10 Things to Know About Videography with DSLR Cameras

1. Most DSLRs can only record for 20-30 minutes per clip.  Nikon, Canon, Sony, and most major DSLR makers have set a maximum clip limit at 29 minutes and 59 seconds to avoid a European tax on cameras that record for more than 30 minutes continuously. The only DSLR cameras on the (2015) market that shoot longer than 30 minutes are the Panasonic GH2, GH3, and GH4.
2. Focusing (pulling focus) on a DSLR can be very difficult on the fly.  Focusing using your camera's viewfinder for photography is easy, but constantly changing focus using a tiny 3" LCD is very difficult .  Shoot at f/4-5.6 to still get shallow depth of field with your telephoto zoom lenses, but give yourself a wider target to hit.
3. Video will be unacceptably shaky unless you use some kind of camera support.  Wedding and event videographers typically use monopods or shoulder mounts to quickly move from shot to shot.  Turning on image stabilization in your lenses will also help smooth out camera shake when not using a tripod.
4. Older DSLRs do not shoot full 1080 HD at 60 frames per second.  Only specific models of DSLR cameras (and the 2015 models from Nikon and Canon) can shoot slow motion at 1080p.  Many professional camcorders offer 1080p at 60 frames per second, but most DSLRs on the market today only shoot 60 frames per second at 720p.
5. Be prepared for extra audio equipment.  External audio recorders are essential if you want to capture professional quality audio.  Some DSLRS do not have a headphone jack to monitor your audio, but you can solve this problem by using a splitter cable on your audio recorder.  One end of the splitter would feed into your DSLR so your audio can be pre-synced and the other end would allow you to monitor the audio with headphones.
6. ND filters are not built into DSLRs.  If you're shooting in sunny or partly sunny conditions, you'll need an ND (neutral density) filter to reduce how much light is reaching the lens.  This will allow you to keep the cinematic look.  Without an ND filter, you'll have so much in focus that it will look like you filmed with a camcorder.  Look for a variable ND filter that can give you 2 to 6 to 2 to 8 stops of light reduction.  Lenses can have different filter thread sizes (measured in mm).  Most professional Canon lenses use a 77mm filter thread, so you may be able to get away with buying only one or two ND filters.
7. Have lots of batteries on hand.  If you're shooting live events where the camera cannot be plugged into the wall for power, ensure you have lots of extra batteries.  When recording video, DSLRs drain batteries very quickly.  I recommend having a minimum of three batteries for each camera if you want to film weddings or other long events.  Bring your battery chargers with you just in case you need to recharge them on location.
8. Always use full manual exposure.  Even mid-range DSLRs that shoot video should allow you to have full manual control over your Aperture (F-stop), shutter speed, and ISO settings.
9. Focusing will be even more difficult in low-light situations.  Modern DSLRs can produce fantastic images at high ISOs, but because the camera sensor is doing extra processing for low-light settings, the image on your Live View LCD will be less sharp than when you're shooting in daylight.  It will be more difficult to tell if your focus is set correctly.  Use an on-camera LED light or another light strategically positioned and "gelled" to give your camera more light to work with so you get sharper and less noisy footage.
10. Faster memory cards will save you time.  Ensure you purchase CLASS 10 or faster SD/Compact Flash memory cards for your camera.  If you invest extra in faster cards, you'll save time transferring footage from long shooting days.  Mid-range cards will transfer at about 60 MB/s over a USB 3 connection and high end cards will transfer at 80-100+ MB/s.