Is it the achromat is neccessary for the PD170 and HVR V1P? at DVinfo.net

Lau Ho Ming · March 10th, 2007, 04:00 AM

It is possible for the PD170 to focus on a Canon EE-S focusing screen even when the screen is placed really close to the camcorder lens(about 5mm). It is possible to 95% fill the frame but not sure if the safety margin cropped it. And it greatly shorten the length of the adapter and make it super compact. And you will have less lightloss since the camcorder is wide open.
What is the problem of doing this?
And what is the advantage of make it 2 inches longer and add a USD$200 high quality achromat?

Bob Hart · March 10th, 2007, 06:21 AM

It is not possible without a close-up lens on front of the PD170 camera.The best close-up lens is an achromatic dioptre.

I used the glass out of a SW5042 telescope eyepiece in reverse arrangement. With this you can put a 24mm wide groundglass image 12mm - 18mm in front of the lens but there is too much corner distortion.

The sort of magification power you would need to frame the 36mm wide image would not be as much as for a smaller groundglass image.

Sitting the groundglass so close to the camera may give you all sorts of hot-spot problems because of the acute angle of the light diffusion from the edges of the image at this short distance. You may also lose edge or corner sharpness.

Sadly, there are no easy short cuts to doing this properly.

March 10th, 2007, 04:00 AM	#1
Lau Ho Ming Regular Crew Join Date: Nov 2006 Location: Hong Kong Posts: 81	Is it the achromat is neccessary for the PD170 and HVR V1P? It is possible for the PD170 to focus on a Canon EE-S focusing screen even when the screen is placed really close to the camcorder lens(about 5mm). It is possible to 95% fill the frame but not sure if the safety margin cropped it. And it greatly shorten the length of the adapter and make it super compact. And you will have less lightloss since the camcorder is wide open. What is the problem of doing this? And what is the advantage of make it 2 inches longer and add a USD$200 high quality achromat?

March 10th, 2007, 06:21 AM	#2
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,476	It is not possible without a close-up lens on front of the PD170 camera.The best close-up lens is an achromatic dioptre. I used the glass out of a SW5042 telescope eyepiece in reverse arrangement. With this you can put a 24mm wide groundglass image 12mm - 18mm in front of the lens but there is too much corner distortion. The sort of magification power you would need to frame the 36mm wide image would not be as much as for a smaller groundglass image. Sitting the groundglass so close to the camera may give you all sorts of hot-spot problems because of the acute angle of the light diffusion from the edges of the image at this short distance. You may also lose edge or corner sharpness. Sadly, there are no easy short cuts to doing this properly. Last edited by Bob Hart; March 10th, 2007 at 06:22 AM. Reason: can't spell properly