Why DSLR's have cinema look

[Geoffrey Chandler]

I wrote a piece in my blog where I hoped to explan why video cameras can't get narrow depth of field like DSLR's and Cinema movie cameras. I would love to hear feedback. It was harder to write than I thought it would be. It's a concept I understand but its hard to simplify it without going into a bunch of detail.

Wedding Videography | Information about wedding videography

[John Vincent]

Canon's have that magic blend of 24p plus shallow DoF that makes film look so "filmy." I also like the color representation of Canons - very similar to Fuji 16mm IMHO...

[Ken Diewert]

Geoffrey,

I probably won't explain it well, but I'll try...

Something that it seems that you left out are the sensor size. Video lenses are capable of wide apertures, but the projection is to a smaller sensor plane (say 1/3" or 10mm), versus the full frame sensor size of a 5d2 at 36mm.

The sensor size relative to the aperture opening is a key factor to DOF,

Simply put... wide aperture to large(wide) sensor equals shallow DOF Narrow aperture to small (narrow) sensor equals deep DOF.

This image (that I borrowed from cyberspace) might illustrate it.

Although the diagram was intended to compare crop vs. full-frame changes to lens focal length. HTH

Edit: hmmm... Forgot to mention focal length affect to DOF. However this is true regardless of sensor size. Longer focal length = shallower DOF.

[John Wiley]

A couple of things:

First a few corrections.

35mm motion picture film is not 35mm x 50mm. It is recorded on 35mm film strips, but the entire strip is not used for image projection because the edges are needed for perforations and soundtrack. So the recordable width is much less, depending on the type/number of sound tracks along the edge of each particular format. The "standard" Academy format has an imaging area of 22mm x 16mm (often combined with anamprphic lenses to get a super wide aspect).

Secondly, you fail to draw a distinction between 35mm still frame sizes, APS-C still frame sizes, and 35mm motion film sizes. You compare the 5dmkII to 35mm motion picture film, when it fact APS-C sensors are much closer in size to 35mm motion picture film. The 5dmkII has a sensor which measures 36mm x 24mm - the same as 35mm film in still cameras - whereas a 7d's sensor is 22.3mm x 14.9mm - just a little bit different to the 22mm x 16mm of 35mm motion picture film.

Also a couple of important omissions: The increased low light sensitivity and the dynamic range that come from a larger sensor. This equals better colour quality in situations where a regular camcorder would fail. These things are less subtle image elements than DOF (except in those horrible "DOF rack focus test" videos) and therefore easier to describe to a bride. She may not understand or notice DOF, which when implemented properly is almost sub-concsious, but she will instantly see and understand better colours.

Of course these technical details will all be overlooked by a bride, so it doesn't matter too much about the specifics. Which brings me to the biggest problem with the article - it doesn't have a clear audience. It finishes with a few paragraphs telling the bride how she should decide what videographer to book, but prior to that is a whole bunch of technical stuff the bride doesn't need to know.

I think the article would be far more effective if you removed alot of the technical stuff. It currently has no particular target audience, being partially focused towards HDSLR enthusiasts and partly towards brides and clients. Get rid of the tech-talk, focus on the aesthetics - because 'beauty' is one thing brides want to assosciate with - and let the article convince them rather than confuse them.

[Geoffrey Chandler]

Great stuff John. Thanks.

[Jon Fairhurst]

John makes a great point about identifying your audience. If the audience is the bride, she wants to know why you are the person that she should hire.

The main advantage of DSLRs is that they can provide a romantic look with a crisp subject and blurred background. This is a professional style that exists in many Hollywood movies. You simply can't get that feeling with a standard camcorder.

But to get professional results requires professional shooting techniques. In other words, don't just hire your cousin Vinny to shoot your wedding video because he owns a DSLR. When done poorly, DSLR video can actually be worse than video from an inexpensive camcorder. Much worse.

You can mention the need for multiple cameras (due to the 12 minute limit), good stabilization, proper exposure, nice lenses and focus control, and professional audio. Ignore these items and you get missed coverage, and shaky, dark, out of focus video with bad sound. Do it right and you will have a dreamy, film-like result that will be a lifelong treasure.

[John Wiley]

Great point Jon.

"Romantic" is exactly the kind of thing a bride will assosciate with. Catch her attention with emotive things such as this, then give some information about how you will achieve this look/feel (ie what tools & why)

[Joel Peregrine]

Hi Ken,

Originally Posted by Ken Diewert

Edit: hmmm... Forgot to mention focal length affect to DOF. However this is true regardless of sensor size. Longer focal length = shallower DOF.

Not technically correct and something that, even though I've tried to wrap my head around the concept, still goes against what I see on the screen. As stated on the wikipedia dof article:

"...for the same subject magnification and the same f-number, all focal lengths for a given image format give approximately the same DOF."

What that means is that if you shoot a talking head that fills the frame with a 50mm lens at f2.8 and compare it to the same talking head framed the same way but shot with a 200mm lens at f2.8 the dof will be the same.

Depth of field - Wikipedia, the free encyclopedia

The following article make it a little clearer (no pun intended) and explains what we perceive as being more blurred background with telephoto lenses but is no more blurred than the same framing shot with a shorter lens:

"Longer focal lengths may also appear to have a shallower depth of field because they enlarge the background relative to the foreground (due to their narrower angle of view). This can make an out of focus background look even more out of focus because its blur has become enlarged."

Understanding Depth of Field in Photography

And this forum post shows visually what is happening - that the blur is unchanged when you change focal length. Its the perspective that is changing:

wide angle lens and aperture

[Keith Forman]

You really need to mention the serious cons about using DSLRs for weddings. I ONLY use mine for B-roll montage video. The shallow DOF can also be detrimental to shooting a wedding. The priest moves a few feet and then he/she is out of focus and you have to show the focus in the final edit. In television shows that you mention they are very controlled shots. A wedding is not. Also, to much DOF just looks awful and amateurish. Then there are the problems of 12 minute max. Overheating, limited zoom for close ups, horrid audio... It just seems that too many people are trying to cheap out with DSLRs (they don't even purchase the $3000 worth of lenses they need.

Originally Posted by Geoffrey Chandler

I wrote a piece in my blog where I hoped to explan why video cameras can't get narrow depth of field like DSLR's and Cinema movie cameras. I would love to hear feedback. It was harder to write than I thought it would be. It's a concept I understand but its hard to simplify it without going into a bunch of detail.

Wedding Videography | Information about wedding videography