</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (tschmid @ Apr 10 2003, 03:17 AM)</td></tr><tr><td id='QUOTE'></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Ed Sukach @ Apr 9 2003, 10:50 PM)</td></tr><tr><td id='QUOTE'>A "Dichroic" filter is better described as a "heat glass", ... an Infrared filter for *really invisible* infrared radiation, otherwise known as "heat".</td></tr></table><span class='postcolor'>
A Dichroic Filter is based on light inference instead of dyes. This is the reason why the don&#39;t wear out (except from getting dirty). Whether a Dichroic Filter absorbs, reflects or passes IR light, depends on the characteristics/specifications of the filter. Not all Dichroic Filters cancel IR nor are all "hot mirrors". Even if they would be, the effect would be dependent on the amount of filtration dialed in.</td></tr></table><span class='postcolor'>
"Poco" described the filter in question to be "on the diffuser box", which would indicate to me that it had, in fact, a heat attenuation purpose. I don&#39;t infer any "adjustablilty" from the original post.

I&#39;ve checked the "Spectral sensitivity" information I have (I only have the data sheets from Agfa) and color paper does have a greater "range" than black and white. Agfa black and white papers drop off to *very little* after about 550 nm, a consideration for safelight use. With their color papers, Spectral and Color sensitivity of the cyan layer end at about 720 nm.

I think some of the confusion here may stem from the term "Infra Red" filter. The filters for use with IR film <on the camera> *PASS* IR and filter out everything else (yeh, I know - oversimplication), while IR filters in OPTICAL PATHS (sometimes referred to as "dichroic filters" or "heat glass, or "heat mirrors" are there to *REMOVE* Infra Red radiation.

I&#39;ve printed color for some time, now, and the idea of controlling IR for some effect or other has never ben a consideration. I&#39;ve never heard anyone critique one of my prints by saying "Needs more IR."