Wide Angle Adapter & Focal Distance Readout? at DVinfo.net

Gabe Spangler · February 27th, 2009, 06:12 AM

I assume having the WD-H72 wide angle adapter screwed on to the end of my lens will nullify the accuracy of the focal distance readout on the A1's LCD monitor? If so, how far will it throw it out of whack? Should I disregard the focal distance readout altogether when the wide angle adapter is on? Can someone who knows for sure please shed some light on this subject. Thanks!

Bill Thesken · February 27th, 2009, 01:30 PM

It blocks the little infrared doohickey on the right front side of the camera that measures distance.
I bought one and had to put it on the bench till I can get a monitor to focus better. I can't focus that great with the little LCD, and without the auto focus, so until I get a little monitor for the field, that wide angle adaptor doesn't work for me. I guess you may be able to do it the old fashioned way and use a tape measure to the subject and focus that way. Someone out there may do it that way.

Colin McDonald · February 27th, 2009, 01:47 PM

So does anyone know where the focal plane on the XH-A1 is exactly? When I were a lad, cameras had a mark on the body so you could measure focus accurately.

To address to original question, peaking on the corner of the picture frame opposite me right now reads 8.2ft without the Canon W/A adaptor and 10ft with it. My measuring tape says 257cm (8ft 5in) but I don't knw where I'm measuring to on the camera.

Bill Thesken · February 27th, 2009, 01:49 PM

Hmmm, so it could be somewhere besides the front of the lenses.

Gabe Spangler · February 27th, 2009, 05:33 PM

Bill, the infrared sensor is only for the instant auto focus and has nothing to do with manual focusing.

I did a little testing myself, and the WD-H72 does throw the distance readout out of whack by a factor of .75, the same as the widening factor of the adapter.

I focused on an object 2.4 feet away and the readout read 3.2 feet. I also focused on an object 5.6 feet away and the readout read 7.5 feet.

Of course this makes total sense, but it's too bad Canon doesn't make a menu option to convert the focal distance range for wide angle adapter on or off. It's a simple conversion, all you have to do is multiply the focal distance number by .75 to get the true range with the WD-H72 on.

Makes follow focusing and planning camera moves a little more difficult, but who said life was easy, right?

Chris Hurd · February 27th, 2009, 05:58 PM

Quote:

Originally Posted by Gabe Spangler

... it's too bad Canon doesn't make a menu option to convert the focal distance range for wide angle adapter on or off.

Fully agreed -- this should have been an option under Custom Functions.

Mark Fry · March 3rd, 2009, 08:56 AM

Quote:

Originally Posted by Bill Thesken

It blocks the little infrared doohickey on the right front side of the camera that measures distance.
I bought one and had to put it on the bench till I can get a monitor to focus better. I can't focus that great with the little LCD, and without the auto focus, so until I get a little monitor for the field, that wide angle adaptor doesn't work for me. I guess you may be able to do it the old fashioned way and use a tape measure to the subject and focus that way. Someone out there may do it that way.

Quote:

Originally Posted by Gabe Spangler

Bill, the infrared sensor is only for the instant auto focus and has nothing to do with manual focusing.

Don't forget that there are two auto-focus modes. "Instant" AF used the infra-red range-finder that the WD72 masks. "Normal" AF just looks for edges on the image, and will work fine when the range-finder is obscured. You can switch between the two in the menu.

Gabe Spangler · March 4th, 2009, 04:26 AM

Thanks, Mark. But I'm talking about manual focus, not auto focus. I know normal auto focus will work when the infrared sensor is obscured. I got to the bottom of the issue if you see my previous posts. I think we can put this one to bed.....

February 27th, 2009, 06:12 AM	#1
Gabe Spangler Regular Crew Join Date: Aug 2008 Location: Milwaukee, WI Posts: 69	Wide Angle Adapter & Focal Distance Readout? I assume having the WD-H72 wide angle adapter screwed on to the end of my lens will nullify the accuracy of the focal distance readout on the A1's LCD monitor? If so, how far will it throw it out of whack? Should I disregard the focal distance readout altogether when the wide angle adapter is on? Can someone who knows for sure please shed some light on this subject. Thanks! Last edited by Gabe Spangler; February 27th, 2009 at 06:14 AM. Reason: spelling error

February 27th, 2009, 01:47 PM	#3
Colin McDonald Trustee Join Date: Dec 2007 Location: Glasgow, Scotland Posts: 1,546	So does anyone know where the focal plane on the XH-A1 is exactly? When I were a lad, cameras had a mark on the body so you could measure focus accurately. To address to original question, peaking on the corner of the picture frame opposite me right now reads 8.2ft without the Canon W/A adaptor and 10ft with it. My measuring tape says 257cm (8ft 5in) but I don't knw where I'm measuring to on the camera. Last edited by Colin McDonald; February 27th, 2009 at 02:13 PM. Reason: Added measurements

February 27th, 2009, 05:33 PM	#5
Gabe Spangler Regular Crew Join Date: Aug 2008 Location: Milwaukee, WI Posts: 69	Bill, the infrared sensor is only for the instant auto focus and has nothing to do with manual focusing. I did a little testing myself, and the WD-H72 does throw the distance readout out of whack by a factor of .75, the same as the widening factor of the adapter. I focused on an object 2.4 feet away and the readout read 3.2 feet. I also focused on an object 5.6 feet away and the readout read 7.5 feet. Of course this makes total sense, but it's too bad Canon doesn't make a menu option to convert the focal distance range for wide angle adapter on or off. It's a simple conversion, all you have to do is multiply the focal distance number by .75 to get the true range with the WD-H72 on. Makes follow focusing and planning camera moves a little more difficult, but who said life was easy, right? Last edited by Gabe Spangler; February 27th, 2009 at 05:35 PM. Reason: grammar correction

February 27th, 2009, 01:30 PM	#2
Bill Thesken Major Player Join Date: May 2008 Location: HI, USA Posts: 622	It blocks the little infrared doohickey on the right front side of the camera that measures distance. I bought one and had to put it on the bench till I can get a monitor to focus better. I can't focus that great with the little LCD, and without the auto focus, so until I get a little monitor for the field, that wide angle adaptor doesn't work for me. I guess you may be able to do it the old fashioned way and use a tape measure to the subject and focus that way. Someone out there may do it that way.

February 27th, 2009, 01:49 PM	#4
Bill Thesken Major Player Join Date: May 2008 Location: HI, USA Posts: 622	Hmmm, so it could be somewhere besides the front of the lenses.

March 4th, 2009, 04:26 AM	#8
Gabe Spangler Regular Crew Join Date: Aug 2008 Location: Milwaukee, WI Posts: 69	Thanks, Mark. But I'm talking about manual focus, not auto focus. I know normal auto focus will work when the infrared sensor is obscured. I got to the bottom of the issue if you see my previous posts. I think we can put this one to bed.....