The 86mm (Coarse Thread) Decamired Blue 1.5 Cooling Filter from Tiffen is for those who want a sure-fire way of getting accurate color temperature readings. Using this formula, you can transpose temperatures from one point to another easily and quickly. This system is also useful when you wish to bring a certain amount of creativity to color photography.

Decamired filters are used to maintain consistent color temperature during the day's shooting. Decamired filters are available in two series - reddish filters that warm the light and bluish filters that cool the light with each series available in four densities: 1.5, 3, 6, and 12. When filters from the same series are used, they can be combined.

Decamired filters can be readily combined to create almost any required color correction. In measuring the color temperature of the light source, and comparing it to that for which the film was designed, required filtration can be easily calculated.

A filter that produces a color temperature change of 100K at 3400K will produce a change of 1000K at 10,000K. This is because the filter relates to a visual scale of color. It will always produce the same visible difference. A color change of 100K at the higher temperature would hardly be noticed.

Calculations
To use this concept, subtract the mired value of the light source from that of the film. If the answer is positive, you need a reddish filter; if negative, use a bluish filter. Mired-coordinated filters are termed as decamireds. Mired value divided by ten yields decamireds. The 60 mired shifts, above, would be produced by an R6 filter, where the higher values were that of the lighting.

Sets of such filters generally come in values of 1.5, 3, 6, and 12 decamireds in both B (bluish) and R (reddish) colors. These numbers are additive; that is, a pair of R3's produces an R6. An R6 plus a B6 cancel each other out to produce a neutral gray.

Used for Accurate Temperature Control    Filters Can Be Combined to Control Color    Made in Specific Increments    Available in Warming and Cooling Variety    ColorCore Glass    Made in the USA    10-Year Warranty

The decamired system has an advantage over the Kelvin system in that the Kelvin scale is not linear

Decamired readings provide more accurate/controllable readings than Kelvin

The difference between the Mired value of the film and the Mired value of the light is the Mired value of the correction filter that correctly balances the light to the film

Related Questions and Answers

Q: 1. Does this records metadata of the image if I use it in Leica M10?

A: You will get metadata just not from the lens. It is fully manual.

Q: 2. Will this fit an M4P?

A: Yes, this is an M-mount lens so it will fit a Leica M4P.

Q: 3. Initially, when the c-Sonnars were first issued about 10 or so years ago, I beleive Zeiss calibrated the optimal focus to 2.8. Later they could be ordered optimized at f/1.5. In the past few years I've read optimum focus is set at f/2. What is the optimum focus on this particular production series? Thanks.

A: The ZEISS C Sonnar 1.5/50 ZM is currently optimized for focus at f/2.0.

Q: 4. Weather sealing for light rain or dust?

A: Unfortunately, the ZEISS C Sonnar T* 50mm f/1.5 ZM Lens (Silver) is not weather sealed for light rain or dust.

Q: 5. Hey guys, is this full frame ? Thanks.

A: Yes

Q: 6. does this lens have the ability to show the framing in the viewfinder?

A: Yes this does show the framing and has proper rangefinder focusing with this lens on the Leica M.

Q: 7. Does this lens work with the Leica M (digital body)?

A: Yes. This is an M mount lens.

Q: 8. Can B&H arrange for the recalibration of the focus to wide open at 1.5?

A: Not that I know of. You need to contact Zeiss directly.

Q: 9. Is there an adapter for the Sony a7r3 for this lens?

A: There are adapters to adapt Leica M-Mount lenses like the Voigtlander Nokton 75mm f/1.5 Aspherical Lens (Black) to the Sony FE-Mount used on the Sony Alpha a7R III. Voigtlander makes the Voigtlander Adapter for Sony E Mount Cameras--VM Mount Lens (Black) linked here. https://bhpho.to/3mescB5. And you can see all the applicable adapters we carry linked here. https://bhpho.to/3mfXZS4

Q: 10. Interested in ordering this Lense to mount on Canon EF mount?

A: I'm sorry there are no adapters that exist to mount Leica M to Canon EF body.