The 81C Filter from Heliopan controls the bluish coloration that affects daylight film. This is a strong salmon colored filter that can bring skin tones back to a respectable tone when the light changes during the day. It is especially useful under cloudy or open shade conditions since as the light changes, so does the color temperature. An 81C will decrease the color temperature by approximately 100 degrees Kelvin more than an 81B. 

It's Autumn. The clouds are low hanging and the sky is "patchy blue". You've gone for a ride upstate to the mountains and the light in open shade is bluish. A photo taken of your girlfriend with daylight balanced film leaning against the side of a barn will yield bluish tones that she might not find particularly flattering. If the sky is significantly cloudy, an 81C filter will bring her skin tones back to a more appealing level than, perhaps, an 81B. The cloudier the day, the warmer the filter you require to eliminate the blue tint often found on such days. An 81C can also be used with electronic flash to reduce the amount of "blue" generated by the flash. An 81C is a strong filter that can also be used to make a warm scene even warmer such as a beach shot where you wish to enhance the overall sense of temperature. 

The filter ring is made from brass yielding a stronger product. Brass filter rings are also less prone to jamming. In addition, the seal between the glass and filter ring is exceptionally strong giving the filter added strength and durability.  

The reputation of Schott glass is world renowned. The high production standards combined with a sturdy brass filter ring make this filter hard to beat. It has a "heft" that is impressive. It may feel heavier but the benefit is in the construction and results. Not only is the glass exceptional but so is the seal between the ring and glass. Schott Glass used in the manufacture of this filter is legendary and synonymous with the highest standards of filter production.

Warmer Than An 81B    Balances Out Skin Tones in Open Shade    Removes Bluish Tone From Strobes    Durable Brass Slimmer Filter Ring    Retains Front Threads    Standard Heliopan Hard Coating    High-Quality Schott Glass

Heliopan filters are "dyed in the mass" and ground, polished and coated to the highest standards of the German optical industry

Heliopan Lichtfilter-Technik of Munich, Germany, has changed their black anodized brass filter rings on most Heliopan non-rotating filters to their "slim" mounts. These slim mounts are made of black anodized brass stock and have so little rim in front of the lens (5.4mm) that they will not vignette with lenses as short as 21mm

Heliopan Lichtfilter-Technik of Munich, Germany has been a leader in the filter industry since 1949. They are known for their high quality and production standards. Their slim mounts facilitate using them with wider angle lenses. Heliopan offers most of their filters with either their standard hard coating or with their industry leading SH-PMC 16 layer multi-coating that transmits over 99.5% of the light striking it on to the image plane for the lowest flare and greatest color saturation

Related Questions and Answers

Q: 1. can you recommend a portable, easy/quick to setup softbox for this light?

A: You may find this being quiet easy to use and store https://www.bhphotovideo.com/c/product/1778107-REG/aputure_aps0005a3t_light_dome_mini_iii.html or https://www.bhphotovideo.com/c/product/1681502-REG/smallrig_3585_ra_d55_parabolic_softbox.html?sts=pi . You can, also,, search by quick release Softbox for Bowen-S mount.

Q: 2. Anyone used the EF version of this lens on a BMPCC 6K pro?

A: The Canon CN-E 30-105mm T2.8 L S Telephoto Cinema Zoom Lens with EF Mount is fully compatible with the Blackmagic Design Pocket Cinema Camera 6K Pro (Canon EF), BH #BL6KPKCAMP. We think it would be a great lens choice for run and gun work, or cinematic shooting.

Q: 3. Any thoughts for newborn photographyer on this led video light?

A: This light could be used if you want to use a continuous light for your work.

Q: 4. Does this lens support the DPAF focus guide as the CN-E Primes do?

A: Yes, the Canon CN-E 30-105mm T2.8 L S Telephoto Cinema Zoom Lens with EF Mount supports the Canon DPAF focus guide.

Q: 5. Will the light of this video light be too bright and cause overexposure?

A: The GVM SD300D is fully dimmable so you can control how bright it would be. Also, you can simply pull the light away from the subject to reduce the output as well.

Q: 6. What's the CRI rating about this led video lighting?

A: The following unit offers a CRI of 97.

Q: 7. Can this light be used to light an outdoor scene from 20 meters away?

A: The GVM SD300D Bi-Color LED Monolight is, 56,600 Lux at 3.3' w/ Reflector. 20 meters away is a lot and so the light will be pretty dim.

Q: 8. fan problem in this Led?

A: The fan does have some noise on in the GVM SD300D Bi-Color LED Video Spotlight. If the light is close up to the subject or the mic is close to the light it can be in some cases heard.

Q: 9. Do you guys carry the metric version?

A: we sell the metric version but it is a special order item

Q: 10. Will this fit the Godox v860ll

A: Unfortunately, this product is not compatible with the Godox V860 II.