Wide-angle [Nikkor 90mm falloff]greenspun.com : LUSENET : Large format photography : One Thread
I shoot strictly landscapes and am getting noticeable and bothersome light falloff around the edges of my 4x5 Velvia chromes shot with my Nikkor 90mm f/8, even when no movements are used. Is noticeable falloff normal in a 90mm/8? Are users of this and other brand 90mm's experiencing the same thing? Would I be better off switching to a 90mm lens with a larger image circle and/or using a cenetr filter available for the Schneider and Rodenstock 90's? Your experiences and suggestions are greatly appreciated!
-- Ross Martin (firstname.lastname@example.org), June 08, 1999
Fall off is normal with all modern type wide angles. A center filter will help to reduce the problem. Heliopan's will work for your lens.
-- Bob Salomon (email@example.com), June 08, 1999.
Just out of curiosity, what apeture setting are you using? Or does the problem occur across the range?
-- Chad Jarvis (firstname.lastname@example.org), June 08, 1999.
I've rarely felt the need for a center filter with my Schneider SA 5.6. Now the 75mm and especially the 47mm are another story. A center filter is very much necessary.
-- Larry Huppert (Larry.Huppert@mail.com), June 08, 1999.
hi, light falloff is normal with wide angles. actually, it occurs with all lenses and is just a lot worse and noticeable with wide angles. essentially, what happens is that light travelling to the corners of the film area (as opposed to light travelling to the center) 1/ has to travel a longer distance with a fall off in intensity and 2/ strikes the film plane at an angle and thus not all the energy in the light is used on the film. how wide can you go before you start using a center filter, is a very personal choice. many people like a little light falloff towards the edges since that seems to draw and keep the eye in the picture (in fact, in B&W photography, edge burning is done for exactly this purpose). however, if it bothers you center filters will help. dj
-- N Dhananjay (email@example.com), June 08, 1999.
Its actually easy to visualize why the falloff occurs. For any aperture setting, then viewed straight on (such as from the center of the film), the aperture appears approx. round. Now, move your eye to the corner of the film, and the aperture now appears as an elipse. The wider the lens, the closer the aperture is to the film plane, and the more eliptical the aperture appears, and the less light the corner area receives.
-- Ron Shaw (firstname.lastname@example.org), June 08, 1999.
Thanks to all for sharing your observations. In response to Chad's question, I shoot mostly at f/22 and f/32, occasionally f/45. It sounds like wide-angle light falloff is common, and my eye is particularly sensitive to it. I will look into the Heliopan center filter (thanks Bob!).
-- Ross Martin (email@example.com), June 08, 1999.
I use a Schneider 90 SA XL and have the corresponding Schneider center filter, but only use it if there's signficant movement and/or if the corners are of a uniform tone where fall off is more obvious, such as blue sky. You don't have to use the filter all the time..only when the darkening is noticeable. A 1.5-2 stop hit in speed when using velvia is pretty serious! I also shoot velvia, and due to the high contrast, it may tend to enhance the darkening in the corners.
-- James Chow (firstname.lastname@example.org), June 08, 1999.