filter & vortex at DVinfo.net

Dan Lim · September 6th, 2005, 09:06 PM

Hi !

To avoid vortex-effect with an old version of the mini35 ,an added filter on the lens is a good thing to reduce the luminosity ?

And to use a very dark filter will result at same effect of vortex that to reduce a little too much the relay lens ?

excuse my english again !

Daniel Limoges

Guy Genin · September 9th, 2005, 07:49 AM

Hello Daniel,

The quick answer is yes, using filters in front of the lens is a good way to control the light.
However the vortex becomes more visible when the exposure of the center of your frame is lower. So you will get better results if the illumination near the center can be maintained a little high. This assumes that you are keeping your film lens at T4 our wider.
Yes the filtration in front of the lens has a similar effect as the iris on the relay lens.

Best regards,

Dan Lim · September 19th, 2005, 05:36 PM

Merci Guy !

Pekka Uotila · September 20th, 2005, 06:38 AM

Hi,
This is new term for me, "vortex" ?
I believe I am not a lone.
Could somebody write few words about it, Charles ?

Guy Genin · September 20th, 2005, 08:15 AM

Hello Pekka,

Yes theses terms do get confusing don’t they; Daniel used the expression “vortex-effect” to describe the swirl motion of the grains in the center of rotation of the ground glass. This was a problem with the early design of the Mini35 where the center of rotation was in the middle of the image. With the current Mini35, that is series 400, the ground glass has an eccentric motion thus correcting this problem.

Best regards,

Pekka Uotila · September 21st, 2005, 10:54 AM

Thanks Guy,
I was guessing something like that, but to know is so much better!

September 6th, 2005, 09:06 PM	#1
Dan Lim New Boot Join Date: Aug 2005 Posts: 24	filter & vortex Hi ! To avoid vortex-effect with an old version of the mini35 ,an added filter on the lens is a good thing to reduce the luminosity ? And to use a very dark filter will result at same effect of vortex that to reduce a little too much the relay lens ? excuse my english again ! Daniel Limoges

September 9th, 2005, 07:49 AM	#2
Guy Genin Sponsor: ZGC Join Date: Feb 2004 Location: Mountain Lakes, NJ. Posts: 36	Hello Daniel, The quick answer is yes, using filters in front of the lens is a good way to control the light. However the vortex becomes more visible when the exposure of the center of your frame is lower. So you will get better results if the illumination near the center can be maintained a little high. This assumes that you are keeping your film lens at T4 our wider. Yes the filtration in front of the lens has a similar effect as the iris on the relay lens. Best regards, __________________ Guy Genin ZGC Technical support

September 20th, 2005, 06:38 AM	#4
Pekka Uotila Regular Crew Join Date: Mar 2005 Location: Helsinki, Finland Posts: 51	Hi, This is new term for me, "vortex" ? I believe I am not a lone. Could somebody write few words about it, Charles ? __________________ Pekka

September 20th, 2005, 08:15 AM	#5
Guy Genin Sponsor: ZGC Join Date: Feb 2004 Location: Mountain Lakes, NJ. Posts: 36	Hello Pekka, Yes theses terms do get confusing don’t they; Daniel used the expression “vortex-effect” to describe the swirl motion of the grains in the center of rotation of the ground glass. This was a problem with the early design of the Mini35 where the center of rotation was in the middle of the image. With the current Mini35, that is series 400, the ground glass has an eccentric motion thus correcting this problem. Best regards, __________________ Guy Genin ZGC Technical support

September 21st, 2005, 10:54 AM	#6
Pekka Uotila Regular Crew Join Date: Mar 2005 Location: Helsinki, Finland Posts: 51	Thanks Guy, I was guessing something like that, but to know is so much better! __________________ Pekka

September 19th, 2005, 05:36 PM	#3
Dan Lim New Boot Join Date: Aug 2005 Posts: 24	Merci Guy !