Ive been using large format for only 12 months now and feel so young in this format but just love the results. I wish to use three filters, graduated Nd , polarizer and enhancer together on my 75mm nikon sw.Im concerned about viggeting but think that by using a customised step up ring say 67mm to 90mm then using 90mm filters and (cokin / singhray)100mm square type filter system for the Grad ND system ,that this would solve this problem. I spoke with linhof dealer about my idea . He was convinced that id still have a viggeting problem. Does anybody think my idea would be sucessful Regards David

-- david lavery (davsca@intecoast.com.au), March 11, 2001

Answers

David, even the use of a polarizer alone I would not recommend with that lens. Surely the uses of 3 will greatly diminish your picture quality. I have used a polarizer on Nikkor SW 65. The corners were very dark and unsharp. Unless this is something you can accept, or use a center filter and oversized polarizer on it(but again with optical losses in the corners), you might have unsatisfactory results. I am assuming you intend to shoot 4x5 and not rollfilm.

-- Paul Schilliger (pschilliger@smile.ch), March 11, 2001.

I use a 52 Minolta Polarizing filter on my Nikkor 20 mm lens all the time. That particular filter flares out from 52 mm to perhaps 62 mm. The front of this filter doesn't have a thread to accept another filter of a lens hood so I don't know the outside dimensions for sure.

Now I know that's 35 mm stuff but the priciples should be the same: A much larger than usual Polarizer and then large Cokin like filters in front of that. But you will probably have to hold those filters with your hands, flush against the Polarizing filter, since I think that the depth of the regular Cokin holder will reintriduce vignetting.

If there is going to be a problem with all those filters, there could be some focus shift, so check your focus after you have all these filters aboard. And any dust or marks on the filters may be more visble if you stop the lens down a lot. It's the same as you can't see dirt on your glasses, until you take them off and hold them away from your eyes a bit.

Then you just have to try it and see.

-- David Grandy (dgrandy@accesscable.net), March 11, 2001.

David:

Obviously, if you get large enough filters, you can avoid vignetting... but that doesn't mean the setup will work well. Stacking 3 filters is always a pain... I cannot imagine trying to carefully position a graduate ND filter in such a setup, particularly with a 75mm where you probably also need a CF. So I would suggest one or more of the following possibilities:

Singh-ray makes a combination enhancer-polarizer of very high quality... that will cut down one filter, and gives you a very high quality, oversized polarizer as well.

If you print digitally, you can off the grad-ND and the enhancer... boost saturation selectively and to the grad-ND digitally as well. The ultimate "grad-ND" is to shoot several frames at different exposures (in the most extreme case, one for shadow, one for middle tones and one for highlights) then feather combine them digitally.

-- Glenn Kroeger (gkroeger@trinity.edu), March 11, 2001.

Hi David

I have a Nikon 75 mm lens and I use it with 72mm polfilter, but I can`t use anymore the full circle of the objectiv without vignetting. But with 3 filters you are loosing a lot of sharpness and brilliance u`ll not be happy with the results. And by the way you can`t take a 35 mm objectiv as an example, because they only have a circle thad covers the 24x36 mm not more, only the shift objectivs covers more! But it should be possible if you go from 90 up to 100mm without vignetting, but with no good quality! I would prever the idea of Glenn!

-- Armin Seeholzer (armin.seeholzer@smile.ch), March 11, 2001.

Wouldn't just switching to Velvia or E100Vs make more sense? That way you could eliminate the Polarizing and the enhancing filters and just worry about the graduated.

But seriously, as every one has pointed out three filters will possibly degrade your image somewhat but if you insist going this route check out Hitech filters and filter holders. The Hitech engineers designed their holder to mount a polarizer on the outermost ring where it can be rotated freely without disturbing the orientation of the graduated filter, and also this is where the polarizer is supposed to be, optically speaking.

To avoid the problem with vignetting you might want to consider a 125mm width filter system.

-- Ellis Vener (evphoto@insync.net), March 12, 2001.

David, A word of caution:

Using a circular polarizer on a lens this wide usually leads to gradually increasing and more severe polarizing effects as you approach the corners of the image, particularly where you have sky areas. With a CP on the 75 SW, the sky will look normally polarized in the central portions of the image and the polarizing effect will increase dramatically as you approach the edges/corners. This is caused by the very wide angle view of the lens.

The progressive darkening into the edges/corners, due to the polarizer's effect with very wide lenses, is often confused with the vignetting effect caused by overly small filters or attachments physically obstructing the light path. When I first observed this progressive darkening I assumed that my CP was vignetting with my 75mm lens. I was wrong. I've since found that a CP can give severe polarizing effects in the edges/corners, rendering the sky almost an inky dark blue. And with Velvia, or other saturated films, the look can be rather strange indeed.

A center filter, used in combination with the circular polarizer seems to lessen this effect somewhat. But the effect is still pronounced and disturbing. And the stacking of filters can be problematic, for the variety of reasons listed above.

-- Sergio Ortega (s.ortega@worldnet.att.net), March 12, 2001.