Is it ok if the gg is not exactly same as the focal flance distance? at DVinfo.net

Lau Ho Ming · June 13th, 2007, 01:49 PM

e.g. make the lens be able to focus "further than infinity" and give up some macro ability. So that I can make sure it can focus on infinity. I set up like this in my DIY adapter.

Bob Hart · June 13th, 2007, 05:18 PM

It is better to have the back focus as close to correct as you can get it. For lenses about 50mm and longer FL it does not matter so much but for 35mm and wider, if the backfocus is off, then these lenses may not achieve sharp results.

These lenses will also aggravate any image fault if the groundglass is not square-on to the focal plane. - soft edge.

June 13th, 2007, 01:49 PM	#1
Lau Ho Ming Regular Crew Join Date: Nov 2006 Location: Hong Kong Posts: 81	Is it ok if the gg is not exactly same as the focal flance distance? e.g. make the lens be able to focus "further than infinity" and give up some macro ability. So that I can make sure it can focus on infinity. I set up like this in my DIY adapter.

June 13th, 2007, 05:18 PM	#2
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	It is better to have the back focus as close to correct as you can get it. For lenses about 50mm and longer FL it does not matter so much but for 35mm and wider, if the backfocus is off, then these lenses may not achieve sharp results. These lenses will also aggravate any image fault if the groundglass is not square-on to the focal plane. - soft edge.