Rough equivalents to Wratten 44a?

[senderoaburrido]

I'm looking for a rough equivalent for the Wratten 44a; a minus-red filter. Ideally it would have a very similar transmission cutoff, around 575nm. My wratten 44a filter tore recently, and it looks like it'll be expensive to replace. These little gelatins are way too fragile. It'd be nice to get a more durable replacement.

I've been using it to meter for my EB/RA x-ray film, so that I don't get wildly different results in different lighting conditions. So far it has really helped me out quite a bit. The sensitivity of EB/RA ends at almost exactly the same wavelength as transmission for the 44a.

[Eric Woodbury]

S, I'm not familiar with that filter, but I've been using thin polyester filters (similar to gels). These are available from Lee or Rosco in 4x4" (100mm) squares. Even these seem a bit pricey, so now I buy 24" lighting filters that are the same matter as the poly filters and cut out a nice clean section for my needs. These giant filters are about $5 at Samys Camera. A while back I needed a very special glass filter. I called somebody in Burbank, don't remember whom. I bought a 4x4" dichroic glass filter for $50. I could have had it any size as they cut it from a blank and only charged by area delivered.

[senderoaburrido]

S, I'm not familiar with that filter, but I've been using thin polyester filters (similar to gels). These are available from Lee or Rosco in 4x4" (100mm) squares. Even these seem a bit pricey, so now I buy 24" lighting filters that are the same matter as the poly filters and cut out a nice clean section for my needs. These giant filters are about $5 at Samys Camera. A while back I needed a very special glass filter. I called somebody in Burbank, don't remember whom. I bought a 4x4" dichroic glass filter for $50. I could have had it any size as they cut it from a blank and only charged by area delivered.

Wratten 44a is an old Kodak filter. Here's the transmission data: http://www.karmalimbo.com/aro/pics/filters/transmision%20of%20wratten%20filters.pdf and a graph can be found here: http://www.newportglass.com/kodak/kod44A.gif

[Doremus Scudder]

I carry an 80a filter and use it in place of the Wratten 44/44a to achieve an orthochromatic effect on panchromatic black-and-white film. It approximates the effect of the 44 filters nicely.

Here's a transmission spectrum graph so you can compare.

161319

Best,

Doremus

[russyoung]

Thanks, DS, that was very illuminating to see them all on one graph.
Russ

[senderoaburrido]

I carry an 80a filter and use it in place of the Wratten 44/44a to achieve an orthochromatic effect on panchromatic black-and-white film. It approximates the effect of the 44 filters nicely.

Here's a transmission spectrum graph so you can compare.

161319

Best,

Doremus

Does the 80a come in glass?

[Doremus Scudder]

Does the 80a come in glass?

Sure, they are (were) a very common color-correction filter for adapting daylight film to 2800K (and lower) tungsten light sources. Look for Hoya HMC filters or the equivalent B+W or Heliopan filter, designated KB 15.

Just FYI: there were several blue conversion filters in the 82 and 80 series. The 82A (B) and C filters were for adapting color film balanced for 3200K light sources to other tungsten sources. The 80A, B and C filters were designed to adapt daylight film to tungsten sources of various color temperatures. Common were photofloods, with a color temp. of 3400K, floodlights with a 3200K color temp and conventional tungsten bulbs with a temp of 2800k or lower. The 80A is usually the strongest of the series, but B+W offers a KB20 that attenuates even more red and is supposed to correct to 2700K.

Best,

Doremus