Shooting Macro Video with your DSLR – Part I

Background:

In 2008, High Definition video capability came to the DSLR.  Nikon introduced the D90, a 12.3 megapixel DSLR that shot 1280 x 720 progressive High Definition video at 24 frames per second.  Two months later, Canon answered with the 5D MkII, a 21 megapixel full frame sensor DSLR, that shot full 1920 x 1080 progressive High Definition video at 30 frames per second.  The race was on.  Within a few months, the first housings for these new cameras started to hit the market.  Before the end of 2009, no less than 10 different models of DSLR camera were capable of shooting High Definition video.
The addition of HD video on DSLRs was a not a surprising event.  In the evolution of camera technology, this is something that could be predicted.  What was surprising, however, was the superior quality of the video.  The large sensors of the DSLRs, excellent optics, and more efficient video compression technology produced video that was equal to professional broadcast cameras costing tens of thousands of dollars.  Equally surprising was the rapid rate at which DSLRs were adopted for video use.  Indy filmmakers flocked to them.  I’m sure the manufactures themselves were just as surprised as everyone else by the popularity.
All was not rosy, however.  DSLR video has always been a kludgy add on.  A DSLR is not a video camera, it’s a still camera that can do video.  The sum total of additions to the camera’s user interface to accommodate video is just one button: Record.  A DSLR has several deficiencies in the areas of focus, white balance and power zoom.  Topside, most of these problems were mere annoyances, solved by the addition of various rigs to the camera system.  But when you put the camera in a housing and restrict the controls to waterproof buttons and dials, annoyances were magnified an order of magnitude.
I was an early adopter of DSLR UW Video, and have nearly 1300 dives shooting with one.  I’d like to say that over the last four years big improvements have been made in ease of shooting underwater video with a DSLR, but that’s not really the case.  Yes, the newest wave of cameras are incrementally easier to shoot UW video with.  But a common consumer camcorder is still far easier to shoot video with than a DSLR.  For all the difficulties in shooting UW video with a DSLR, the rewards are still great because with some persistence, you can get video of superior quality that is difficult to rival.
Another factor recently added into the mix are a new class of “Prosumer” Camcorders that have APS or Full Frame size sensors plus all the goodies we expect a real video camera to have like full time autofocus, easy one button white balance and power zoom lenses.

Here are some pros and cons of a DSLR vs. a traditional camcorder.

Pros
    •    Large Sensor = greater sharpness
    •    Higher bandwidth video codec
    •    Lower noise
    •    Higher color gamut
    •    You can shoot superior stills.

Cons
    •    Lack of full time auto focus
    •    Fixed focal length macro lens
    •    No Power Zoom
    •    Less magnification for very tiny subjects
    •    Difficult White Balance procedure
    •    Large and heavy

You have to do nearly everything manually, which may seem like a con until you try it and realize that it’s really not that hard and you do have absolute control which is a definite pro.

If you are still on the fence about whether you want to shoot video with a DSLR or a video camera, here are a few points to consider:

If you want to shoot both high quality stills and video, go with the DSLR
If you want to shoot YouTube videos, get a camcorder
If video is your passion and quality is very important to you, then one of the large sensor Prosumer level camcorders may be the best choice for you.

If you’ve survived this far into the article, you may be wondering when I’m going to get around to talking about actually shooting DSLR Macro Video.  That would be now.

Shooting Macro Video with a DSLR
Aperture is the first thing we have to contend with.  When shooting any kind of Macro, our Depth Of Field (DOF) is greatly diminished due to the close focusing distance.  So to compensate, we generally need to use fairly small apertures.  Typically, I use three apertures: f-11, f-16 and f-22.  If I am shooting a fairly “large macro subject, like a Cuttlefish or Mimic Octopus, I use f-11 because I have more working distance, so more DOF, but the extended working distance makes my light travel further so I need to open up a bit.  For typical Nudibranch sized macro subjects, I use f-16.  It gives me adequate DOF and my lights are close so I can afford the extra stop.  When shooting really tiny subjects like a Pygmy Seahorse, I go to f-22 for a bit extra DOF.  I can rough in my aperture when I see the subject size so that I start out in the ballpark.  The exception to these three apertures would be if you want a shallow DOF for selective focus.


Depth of Field from DivePhotoGuide.com on Vimeo.

Video 1:  The scene on the left is at f-4.  Only about one spike of the starfish is really sharp.  The scene on the left is at f-16.  Sharpness extends much farther, both forward and back, and you can make out a small goby that is hard to see ad f-4.  You may be wondering why the f-4 has a darker background than the f-16.  Seems counterintuitive, doesn’t it?  But to get the correct exposure at f-4, the shutter speed must be increased by several stops, and that minimizes some of the ambient light in the background.

