A 138mm Light Yellow #6 Filter from Tiffen is used for a slight increase in contrast with black and white films. Although not as strong as a traditional Yellow #8, it can still be used to make a difference in your photography. You'll find it boosts your contrast just enough to make the difference between a black and white print flat appears "flat" and one that displays the proper correction.
Tiffen's ColorCore glass is produced through a process that entails permanently laminating the filter material in between two pieces of optical glass that are ground flat to tolerances of a ten-thousandth of an inch, then mounting them in precision aluminum rings.
Especially useful for added contrast between blue sky with clouds and foreground
Tiffen's ColorCore glass is sealed between two optical glass sheets. In this way, Tiffen can better control the various densities of their filters and thereby create more exact degrees of filtration. This process makes for greater accuracy of color as opposed to glass that is simply dyed and become subject to deviation during the dye process
Tiffen, a leader in the filter industry, proudly makes its filters in the USA and backs up its products with a solid 10-year warranty