Front Thread Size on B+W's Extra Wide Series Filters?

[Andre Noble]

Does anyone know what would be the front filter thread size on the 67mm B+W Kaes emann Circular Polarizer Extra-Wide Glass Filter?

This is a very specific question for which a search of the manufacturer's brochu re and the internet provided no clue, so I reluctantly ask it here. Hopefully s omeone knowledgeable can also turn the answer into a genral response on how much larger the front thread is than the rear thread on this particular type of filt er from B+W - meaning the "extra-wide" variety in which the glass and front thre ad is larger than the thread which attaches to the lens (in order to avoid mecha nical vignetting on wide angle lenses).

Thanks alot for your help. Andre

[Michael S. Briggs]

The retailer "The Filter Connection" has this information on their website: http://www.2filter.com/prices/products/bwsizepola.html. The row "67EW" indicates that the front thread is 86 mm.

They also have a table for regular filters, http://www.2filter.com/prices/products/bwregsizes.html, but it is missing the front thread sizes for EW filters. One could try guessing a few mm smaller than the value given for the Mount O.D.

[Andre Noble]

Micheal, excellent help. I checked that site earlier but somehow not well enough. Thanks again. Andre

[Jorge Gasteazoro]

I don't get it though, you are going from 67 mm to 86 mm in the space of the glass thickness? this does not sound right to me, the difference is more than half an inch, it sounds excessive to me. I would check with schnider I am sure the US distribuitor has an 800 number you can call....good luck.

[Bob Salomon]

WA filters are essentially step up rings with a filter in them.

So a 67 to 86mm WA filter has a 67mm male thread in back and an 86mm female thread in front and an 86mm diameter glass in the ring. It is not a piece of glass that steps from 67 to 86mm.

Since these are usually special order and perhaps more expensive then regular filters we, as the Heliopan supplier, normally suggest using a Heliopan brass step up ring (it is very thin) from the len's filter size to a standard size 2 to 3 sizes larger (depending on how wide the lens is) and then using a regular Heliopan filter (a UV, color correction, B&W filters from Heliopan are only in slim mounts today) ar using a slim pol.

This way you are using filters that are not special order, perform the same purpose and are not more expensive. theyu are also quickly available (although the step up ring may require a special order.

[Jorge Gasteazoro]

now see, Bob's solution makes more sense to me. THanks Bob for the explanation.

[Bob Salomon]

Unfortunately we don't have a 67 to 86mm in stock but I did find a 67 to 82mm ring to measure.

The portion of the ring that extends beyond the threads of the lens on this ring is 5.54mm thick. A Kaesmann type polarizer is the thickest type.

[Andre Noble]

Bob, your solution sounds reasonable, and that's what I ended up doing: just ordering a $40 Hoya 77mm linear polarizer for my B+W 67- 77 step up ring, which I am already employing.

However, if it's built anything like the smaller Nikon wide angle version polarizers, the B+W Kaesmann extra wide (at $210 US)looked like a much better, albeit more expensive solution to completely avoid mechanical vignetting with the the Nikkor 90/8 or the Nikkor 75/5.6 lenses. Andre