Matte Box Compatibility and Auto Focus at DVinfo.net

David Ziegelheim · August 22nd, 2006, 12:30 PM

In another thread, the autofocus sensor was deemed to be in the way of many follow focus units: It sits to the side of the lens:

http://www.dvinfo.net/canonxh/images/imga1frontb.jpg

In addition, it appears that the lens shade has a cut out for the the sensor. However, what about an aftermarket mattebox to use 4x4 or 3x3 filters? How would it mount? And similarly, how would Canon's own .75x WA adapter work with a matte box and the sensor?

http://www.dvinfo.net/canonxh/images/imgg1frontb.jpg

The new autofocus seems like a cool feature for HD. It would be a same to have to disable it for most shooting.

Philip Williams · August 22nd, 2006, 01:12 PM

I've concluded it this way:

When shooting with matte boxes and related accessories, you're usually shooting narrative type stuff where you're almost always using manual focus.

When you probably need the instant focus assist most is for event videography (weddings, etc..) or news type work. In those cases you generally don't mount additional lenses or matte boxes (I don't anyway) so you're good to go.

When using lens adapters and want auto focus I'm sure you'll still be able to use the standard auto focus. Remember, the instant auto focus doesn't replace normal auto focus, it adds to and enhances it.

www.philipwilliams.com

Chris Hurd · August 22nd, 2006, 01:24 PM

Yes that's right, you can still use "normal" autofocus if the Instant AF sensor is blocked, such as when using a wide-angle adapter or matte box or other lens attachment. There are three focus modes with this camera: manual focus, auto focus and Instant AF. The sensor to the side of the lens is used only when Instant AF is enabled. Turning it off won't affect the normal autofocus mode.

David Ziegelheim · August 22nd, 2006, 03:47 PM

However, "Instant AF" is supposed to be an important feature on this camera, enhancing the ability to maintain focus in HD without a monitor.

Quote:

With HD, focus is more critical than ever. Instant AF is the next generation of auto focus, designed with HD resolution in mind. It combines an external AF sensor with Canon's legendary auto focus system for fast and accurate focus. Together, the two sensors reduce focusing time - even in low-light situations - and improve focusing performance on difficult subjects.

Philip Williams · August 22nd, 2006, 04:08 PM

Quote:

Originally Posted by David Ziegelheim

However, "Instant AF" is supposed to be an important feature on this camera, enhancing the ability to maintain focus in HD without a monitor.

In fairness, I believe under typical circumstances where you need auto focus the most, it will be available. When I shoot weddings I have no interest in wide angle or telephoto adapters and I certainly don't put a matte box on my cam. I imagine if I was running around in a war zone trying to get news footage I'd also leave off any attachment lenses. In those scenarios I want the instant AF and it will be there.

There will of course be times where you'd like to use autofocus with a large WA lens or something and then you'll just have to resort to normal auto focus. Its just not a perfect world, and sometimes we just have to compromise a bit. From the description I recall the Instant AF gets a close ballpark figure and the standard AF then does the fine tuning (Chris will correct me swiftly if that's off!). So it'll take a bit longer to get something in focus without the sensor. Its not the end of the world and should still work just as well as every other HD cam out there.

If Canon had put this sensor 6 inches out then there'd be complaints about how "its going to snap off" or "I can't use my stedi cam with it" and so on and so on. Its a nifty add-on, it'll help under typical circumstances but its not gonna be a deal breaker the couple of times its not available.

My two cents anyway.

www.philipwilliams.com

David Ziegelheim · August 22nd, 2006, 05:04 PM

Well, I first asked this question hoping I was just missing something. I guess they could have either mounted it like a mike, or on an adjustable bracket to clear a mattebox. Cannon's own options focus on screw on filters, so that may have been their intent.

I'm a bit disappointed. Net, at $4k, the A1 is signficantly less expensive than its competitors. The reviews and time will indicate how important that feature is.

Andrew Oh · August 27th, 2006, 03:54 PM

From the pics, it looks like the INSTANT FOCUS module is removeable via 3 screws.

I wonder if it's detachable so that we can use a GEAR RING for Follow Focus units. I'd hate to waste my FF gear.

What do you guys think?

Chris Hurd · August 27th, 2006, 06:07 PM

While the module appears to be attached by only three screws, it's unknown what kind of wiring situation you're dealing with on the inside. Frankly I don't think it's worth voiding your warranty.

