Schneider 95mm centre filter and Nikkor 150mm

[Murray Fredericks]

Hi There,

I have read various archived topics concerning the NikkorSW 150mm's disputed need for a centre filter.

While there appears still to be debate over this lens's need for a centre filter, has anyone used one and found it to be a problem i.e. unwanted lightening of the edges? I am about to shoot some 8" x 10" images of extrememly uniformly toned subjects. Any, even minor, vignetting may ruin the images...I feel inclined to purchase the centre filter and use it as a precaution - unless it can actually cause a new problem.

Thanks

Murray

[Bob Salomon]

It has the same fall-off as other manufacturer's wide angle designs. The difference is that Rodenstock and Schneider, as well as Heliopan, make center filters and Nikon does not.

Not making a center filter does not eliminate the reason why a center filter is needed.

[Michael S. Briggs]

A lens doesn't "need" a center filter. One photographer may find the results from the lens fully acceptable, while another may find the illumination falloff objectionable. Viewing the issue as the lens's "need" for a center filter is what makes it seem like a "dispute" -- I view it instead as a range of opinions about usefulness of a center filter. Of course the usefulness depends on the lens and format. It also depends on the film type, negative vs transparency, because of the differing exposure latitudes. It also depends on the extnet of movements that are used, and on the photographer's taste. I have seen statements on the LF forums that a lens has "no falloff" when the manufacturer's own illumination graph shows that the lens has a falloff of several stops for the usage that the poster described.





Optical theory says that the 150 Nikkor-SW should have a falloff of about 1.5 stops to the corners of an 8x10 film. Bob is correct, all of the manufacturers use the same design type for their LF wide-coverage lenses -- the design principles have been known for decades. The cross-section diagrams that all of the manufacturers publish show that they are using similar designs. A 150 mm wide-coverage lens for 8x10 will have about the same illumination falloff as a 75 mm lens on 4x5, if you have any experience with that combination.





A previous discussion with links to more: http://www.largeformatphotography.info/lfforum/topic/501033.html.