Polarizer, grads on wide-anglegreenspun.com : LUSENET : Large format photography : One Thread
This is about using filters on a 90 and 110 lens in 5x7. Both of them have a filter thread of 67mm and a coverage angle of 105 deg. 1. Will a wide-angle polarizer (which has a 77mm front element, kind of a built-in step up ring) vignette less than a slim polarizer (no threads) ? 2. If I use a wide-angle polarizer, will the Lee holder vignette if stacked on top of it with the 77 wa ring, and used only with one more filter ? 3. I assumed that stacking two Lee holders (one for a grad, the other for the Lee polarizer) would vignette. I am correct ?
-- Q.-Tuan Luong (email@example.com), October 10, 2000
Regarding stacking two Lee holders...
I can only give you some data which might suggest what might work w/ 2 Lee holders connected with a tandem adapter. I took a 110 lens w/ 67mm Lee WA adapter and stacked a standard Lee holder on top of a Lee FK100 holder (I don't have two standard Lee holders) held together w/ tape. I then rotated the holders to an angle to simulate the worst vignetting situation. I set my camera (a 4x5) in landscape format with 26mm of shift and 13mm of rise (to simulate the corner of a 5x7) and viewed the iris through the cut-out corners. At f=45, I could still see a bit of the filter holder. If the holder is rotated to a less interfering angle, it could disappear at f=16. There might be a slight change that 2 Lee holders will do the job. Can't speak to the 90mm situation, but I wouldn't count on it working. In my mind, your question points out one of the significant problems with all of the filter holders I know of on the market. It's not easy to rotate two filters independently. Hope this helps.
-- Larry Huppert (Larry.Huppert@mail.com), October 10, 2000.
I use a Nikkor 20mm lens and a 52mm Minolta Polarizing filter of the type you've described - kind of a built in step up ring.
There is no sign of vignetting at all (albeit it's only 94 degrees) when I use this lens and filter combination. I would expect LOTS of vignetting if I tried to add a Lee or (in my case) a Coking filter in front of the polarizing filter.
Interestingly (or maybe not) there is no filter thread on the outside of this filter, so you couldn't stack conventional filters. And that may well be Minolta's way of saying, "We aren't even going to let you TRY to get this filter to vignette!"
-- David Grandy (firstname.lastname@example.org), October 10, 2000.
Q- try the combination on a paper negative. Won't cost much money or time to find out. James
-- james (email@example.com), October 10, 2000.
James: if I had all the gear at hand, I'd just look through the corner of my ground glass. I'll need to mail-order the stuff.
-- Q.-Tuan Luong (firstname.lastname@example.org), October 11, 2000.
I have taken a somewhat different approach. I keep a 77mm step up ring on my 110, as well as all my other lenses, and base all my filtration on that size. I have no problem with either polarizing filters (standard B&W Kasserman) or Lee system. The step up adapter keeps the glass filters away from the front element of the 110 and allows me to standardize, thus limit, the filters that I carry.
-- D. Benson (email@example.com), October 12, 2000.