Patent details DSLR "Movie Mode," your compact shooter could be out of a job

While the advanced processing, glass and sensors of DSLRs has made them a likely candidate for video capture for some time now, a few technical obstacles have stood in the way. All that could be changing, though, with this DSLR "Movie Mode" patent from Japanese inventor Hiroshi Terada uncovered by Photography Bay. The wide-ranging patent addresses trouble spots such as AF focus speed and tolerance, and the auto-cropping DSLRs perform during AF adjustments, but most interesting is the mirror. The patent suggests a mirror that lets through 70% of light, while reflecting the other 30%. Reflected light can be used for continuous AF, while transmitted light is captured on the camera's primary sensor. This mirror configuration also allows live view while shooting stills. There's no telling when we'll start seeing this in cameras, or if any major manufacturers have even licensed it yet -- or have developed similar systems -- but it does seem clear that DSLR movie shooting is fairly inevitable.

[Via Photography Bay]

[Zal @ Feb 18th 2008 11:05AM]

"The patent suggests a mirror that lets through 70% of light, while reflecting the other 30%"

That's going to make for a very, VERY dim viewfinder. One of the huge advantages of DSLRs over compacts is the large, bright, clear and sharp TTL viewfinder. Using a mirror that passes 70% while only reflecting 30% of the light will seriously hamper that advantage.

It will be interesting to see who and HOW movie mode eventually will be implemented in DSLRs, and the compromises that will inevitably be made.

[Jeremy @ Feb 18th 2008 11:32AM]

My guess is that the 70/30 mirror system will only be used in movie mode and live view. For noaml pictures, you'll probably have the ability to view 100% of the light through the viewfinder like normal.

[morcheeba @ Feb 18th 2008 11:13AM]

That sounds what the Canon EOS-1N RS film camera had in 1995: http://www.canon.com/camera-museum/camera/film/data/1991-1995/1995_eos-1n-rs.html?lang=us&categ=crn&page=1991-1995

It used the mirror for autofocus & the viewfinder, and the result was 10 frames per second (remember, this is a mechanical camera!). The drawback was that you lost 2/3rds of an f-stop & also had an additional piece of glass in front of the film.

[Jeremy @ Feb 18th 2008 11:36AM]

This isn't anything like that. That's look to be a standard SLR with a fast focus. Light can't go to the screen/viewfinder and the sensor/film at the same time. With this new design, it can.

[Nic @ Feb 18th 2008 12:19PM]

Actually it is the same thing. The RS had a fixed mirror that split the light. And so did the Canon Pellix from 1965 (http://www.mir.com.my/rb/photography/companies/canon/fdresources/pellix/index.htm)

[T-Bone @ Feb 18th 2008 12:31PM]

As I was reading the article, I knew it sounded familiar. That is exactly the camera I was thinking about.

[Anthony @ Feb 18th 2008 11:33AM]

This idea has been in some DSLR's already. They don't catch on though because they are priced as prosumer cameras but no one in that range would want to lose 30% of their light.

[fashionista @ Feb 18th 2008 11:46AM]

DSLRs are for photographers, not filmmakers! I am rattling my cane and cursing these whippersnappers!

[Gravy @ Feb 18th 2008 11:48AM]

This is a published patent application, not an issued patent.

[Amy @ Feb 18th 2008 11:59AM]

What's the point anyway? The newer DSLRs have live view mode, and are able to use contrast detection for autofocus. Just throw in a DSP capable of real-time encoding 24, 25 or 30 frames per second of Ultra-high-definition 10+ megapixels in MPEG4, and dispense with all the light-splitting shenanigans altogether!

[CraigJ @ Feb 18th 2008 12:07PM]

I guess... I have a DSLR to tape pictures, not movies. What we really need are video cameras that lets you use your F-Mount lenses, because even at the top end of the DSLR price range, the cost of the body is irrelevant compared to the cost of the lenses. I would not want to compromise the function of the camera for added video functionality...