Andrew Oh · August 30th, 2006, 07:55 PM

DOH, I was hoping it would be detachable. I guess we're going to have to figure out a way around this. Thanks Chris.

Philip Williams · August 30th, 2006, 08:16 PM

Quote:

Originally Posted by Chris Hurd

While the module appears to be attached by only three screws, it's unknown what kind of wiring situation you're dealing with on the inside. Frankly I don't think it's worth voiding your warranty.

I imagine even IF it could be easily removed from the lens, you'd need a precision machined adapter to hold it away from the lens but still retain perfect alignment. Imagine what would happen if the sensor was missaligned even slightly... the autofocus would probably never find anything.

Andrew Oh · September 2nd, 2006, 08:47 PM

Quote:

Originally Posted by Philip Williams

I imagine even IF it could be easily removed from the lens, you'd need a precision machined adapter to hold it away from the lens but still retain perfect alignment. Imagine what would happen if the sensor was missaligned even slightly... the autofocus would probably never find anything.

From what I've read, the instafocus module is seperate from the regular autofocus. Also, I would never use Auto/insta at all so I want to remove it completely. Well, I hope Canon has an option of removing it.

August 22nd, 2006, 12:30 PM	#1
David Ziegelheim Major Player Join Date: Jul 2003 Location: Warren, NJ Posts: 398	Matte Box Compatibility and Auto Focus In another thread, the autofocus sensor was deemed to be in the way of many follow focus units: It sits to the side of the lens: http://www.dvinfo.net/canonxh/images/imga1frontb.jpg In addition, it appears that the lens shade has a cut out for the the sensor. However, what about an aftermarket mattebox to use 4x4 or 3x3 filters? How would it mount? And similarly, how would Canon's own .75x WA adapter work with a matte box and the sensor? http://www.dvinfo.net/canonxh/images/imgg1frontb.jpg The new autofocus seems like a cool feature for HD. It would be a same to have to disable it for most shooting.

August 22nd, 2006, 01:24 PM	#3
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,368 Images: 513	Yes that's right, you can still use "normal" autofocus if the Instant AF sensor is blocked, such as when using a wide-angle adapter or matte box or other lens attachment. There are three focus modes with this camera: manual focus, auto focus and Instant AF. The sensor to the side of the lens is used only when Instant AF is enabled. Turning it off won't affect the normal autofocus mode. __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!

August 27th, 2006, 06:07 PM	#8
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,368 Images: 513	While the module appears to be attached by only three screws, it's unknown what kind of wiring situation you're dealing with on the inside. Frankly I don't think it's worth voiding your warranty. __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!

August 22nd, 2006, 01:12 PM	#2
Philip Williams Major Player Join Date: Aug 2004 Location: Snellville, Georgia Posts: 614	I've concluded it this way: When shooting with matte boxes and related accessories, you're usually shooting narrative type stuff where you're almost always using manual focus. When you probably need the instant focus assist most is for event videography (weddings, etc..) or news type work. In those cases you generally don't mount additional lenses or matte boxes (I don't anyway) so you're good to go. When using lens adapters and want auto focus I'm sure you'll still be able to use the standard auto focus. Remember, the instant auto focus doesn't replace normal auto focus, it adds to and enhances it. www.philipwilliams.com

August 22nd, 2006, 05:04 PM	#6
David Ziegelheim Major Player Join Date: Jul 2003 Location: Warren, NJ Posts: 398	Well, I first asked this question hoping I was just missing something. I guess they could have either mounted it like a mike, or on an adjustable bracket to clear a mattebox. Cannon's own options focus on screw on filters, so that may have been their intent. I'm a bit disappointed. Net, at $4k, the A1 is signficantly less expensive than its competitors. The reviews and time will indicate how important that feature is.

August 27th, 2006, 03:54 PM	#7
Andrew Oh Regular Crew Join Date: Jan 2005 Location: Los Angeles, CA Posts: 86	From the pics, it looks like the INSTANT FOCUS module is removeable via 3 screws. I wonder if it's detachable so that we can use a GEAR RING for Follow Focus units. I'd hate to waste my FF gear. What do you guys think?

August 30th, 2006, 07:55 PM	#9
Andrew Oh Regular Crew Join Date: Jan 2005 Location: Los Angeles, CA Posts: 86	DOH, I was hoping it would be detachable. I guess we're going to have to figure out a way around this. Thanks Chris.