Increasing camera low light and range performance

Tom Hardwick · April 23rd, 2004, 09:19 AM

6.5mm

Wayne Morellini · April 24th, 2004, 03:32 AM

That much, going from 35mm flim to 70mm film the standard focal length goes from 50mm to 6.5mm?

By the way, does any body have an old, nice, lense with plenty of wide fast glass with low f, for a film format close to 70mm, they can sell me very cheap? Prime or multifocal with low f. I want to do an adpater, maybe using a low angle holographic diffuser for HD camera.

Thanks Tom

Tom Hardwick · April 24th, 2004, 06:32 AM

Sorry Wayne - I think I got my wires crossed. I thought you were asking what focal length feeding 1/3" chips gives the same angle of view as a 50mm feeing 35 mm (still) film.

Wayne Morellini · April 24th, 2004, 07:41 AM

Well thanks anyway Tom. I will try asking this question elsewhere once I catch up on some other research stuff.

Wayne Morellini · May 8th, 2004, 08:54 AM

I forgot to post this quote from:

http://www.dvinfo.net/conf/showthread.php?s=&threadid=22715

Basically what I was talking about all along, and this thread was never a Panasonic thread, so why is it in this forum.

<<<-- Originally posted by Jonathon Wilson : Yes, I'm sorry, Eric - but you will lose the desireable (== short) depth of field most people are striving for in these adapters.

I actually built one exactly as you described because I was frustrated at the amount of light loss with the ground glass. I replaced my ground glass with a 'relay lens' which changes the magnification at the focal point down to the size of my ccd. It worked beautifully -- incredibly bright image... but very long Video-looking depth of field. I basically had the focal length/field of view of my SLR Lens, but depth of field of video.

This makes sense based on how depth of field works. Without painful details - its a factor of the size of the opening the light comes in - and the size if the image plane. With a relay lens, you don't really have an image plane until you hit the ccd. So the math goes from 35mm lens aperture to ccd, just like your video cam lens would do.

With the GG, this becomes a real imaging plane, so the depth of field math is from 35mm lens aperture to the ground glass. Then we just take a picture of that image plane. -->>>

April 23rd, 2004, 09:19 AM	#61
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	6.5mm

April 24th, 2004, 03:32 AM	#62
Wayne Morellini Inner Circle Join Date: May 2003 Location: Australia Posts: 2,762	That much, going from 35mm flim to 70mm film the standard focal length goes from 50mm to 6.5mm? By the way, does any body have an old, nice, lense with plenty of wide fast glass with low f, for a film format close to 70mm, they can sell me very cheap? Prime or multifocal with low f. I want to do an adpater, maybe using a low angle holographic diffuser for HD camera. Thanks Tom

April 24th, 2004, 06:32 AM	#63
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	Sorry Wayne - I think I got my wires crossed. I thought you were asking what focal length feeding 1/3" chips gives the same angle of view as a 50mm feeing 35 mm (still) film.

April 24th, 2004, 07:41 AM	#64
Wayne Morellini Inner Circle Join Date: May 2003 Location: Australia Posts: 2,762	Well thanks anyway Tom. I will try asking this question elsewhere once I catch up on some other research stuff.

May 8th, 2004, 08:54 AM	#65
Wayne Morellini Inner Circle Join Date: May 2003 Location: Australia Posts: 2,762	I forgot to post this quote from: http://www.dvinfo.net/conf/showthread.php?s=&threadid=22715 Basically what I was talking about all along, and this thread was never a Panasonic thread, so why is it in this forum. <<<-- Originally posted by Jonathon Wilson : Yes, I'm sorry, Eric - but you will lose the desireable (== short) depth of field most people are striving for in these adapters. I actually built one exactly as you described because I was frustrated at the amount of light loss with the ground glass. I replaced my ground glass with a 'relay lens' which changes the magnification at the focal point down to the size of my ccd. It worked beautifully -- incredibly bright image... but very long Video-looking depth of field. I basically had the focal length/field of view of my SLR Lens, but depth of field of video. This makes sense based on how depth of field works. Without painful details - its a factor of the size of the opening the light comes in - and the size if the image plane. With a relay lens, you don't really have an image plane until you hit the ccd. So the math goes from 35mm lens aperture to ccd, just like your video cam lens would do. With the GG, this becomes a real imaging plane, so the depth of field math is from 35mm lens aperture to the ground glass. Then we just take a picture of that image plane. -->>>