My current thoughts on filters on WA lenses

[Jim Rice]

Someone please tell me if my logic is flawed here. I've been flailing away at this issue for some time, so here goes the latest permutation:
I've been having vignetting problems with a 67-72 step-up ring and a standard B+H polarizer on a 90/6.8 Caltar II-N (Grandagon). Well my s/u ring has been pressed (literally) into serving as filter threads for the Artar. So now my decision is whether to get a 67mm wide angle pola or go with the ring route again. Then, i checked out center filters, and found the female (front) end to be 86mm. So I'm thinking 67-86 ring and new 86 pola. It's still cheaper (by considerable margin) than the WA filter, and is not special order at B&H. In addition, if I ever spring for a CF I won't have to sell it off. So, what's my mistake here?

[Andre Noble]

Jim, In my opinion from someone who's been there before, I'd suggest that you skip all this and start building up a Lee filter sytem with their hard resin (and not their polyester) filters. The have such a versatile system including a holder for a 105mm polarizing filter.

In my opinion, the only circular glass filters you should do are the center filters and the expensive opaque glass IR filters.

others, naturally may not agree.

[Jim Rice]

I must admit that i don't understand the resin scene at all. Are CCs available?

[Daniel Geiger]

I recently tried with a Schneider 90 f/8 on a 4x5 and a Lee filter holder (three slot) plus polarizer ring. There is significant vignetting even without movements. So here the Lee system fails. For WA you need the polarizer closer to the lens. I ended up hanging the 105 mm polarizer with the rim of the filter from the front ring of the lens. The photo was without vignetting, but my sweat glands were also significanty depleted.

Interestingly, the sky darkened very much towards the margin, much more with pol than in normal view. I trust that has something to do with the wide collection angle of the lens, and the angular distribution of light of a particular orientation. Never did that well in physics, so can't go further than that.

Daniel

[Andre Noble]

(Three slot) plus polarizer ring is at least two slots too many for a W.A. lens. Take two slots out and try again.

[Eric Leppanen]

The Lee system can work with 4x5 wide-angle lenses if you use a 4x4" square polarizer rather than the 105mm round filter holder. For example, on my SA58XL and SS80XL lenses, I attach a Lee FK100 slip-on filter holder and FKD100/90 "doughnut" converter ring onto my Schneider #3b center filter (I always use the CF with these lenses) and I have no vignetting problems. The slip-on holder brings the filters closer to the lens, plus I configure the holder with only two 2mm slots (not a big deal for me, as I don't need a slot for the Lee hood when using WA lenses). However, I'm not sure if the slip-on holder is needed for a 90mm lens, maybe you can get by with a standard holder with wide angle adapter ring. You'd have to contact Lee to be sure.

The main drawbacks to using the square polarizer are: 1) the entire filter holder must rotate to orient the polarizer, therefore you cannot use a polarizer and ND grad filter simultaneously; 2) 4x4" square polarizers (available from Lee and Tiffen in 2mm thickness) are large and fairly expensive; 3) square polarizers are uncoated (not a big deal if you shade the lens properly and avoid shooting into the sun or other bright light source); and 4) in addition to the standard Lee holder, you also may have to purchase the slip-on holder depending on which wide-angle lenses you own.

The benefit of the Lee system is that, to my knowledge, it is the only reasonably priced, practical filter system that allows a single set of filters to be used over a complete range of LF lenses. I use a square polarizer, warming polarizer, and various ND grad, B&W and color conversion filters on lenses ranging from 58mm to 1200mm. Various Lee components also show up frequently on Ebay.

[Emmanuel BIGLER]

From Daniel G. :
...the sky darkened very much towards the margin, much more with pol than in normal view. I trust that has something to do with the wide collection angle of the lens, and the angular distribution of light of a particular orientation.



Daniel. A few ideas but it is difficult to understand everything without actually seing the scene and the picture. The angular distribution of polarised light in a blue sky is highly non uniform. The first idea that comes to mind is : with a narrower angle of view, say normal (53 degrees in diagonal) or less, the darkening effect may look uniform within the field. With a wide angle lens, the change of the darkening effect is more obvious across the field. A 90mm on 4"x5" will cover a maximum of ~80 degrees at the same time in diagonal.

The maximum polarising effet occurs for light rays scattered by a clear blue sky at 90 degrees from incident sun rays. In space, those rays simply form a plane attached to the camera and perpendicular to incident parallel (almost, with 1/2 degree..) sun rays, but the important additional, 'natural', and polarisation-independant darkening of the image in the corners (behind a wide angle lens used without centre filter), makes the final effect hard to predict in general "with hands".

A good example of the 90 degrees rule that you could easily experience some day, is the sky above the Mont Blanc as seen in summer in the afternoon from the middle of the Jura range. Sun will come from the West whereas the highest European mountain range will be seen in the direction of the South. So the contrast with a properly oriented polariser will be absolutely perfect in these conditions.
To do the same with the Eiger and Jungfrau you would probably need to go to the Black Forest ;-) but in both cases you'll probably favour a long focal length and not a wide angle ;-);-)

[Graeme Hird]

I'll say what Emmanuel didn't - don't use a polarising filter to darken the sky with a wide angle lens. It looks terrible.

[Diane Maher]

You don't necessarily need the circular opaque IR filters. Harrison and Harrison sells glass IR filters that are usable in the Lee filter holders, though you might need to get the 4 mm spacers as not all filters are made in the 2 mm sizes.

[John C Murphy]

Eric, does the 100mm to 90mm doughnut adapter work for the SS80XL? (I've been thinking about buying that lens myself.) The Schneider website lists the outer diameter as 70mm not 90mm.

[Eric Leppanen]

John, The doughnut adapter allows the FK100 slip-on holder to fit onto the SS80XL center filter (type 3b). which has an outside diameter of 90mm. The FK100 will not fit onto the SS80XL directly, for that you'd need the standard holder with a 67mm screw-on wide-angle adapter ring, although I've never tried this and can't say whether it would vignette or not (I'd suggest checking with John Adler of Lee). I use the CF with all of my SS80XL shots, so the slip-on holder and doughnut is all I've needed.