Hi, Bought a great Schneider Symmar 6.8/360 used for my Toyo Field 8x10 lately. This is a very large LF lens undeed - 112 MM filter screw mount.

B&W Filters told me they do not make filters for b&W photography that size. Does anybody know about the new Cokin X-Pro system? Or is the toyo compendium with glass filters a better choice? If so, what filters are on the market?

Thanks, Erich

-- Decker, Erich C. (fotair@eurogay.net), April 22, 2000

Answers

Can you use a rear filter system attachment on this lens? You might check the rear diameter and see if it is small/reasonable enough for use with the rear filter holder marketed by Calumet and others?

-- Bob Moulton (bobmargaretm@home.com), April 22, 2000.

One option is to mount the filter on the rear. The OD of the rear cell is 90mm, I believe. You should be able to find a series 9 slip on filter adapter. Series 9 filters for black & white are available, although not as many types. You should be able to get 8, 11, 16 and 25 and of course, a polarizer.

-- Robert A. Zeichner (razeichner@ameritech.net), April 22, 2000.

Heliopan makes 112 filters including polarizers so the filters will add protection to the lens, have no focus shift and be simple to add or adjust. Unlike rear filters that affect focus, resolution add no protection and are difficult and cumbersome to add, replace or adjust.

-- Bob Salomon (bobsalomon@mindspring.com), April 22, 2000.

Heliopan makes 112mm filters including polarizers so the filters will add protection to the lens, have no focus shift and be simple to add or adjust. Unlike rear filters that affect focus, resolution add no protection and are difficult and cumbersome to add, replace or adjust.

-- Bob Salomon (bobsalomon@mindspring.com), April 22, 2000.

The Cokin X-pro filter holder will fit a lens with max. 122 mm external diameter. It is attached on the lens with four screws. I'ts great for graduated filters because you can adjust the position of the filter. The filter sizes for this holder are 130x170 mm. Personally I prefer the screw in models for other filters because they take less space, but one benefit with the Cokin is that you can use it on many different sized lenses.

-- Jan Eerala (jan.eerala@itameri.net), April 23, 2000.

I think the manufacturer is Xenophon for a rear lens filter mount. They are sold in the Calumet catalogue and work really well. Kodak wrattens (4" squares) should fit over the rear mount. With the filter holder comes with filter frames to make the wratten more rigid. Cheers, Scott

-- Scott Walton (scotlynn@shore.net), April 23, 2000.

Actually, B+W does make 112m filters. We usually don't keep them in stock, so we would probably have to special order them, but they are possible to get. LEt me know what you're looking for and I'll check stock.

-- Michael Klayman (michael@schneideroptics.com), April 24, 2000.

Erich, check out the B$H web site for Cokin X-series filter system. It's summarized well.

-- Masayoshi Hayashi (mhayashi@phys.ufl.edu), April 24, 2000.

hi, are you sure your Schneider Symmar 6.8/360 is 112mm? My Schneider Symmar-S 6.8/360 is 120mm. i have no idea about any filter can fit this lens(120mm)

-- jeff liao (jliao66@aol.com), April 24, 2000.

"hi, are you sure your Schneider Symmar 6.8/360 is 112mm? My Schneider Symmar-S 6.8/360 is 120mm. i have no idea about any filter can fit this lens(120mm) "

heliopan makes even larger filters then this

-- Bob Salomon (bobsalomon@mindspring.com), April 24, 2000.

I use the Xenophone rear mounting system on my Arca-Swiss. I have a front adapter for smaller lensboards, so I've mounted the Xenophone for 4" filters onto the adaptor. This simple system, plus a few 4" Wratten filters, meets all my filtration needs for all my lenses from 90mm to 355mm.

I ran into one problem, though. The Xenophone finish isn't a perfect flat black, and I experienced some reflection onto the film for the 90mm only. As a remedy, I glued some cut-to-fit black felt onto the back portion of the Xenophone. Also, an Arca-Swiss 4x5 has an over-sized bellows. I don't think this system would work for smaller cameras like Wistas, Toyo's, etc.

Let me add my own comments on rear filtration. There can be three effects: image degradation, possible flare, and a focus shift. According to Schneider, degradation will be the same, regardless of whether the filter is front or rear-mounted, and flare can actually be greater for front-mounted filters. Focus shift can be corrected by adjusting focus with the filter in place. In any event, focus-shift is about 1/3rd the thickness of the filter, which is minimal for a gel. Although I've never seen a difference, both AA and Wisner claim that gels are optically superior to glass filters. While I would be reluctant to rear-mount a glass filter, I see no problem with gels.

-- neil poulsen (neil.fg@worldnet.att.net), April 25, 2000.

"According to Schneider, degradation will be the same, regardless of whether the filter is front or rear-mounted, and flare can actually be greater for front-mounted filters."

This is a misleading comment.

A pristine filter will have the same effect in front or behind the lens.

A filter with dust, dirt,smudges, fingerprints, etc. will have more of a detrimental effect behind the lens

-- Bob Salomon (bobsalomon@mindspring.com), April 25, 2000.