View Full Version : Proprietary warming filters

John C Murphy
1-Apr-2005, 07:44
I am wondering what the components of some of my warming filters are. I use a Lee 81 + CC05 red combo and the B+W KR 1.5 a lot with Velvia and though I know the difference in their effects, I still wonder what is actually "in" the KR1.5? Also, what about the KR3 and the Tiffen 812?

Bob Salomon
1-Apr-2005, 08:12
What do you mean by "in"?

A KR or a KB filter is either a warming filter (KR) series or a cooling filter (KB) calibrated according to the decamired system. KR or KB filters are additive so a KR 1.5 and a KR 3 become a KR4,5.

KR 1.5, 3 and 6 are also called skylight filters. The higher the number the stronger the effect.

Light has a mired value as does film. Subtract one from the other and the answer will indicate which KR or KB filter is required to correct the film for that lighting condition.

Nothing is "in" the KR or KB filter. They are solid glass and the strength is determined by hoe thick or thin they are ground by the manufacturer. All KR filters are the same color. The differences between them are due to their thickness. The only exception to this would be a filter that is a sandwiched gel or colored glue.

Donald Hutton
1-Apr-2005, 08:18

You should be able to "measure" any filter's corrective effects using a color meter - you'll get an exact number for temperature and color and can then make up a "generic" using your Lee system.

The KR1.5 warms by 15 Mired or about 150K - so it's exactly midway between an 81A and an 81B.

John C Murphy
1-Apr-2005, 08:29
I guess what I'm trying ask is this: what would be the Lee equivalent of the KR 1.5? When I use a polarizer on a wide angle lens I can't afford to put another screw-in filter on without risking vignetting, so I usually use a screw-in polarizer with the color correction filter in the Lee filter holder in front of the polarizer. I know this is not the "correct" way to do it, but Heliopan doesn't make a 105mm polarizer that will fit on the front of the Lee system.

Donald Hutton
1-Apr-2005, 08:41
Sorry - I made an error in my previous post - the 150K is exactly in between an 81 and an 81A - so you do not have an exact substitute. However, I doubt you will ever notice the difference if you use an 81A (it's only 50K warmer than the KR1.5). You can get an adaptor ring and a B&W 105mm polarizer which, with another foundation set, allows you to use all sorts of iterations of filters with your Lee system. Personally, for wide angle use, I bought the square linear polarizer and can use this with another filter without vignetting on any of my wide lenses. It does have a limitation in that it cannot be used with a ND Grad (the polarizer needs to be rotated, so the "line" of the grad is pretty much guaranteed to be in the wrong position). The 105mm polarizer and adaptor ring set-up works well for most things, but does vignette on wide angle lenses.

John C Murphy
1-Apr-2005, 08:47
Don, Really? so even the 105mm ring doesn't prevent vignetting?

Donald Hutton
1-Apr-2005, 09:04
If you need movements with wide angle lenses, you will have a problem. In theory, the 105mm ring should help, but the reality is that it adds the equivalent on a few extra filter slots onto the front of the foundation kit. I returned it because it didn't solve my problem. If you only shoot landscapes, it may be a feasible solution as movements are likely to be much more limited.

Bob Salomon
1-Apr-2005, 09:18

Heliopan makes linear, circuar, linear SH-PMC, circular SH-PMC, circular slim SH-PMC, linear Kasemann, circular Kasemann, linear warmtone Kasemann and circular warmtone Kasemann all with 105mm x 1 thread. That is the satandard 105mm thread for lenses. Whay won't these fit the 105 thread of a Lee holder?

A KR 1.5 makes a 15 point shift in mired value and a 200K shift in K temperature. A 81A makes a 20 point shift in mired value and a 200K shift in K. An 81B makes a 27 point shift in mired and a 300K shift in K. A KR 3 makes a 30 point shift in mired and a 400K shift in Kelvin temperature.

All of the mired and K changes for the KR 1.5 to KR 15 and for 81 A. B. C are found on page 14 of the Heliopan brochure and Pg 15 has the shifts for KB 1.5 to KB20.

These brochures are free for the asking in English as long as you supply a mailing address.

In German they are available on line at:
http://www.heliopan.de/start1.html for warming filters
and at:
http://www.heliopan.de/start1.html for cooling filters.

Both the brochure and the German site also has the transmission curves for these filters.

Donald Hutton
1-Apr-2005, 09:47

How can a 15 point shift in mired value translate to 200K - surely that is a simple rounding adjustment, the Heliopan brochure is wrong, or am I completely in the dark on the relationship between mired values and Kelvin.

As I understand it, the MI-cro RE-cirpocal D-egree value for a specific colour temperature is arrived at by multiplying the inverse of the value in Kelvin by 1,000,000. Usually expressed in tens, hence deca-Mired (dM). If this is so, a 15 point shift in mired value is a 150K shift and the exact filter is not available in the Lee system as they manufacture only an 81 and an 81A (which provide 100K and 200K respectively of shift).

The Heliopan polarizers can be used on the Lee system - same problem - albeit slightly less if the slightly thinner "slim model" is used - the adaptor ring added to the thickness of the polarizer add a substantial thickness out in front of the foundation kit which causes vignetting when movements are used with wide angle lenses.

John C Murphy
1-Apr-2005, 10:03
Bob, I stand corrected.
Don, when you say the adapter ring for the polarizer causes vignetting, is that with it on top of 2 filter holder slots? I notice that my wide angle lens only vignettes when all 3 of the filter holder slots on the foundation kit are in place.

Donald Hutton
1-Apr-2005, 10:24
That's on top of two slots, but I am certain you will still be limited with one slot.