Vendi-Agus-35s and SLR converters? at DVinfo.net

Riley Florence · December 29th, 2003, 12:17 AM

Ok, my question is why would I want to make one of these instead of just buying an SLR converter for my camera, i have an xl1s so couldnt i just attach a Canon SLR lens onto my camera with the adapter and and get the same DoF? Or is something special happening with the DoF when it it projected onto the ground glass and then filming that? Or is it all a money and non-interchangable lense issue? Just wondering before I spend time on one of these nice gadgets.

Thanks

Andreas Fernbrant · December 29th, 2003, 09:30 AM

When using SLR Converter and Lens on your XL1 you in short looses the depth of feild effect. When using Agus35 model or Mini35 you keep the depth of feild from the lens, that's the short version. (It all has to do with the target area = CCD size)
35mm large format, a CCD is very small.

I know someone will explain this better then me.

Riley Florence · December 29th, 2003, 11:02 AM

well thats lame, heh, thanks, i've wondered that since i got my camera.

Martin Hesse · March 13th, 2005, 01:58 AM

I'd like to give more detail on that answer...

A) The SLR lens adaptor that Canon sells has another lens element in it and my understanding is that it has an effect on the DOF. I've never touched one my self, but that's what I hear.

B) More importantly, it is the focal length of the lens in relation to the imaging size (in this case the CCD). A lens with a "long focal length has shalower DOF, while a "short" or wide lens has more DOF.
A 35mm SLR lens is meant to project an image onto a surface that is 36mm x 24mm. If you have a ruler draw a rectangle 36mm x 24mm (approx. 1-7/16" x 1"). Then, right in the center of that rectangle, draw another rectangle about 3mm x 4mm (1/8" x 3/16") which is pretty close to the size of a 1/3" CCD. Now imagine there is a picture of someone's face filling the frame of the 36mm x 24mm rectangle. Notice that rectangle representing the CCD is only framing that persons nose? Essentually, you magnify the image. The next logical step in trying to solve this problem is to use a wider lens so that the image fits onto the CCD, but the wider you get the deeper the depth of field and we want shallow DOF. As you probobly know, in the 35mm format, a 50mm lens is considered a "normal" lens. Normal basically means that the size of the object(s) you see in the viewfinder match what you see with your eye. A "normal lens in the 16mm format is considered to be a 24mm lens. A "normal" lens for a 1/3" CCD is about a 6mm lens. So, to get the same field of view you would get with a 50mm lens on a SLR camera, you would have to mount a 6mm lens on your XL-1. Getting shallow DOF with a 6mm lens is possible only if you are really close to your subject (like 1").
I'm sorry... What was your question again? (smile)

December 29th, 2003, 12:17 AM	#1
Riley Florence Regular Crew Join Date: Jun 2002 Location: Salt Lake City, Utah Posts: 61	Vendi-Agus-35s and SLR converters? Ok, my question is why would I want to make one of these instead of just buying an SLR converter for my camera, i have an xl1s so couldnt i just attach a Canon SLR lens onto my camera with the adapter and and get the same DoF? Or is something special happening with the DoF when it it projected onto the ground glass and then filming that? Or is it all a money and non-interchangable lense issue? Just wondering before I spend time on one of these nice gadgets. Thanks __________________ -------------------------- -Riley Florence SLC, Utah. http://www.secondsection.com

December 29th, 2003, 11:02 AM	#3
Riley Florence Regular Crew Join Date: Jun 2002 Location: Salt Lake City, Utah Posts: 61	well thats lame, heh, thanks, i've wondered that since i got my camera. __________________ -------------------------- -Riley Florence SLC, Utah. http://www.secondsection.com

December 29th, 2003, 09:30 AM	#2
Andreas Fernbrant Major Player Join Date: Oct 2002 Location: Sweden - Helsingborg Posts: 283	When using SLR Converter and Lens on your XL1 you in short looses the depth of feild effect. When using Agus35 model or Mini35 you keep the depth of feild from the lens, that's the short version. (It all has to do with the target area = CCD size) 35mm large format, a CCD is very small. I know someone will explain this better then me.

March 13th, 2005, 01:58 AM	#4
Martin Hesse New Boot Join Date: Dec 2004 Location: San Francisco CA. USA Posts: 15	I'd like to give more detail on that answer... A) The SLR lens adaptor that Canon sells has another lens element in it and my understanding is that it has an effect on the DOF. I've never touched one my self, but that's what I hear. B) More importantly, it is the focal length of the lens in relation to the imaging size (in this case the CCD). A lens with a "long focal length has shalower DOF, while a "short" or wide lens has more DOF. A 35mm SLR lens is meant to project an image onto a surface that is 36mm x 24mm. If you have a ruler draw a rectangle 36mm x 24mm (approx. 1-7/16" x 1"). Then, right in the center of that rectangle, draw another rectangle about 3mm x 4mm (1/8" x 3/16") which is pretty close to the size of a 1/3" CCD. Now imagine there is a picture of someone's face filling the frame of the 36mm x 24mm rectangle. Notice that rectangle representing the CCD is only framing that persons nose? Essentually, you magnify the image. The next logical step in trying to solve this problem is to use a wider lens so that the image fits onto the CCD, but the wider you get the deeper the depth of field and we want shallow DOF. As you probobly know, in the 35mm format, a 50mm lens is considered a "normal" lens. Normal basically means that the size of the object(s) you see in the viewfinder match what you see with your eye. A "normal lens in the 16mm format is considered to be a 24mm lens. A "normal" lens for a 1/3" CCD is about a 6mm lens. So, to get the same field of view you would get with a 50mm lens on a SLR camera, you would have to mount a 6mm lens on your XL-1. Getting shallow DOF with a 6mm lens is possible only if you are really close to your subject (like 1"). I'm sorry... What was your question again? (smile)