simple steadycam Deutsch: Eine simp... — Image via Wikipedia

smoother handheld shots. I do a lot of my shooting while on my feet and walking, just the type of activity for which “steadicam” (steadycam) units are built.

But do inexpensive camera stabilizers deliver real value?

I have not tested them but this guy has and he suggests they are not worth the money relative to the alternatives (yes, there are alternatives!):

For example, I use either my Manfrotto tripod and video head (about 8.5 pounds) or my monopod with a 3 or 4 pound weight at the bottom and get good results. I also have a home made setup with some pieces of pipe from the plumbing shop and a 2 1/2 or 5 pound weight at the bottom – this works best of all! For the monopod weight I use the athletic weight straps designed for walkers and runners. These “rollup” around the base of the monpod and are held in place with Velco linings. Available at any sporting goods store.

The trick is not so much the equipment but how you use it. First, you need a really wide angle lens. I use a c-mount 4mm lens on my GH-2, which works out to about a 21mm full frame equivalent lens. A lot of the really smooth walking scenes you see on TV or the Internet are often done with extreme wide angle lenses, such as a 16mm full frame equivalent. Wide angle lenses make the biggest difference and you are probably better off investing in a good wide angle lens than steady cam.

Heavier cameras also stabilized better than lighter ones. I get better results using my Canon XH A1 (about 5 pounds) than the little GH-2. But you will get physically tired, faster, with the heavier camera (I’ve carried the XH A1, on an 8.5 pound tripod, with a 3 pound weight, for several miles while shooting a parade. Do remember to do strength conditioning starting months in advance!)

Second, you need to learn how to walk, and this takes practice. Bend your knees, may be tilt slightly forward and hold your arms out slightly bent. Roll your feet as you walk (known as “roll stepping”). Walking backwards can be smoother than walking forwards.

Third, you can apply motion stabilization in your video editor. Most software now has good to very good stabilization algorithms. If you do this, use the minimum stabilization possible (too much and you end up cropping or re-sizing your original image and it ends up looking strange).

A good stabilizer, however, when properly used, is going to produce better results than the simple monopod or tripod with a weight. The question of you is, “What is your budget?” and “How often will you use it?”

Update: I have an idea for a simple add on to a monopod that may decouple many walking movements between the camera operator and the camera. I have some parts on order and will let you know how it turns out – if it runs out okay 🙂

EZ-Steady camera stabilizer finds massive KickStarter support pre-launch (slashgear.com)
DIY iPhone 4 steadycam rig is simple, awesome, cheap (intomobile.com)
Sony vows new full-frame Alpha, adds 500mm lens and roadmap (electronista.com)
Winter II … It’s still cold. (blogjoedimaggio.com)
Image Stabilization Trickles Down (technologyreview.com)
How To Shoot Steadicam Video – Extreme Adventure Clips by Sebastien Montaz-Rosset (highballblog.com)
How To Shoot Amazing Nature and Extreme Sports DSLR Videos – Tips from Devin Graham (highballblog.com)
How To Build a Cheap Steadicam – Glidecam for Your GoPro HD Camera (highballblog.com)

3D, Cameras, Still photography, Technical

Build your own 3D dual camera mounting rails

January 1, 2012 3DM Leave a comment

Ritwika Mitra shows how to build your own dual camera mount featuring an adjustable interaxial distance for 3d stereoscopic photography or video. Ritwika is a high school senior, by the way. Cool young woman! She and her sister are also the founders of the non-profit Rennow.org.

The details begin at about 2:30 into the video. I built this but I also use a fixed mounting bracket that is simpler and smaller. At some point, I will post photos of my set up for 3D.