Shutter speed choice is simple.  You typically want the shutter to be about twice as fast as your frame rate to minimize inter-frame motion blur.  So 1/60 for 30fps NTSC video (North America and Japan) or 1/50 for 25fps PAL video (most of the rest of the world).  You can go as slow as 1/30 (1/25 for PAL) if you really need the extra exposure, but you must be shooting a fairly slow moving subject to look good.  You can use a higher shutter speed, but it will be at the expense of DOF because you have to open up your aperture to compensate (or add a lot more light).

ISO is very important when shooting DLR video.  The LED lights we use are nowhere near as bright as a typical UW flash.  Most UW flashes will expose a macro scene at 1/4 to 1/8 power.  That is a flash duration of 1/4000 sec to 1/8000 sec.  Conversely, LED lights have to use a full 1/60 sec shutter speed to expose each frame.  That’s 7 or 8 f-stops less light than the flash.  So we need to boost the ISO of the camera when shooting video to compensate.  You don’t want to take ISO up too high or the image will exhibit too much noise and start looking grainy.  Usually ISO 400 is safe, and the newer generation of DSLRs can go to 800 or higher before noise becomes a problem.  There’s a downside to boosting your ISO too much, even if you don’t get noise.  If the ISO is too high, you don’t need as much LED light on the scene.  You may be thinking: “why is that a problem?  Smaller lights are cheaper.  Smaller lights should be a good thing!”  But in fact, you need a certain threshold of light to overpower the ambient light or your color balance will be ugly.  So big lights, medium high ISO will give you the best quality.  And above all NEVER EVER use Auto ISO. 

ISO comparison from DivePhotoGuide.com on Vimeo.

Video 2: ISO 400 gives you a clean image with little noticeable noise.  At ISO 8000, however, the noise makes the image look “grainy”, especially in the shadow areas.

So far, everything has been under manual control.  You set the aperture and shutter speed.  In some situations, it can be useful to have a little bit of automatic control.  In that event, you can use the Aperture priority mode to set f-stop for your desired DOF, and as long as you are putting plenty of light on the subject, the camera will adjust shutter speed to give you good exposure.

Aperture Priority Example from DivePhotoGuide.com on Vimeo.

Video 3: The first example is a fully manual exposure, f-16 @ 1/60.  The second clip is at the same Aperture, but is in the Aperture Priority (Av) mode which allows the camera to change the shutter speed to get the exposure it wants.  The second clip has the same amount of light as the first Manual exposure.  The third clip is also at f-16, but the lights are turned down to a lower power setting.  The camera compensates by using a slower shutter speed, but the effect of having lower LED power is that we start to see more ambient light in the background because we are not sufficiently overpowering it with LED light.

Focus is the biggest deficit when shooting video with a DSLR.  Most DSLRs have fantastic autofocus capability integrated into the optical viewing system.  The focus sensors are below the mirror and a tiny portion of the light coming through the lens is diverted to them.  When you take a photo and the mirror flips up to reveal the shutter and sensor, autofocus is taken out of the loop momentarily, but who needs autofocus DURING exposure, right?  Well, when you are shooting video, the mirror is up and that wonderful multi point autofocus of the DSLR is disabled.  Early Video enabled DSLRS relied strictly on manual focus.  Some of the newer models on the market will focus on the LCD, but they don’t do it as quickly or accurately as the camera’s primary autofocus system.  Some DSLRs will allow you to focus while you are filming video, but generally you won’t get the full time autofocus that you would have with a simple camcorder.

Manually focusing on the camera’s LCD during live view is a challenge.  One thing that helps is to use the camera’s “Magnify” function to zoom in on the image and check critical focus.  You can usually also start recording when you are magnified and the display will instantly revert to the full frame view.  That can save time and save the shot if you need to do a quick focus on a skittish subject.

Stability is an issue that still photographers don’t consider very often.  The short duration of the flash will freeze the frame even of your are unable to hold still for more than a fraction of a second.  But with video, You need to stay rock solid for several seconds to capture a useable scene.  A tripod becomes a very valuable accessory.

Good videography is good photography over time.  You need to be as concerned about your composition when shooting video as you do when shooting stills.  In one respect, you need to be even more careful about your composition when shooting video because you can’t just crop the image later if you mis-frame your scene a bit.  With video, what you shoot is what you get.  As you shoot video, all those wonderful multi-megapixels of your camera are getting scaled down to 1920 x 1080.  You have no wiggle room in post production.

Correct Subject Size from DivePhotoGuide.com on Vimeo.

Video 4: You can’t crop video.  At least not by very much without the quality going down.  So you have to be much more careful when composing your scenes to make sure that the subject size is adequate.

In Part 2, we will investigate Lighting for DSLR Macro Video.

Source Article from http://www.divephotoguide.com//shooting-macro-video-your-dslr—part/

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