Alternative Center Filters for Rodenstock 75/4.5 Grandagon N?

[acapela]

I came into a used Rodenstock 75/4.5 Grandagon N recently, but am without a "dedicated" center filter.

I can watch eBay for the original Rodenstock center filter (a 1.5-stop/3x in a 67-86mm size). But in the meantime (none appear to be listed at the moment), what might those with actual user experience recommend as a substitute?

I have Schneider 3b center filters already, for my 47/5.6 Super Angulon XL and 80/5.6 Super Symmar XL lenses. The 3b is a 1.5-stop/3x 67-86mm filter, so would be mechanically compatible and hopefully at least somewhat optically compatible as well.

I also have a source for new/old stock for Schneider "plain 3" (i.e. "III") filters, originally for use with the 65/5.6 and 75/5.6 Super Angulon, though I would have to buy one even just to test with it. Finally, I also see a Schneider "IIIa" filter for auction currently on eBay. I can't find any documentation on a 3a anywhere, but photos in the listing clearly show "IIIa" on the filter mount. I am assuming this actually a "plain 3/III", bearing a relatively recent cosmetic change in designation when additional variants of 67-86mm center filter ("IIIb/c/etc", for other Schneider lenses) reached the market.

Any actual user testimonials/advice would be welcome. In the meantime, my simplest option is to start with the 3b filter I actually have in hand and see if that is "good enough", even illumination, free of banding, etc.

Thanks.

[Oren Grad]

I would try the IIIb that you already have. In my occasional experience of center-filter-shopping, Rodenstock center filters have been much harder to find than Schneiders.

See also this thread:

http://www.largeformatphotography.in...IIb-difference

[Bob Salomon]

The Heliopan is virtually identical to the Rodenstock.

[acapela]

See also this thread:

http://www.largeformatphotography.in...IIb-difference

Aha, confirmation of the existence of the "IIIa", interesting. Sounds as if the IIIa is for "older" lenses, rather than the more recent XL/wide-field lenses.

Thanks!

[Steve Goldstein]

I have copies of Schneider's 1977 and 1984 center filter brochures, both of which contain the III and IIIa. The III is listed for the f/5.6 65mm and 75mm Super Angulons, as acapela has stated, while the IIIa is for the 90mm f/8 SA. They are mechanically the same (67mm male, 86mm female) and both are stated as 3x. I assume there's a difference in the filter pattern between the two, but the documents don't give any clues aside from the different stock numbers.

The IIIa doesn't appear in the 2007 specs. The IIIb is added, with applications for the 58mm SAXL, 80mm and 110mm SSXL, in addition to the 90mm f/8 SA. There's also a IIIc for the 47mm SAXL, though a footnote says the IIIb is also usable with that lens. Again, Schneider provides no information as to any differences between the III/IIIa/IIIb/IIIc.

Here's a link to some info on Rodenstock's filters: http://www.prograf.ru/rodenstock/acc...n.html#filters
Unlike Schneider, they don't provide part numbers so it's impossible to know if the various 67/86 3x filters are specific to individual focal lengths or if they're "one size fits all". Bob may know as he was the Rodenstock rep for many years.

I agree with Oren - give your IIIb a go. Remember that the lens should be closed down at least two stops from wide open per Schneider's instructions.

If you drop me a PM or email with your email address I'll be happy to send you all five Schneider PDFs I've acquired over the years.

[Bob Salomon]

I have copies of Schneider's 1977 and 1984 center filter brochures, both of which contain the III and IIIa. The III is listed for the f/5.6 65mm and 75mm Super Angulons, as acapela has stated, while the IIIa is for the 90mm f/8 SA. They are mechanically the same (67mm male, 86mm female) and both are stated as 3x. I assume there's a difference in the filter pattern between the two, but the documents don't give any clues.

The IIIa doesn't appear in the 2007 specs. The IIIb is added, with applications for the 58mm SAXL, 80SSXL, and 110SSXL in addition to the 90mm f/8 SA. There's also a IIIc for the 47mm SAXL, though a footnote says the IIIb is also usable with that lens. Again, Schneider provides no information as to any differences between the IIIa/IIIb/IIIc.

Here's a link to some info on Rodenstock's filters; http://www.prograf.ru/rodenstock/acc...n.html#filters
Unlike Schneider, they don't provide part numbers so it's impossible to know if the various 67/86 3x filters are specific to individual focal lengths or if they're "one size fits all".

I agree with Oren - give your IIIb a try. Remember that the lens should be closed down at least two stops from wide open per Schneider's orders.

If you drop me a PM or email with your email address I'll be happy to send you all five Schneider PDFs I've acquired over the years.

Of course the Rodenstock 3x center filter is correct for that lens. The Apo Grandagon series required a different center filter.
Rodenstock listed the part numbers in their price list and we listed the catalog numbers in our literature and press releases. Don’t know what the Russian distributor did. Don’t even know if they used Rodenstock numbers or their own.
Also note that Rodenstock offered two different 67mm center filter for their analog lenses, not one as per the site you suggested. Also, this statement in their center filter description is completely wrong!

“....Rodenstock center filters are neutral gray concentric graduated filters whose density decreases from the center up to the translucent rim.”

They do not have a translucent rim, the filter goes from maximum density in the center to transparent at the edge. The rim is metal and translucent is not transparent!

[Oren Grad]

The IIIa doesn't appear in the 2007 specs. The IIIb is added, with applications for the 58mm SAXL, 80mm and 110mm SSXL, in addition to the 90mm f/8 SA. There's also a IIIc for the 47mm SAXL, though a footnote says the IIIb is also usable with that lens. Again, Schneider provides no information as to any differences between the III/IIIa/IIIb/IIIc.

FWIW, in my later documentation, the IIIb is specified as 3x and the IIIc as 4x. The latter is preferred if full correction is required for the 47 XL, but of course not every application requires that.

[Steve Goldstein]

Right you are, Oren, I missed that in the 2007 document. The IIIc is given as 4x.

[Dan Fromm]

Folks, this site has resources. This one http://www.largeformatphotography.in...mainly)-lenses has a link to a list of links that includes one to an article on center filters that lays out equivalences.

[Oren Grad]

I plead guilty to not remembering everything that's in Dan's very extensive, extraordinarily useful list. Here is a direct link to his center-filter article...

http://www.galerie-photo.com/center-...at-lenses.html

...but I encourage anyone who hasn't seen Dan's resource to follow his link to the sticky thread at the top of this (Lenses) subforum and check it out.