Square Filters for Hasselblad Proshade

I am getting a Hasselblad Proshade and I am aware it takes square 100x100mm filters, but who makes them?
I already have a good set of Hoya MC 67mm threaded filters, but since I will be also getting a CFi 4/50 Distagon which has a Bay70 filter mount, I want to buy a line of filters I can exchange between my Bay60 and 70 lenses.

Kodak gel filters are still available in 4" (100mm) square, along with Tiffen (polyester, I believe) and a couple of others from most large retailers (e.g. Calumet). You'll also find them on eBay, if you want to buy used.

On more afterthought, Ari. As you likely know, the #6093 ProShade attaches via the bayonet mount at the front of the lens (or lens-mounted filter). The rear portion of the shade swings open for insertion of the gel filters. Once open, the conical-shaped lens-mounting plate can also be changed to fit different sized bayonet mounts. But, I'm not sure that's something I'd want to do in the field, as there are tiny, Phillips-head screws that must be loosened to switch mounting plates. Lose one of those screws, and you'd be, well . . . screwed.

The alternative is to have the Bay-70 mounting plate on the ProShade, and use a Bay 60-70 step up ring to attach the shade to your Bay 60 lenses.

BTW, you can make the little cardboard filter holders yourself from heavy craft paper or file-folder material. Much less expensive than buying the pre-made Hasselblad holders.

I was facing the same issue sometime ago and after exploring almost all makers and retailers, I choosed SLF (South London Filters at www.camerafilters.co.uk) because they are able to provide any brand in any dimension and thickness (including of course 100 x 100 mm) and in any material (gels, resin, glass, etc.). Their price is normal and delivery and service excellent. I think that you made a good decision to turn to the Proshade and square filters. I really enjoy just having the same standard for all my filters. Good hunting!

You may use an accessory adapter 60 or an accessory adapter 70 that attaches to the lens. Buying Kodak wratten four inch filters will work on all Hasselblad lenses. The 3 inch which you can still purchase will work on lenses 60mm and up. You can also use up to two glass filters on the lens in addition to your Wrattens in the pro-shade. You can use up to 5 filters in the shade as the Hasselblad package comes with 5 but it is recommended to use one, and empty holder, then another filter. A very good read on the use of this shade starts on page 210 in the "Hasselblad Manual" by Ernst Wildi, 4th edition. I would highly recommend it. I also recommend you purchase an Open L-connector to facilitate the use of a shutter release.
Barney

Thank you guys.
I am getting all sorts of new toys and the filters has been the hardest thing to figure out. I have the Wildi book, fifth edition but it doesn't give that much information I can use.