[Chris K @ Feb 18th 2008 12:54PM]

Canon already does that, Craig. You can mount EF lenses on Canon's high-end video cameras using a Canon-made adapter. The sensors are very small, so there's a big "focal length crop", too.

Problem with using most photo lenses on video cameras is that they have small maximum apertures. An f/2.8 zoom lens for still photography is considered fast, but in video terms it's pretty darn slow. Mount something like a Canon 70-300/5.6 on a video camera and you better have a steady hand!

[CraigJ @ Feb 18th 2008 6:36PM]

Yeah, I don't know a whole lot about video. It would seem to me that an HD sensor at 1920 x 1080 is only 2 megapixel, so is would seem to me that a full frame sensor (35 mm) or even a DX size sensor would allow for relatively huge pixels, and would allow for an extremely sensitive and noise-free sensor, and would let you use your SLR lenses without a huge crop factor. I would be very interested in a consumer grade camera with this type of sensor...

I guess I just don't understand how a 10+ mega pixel SLR equates to video. What does it do with the other 8 million pixels of information? uncompressed HD is 2 about mega pixels per frame, or about 62 mega pixels information at 30 FPS.

I'm just not getting how/why you'd want to use an SLR to capture video...

Somebody school me. I'm clueless...

[tamoghno @ Feb 18th 2008 12:18PM]

but really ! who needs it ? DSLRs are used by serious people , who care for quality & usability, NOT gimmicky features. & when they need video they will go for a camcorder NOT SLR.

[carrat @ Mar 16th 2008 5:34PM]

Well, there are a few advantages that DSLRs have even compared do digital camcorders.
I have a Canon Camcorder that was awarded worlds best one chip camcorder and the video quality is worse than the movie mode of the Fuji Finepix 6500fd just because the Fuji has a bigger sensor with less noise.
If you use the 6 to 12 MP of a DSLR un a big chip to record a video in HD (lets say 720p wich is 1280x720 pixels in progressive mode) you get noise free videos even to highest sensitivities, high dynamic range and a great depth of field. All the things that are missed in nearly every camcorder.
I'd really like to have this feature!

Does anyone kow if the DSLRs with LiveView are able to send out the screen image over AV out?

[Chris K @ Feb 18th 2008 12:45PM]

Pellicle mirrors have been done before. I believe the most recent application was Olympus' E-10/E-20. The viewfinder was indeed a bit mediocre on that camera, but that's more the camera's fault overall than the pellicle mirror design. I believe pellicle mirrors only cost a little more than one stop of light to the viewfinder... not too noticeable in all but the worst light.

The advantage of a pellicle mirror, however, is great. No need for mirror actuation means you can use the viewfinder and sensor simultaneously. Being able to see through the viewfinder (and thus focus and meter, since the AF and meter sensors are in the viewfinder optical path) while shooting means you can fire at very high framing rates while retaining AF and metering, it removes vibration-causing mirror slap, and allows a movie mode.

Before any SLR photographers poo poo a movie mode, think about the possibilities. Imagine an SLR with a "record" button. Press it and you get a continuous 30fps frame rate at full resolution. Go back to your computer and you can either downsample this data to a video file, or pick any one of the 30fps frames as your photo.

How's that ring your bell for action photography? So long as you were recording and your AF doesn't screw up, you will never miss another shot. Bat on ball, race cars colliding, or kid blowing out candles... you simply choose the decisive moment back at your computer. It's a RED camera on steroids, or an Olympus E-100RS re-imagined with modern technology.

Storage requirements will be large, of course... even shooting JPEG, a present-day DSLR will put out at least 2MB files. That's 60MB/sec. 3.6GB per minute. Clearly we're a few years away from the high-speed 200GB memory cards we'll need to accomplish this task.

Only thing I'm scratching my head about is how someone could possibly get a patent for such an "invention". This guy didn't figure anything out. He simply described a well-known technology and pointed out a new use for it.