Thinking Out Loud! at DVinfo.net

Gary Harper · July 13th, 2007, 01:36 PM

Just a thought... With all the interest in 35 adapters, has anyone thought of asking a lens mfgr. to perhaps make a prime lens set for the 1/3" format mount (JVC ProHD and Canon)? A prime lens with a large effective aperture could come close to the same depth of field as the equivlent 35 film camera lens.
A 24mm lens on a 1/3" camera has the same angle of view as a 125mm lens on a 35mm camera. At F/1.4 its depth of field when focused at 10' is nearly the same as the 125mm at F2.8... At a 10mm setting at f/1, it has a 27 degree angle of view, with a depth of focus of 7.9' to 15', while a 50mm lens for 35mm film camera has also the same angle of view, with its depth being 9.2' to 10.9' at f/2.8. So, perhaps a fast (f/1), sharp prime lens set, 4mm,8mm,16mm,24mm, might be the ticket. No Flip Moduls, Inverted Monitors, Magnet Tricks, or Light loss issues, (actually, a light gain instead).

Paul Martin · July 20th, 2007, 03:47 AM

This sounds like a fantastic idea...

Ian Holb · July 20th, 2007, 04:33 AM

You can make prime lenses but you're still limited by the tiny sensor size; being that it is the number one reason why DOF is so deep.

Gary Harper · July 20th, 2007, 02:36 PM

The Size of the CCD does matter, HOWEVER, if you check depth of field charts, and compare the relative angle of views of the various formats, you will see that a camera with a 1/3" CCD, a 10mm f/1.4 lens at 10 feet has the same image angle of view as a 35mm film camera with a f/2.8 50mm lens at ten feet. Both being 27 degrees. The depth of field would be 6.7ft. to18ft. for the 1/3" camera and 9.2ft to 10.9ft for the 35mm camera. Creating a prime lens set to cover a 1/3" CCD would be no problem, however attaining the needed back focus depth (Flange thru optical block to CCD might be an issue. There are plenty of high quality Astronomical Eyepieces with short focal lengths and fast apertures that could be modified.

Ben Winter · July 20th, 2007, 02:58 PM

Quote:

Originally Posted by Gary Harper

The Size of the CCD does matter, HOWEVER, if you check depth of field charts, and compare the relative angle of views of the various formats, you will see that a camera with a 1/3" CCD, a 10mm f/1.4 lens at 10 feet has the same image angle of view as a 35mm film camera with a f/2.8 50mm lens at ten feet. Both being 27 degrees. The depth of field would be 6.7ft. to18ft. for the 1/3" camera and 9.2ft to 10.9ft for the 35mm camera. Creating a prime lens set to cover a 1/3" CCD would be no problem, however attaining the needed back focus depth (Flange thru optical block to CCD might be an issue. There are plenty of high quality Astronomical Eyepieces with short focal lengths and fast apertures that could be modified.

I recall a discussion on this a while back, from what I remember these lenses would be prohibitively expensive to produce. I can't remember details, just something about the exactness of the lens construction required to resolve the image on such a small area at such short focal lengths.

Astronomical eyepieces are of course built for a different purpose, and would require quite a lot of modification to produce a 1/3" projected image. Remember they work in tandem with the rest of the assembly. Not to mention that the chroma aberration would be horrible. They are quite different optical pieces.

July 13th, 2007, 01:36 PM	#1
Gary Harper Regular Crew Join Date: Oct 2005 Posts: 47	Thinking Out Loud! Just a thought... With all the interest in 35 adapters, has anyone thought of asking a lens mfgr. to perhaps make a prime lens set for the 1/3" format mount (JVC ProHD and Canon)? A prime lens with a large effective aperture could come close to the same depth of field as the equivlent 35 film camera lens. A 24mm lens on a 1/3" camera has the same angle of view as a 125mm lens on a 35mm camera. At F/1.4 its depth of field when focused at 10' is nearly the same as the 125mm at F2.8... At a 10mm setting at f/1, it has a 27 degree angle of view, with a depth of focus of 7.9' to 15', while a 50mm lens for 35mm film camera has also the same angle of view, with its depth being 9.2' to 10.9' at f/2.8. So, perhaps a fast (f/1), sharp prime lens set, 4mm,8mm,16mm,24mm, might be the ticket. No Flip Moduls, Inverted Monitors, Magnet Tricks, or Light loss issues, (actually, a light gain instead).

July 20th, 2007, 03:47 AM	#2
Paul Martin Regular Crew Join Date: Dec 2002 Location: San Francisco, CA Posts: 47	This sounds like a fantastic idea...

July 20th, 2007, 04:33 AM	#3
Ian Holb Regular Crew Join Date: Nov 2006 Location: Canada Posts: 127	You can make prime lenses but you're still limited by the tiny sensor size; being that it is the number one reason why DOF is so deep.

July 20th, 2007, 02:36 PM	#4
Gary Harper Regular Crew Join Date: Oct 2005 Posts: 47	The Size of the CCD does matter, HOWEVER, if you check depth of field charts, and compare the relative angle of views of the various formats, you will see that a camera with a 1/3" CCD, a 10mm f/1.4 lens at 10 feet has the same image angle of view as a 35mm film camera with a f/2.8 50mm lens at ten feet. Both being 27 degrees. The depth of field would be 6.7ft. to18ft. for the 1/3" camera and 9.2ft to 10.9ft for the 35mm camera. Creating a prime lens set to cover a 1/3" CCD would be no problem, however attaining the needed back focus depth (Flange thru optical block to CCD might be an issue. There are plenty of high quality Astronomical Eyepieces with short focal lengths and fast apertures that could be modified.